Double-blind, placebo-controlled, dose-finding study of rizatriptan (MK-462) in the acute treatment of migraine

Comparison between metamizole and triptans for migraine treatment: a systematic review and network meta-analysis

Objective The aim of this systematic review was to evaluate the efficacy of metamizole and triptans for the treatment of migraine. MethodsRandomized controlled trials including people who received metamizole or triptan by multiple routes of administration and at all doses as treatment compared to subjects who received another treatment or placebo were included in the systematic review. The primary outcomes were freedom from pain at 2 hours; pain relief at 2 hours; sustained headache response at 24 hours; sustained freedom from pain at 24 hours. The statistical analysis of all interventions of interest were based on random effect models compared through a network meta-analysis. Results 209 studies meeting the inclusion and exclusion criteria were analyzed. Of these, 130 had data that could be analyzed statistically. Only 3.0% provided enough information and were judged to have a low overall risk of bias for all categories evaluated; approximately 50% of the studies presented a low risk of selection bias. More than 75% of the studies presented a low risk of performance bias, and around 75% showed a low risk of detection and attrition bias. ConclusionThere is no evidence of a difference between dipyrone and any triptan for pain freedom after 2 hours of medication. Our study suggests that metamizole may be equally effective as triptans in acute migraine treatment.

Intranasal Eutectic Powder of Zolmitriptan with Enhanced Bioavailability in the Rat Brain

Intranasal administration can potentially deliver drugs to the brain because of the proximity of the delivery site to the olfactory lobe. We prepared triturates of micronized or crystalline zolmitriptan with a GRAS substance, nicotinamide, to form a eutectic. We characterized the formulation using differential scanning calorimetry, powder X-ray diffraction, and FTIR spectroscopy to confirm its eutectic nature and generated a phase diagram. The eutectic formulation was aerosolized using an in-house insufflator into the nares of rats. Groups of rats received zolmitriptan intravenously or intranasally, or intranasal eutectic formulation. Zolmitriptan was estimated in the olfactory lobe, cerebral cortex, cerebellum, and blood plasma at different time-points by LC-MS. Pharmacokinetics in these tissues indicated the superiority of the intranasal eutectic formulation for brain targeting when compared with results of IV solution and intranasal pure zolmitriptan powder. Enhancement of nose-to-brain transport is likely to have resulted from more rapid dissolution of the eutectic as compared to pure drug.

Comparative tolerability of treatments for acute migraine: A network meta-analysis

Introduction

Migraine headache is a neurological disorder whose attacks are associated with nausea, vomiting, photophobia and phonophobia. Treatments for migraine aim to either prevent attacks before they have started or relieve attacks (abort) after onset of symptoms and range from complementary therapies to pharmacological interventions. A number of treatment-related adverse events such as somnolence, fatigue, and chest discomfort have previously been reported in association with triptans. The comparative tolerability of available agents for the abortive treatment of migraine attacks has not yet been systematically reviewed and quantified.

Methods

We performed a systematic literature review and Bayesian network meta-analysis for comparative tolerability of treatments for migraine. The literature search targeted all randomized controlled trials evaluating oral abortive treatments for acute migraine over a range of available doses in adults. The primary outcomes of interest were any adverse event, treatment-related adverse events, and serious adverse events. Secondary outcomes were fatigue, dizziness, chest discomfort, somnolence, nausea, and vomiting.

Results

Our search yielded 141 trials covering 15 distinct treatments. Of the triptans, sumatriptan, eletriptan, rizatriptan, zolmitriptan, and the combination treatment of sumatriptan and naproxen were associated with a statistically significant increase in odds of any adverse event or a treatment-related adverse event occurring compared with placebo. Of the non-triptans, only acetaminophen was associated with a statistically significant increase in odds of an adverse event occurring when compared with placebo. Overall, triptans were not associated with increased odds of serious adverse events occurring and the same was the case for non-triptans. For the secondary outcomes, with the exception of vomiting, all triptans except for almotriptan and frovatriptan were significantly associated with increased risk for all outcomes. Almotriptan was significantly associated with an increased risk of vomiting, whereas all other triptans yielded non-significant lower odds compared with placebo. Generally, the non-triptans were not associated with decreased tolerability for the secondary outcomes.

Discussion

In summary, triptans were associated with higher odds of any adverse event or a treatment-related adverse event occurring when compared to placebo and non-triptans. Non-significant results for non-triptans indicate that these treatments are comparable with one another and placebo regarding tolerability outcomes.

Placebo Effects in Oral Triptan Trials: the Scientific and Ethical Rationale for Continued use of Placebo Controls

The aim of this study was to determine the characteristics of placebo effects in acute migraine treatment trials of triptans performed over 12 years and assess whether the use of placebo controls in trials of acute migraine treatment remains ethically and scientifically appropriate. We conducted a search for all controlled trials published in English between January 1991 and April 2002 in which adult subjects with migraine were randomly assigned to receive an oral triptan or placebo for the acute treatment of a migraine attack. Thirty-one trials met our criteria for inclusion. Placebo results for each study and pooled placebo results were calculated for the endpoints of headache response, pain-free response and adverse events. Heterogeneity was assessed using the Q statistic, and meta-regression using prespecified covariates was performed to investigate heterogeneity. The study results show a significant degree of heterogeneity. Efforts to explain heterogeneity with available data were not successful, with the exception of adverse event rates to placebo, for which study location (Europe vs. North America) partially explained differences in study results. AE rates were lower in European studies than in North American studies. Across all studies, the mean proportion of subjects who experienced a treatment response at two hours to placebo was 28.48 + 8.73% (range 17-50%). The mean proportion of subjects who experienced an adverse event to placebo was 23.40 + 14.05% (range 4.86-74%). The mean proportion of subjects who experienced a pain-free response to placebo at two hours was 6.08 + 4.43% (range 5-17%). Results of studies allowing use of prophylaxis did not differ significantly from those that did not allow prophylaxis. Placebo effects appear to be enhanced in studies involving children and adolescents. In contrast to an earlier, smaller review, our results do not suggest that randomization ratios influence placebo rates. We conclude that placebo effects in published trials of acute migraine medications are highly variable and often substantial. This variability in placebo response means that active control equivalence trials or the use of historical controls will not provide adequate proof of the safety or efficacy of new drugs, and will not differentiate between drugs that are active vs. placebo but of unknown efficacy relative to each other. The potential for approval of ineffective drugs, inability to compare results of studies performed in different locations, and poor characterization of the tolerability and safety profiles of new drugs represent a greater danger to migraineurs than does the limited-duration use of placebo in carefully monitored clinical trials of consenting subjects. These observations support the view that the inclusion of a placebo group remains of major scientific and ethical importance in trials of migraine medications.

Review of dose-response curves for acute antimigraine drugs: triptans, 5-HT1F agonists and CGRP antagonists

INTRODUCTION

Dose-response curves for efficacy and tolerability are the important determinants for the choice of doses of acute migraine drugs.

AREAS COVERED

Dose-response curves for the efficacy of seven triptans (5-HT1B/1D receptor agonists), a 5-HT1F receptor agonist (lasmiditan) and four oral calcitonin-gene related peptide receptor antagonists (telcagepant, MK-3207, BI 44370 TA and BMS-927711) in placebo-controlled trials were reviewed. In addition, dose-response curves for adverse events (AEs) were reviewed.

EXPERT OPINION

For most triptans, the dose-response curve for efficacy is flat, whereas AEs often increase with increasing doses. The two other groups of drugs also have flat dose-response curves for efficacy. Overall, the triptans still have the most favorable efficacy-tolerability profile. Current acute antimigraine drugs do not fulfill the expectations of the patients, and thus, there are many unmet needs. Although upcoming drugs may not be superior to triptans, migraine patients will potentially benefit greatly from these, especially patients who are triptan non-responders and patients with cardiovascular disease.

Frovatriptan and rizatriptan economic EVAluation: the FREEVA study

Background

The present pharmacoeconomic study compared the direct and indirect costs of using frovatriptan versus rizatriptan in the acute treatment of migraine.

Methods

Data on the cost-efficacy of the two triptans were derived from a recently published Italian, multicenter, randomized, double-blind, cross-over patient preference study, comparing frovatriptan versus rizatriptan. The direct costs were obtained by calculating the drug consumption, both of triptans and rescue medications. Prices of currently marketed drugs were obtained from Italian Drug Agency price list. The indirect costs were those related to absenteeism from the workplace due to migraine.

