Rizatriptan: a review of its efficacy in the management of migraine

High Turnover Pd/C Catalyst for Nitro Group Reductions in Water. One-Pot Sequences and Syntheses of Pharmaceutical Intermediates

Commercially available Pd/C can be used as a catalyst for nitro group reductions with only 0.4 mol % Pd loading. The reaction can be performed using either silane as a transfer hydrogenating agent or simply a hydrogen balloon (∼1 atm pressure). With this technology, a series of nitro compounds was reduced to the desired amines in high chemical yields. Both the catalyst and surfactant were recycled several times without loss of reactivity.

Guidelines of the International Headache Society for controlled trials of acute treatment of migraine attacks in adults: Fourth edition

The quality of clinical trials is an essential part of the evidence base for the treatment of headache disorders. In 1991, the International Headache Society Clinical Trials Standing Committee developed and published the first edition of the Guidelines for controlled trials of drugs in migraine. Scientific and clinical developments in headache medicine led to second and third editions in 2000 and 2012, respectively. The current, fourth edition of the Guidelines retains the structure and much content from previous editions. However, it also incorporates evidence from clinical trials published after the third edition as well as feedback from meetings with regulators, pharmaceutical and device manufacturers, and patient associations. Its final form reflects the collective expertise and judgement of the Committee. These updated recommendations and commentary are intended to meet the Society's continuing objective of providing a contemporary, standardized, and evidence-based approach to the conduct and reporting of randomised controlled trials for the acute treatment of migraine attacks.

A double-blind, randomized, multicenter, Italian study of frovatriptan versus rizatriptan for the acute treatment of migraine

The objective of this study was to assess patient satisfaction with acute treatment of migraine with frovatriptan or rizatriptan by preference questionnaire. 148 subjects with a history of migraine with or without aura (IHS 2004 criteria), with at least one migraine attack per month in the preceding 6 months, were enrolled and randomized to frovatriptan 2.5 mg or rizatriptan 10 mg treating 1-3 attacks. The study had a multicenter, randomized, double-blind, cross-over design, with treatment periods lasting <3 months. At the end of the study, patients assigned preference to one of the treatments using a questionnaire with a score from 0 to 5 (primary endpoint). Secondary endpoints were pain-free and pain relief episodes at 2 h, and recurrent and sustained pain-free episodes within 48 h. 104 of the 125 patients (83%, intention-to-treat population) expressed a preference for a triptan. The average preference score was not significantly different between frovatriptan (2.9±1.3) and rizatriptan (3.2±1.1). The rates of pain-free (33% frovatriptan vs. 39% rizatriptan) and pain relief (55 vs. 62%) episodes at 2 h were not significantly different between the two treatments. The rate of recurrent episodes was significantly (p<0.001) lower under frovatriptan (21 vs. 43% rizatriptan). No significant differences were observed in sustained pain-free episodes (26% frovatriptan vs. 22% rizatriptan). The number of patients with adverse events was not significantly different between rizatriptan (34) and frovatriptan (25, p=NS). The results suggest that frovatriptan has a similar efficacy to rizatriptan, but a more prolonged duration of action.

Economic evaluation of pharmacotherapy of migraine pain: a review of the literature

This paper reviews the economic evaluation literature on pharmacotherapy for migraine and identifies important trends and gaps in the literature. Given the tremendous economic burden of migraine and the availability of various therapies for migraine treatment, economic evaluation of alternative therapies plays a critical role in identifying the most cost-effective therapy to optimize health care resource allocation and clinical decisions. Particularly, physicians and clinical administrators are expected to take an active role in resource allocation decisions at the clinical level. Thus, it is important for them to be familiar with the economic evaluation in migraine pain management, and most importantly, methodologies of economic analyses and the associated shortcomings of published estimates. In this paper, the methodological characteristics of these studies are examined and their results are compared and interpreted. Alternative treatment and health outcome measures are defined and data sources described while methods for assessing the direct and indirect costs are explored. Directions for future research are identified and discussed.

Renal Infarction During the Use of Rizatriptan and Zolmitriptan: Two Case Reports

Rizatriptan and zolmitriptan are both used to relieve acute migraine and cluster headaches. The mechanism of action is similar to the other triptans, in that they reverse abnormal cerebral vasodilation through their activity as 5-HT1B receptor agonists. Triptan-induced vasoconstriction is attributed to its activity on peripheral 5-HT1B receptors and has rarely been reported to result in stroke, myocardial infarction and ischemic colitis. We present two cases of renal infarction associated with therapeutic triptan use. The first patient is a 57-year-old man with a history of hypertension that was well controlled on valsartan and hydrochlorothiazide. He was recently diagnosed with cluster headaches and was treated with indomethacin, prednisone, butalbital-acetaminophen-caffeine and hydrocodone without relief. He then received two therapeutic doses of rizatriptan on each of the two days prior to presentation. Subsequently, he presented to the emergency department complaining of nausea, vomiting and right-sided abdominal pain. A computerized tomography (CT) scan of the abdomen and pelvis with intravenous contrast revealed a very large wedge shaped infarction of the right kidney. The second patient is a 34-year-old man with a past medical history significant only for life-long migraine headaches successfully treated for the past six years with zolmitriptan. Shortly after taking one therapeutic dose of zolmitriptan, he presented to the emergency department complaining of nausea and left-sided abdominal pain. A CT scan of the abdomen and pelvis with intravenous contrast revealed multiple wedge-shaped infarctions of the left kidney. Renal infarction was confirmed in both patients by arteriogram of the renal arteries. Although both rizatriptan and zolmitriptan are effective in the treatment of migraine and cluster headaches, they may induce peripheral vasospasm leading to renal infarction.