Results

129 of the 148 patients with a current history of migraine randomized to the two study drugs and completing the study were analyzed. The number of attacks treated with only 1 dose of study drug was higher with frovatriptan (157 vs. 147), whereas the number of attacks treated with ≥2 doses of study medication was higher with rizatriptan (122 vs. 110 and 74 vs. 67, respectively). However, more patients treated with frovatriptan took a rescue medication (71 vs. 59). The total direct cost per attack (including study drug rescue medication) was 9.12 € for frovatriptan and 13.54 € for rizatriptan (p < 0.05 between-treatments). As for indirect costs, in the group of patients treated with frovatriptan the mean number of lost working hours was significantly (p < 0.05) lower (1.5 h) compared to the subjects who used rizatriptan (2.8 h). Based on the earned income per unit of work, indirect costs per attack resulted to be 24.55 € for frovatriptan and 45.84 € for rizatriptan. Overall, the total costs, including direct and indirect costs, were evaluated to be 33.67 € for frovatriptan and 59.38 € for rizatriptan, respectively.

Conclusions

Within the limitations of this model analysis, frovatriptan was found to be significantly more cost-effective than rizatriptan. This outcome can be explained by the lower acquisition cost of frovatriptan, the need for fewer doses, and the loss of fewer working hours. This finding could drive selection of the most appropriate oral treatment for acute migraine attacks based on both individual patient’s needs and the cost-effectiveness of the available drugs.

Trial registration

2006-002572-17 (EudraCT).

Optimal balance of efficacy and tolerability of oral triptans and telcagepant: a review and a clinical comment

Dose–response curves for headaches relief and adverse events (AEs) are presented for five triptans: sumatriptan, zolmitriptan, naratriptan, almotriptan, and frovatriptan, and the CGRP antagonist telcagepant. The upper part of the efficacy curve of the triptans is generally flat, the so-called ceiling effect; and none of the oral triptans, even in high doses, are as effective as subcutaneous sumatriptan, In contrast, AEs increases with increasing dose without a ceiling effect. The optimal dose for the triptans is mainly determined by tolerability. Telcagepant has an excellent tolerability and can be used in migraine patients with cardiovascular co-morbidity. Based on the literature the triptans and telcagepant are rated in a table for efficacy and tolerability.

Ten years of rizatriptan: from development to clinical science and future directions

The year 2008 marked the 10th anniversary since rizatriptan was first launched for the acute treatment of migraine. In this article we discuss the concepts that motivated the preclinical and clinical development of rizatriptan, the clinical evidence that has driven its use over the past decade, rizatriptan's overall contribution to the field, and future directions for research.

Marketed oral triptans in the acute treatment of migraine: a systematic review on efficacy and tolerability

BACKGROUND

In the current literature, there is neither a reported systematic review comparing the efficacy of triptans at 30 minutes and 1 hour after the migraine treatment, nor data related to efficacy of new marketed triptans.

OBJECTIVE

The main objective of this analysis was to compare the efficacy and tolerability of currently marketed oral, non-reencapsulated triptan formulations vs placebo in the treatment of moderate-to-severe migraine attacks.

METHODS

A systematic review of double-blind, randomized clinical trials reporting data after a single migraine attack was conducted. Efficacy results are shown using relative risk ratios with 95% confidence intervals. A sensitivity analysis was also conducted.

RESULTS

After reviewing 221 publications, 38 studies were included. All marketed triptans provided significant relief and/or absence of pain at 2 hours, and relief at 1 hour when compared with placebo. After 30 minutes, fast-dissolving sumatriptan 50 and 100 mg, sumatriptan 50 mg, and rizatriptan 10 mg showed significant relief when compared to placebo, whereas the fast-dissolving formulation of sumatriptan 100 mg was the only oral triptan that was superior to placebo in meeting the pain-free endpoint. On the other hand, fast-dissolving sumatriptan 50 and 100 mg and eletriptan 40 mg showed a lower rate of recurrence than placebo, whereas rizatriptan 10 mg was the only triptan with a recurrence rate greater than that of placebo. Adverse events associated with treatment with tablet formulations of sumatriptan and zolmitriptan were significantly more frequent than those of the placebo group. The inclusion of trials with reencapsulated triptans in the analysis introduced minor specific changes in these results.

CONCLUSION

This analysis updates the comparative data available for the 7 currently marketed oral triptans and clearly demonstrates their efficacy when compared to placebo, even with stricter endpoints, such as efficacy at 30 minutes. No triptan exhibited better tolerability than placebo. Results are diverse, depending on the triptan, which probably is a reflection of heterogeneous pharmacokinetics.

WITHDRAWN: Rizatriptan for acute migraine

BACKGROUND

There are a number of different drug treatments for acute migraine, including currently four triptans, with several more likely to become available in the future. There is a need for evidence-based information to help determine the balance of benefit and harm for acute migraine treatment.

OBJECTIVES

To quantitatively assess the efficacy of a single dose of rizatriptan (Maxalt) for treating a single migraine attack using the outcomes of headache response and pain-free response at half-an-hour, one hour, two hours, and sustained relief over 24 hours. To express efficacy in terms of numbers-needed-to-treat (NNTs).

SEARCH STRATEGY

Trials were identified by searching MEDLINE (1966-July 2000), EMBASE (1980-June 2000), the Cochrane Library (Issue 3, 2000) and the Oxford Pain Relief Database (1950-1994). Date of last search: July 2000.

SELECTION CRITERIA

The inclusion criteria were randomised, placebo-controlled trials of rizatriptan for acute migraine; double-blind design; International Headache Society diagnostic criteria for migraine with or without aura; single migraine attack; single-dose treatment at standard doses; adult population; baseline pain of moderate or severe intensity using a four-point standardised rating scale; dichotomous or percentage data for at least one of the main efficacy outcomes; and full journal publication.

DATA COLLECTION AND ANALYSIS

Main outcomes considered were i) headache response at two hours, ii) headache response at one hour, iii) pain-free response at two hours, iv) sustained relief over 24 hours, v) pain-free response at 24 hours and vi) adverse effects. Minor outcomes were headache response and pain-free response at half-an-hour and four hours, and pain-free response at one hour. Dichotomous or percentage data were extracted and used to calculate the relative benefit (RB) and number-needed-to-treat (NNT) for each outcome.

MAIN RESULTS

Seven trials met our inclusion criteria, with 2626 patients given rizatriptan and 902 given placebo. Significant benefit of rizatriptan over placebo was shown for both doses of rizatriptan (5 mg and 10 mg) for all five main efficacy outcomes (ranging from one to 24 hours). A dose response was seen for the main outcomes. It was not possible to analyse adverse effects information in a meaningful way.

AUTHORS' CONCLUSIONS

Rizatriptan 5 mg and 10 mg are effective in treating acute migraine, with a dose-related increase in efficacy.

Rizatriptan vs. rizatriptan plus trimebutine for the acute treatment of migraine: a double-blind, randomized, cross-over, placebo-controlled study

Gastroparesis frequently happens during migraine attacks, postponing the onset of action of orally administered drugs. Furthermore, triptans seem to work better in the earlier phases of the migraine attacks. Therefore, associating a gastrokinetic drug with a triptan may translate into better efficacy and higher consistency of response. Trimebutine is an opioid derivative with exclusive action on receptors of the Meissner and Auerbach plexus throughout the digestive tube. It has no absorption or central penetration. Herein we contrast the combination of rizatriptan plus trimebutine with rizatriptan alone in the acute treatment of migraine. Forty patients with migraine consecutively seen in our clinic were randomized to treat two consecutive moderate or severe attacks with one tablet of 10 mg rizatriptan plus one capsule of 200 mg trimebutine and two attacks with the same triptan and placebo, in counterbalanced order. We collected information on the severity of the attack, as well as presence of nausea and photophobia at the time of drug intake, and after 1, 2 and 4 h. Recurrence and adverse events were also contrasted. Sixty-four attacks were treated with each drug regimen. At 1 h postdose, 30 (46.8%) of 64 attacks treated with the combination resolved completely, vs. eight (12.5%) of the rizatriptan-treated attacks, a difference of 34% (P < 0.01). At 2 h postdose, 47 (73.4%) attacks treated with the combination vs. 20 (31.2%) of those treated with rizatriptan alone resolved completely, a difference of 42% (95% confidence interval 26, 58, P < 0.001). Regarding nausea and photophobia, the combination was also associated with significantly better response. Recurrence was similar among the two drug regimens, as well as adverse events. The combination rizatriptan and trimebutine is more effective than rizatriptan alone. The combination does not increase adverse events or recurrence of pain.

Rizatriptan in the treatment of migraine

Migraine is a common, disabling disorder associated with considerable personal and societal burden. Current guidelines recommend triptans for the acute treatment of migraine unlikely to respond to less effective therapies. Rizatriptan is a second-generation triptan available in tablet or orally disintegrating tablet (wafer) formulations that offers several advantages over other members of its class. Rizatriptan is rapidly absorbed from the gastrointestinal tract and achieves maximum plasma concentrations more quickly than other triptans, providing rapid pain relief. Clinical trials have shown that rizatriptan is at least as effective or superior to other oral migraine-specific agents in the acute treatment of migraine, and has more consistent long-term efficacy across multiple migraine attacks. Rizatriptan has a favorable tolerability profile, and patients have reported greater satisfaction and a preference for rizatriptan over other migraine-specific agents. Improvements in quality of life reported with rizatriptan are consistent with its favorable efficacy and tolerability profiles. Notably, multi-attribute decision models that combine clinical data with patient- and physician-reported treatment preferences have identified rizatriptan as one of three triptans closest to a hypothetical "ideal". The efficacy and tolerability of rizatriptan for the acute treatment of migraine have thus been well established.

Rizatriptan in migraine

The prevalence of migraine is high, affecting a significant proportion of the adult population during their most productive years of life and promoting impairment of their normal daily activities. Although guidelines for the acute treatment of migraine are available, outcome parameters are sometimes still below the expectations of both patients and physicians. Triptans represented an advance in clinical practice and have become the most well-studied class of medication for migraine. These agents present class I evidence for efficacy. However, they differ with regard to several of their clinical parameters, including onset of relief and consistency of response. Rizatriptan is a selective agonist of the 5-hydroxytryptophan(1B/1D )receptors, with proven superiority over placebo, ergotamine and selected oral triptans, demonstrating a good profile of safety and tolerability.

Methodological issues in systematic reviews of headache trials: adapting historical diagnostic classifications and outcome measures to present-day standards

Recent efforts to make headache diagnostic classification and clinical trial methodology more consistent provide valuable advice to trialists generating new evidence on effectiveness of treatments for headache; however, interpreting older trials that do not conform to new standards remains problematic. Systematic reviewers seeking to utilize historical data can adapt currently recommended diagnostic classification and clinical trial methodological approaches to interpret all available data relative to current standards. In evaluating study populations, systematic reviewers can: (i) use available data to attempt to map study populations to diagnoses in the new International Classification of Headache Disorders; and (ii) stratify analyses based on the extent to which study populations are precisely specified. In evaluating outcome measures, systematic reviewers can: (i) summarize prevention studies using headache frequency, incorporating headache index in a stratified analysis if headache frequency is not available; (ii) summarize acute treatment studies using pain-free response as reported in directly measured headache improvement or headache severity outcomes; and (iii) avoid analysis of recurrence or relapse data not conforming to the sustained pain-free response definition.

A review of rizatriptan, a quick and consistent 5-HT1B/1Dagonist for the acute treatment of migraine

Rizatriptan is a second-generation triptan marketed as 5 and 10 mg tablets and rapidly disintegrating wafer formulations. In > 5000 acute migraine patients enrolled in short-term trials and almost 1800 patients in long-term, open-label trials treating approximately 47000 attacks, rizatriptan was effective and well-tolerated. Controlled head-to-head data and a meta-analysis of 53 randomised, placebo-controlled trials of oral triptans in > 24000 patients have shown that rizatriptan 10 mg offers efficacy advantages over oral sumatriptan 50 and 100 mg and other oral triptans, both in terms of speed of onset of action and consistency. These advantages may reflect its improved pharmacological profile over sumatriptan in terms of higher oral bioavailability and a shorter time to maximum concentration. The wafer formulation offers the convenience of being administered without water. As a result of its superior efficacy profile and generally good tolerability, rizatriptan can be considered as a first-line treatment for acute migraine.

Rizatriptan: a new 5-HT1B/1D receptor agonist for the treatment of migraine

Rizatriptan (MAXALT MK-0462) is a new 5-HT(1B/1D) receptor agonist for the acute treatment of migraine. The marketed 10 mg and 5 mg oral doses are rapidly and consistently effective in relieving headache pain with associated migraine symptoms, and in enabling patients to return to their normal activities of daily living. Rizatriptan 10 mg is more effective than rizatriptan 5 mg. Compared to oral sumatriptan, the established agent in this class, rizatriptan has a shorter Tmax and greater bioavailability. In comparative clinical trials, the probability of having pain relief sooner was higher for rizatriptan 10 mg than for sumatriptan 100 mg or 50 mg. Over the 2 h after dosing, rizatriptan 10 mg was also superior to sumatriptan 100 mg and 50 mg on a range of other outcome measures. Both doses of rizatriptan are well-tolerated. The most common side-effects are dizziness, drowsiness, and asthenia/fatigue, which are short-lasting and of mild or moderate severity. In summary, rizatriptan is an effective and well-tolerated acute treatment for migraine, which may offer some advantages over oral sumatriptan.

Rizatriptan: a pharmacoeconomic review of its use in the acute treatment of migraine

Rizatriptan (Maxalt; Maxalt-MLT; Maxalt-Melt) is an oral serotonin 5-HT(1B/1D) receptor agonist (triptan) used in the acute treatment of migraine with or without aura in adults. Rizatriptan 5 mg and 10 mg are effective in relieving the symptoms of migraine and the 10 mg dose provided faster pain relief than sumatriptan 50 mg, naratriptan 2.5 mg, ergotamine/caffeine 2 mg/200 mg and possibly zolmitriptan 2.5 mg, while displaying similar tolerability. Two cost-utility analyses performed from a societal perspective indicated that rizatriptan 10 mg was dominant over ergotamine/caffeine 2 mg/200 mg, sumatriptan 50 mg or 100 mg, naratriptan 2.5 mg, zolmitriptan 2.5 mg and analgesic-based usual care in the acute treatment of migraine. In one analysis also performed from the perspective of a healthcare payer, rizatriptan was still dominant over naratriptan, sumatriptan and zolmitriptan. Rizatriptan was cost effective compared with usual care with an incremental cost per quality-adjusted life-year (QALY) gained of 31,845 Can dollars (2002 values) and an incremental cost per additional attack aborted of 49.82 Can dollars. A modelled cost-effectiveness analysis conducted from a healthcare payer's perspective indicated that almotriptan 12.5 mg was more cost effective than rizatriptan 10 mg as a result of better tolerability. The incremental cost per additional successfully treated patient (defined as being sustained pain free without adverse events) with almotriptan was 6.94 US dollars (1999 values). In other nonmodelled cost-effectiveness analyses, rizatriptan 10 mg, eletriptan 40 mg and almotriptan 12.5 mg most consistently displayed the greatest cost effectiveness in different analyses using different clinical endpoints. A modelled analysis of the costs of migraine-related productivity losses in US corporations indicated that the use of rizatriptan rather than usual care to treat migraines could result in annual cost offsets of approximately 84-118 US dollars (2000 values) per employee in lost productivity avoided. An intervention study in Spanish postal service workers demonstrated that replacement of usual care with rizatriptan reduced the mean per-patient cost of lost productivity per migraine attack from 34.47 euros (2001/2002 values) before the intervention to 13.94 euros and 4.59 euros for the first and second post-intervention migraine attacks. In conclusion, rizatriptan is one of the more clinically effective and therefore cost-effective oral triptans available for the acute treatment of migraine. The available data from cost-utility analyses suggest that rizatriptan is more cost effective than ergotamine/caffeine, simple analgesics, naratriptan, zolmitriptan and sumatriptan. The economic value of rizatriptan depends on the payer's perspective, as the greatest savings can be expected to be achieved in terms of reduced migraine-related loss of work productivity compared with less effective treatments. For healthcare payers, the high acquisition cost appears to be at least partly offset by reduced migraine-related healthcare resource use when compared with usual care. The comparative cost effectiveness of the newer triptans requires further elucidation from comprehensive direct comparisons.

Cost effectiveness of oral triptan therapy: a trans-national comparison based on a meta-analysis of randomised controlled trials

OBJECTIVE

The objective of this study was to appraise the relative cost effectiveness of oral triptan therapy in the management of acute migraine, comparing the results obtained using drug cost data from six different countries, USA, UK, Canada, Germany, Italy and The Netherlands.

METHOD

A meta-analysis of randomised placebo controlled trials of single dose oral triptans was carried out in order to calculate aggregate Numbers Needed to Treat (NNT) for each triptan and dose. Cost effectiveness ratios were then derived for each treatment by applying mean drug acquisition costs for each country to these NNTs. Using a graphical plot for each country, incremental cost effectiveness comparisons were then made versus sumatriptan 100 mg, the most commonly used oral triptan.

RESULTS

When analysed in terms of 2-h pain one country to another. When compared to free outcomes, rizatriptan 10 mg and eletriptan 40 and 80 mg were the most effective oral triptans. Rizatriptan 10mg has the most advantageous absolute cost effectiveness ratio in all six countries studied, although levels of statistical significance compared to other agents varied from sumatriptan 100mg, rizatriptan 10 mg and eletriptan 40 mg are most consistently the cost effective treatment choices, both being cost dominant in five out of six countries studied.

CONCLUSIONS

There are systematic differences in triptan efficacy that have an impact on treatment choice. Differences in pricing structure between countries mean that hierarchies of cost effectiveness will vary. Country-specific data should therefore be examined before defining treatment strategies.

Placebo adverse events in headache trials: headache as an adverse event of placebo

We analysed the adverse events of placebo in acute and preventive randomized, double-blind, placebo-controlled studies for migraine treatment. Fifty-seven trials (oral triptans, non-steroidal anti-inflammatory drugs, nasal ergot alkaloids and preventive agents) were included. From 10 to 30% of subjects reported adverse events after placebo. Most common were features associated with a migraine attack, such as nausea, phono- and photophobia. Other frequent complaints resembled those of the active drug (e.g. chest pressure in triptan trials). A third group of adverse events appeared to be coincidental (e.g. sleep disturbance). Adverse events following placebo are probably related to the drug under study and the symptomatology of migraine; some have no obvious explanation.

Migraine headache recurrence: relationship to clinical, pharmacological, and pharmacokinetic properties of triptans

BACKGROUND AND OBJECTIVES

Triptan use is associated with headache recurrence, and this has been cited as an important reason for patient dissatisfaction with the treatment. The mechanism by which recurrence occurs is not clear, and the incidence of recurrence varies with the triptan used. In order to explore the pharmacological and physiological interaction of triptans and migraine headache recurrence further, some specific clinical, pharmacological, and pharmacokinetic factors that might influence migraine recurrence were evaluated in a review of the major efficacy data for the drugs in the triptan class. These factors were 5-HT1B and 5-HT1D receptor activities, the pharmacokinetic elimination half-life of each triptan, and the clinical efficacy of each compound, determined by the proportion of patients with headache relief and the therapeutic gain over placebo.

METHODS

Clinical data were derived from 31 triptan, placebo-controlled, major efficacy studies used in a previous meta-analysis. The mean recurrence rate, mean headache response, and therapeutic gain were calculated using the results from the individual clinical studies. Mean headache response and therapeutic gain were calculated at the time point used to define recurrence in each study. Data for binding affinity and potency were taken from a direct-comparison in vitro pharmacology study, and the elimination half-life quoted in the data sheet for each triptan was used. Rank correlation with recurrence rate was performed for each of the test parameters.

RESULTS

Mean headache recurrence rates ranged from 17% for frovatriptan 2.5 mg to 40% for rizatriptan. Elimination half-life and recurrence were inversely correlated (r = -1.0, P =.0016). There was also a significant inverse correlation between 5-HT1B receptor potency and recurrence (r = -0.68, P =.034), but 5-HT1D receptor potency was not correlated with recurrence (r = -0.20, P =.54). In addition, the binding affinities for the 5-HT1B and 5-HT1D receptors were not correlated to headache recurrence. Importantly, it also was demonstrated that initial clinical efficacy was not correlated to headache recurrence. The correlation coefficient for headache response was 0.18 (P =.53) and for therapeutic gain, -0.11 (P =.71).

CONCLUSION

The incidence of migraine headache recurrence varies between drugs in the triptan class. Migraine recurrence does not appear to be related to initial clinical efficacy, but is influenced by the pharmacological and pharmacokinetic properties of the individual triptans. The triptans with longer half-lives and greater 5-HT1B receptor potency had the lowest rates of headache recurrence.

Spotlight on rizatriptan in migraine

Rizatriptan is an orally active serotonin 5-HT(1) receptor agonist that potently and selectively binds to 5-HT(1B/1D) subtypes. Earlier clinical trials demonstrated that rizatriptan 5 or 10mg is more effective than placebo at providing pain relief and a pain-free state, relieving associated symptoms of migraine, normalising functional ability and improving patient quality of life, and showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recently, rizatriptan 10mg was shown to be more effective than zolmitriptan 2.5mg or naratriptan 2.5mg at producing a pain-free state 2 hours postdose. Furthermore, compared with naratriptan, significantly more patients who received rizatriptan were pain free or had pain relief from 1 hour onwards. The number of patients with normal functional ability at 2 hours was significantly higher after rizatriptan than after naratriptan or zolmitriptan. Rizatriptan was also generally more effective than zolmitriptan or naratriptan at relieving migraine-associated symptoms. Rizatriptan is generally well tolerated, and adverse events are usually mild and transient. The most common adverse events associated with rizatriptan in recent randomised trials were asthenia/fatigue, dizziness, somnolence and nausea. There was a trend towards a lower incidence of adverse events with rizatriptan compared with zolmitriptan (31.2 vs 38.8%). However, rizatriptan was associated with a significantly higher incidence of adverse events than naratriptan (39 vs 29%). The incidence of chest pain was similar after the administration of rizatriptan, zolmitriptan or naratriptan (2-4%). In conclusion, rizatriptan is an effective drug for the acute treatment of moderate or severe migraine. Oral rizatriptan 5 and 10mg have shown greater efficacy than placebo in providing pain relief, an absence of pain, relief from associated symptoms, normal functional ability and an improvement in patient quality of life. Earlier results showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recent studies have shown that rizatriptan 10mg provides faster pain relief and a higher percentage of patients with an absence of pain and normal functional ability at 2 hours than naratriptan 2.5mg or zolmitriptan 2.5mg. The efficacy of rizatriptan is retained when used in the long term, and the drug is generally well tolerated. Although well designed studies comparing rizatriptan with almotriptan, eletriptan and frovatriptan would further define the position of rizatriptan, current data suggest that rizatriptan should be considered as a first-line treatment option in the management of migraine.

Triptans (serotonin, 5-HT1B/1D agonists) in migraine: detailed results and methods of a meta-analysis of 53 trials

The triptans, selective serotonin 5-HT1B/1D agonists, are very effective acute migraine drugs. Soon, seven different triptans will be clinically available at 13 different oral doses, making evidence-based selection guidelines necessary. Triptan trials have similar designs, facilitating meta-analysis. We wished to provide an evidence-based foundation for using triptans in clinical practice, and to review the methodological issues surrounding triptan trials. We asked pharmaceutical companies and the principal investigators of company-independent trials for the 'raw patient data' of all double-blind, randomized, controlled, clinical trials with oral triptans in migraine. All data were cross-checked with published or presented data. We calculated summary estimates across studies for important efficacy and tolerability parameters, and compared these with those from direct, head-to-head, comparator trials. Out of 76 eligible clinical trials, 53 (12 not yet published) involving 24089 patients met the criteria for inclusion. Mean results (and 95% confidence intervals) for sumatriptan 100 mg, the first available and most widely prescribed oral triptan, are 59% (57-60) for 2 h headache response (improvement from moderate or severe to mild or no pain); 29% (27-30) for 2 h pain free (improvement to no pain); 20% (18-21) for sustained pain free (pain free by 2 h and no headache recurrence or use of rescue medication 2-24 h post-dose), and 67% (63-70) for consistency (response in at least two out of three treated attacks); placebo-subtracted proportions for patients with at least one adverse event (AE) are 13% (8-18), for at least one central nervous system AE 6% (3-9), and for at least one chest AE 1.9% (1.0-2.7). Compared with these data: rizatriptan 10 mg shows better efficacy and consistency, and similar tolerability; eletriptan 80 mg shows better efficacy, similar consistency, but lower tolerability; almotriptan 12.5 mg shows similar efficacy at 2 h but better sustained pain-free response, consistency, and tolerability; sumatriptan 25 mg, naratriptan 2.5 mg and eletriptan 20 mg show lower efficacy and better tolerability; zolmitriptan 2.5 mg and 5 mg, eletriptan 40 mg, and rizatriptan 5 mg show very similar results. The results of the 22 trials that directly compared triptans show the same overall pattern. We received no data on frovatriptan, but publicly available data suggest substantially lower efficacy. The major methodological issues involve the choice of the primary endpoint, consistency over multiple attacks, how to evaluate headache recurrence, use of placebo-subtracted proportions to control for across-study differences, and the difference between tolerability and safety. In addition, there are a number of methodological issues specific for direct comparator trials, including encapsulation and patient selection. At marketed doses, all oral triptans are effective and well tolerated. Differences among them are in general relatively small, but clinically relevant for individual patients. Rizatriptan 10 mg, eletriptan 80 mg and almotriptan 12.5 mg provide the highest likelihood of consistent success. Sumatriptan features the longest clinical experience and the widest range of formulations. All triptans are contra-indicated in the presence of cardiovascular disease.

Rizatriptan: an update of its use in the management of migraine

Rizatriptan is an orally active serotonin 5-HT(1) receptor agonist that potently and selectively binds to 5-HT(1B/1D) subtypes. Earlier clinical trials demonstrated that rizatriptan 5 or 10mg is more effective than placebo at providing pain relief and a pain-free state, relieving associated symptoms of migraine, normalising functional ability and improving patient quality of life, and showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recently, rizatriptan 10mg was shown to be more effective than zolmitriptan 2.5mg or naratriptan 2.5mg at producing a pain-free state 2 hours postdose. Furthermore, compared with naratriptan, significantly more patients who received rizatriptan were pain free or had pain relief from 1 hour onwards. The number of patients with normal functional ability at 2 hours was significantly higher after rizatriptan than after naratriptan or zolmitriptan. Rizatriptan was also generally more effective than zolmitriptan or naratriptan at relieving migraine-associated symptoms. Rizatriptan is generally well tolerated and adverse events are usually mild and transient. The most common adverse events associated with rizatriptan in recent randomised trials were asthenia/fatigue, dizziness, somnolence and nausea. There was a trend towards a lower incidence of adverse events with rizatriptan compared with zolmitriptan (31.2 vs 38.8%). However, rizatriptan was associated with a significantly higher incidence of adverse events than naratriptan (39 vs 29%). The incidence of chest pain was similar after the administration of rizatriptan, zolmitriptan or naratriptan (2 to 4%).

CONCLUSION

Rizatriptan is an effective drug for the acute treatment of moderate or severe migraine. Oral rizatriptan 5 and 10mg have shown greater efficacy than placebo in providing pain relief, an absence of pain, relief from associated symptoms, normal functional ability and an improvement in patient quality of life. Earlier results showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recent studies have shown that rizatriptan 10mg provides faster pain relief and a higher percentage of patients with an absence of pain and normal functional ability at 2 hours than naratriptan 2.5mg or zolmitriptan 2.5mg. The efficacy of rizatriptan is retained when used in the long term and the drug is generally well tolerated. Although well designed studies comparing rizatriptan with almotriptan, eletriptan and frovatriptan would further define the position of rizatriptan, current data suggest rizatriptan should be considered as a first-line treatment option in the management of migraine.

Practical approaches to migraine management

Migraine is a recurrent clinical syndrome characterised by combinations of neurological, gastrointestinal and autonomic manifestations. The exact pathophysiological disturbances that occur with migraine have yet to be elucidated; however, cervico-trigemino-vascular dysfunctions appear to be the primary cause. Despite advances in the understanding of the pathophysiology of migraine and new effective treatment options, migraine remains an under-diagnosed, under-treated and poorly treated health condition. Most patients will unsuccessfully attempt to treat their headaches with over-the-counter medications. Few well designed, placebo-controlled studies are available to guide physicians in medication selection. Recently published evidence-based guidelines advocate migraine-specific drugs, such as serotonin 5-HT(1B/1D) agonists (the 'triptans') and dihydroergotamine mesylate, for patients experiencing moderate to severe migraine attacks. Additional headache attack therapy options include other ergotamine derivatives, phenothiazines, nonsteroidal anti-inflammatory agents and opioids. Preventative medication therapy is indicated for patients experiencing frequent and/or refractory attacks.

Assessing health-related quality of life in patients with migraine

BACKGROUND

The place of health-related quality of life (HRQoL) instruments in clinical research trials and clinical practice as compared to more traditional clinical outcome measures such as headache intensity and frequency is unclear.

OBJECTIVES

To review the current status of HRQoL measurement in migraine.

METHODS

A literature search was done for HRQoL and migraine. Selected articles dealing with migraine and commonly used HRQoL instruments and HRQoL measures used in recent clinical trials were reviewed.

RESULTS

Several general and migraine specific HRQoL instruments can detect changes over time in response to at least major changes in migraine therapy. Both also show a correlation with clinical headache features. However, their sensitivity to detect clinically significant changes over time is not clear.

CONCLUSION

The SF-36, a general HRQoL measure and several migraine-specific HRQoL instruments are useful endpoints for migraine clinical trials. Their role in clinical practice is yet to be established.

CNS effects of sumatriptan and rizatriptan in healthy female volunteers

This study investigates the CNS effects of sumatriptan and rizatriptan, with temazepam as an active comparator, in healthy female volunteers. Sixteen volunteers completed a randomized, double-blind, crossover study and on four separate occasions received either 100 mg sumatriptan, 20 mg rizatriptan or 20 mg temazepam. The main parameters were eye movements, EEG, body sway, visual analogue scales and a cognitive test battery. Rizatriptan and sumatriptan decreased saccadic peak velocity by 18.3 (95% CI: 5.7, 30.8) and 15.0 (2.2, 27.9) degrees/sec, respectively, about half the decrease induced by temazepam (35.0 (22.1, 47.8) degrees/sec). Body sway increased (30% for rizatriptan (16%, 45%) and 14% for sumatriptan (1%, 27%), respectively). Temazepam caused larger, similar effects. In contrast to temazepam, sumatriptan and rizatriptan decreased reaction times of recognition tasks and increased EEG alpha power (significant for sumatriptan, 0.477 (0.02, 0.935). Therapeutic doses of sumatriptan and rizatriptan caused CNS effects indicative of mild sedation. For EEG and recognition reaction times the effects were opposite to temazepam, indicating central stimulation.

The pharmacokinetics of sumatriptan when administered with clarithromycin in healthy volunteers

BACKGROUND

Macrolide antibiotics such as clarithromycin are potent inhibitors of the cytochrome P450 (CYP)3A4 isozyme and have the potential to attenuate the metabolism and increase blood concentrations of drugs metabolized by this pathway. In vitro studies have suggested that sumatriptan is metabolized primarily by the monoamine oxidase-A isozyme and not by CYP3A4.

OBJECTIVE

This study sought to determine the effect of coadministration of clarithromycin dosed to steady state on the pharmacokinetics of a single dose of sumatriptan. A secondary objective was to assess the safety and tolerability of combining these agents.

METHODS

This was an open-label, randomized, 2-way crossover study in healthy volunteers. During treatment period 1, subjects received either a single oral dose of sumatriptan 50 mg (sumatriptan alone) or clarithromycin 500 mg orally every 12 hours on days 1 to 3 and a single oral dose of sumatriptan 50 mg plus a single oral dose of clarithromycin 500 mg on the morning of day 4 (combination treatment). During treatment period 2, they received the alternative regimen. Equivalence between sumatriptan alone and combination treatment was concluded if the 90% CI for the ratio of reference to test means of loge-transformed data for area under the plasma concentration-time curve extrapolated to infinity (AUC(infinity)) and maximum plasma concentration (Cmax) fell within the interval from 0.8 to 1.25.

RESULTS

In the 24 evaluable subjects (12 men, 12 women) included in the pharmacokinetic analysis, mean sumatriptan AUC(infinity) and Cmax values after administration of combination treatment were 9% and 14% higher, respectively, than the corresponding values after administration of sumatriptan alone. The 90% CI for the ratio of reference to test means for AUC(infinity) was 1.03 to 1.15. The 90% CI for the ratio of reference to test means for Cmax was 1.03 to 1.26, above the traditional bioequivalence criterion. All other pharmacokinetic parameters tested, including nonparametric analysis of the time to Cmax, met the criterion for equivalence between treatments. Both treatments were well tolerated in the 27 subjects (13 men, 14 women) included in the safety analysis.

CONCLUSIONS

The extent of absorption of sumatriptan was similar after oral administration alone and in combination with clarithromycin dosed to steady state. These data are consistent with previous reports that sumatriptan is unaffected by coadministration with the potent CYP3A4 inhibitor clarithromycin, supporting concomitant administration of these agents without the need for dose adjustment of sumatriptan in the acute treatment of migraine.

How does almotriptan compare with other triptans? A review of data from placebo-controlled clinical trials

Almotriptan, the new selective 5-HT1B/1D agonist, has a higher oral bioavailability than any other triptan, with more than two thirds of the administered dose absorbed within the first hour both inside and outside of a migraine attack. Gender or the presence of food in the stomach does not affect its pharmacokinetic profile, and the compound has no clinically relevant interactions with other drugs. Among the available triptans, response rates at 2 hours range from 50% to 80%, with 20% to 50% of patients pain-free. Almotriptan 12.5 mg provides similar efficacy, with significant advantage over placebo at 30 minutes and a reliable consistency (75% in two of three attacks). Headache typically recurs in 25% to 45% of patients with most triptans. The recurrence rate with almotriptan 12.5 mg, 18% to 27%, is among the lowest reported. The tolerability of almotriptan 12.5 mg is close to that of placebo with a low incidence of central nervous system side effects and chest symptoms. In conclusion, almotriptan's consistent pharmacokinetics and good efficacy, in combination with excellent tolerability, make it an attractive choice in the acute treatment of migraine attacks.

Influence of beta-adrenoceptor antagonists on the pharmacokinetics of rizatriptan, a 5-HT1B/1D agonist: differential effects of propranolol, nadolol and metoprolol

AIMS

Patients with migraine may receive the 5-HT1B/1D agonist, rizatriptan (5 or 10 mg), to control acute attacks. Patients with frequent attacks may also receive propranolol or other beta-adrenoceptor antagonists for migraine prophylaxis. The present studies investigated the potential for pharmacokinetic or pharmacodynamic interaction between beta-adrenoceptor blockers and rizatriptan.

METHODS

Four double-blind, placebo-controlled, randomized crossover investigations were performed in a total of 51 healthy subjects. A single 10 mg dose of rizatriptan was administered after 7 days' administration of propranolol (60 and 120 mg twice daily), nadolol (80 mg twice daily), metoprolol (100 mg twice daily) or placebo. Rizatriptan pharmacokinetics were assessed. In vitro incubations of rizatriptan and sumatriptan with various beta-adrenoceptor blockers were performed in human S9 fraction. Production of the indole-acetic acid-MAO-A metabolite of each triptan was measured.

RESULTS

Administration of rizatriptan during propranolol treatment (120 mg twice daily for 7.5 days) increased the AUC(0, infinity) for rizatriptan by approximately 67% and the Cmax by approximately 75%. A reduction in the dose of propranolol (60 mg twice daily) and/or the incorporation of a delay (1 or 2 h) between propranolol and rizatriptan administration did not produce a statistically significant change in the effect of propranolol on rizatriptan pharmacokinetics. Administration of rizatriptan together with nadolol (80 mg twice daily) or metoprolol (100 mg twice daily) for 7 days did not significantly alter the pharmacokinetics of rizatriptan. No untoward adverse experiences attributable to the pharmacokinetic interaction between propranolol and rizatriptan were observed, and no subjects developed serious clinical, laboratory, or other significant adverse experiences during coadministration of rizatriptan with any of the beta-adrenoceptor blockers. In vitro incubations showed that propranolol, but not other beta-adrenoceptor blockers significantly inhibited the production of the indole-acetic acid metabolite of rizatriptan and sumatriptan.

CONCLUSIONS

These results suggest that propranolol increases plasma concentrations of rizatriptan by inhibiting monoamine oxidase-A. When prescribing rizatriptan to migraine patients receiving propranolol for prophylaxis, the 5 mg dose of rizatriptan is recommended. Administration with other beta-adrenoceptor blockers does not require consideration of a dose adjustment.

Efficacy and tolerability of rizatriptan 10 mg in migraine: experience with 70 527 patient episodes

As patients who suffer from migraine need long-term treatment, the safety and consistent efficacy of such therapy is very important. Concurrent illness and additional medication can interfere with the treatment chosen for the attacks of migraine. The objective of this open-label study was to investigate the efficacy and tolerability of rizatriptan, in the treatment of up to three attacks of migraine, in the clinical setting. From October 1998 to July 1999, 6 174 doctors enrolled 33 147 patients into the study (26 644 women, 650 men). The mean age was 42.7 years. We were able to examine standardized migraine diaries relating to 25 501 patients and 70 537 migrainous episodes. Rizatriptan scored consistently high on efficacy and showed a consistently rapid onset. There was no evidence of tolerance to repeated use. An effect was reported within 1 hour of ingestion in 79% of attacks treated. In 27.8% of attacks, remission of headache was complete at 1 hour. Two hours after ingestion, 74% of attacks had subsided completely. Repeated administration of rizatriptan was well tolerated, and few adverse effects were seen. The most common unwanted effects were dizziness, weakness, fatigue, and nausea. No cardiovascular disturbance was seen. In the clinical setting, rizatriptan, 10 mg, is an effective and well-tolerated agent for the treatment of migraine attacks. Particularly noteworthy is the rapid onset of effect, with swift disappearance of headache. Rizatriptan has a favorable side effect profile, and, provided contraindications are observed, severe adverse cardiovascular complications are extremely unlikely.

Meta-analysis of rizatriptan efficacy in randomized controlled clinical trials

Data from seven randomized, placebo-controlled, double-blind phase III clinical trials were analysed to further evaluate the efficacy of rizatriptan 10 mg (n = 2068) in comparison with placebo (n = 1260) and rizatriptan 5 mg (n = 1486) for the acute treatment of a migraine attack. Migraine was diagnosed according to International Headache Society criteria. Headache severity, associated migraine symptoms and functional disability were measured immediately before dosing and at 0.5, 1, 1.5 and 2 h. Headache recurrence (return of moderate or severe headache after an initial response) was also recorded. In addition to conventional pain relief (reduction of moderate or severe headache to mild or none) and pain free measures, the analysis looked at the elimination of associated migraine symptoms and disability in patients who had symptoms or disability at baseline. Maintenance of pain relief or pain-free status over 24 h was also analysed. At 2 h, rizatriptan 10 mg was significantly more effective than placebo for pain relief (71% vs. 38%, P < 0.001), and for elimination of pain, nausea, photophobia, phonophobia and functional disability. The benefit was maintained over 24 h; 37% of patients on rizatriptan 10 mg had sustained pain relief vs. 18% for placebo (P < 0.001). Rizatriptan 10 mg was also more effective than rizatriptan 5 mg, with a significant superiority at 2 h on all measures except for elimination of nausea. The benefit was maintained over 24 h; 38% of patients on rizatriptan 10 mg had sustained pain relief vs. 32% for rizatriptan 5 mg (P = 0.001).

Differentiating the efficacy of 5-HT(1B/1D) agonists

OBJECTIVE

To examine, for a set of published clinical trials of serotonin (5-HT(1B/1D)) agonists as acute treatments for migraine, whether transformation of efficacy data into therapeutic gain (TG) or number needed to treat (NNT) is useful.

BACKGROUND

Pivotal clinical trials of 5-HT(1B/1D) agonists in migraine use a primary end point of change in pain score from 3 or 2 to 1 or 0. Placebo response rates among such studies are variable. Meta-analytic comparisons of 5-HT(1B/1D) agonists often employ TG and NNT as efficacy measures.

METHODS

Data from US product labeling or published sources were converted into TG (TG = active response rate [%] - placebo response rate [%]) and NNT (NNT = 1/TG). Pivotal clinical trial data were compared before and after transformation.

RESULTS

Therapeutic gain ranged from 17.5% to 51%. The transformation of TG into NNT yielded no clinically significant difference in efficacy estimate for the range of 17.5% to 47% (N = 29 clinical trials). However, NNT and TG had a nonlinear relationship for some secondary end points. When the relationship between the standard primary and secondary end points was compared, the correlation of TG with clinical disability (Pearson coefficient R = 0.93) was stronger than for NNT. Placebo response rates correlated more strongly with NNT (R = 0.66) than active response rates (R = 0.42; N = 29 clinical trials), although both TG and NNT were sensitive to placebo response rate.

CONCLUSIONS

Transforming efficacy rates into TG or NNT adds no new information to placebo-controlled trials. The variables, TG and NNT, should not be used to compare members of this class of drugs. Migraine therapies can only be compared using well-designed head-to-head studies and not by meta-analysis. Broader measures of efficacy should be used to describe and compare 5-HT(1B/1D) efficacy.

Gastric motor effects of triptans: open questions and future perspectives

Sumatriptan is a 5-HT1B/D receptor agonist of documented efficacy in relieving migraine and associated symptoms such as nausea and vomiting. In the past decade, several studies reported an important delay of gastric emptying induced by sumatriptan in healthy humans. The impact of this gastric motor effect of sumatriptan in migraineurs is difficult to predict: a further delay in gastric emptying could be detrimental (i.e. increased nausea and epigastric symptoms) in patients already having delayed gastric emptying. However, in patients with functional dyspepsia, sumatriptan is also reported to improve gastric accommodation to a meal and reduce perception of gastric distention, hence relieving epigastric symptoms. Thus, reduced visceral perception could be a mechanism involved in reducing nausea during a migraine attack. Paradoxically, sumatriptan is reported both to relieve the nausea of a migraine attack and to have nausea as a side effect. Although careful analysis of the time of onset of nausea may offer a clue as to the origin of this symptom, available data do not support definite conclusions, all the more so because the gastric motor effect of second-generation triptans are still unexplored. Taken together, the available evidence warrants further studies to clarify the following issues: first, the mechanism responsible for the gastric motor effect of sumatriptan [receptor subtype(s) involved; central vs peripheral mechanism]; secondly, the effects on gastric motility/visceral sensitivity of second-generation triptans (which are 5-HT1B/D receptor agonists) and more recent selective 5-HT1D receptor agonists (proposed as investigational antimigraine agents with less potential to induce coronary vasoconstriction through 5-HT1B receptors); finally, the possible use of drugs improving gastric accommodation to a meal in the management of those dyspeptic patients with impaired fundic relaxation/altered visceral sensitivity.

A systematic review of the use of triptans in acute migraine

OBJECTIVE

A systematic review of the literature was undertaken, to consolidate evidence concerning the efficacy and safety of triptans currently available in Canada (sumatriptan, rizatriptan, naratriptan, zolmitriptan), and to provide guidelines for selection of a triptan.

METHODS

Data from published, randomized, placebo-controlled trials were pooled and a combined number needed to treat (NNT) and number needed to harm (NNH) was generated for each triptan. Direct comparative trials of triptans were also examined.

RESULTS

The lowest NNT for headache response/pain-free at one/two hours is observed with subcutaneous sumatriptan. Among the oral formulations, the lowest NNT is observed with rizatriptan and the highest NNT with naratriptan. The lowest NNH is observed with subcutaneous sumatriptan.

CONCLUSIONS

Triptans are relatively safe and effective medications for acute migraine attacks. However, differences among them are relatively small. Considerations in selecting a triptan include individual patient response/tolerance, characteristics of the attacks, relief of associated symptoms, consistency of response, headache recurrence, delivery systems and patient preference.

Almotriptan: a balanced approach to migraine

Effective acute treatment of migraine is possible with the 4HT(1B/1D) agonists (triptans), but their use has been limited in the UK because of concerns about limited efficacy, recurrence of attacks, adverse events, and cost. Almotriptan (Almogran, Lundbeck Ltd, Milton Keynes), the most recently available member of the class, offers some advantages over previously available agents.

Rizatriptan for acute migraine

BACKGROUND

There are a number of different drug treatments for acute migraine, including currently four triptans, with several more likely to become available in the future. There is a need for evidence-based information to help determine the balance of benefit and harm for acute migraine treatment.

OBJECTIVES

To quantitatively assess the efficacy of a single dose of rizatriptan (Maxalt) for treating a single migraine attack using the outcomes of headache response and pain-free response at half-an-hour, one hour, two hours, and sustained relief over 24 hours. To express efficacy in terms of numbers-needed-to-treat (NNTs).

SEARCH STRATEGY

Trials were identified by searching MEDLINE (1966-July 2000), EMBASE (1980-June 2000), the Cochrane Library (Issue 3, 2000) and the Oxford Pain Relief Database (1950-1994). Date of last search: July 2000.

SELECTION CRITERIA

The inclusion criteria were randomised, placebo-controlled trials of rizatriptan for acute migraine; double-blind design; International Headache Society diagnostic criteria for migraine with or without aura; single migraine attack; single-dose treatment at standard doses; adult population; baseline pain of moderate or severe intensity using a four-point standardised rating scale; dichotomous or percentage data for at least one of the main efficacy outcomes; and full journal publication.

DATA COLLECTION AND ANALYSIS

Main outcomes considered were i) headache response at two hours, ii) headache response at one hour, iii) pain-free response at two hours, iv) sustained relief over 24 hours, v) pain-free response at 24 hours and vi) adverse effects. Minor outcomes were headache response and pain-free response at half-an-hour and four hours, and pain-free response at one hour. Dichotomous or percentage data were extracted and used to calculate the relative benefit (RB) and number-needed-to-treat (NNT) for each outcome.

MAIN RESULTS

Seven trials met our inclusion criteria, with 2626 patients given rizatriptan and 902 given placebo. Significant benefit of rizatriptan over placebo was shown for both doses of rizatriptan (5 mg and 10 mg) for all five main efficacy outcomes (ranging from one to 24 hours). A dose response was seen for the main outcomes. It was not possible to analyse adverse effects information in a meaningful way.

REVIEWER'S CONCLUSIONS

Rizatriptan 5 mg and 10 mg are effective in treating acute migraine, with a dose-related increase in efficacy.

The pharmacology of headache

Headache is a common problem which besets most of us at some time or the other. The pharmacology of headache is complex in an overall sense but can be understood in terms of the anatomy and physiology of the pain-producing structures. Migraine can be used as a template to understand the activation of nociceptive systems in the head and thus their neurotransmitter mediation and modulation. In recent years, the role of serotonin (5-HT) in headache pharmacology has been unravelled in the context of both understanding its role in the nociceptive systems related to headache and by exploiting its 5-HT1 receptor subtypes in headache therapeutics. The pharmacology of the head pain systems, as they are known and as they might evolve, are explored in the context of both, the anatomy and physiology of trigeminovascular nociception and in the context of clinical questions, such as those of efficacy, headache recurrence and adverse events.

Current and emerging second-generation triptans in acute migraine therapy: a comparative review

Sterile neurogenic inflammation within cephalic tissue, involving vasodilation and plasma protein extravasation, has been proposed as a pathophysiological mechanism in acute migraine. The action of 5-hydroxytryptamine (5-HT1B/1D) agonists--so-called triptans--on receptors located in meningeal arteries (5-HT1B) and trigeminovascular fiber endings (5-HT1D) has an inhibitory effect on this neurogenic inflammation. Recently, a series of second-generation 5-HT1B/1D agonists (almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, and zolmitriptan) have been developed and are reviewed in this article. Their in vitro pharmacological properties, pharmacokinetics, clinical efficacy, drug interactions, and adverse effects are evaluated and compared to the golden standard in the treatment of acute migraine, sumatriptan.

Migraine pharmacotherapy with oral triptans: a rational approach to clinical management

The recent clinical development of a number of migraine specific 5-HT1B/1D agonist triptans with enhanced lipophilicity (TELs), relative to the first drug of this class sumatriptan, and with a range of different metabolic, pharmacokinetic and receptor affinity profiles, provides the potential for critically different clinical profiles. Eletriptan, naratriptan, rizatriptan and zolmitriptan display both increased stability to first pass metabolic inactivation by monoamine oxidase (MAO-A) and enhanced lipophilicity (4- to > 120-fold more than sumatriptan), leading to increased oral bioavailability (2- to 5-fold more than the 14% reported for oral sumatriptan). Central penetration and increased receptor affinity and selectivity for the neuronal (5-HT1D) receptor also combine to allow for lower total oral dosing (i.e., unit doses of 15 mg or less compared with 50-300 mg doses of sumatriptan) and reduced peripheral exposure to the coronary vasoconstrictor (5-HT1B) receptor. The notable exception being eletriptan, where an active P-glycoprotein blood-brain barrier efflux system effectively negates these benefits and requires an 80 mg oral dose. Differences in the metabolic balance between hepatic P450 (especially CYP 1A2) and MAO-A inactivation lead to potential drug interactions for all TELs with the oral contraceptive pill (OCP), fluvoxamine and the quinilone antibiotics (with increased triptan levels). An important but complex MAO-A interaction between a metabolite of propranolol and rizatriptan mandates dosage reduction (to 5 mg) for rizatriptan in the presence of propranolol treatment. There is also an absolute contraindication for the concurrent administration of the MAO-A inhibitor moclobemide and rizatriptan. All the new-marketed TELs have potential clinical benefits and were well-tolerated relative to sumatriptan. Both rizatriptan (10 mg) and zolmitriptan (2.5 mg and 5 mg) demonstrate at least equivalent efficacy to sumatriptan 25, 50 and 100 mg, respectively, making them suitable first line agents for moderate or severe migraine headaches. Rizatriptan has the fastest onset of effect of the TELs. Naratriptan would appear to have lower recurrent headache rate than sumatriptan, rizatriptan or zolmitriptan. Therefore, for headaches of long duration and with a tendency to recur naratriptan may be the most appropriate treatment. Thus, knowledge of the metabolic, pharmacokinetic and clinical profiles of the TELs facilitates the selection of a triptan which allows optimisation of the clinical benefits for individual patients, minimising the risk of drug interactions and a minimally effective dose to reduce potential adverse events (AEs).

Migraine: a comprehensive review of new treatment options

Headaches are among the most common complaints reported to health care professionals and are classified by the International Headache Society as migraine, tension-type, or cluster, with additional subtypes. Classification and etiology of headache should be determined after thorough review of the patient's history. Once diagnosed, migraine can be treated by preventive or abortive measures. Recent developments add new options, including availability of drugs for intranasal administration (sumatriptan, dihydroergotamine) and 5-HT1B/1D agonists (rizatriptan, zolmitriptan, naratriptan, eletriptan). Although placebo-controlled trials are available, few comparative clinical trials of these agents have been conducted; however, important pharmacologic, pharmacokinetic, and clinical differences exist among the drugs.

Naratriptan: an alternative for migraine

OBJECTIVE

To critically evaluate the literature regarding naratriptan's clinical pharmacology, efficacy, safety, and indications.

DATA SOURCE

A MEDLINE search was conducted for the period from January 1990 to June 1998. Key words used included naratriptan, triptan, serotonin agonists, migraine, and migraine therapy. In addition, pertinent references cited in articles obtained from MEDLINE and product information for triptans were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All original and review articles and abstracts pertaining to naratriptan were reviewed, as were product information extracts. Clinical trials of naratriptan were critically reviewed and compared with pertinent clinical trials of other oral triptans.

DATA SYNTHESIS

The treatment of migraine has been dramatically improved with the use of sumatriptan, other triptans, and serotonin-receptor subtype 1B and 1D agonists. Drawbacks to these medications, however, have included poorly tolerated adverse effects and the recurrence of the migraine. Naratriptan has been recently approved for acute oral migraine therapy. In two Phase III trials of naratriptan compared with placebo, relief at four hours was obtained in 60% and 68% of patients using the 2.5-mg dose, with recurrence of headache in 24 hours in 27% and 28% of patients. The data on migraine recurrence were similar to those of other oral triptans; the efficacy of naratriptan at two hours was not specifically analyzed. Adverse effects of naratriptan were similar to placebo, and its tolerability seemed superior compared with studies of other oral triptans.

CONCLUSIONS

Naratriptan is a promising new oral therapy for acute migraine; it may successfully treat patients who poorly tolerate other triptan therapies or have longer duration migraine headaches.

Serotonin in migraine: theories, animal models and emerging therapies

A role for serotonin in migraine has been supported by changes in circulating levels of serotonin and its metabolites during the phases of a migraine attack, along with the ability of serotonin-releasing agents to induce migraine-like symptoms. The development of serotonin receptor agonists with efficacy in the clinic for the alleviation of migraine pain further implicates serotonin as a key molecule in migraine. Several theories regarding the etiology of migraine have been proposed. The vasodilatory theory of migraine suggested that extracranial arterial dilation during an attack was related to migraine pain; a theory supported when vasoconstrictors such as sumatriptan alleviated migraine pain. The neurological theory of migraine proposed that migraine resulted from abnormal firing in brain neurons. Cortical spreading depression, one facet of the neurological theory, could explain the prodrome of migraine. The neurogenic dural inflammation theory of migraine supposed that the dural membrane surrounding the brain became inflamed and hypersensitive due to release of neuropeptides from primary sensory nerve terminals. Substance P, calcitonin gene related peptide and nitric oxide are all though to play a role in the dural inflammatory cascade. Animal models of migraine have been utilized to study the physiology of migraine and develop new pharmaceutical therapies. One model measures the shunting of blood to arteriovenous anastomoses based on a proposal that migraine primarily involves cranial arteriovenous vasodilation. Another model utilizes electrical stimulation of the trigeminal ganglion to induce neurogenic dural inflammation quantified by the resulting extravasation of proteins. Pharmacological agents such as meta-chlorophenylpiperazine (mCPP) and nitroglycerin have also been used to induce dural extravasation in animals. Both compounds also induce migraine attacks in individuals with a history of migraine. In addition, Fos, a protein produced by activation of the c-fos gene, has been measured as an index of migraine-like pain transmission to the CNS following chemical or electrical stimulation of the trigeminal nerve. A role for serotonin in migraine is further supported by the efficacy of serotonin receptor ligands. Sumatriptan is an agonist at 5-HT1D and 5-HT1B receptor subtypes, and effective in treating migraine pain and associated symptoms. Recently, selective 5-HT1F agonists have been proposed for the treatment of migraine, without the side effects associated with the present 5-HT1D and 5-HT1B receptor agonists. A role for 5-HT2B receptors has also been suggested the initiation of migraine, supporting use of selective 5-HT2B receptor antagonists in migraine. Thus, agents that modulate 5-HT1B, 5-HT1D, 5-HT1F and 5-HT2B receptors either have or may have clinical utility in the therapy of migraine headache.

Improvement in migraine-specific quality of life in a clinical trial of rizatriptan

A validated migraine-specific questionnaire (24-h Migraine Quality of Life Questionnaire: 24-h MQoLQ) was used to assess the impact of migraine and migraine therapy on health-related quality of life during an acute migraine attack. Male and female migraineurs aged 18-55 years were randomized to placebo (n=41), rizatriptan 2.5 mg (n=47), 5 mg (n=74), or 10 mg (n=85) in a triple-blind, placebo-controlled clinical trial. Rizatriptan 5 mg and 10 mg were significantly more efficacious than placebo on pain relief and functional disability. After accounting for multiple comparisons to placebo, rizatriptan 10 mg showed significantly better responses compared to placebo on three of five domains of 24-h MQoLQ (social functioning, migraine symptoms, and feelings/concerns). The O'Brien's Rank Sum Test statistic showed a statistically significant overall difference on the 24-h MQoLQ between the 10 mg rizatriptan and placebo groups (p=0.005) and for the overall dose trend (p< or =0.001).