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.

Time to pain freedom and onset of pain relief with rizatriptan 10 mg and prescription usual-care oral medications in the acute treatment of migraine headaches: A multicenter, prospective, open-label, two-attack, crossover study

BACKGROUND

Patients and physicians consider rapid onset of pain relief and pain freedom among the most important attributes of migraine therapy.

OBJECTIVE

This study compared the effectiveness of rizatriptan 10 mg and usual-care oral migraine medications in everyday clinical practice settings.

METHODS

This was a multicenter, prospective, open-label study. Adult patients treated 2 sequential migraine attacks with rizatriptan 10 mg and a usual-care prescription migraine medication in a crossover manner. Patients chose which medication to take first. They recorded the treatment outcomes using a stopwatch and a treatment diary. End points included time to pain freedom (length of time from dosing to no pain) and time to onset of pain relief (mean time to onset of pain relief and proportion of patients reporting onset of pain relief at 30 minutes), satisfaction with treatment, and medication preference. Information on adverse events was collected through the normal post-marketing reporting mechanism. Comparisons were made using the paired t test and McNemar test for continuous and categorical variables, respectively. A mixed model, accounting for multiple observations per patient, was fitted for the time to pain freedom, controlling for age, sex, treatment period, medication, and headache severity.

RESULTS

Of 2346 enrolled patients, 1489 treated 2 migraines in a crossover manner and were included in the analysis (86.8% women, 13.2% men; mean age, 41.7 years). A majority of patients (80.6%) treated both migraines with oral triptans. The most commonly used nontriptans were NSAIDs (5.4%), butalbital-containing combinations (4.3%), and isometheptene (3.4%). Over-the-counter medications were used by 22.3% of patients during rizatriptan-treated attacks and by 28.9% of patients during attacks treated with usual-care medications. The mean time to pain freedom was significantly shorter when an attack was treated with rizatriptan compared with usual-care medications (222 vs 298 minutes, respectively; P<0.001), and the onset of pain relief was significantly more rapid (85 vs 107 minutes; P=0.003), with significant differences noted as early as 15 minutes after dosing (P<0.001). The findings remained similar after adjustment for potential confounding factors. No significant sequence effect was detected. Significantly more patients reported being very satisfied or satisfied with rizatriptan compared with usual-care medications (65.4% vs 57.7%; P<0.001) and preferred rizatriptan (58.0% vs 42.0%; P<0.001). One female patient reported having hives and itchy skin the day after taking rizatriptan; the symptoms subsided after treatment with methylprednisolone.

CONCLUSIONS

In this selected population, treatment of a migraine attack with rizatriptan 10 mg was associated with a faster time to pain freedom and onset of pain relief compared with treatment with usual-care oral migraine medications. Patients reported greater satisfaction with and preference for rizatriptan.

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.

A review of the effects of almotriptan and other triptans on clinical trial outcomes that are meaningful to patients with migraine

BACKGROUND

Traditional end points in clinical trials of migraine therapy, such as 2-hour pain response, may not fully address the outcomes patients consider most important: rapid and sustained freedom from pain over 24 hours, and a low, placebo-like incidence of adverse events. A composite efficacy measure such as the sustained pain-free rate (no pain by 2 hours after dosing, no recurrence, no use of rescue medication from 2 to 24 hours after dosing) may be more appropriate.

OBJECTIVE

Clinically relevant differences between almotriptan and other triptans were reviewed in the context of the attributes of acute migraine treatment that patients consider most important.

METHODS

This review was based on published reports of open-label and placebo-controlled clinical trials of almotriptan, results of a survey concerning the attributes patients consider most important in a migraine medication, and a published meta-analysis of 53 placebo-controlled clinical trials of triptans involving >24,000 patients.

RESULTS

Almotriptan was effective and well tolerated in the placebo-controlled clinical trials; results of the 6- and 12-month open-label studies supported its good tolerability profile. A respective 87% and 86% of respondents to the patient survey indicated that they considered complete freedom from pain and no recurrence among the most important attributes of migraine treatment, both of which are included in the sustained pain-free rate. In the meta-analysis, almotriptan had a favorable efficacy and tolerability profile compared with other triptans, particularly with respect to sustained pain-free rate, which was significantly higher with almotriptan 12.5 mg compared with sumatriptan 100 mg (25.9% vs 20.0%, respectively; P < 0.05). In addition, the placebo-subtracted rate of adverse events was significantly lower with almotriptan compared with sumatriptan (1.8% vs 4.4%, respectively; P < 0.05). Results of a head-to-head placebo-controlled trial of almotriptan 12.5 mg and sumatriptan 100 mg supported the balance of efficacy and tolerability observed for almotriptan in the meta-analysis.

CONCLUSIONS

Data from clinical trials suggest that almotriptan is effective and well tolerated in the treatment of acute migraine pain. Based on a sustained pain-free rate that is among the highest and an adverse-event rate that is among the lowest for the triptans, almotriptan represents a therapeutic option for the initial treatment of acute migraine with or without aura.

Efficacy and safety of eletriptan 20 mg, 40 mg and 80 mg in Japanese migraineurs

This prospective multicentre, double-blind, randomized, parallel-group, placebo-controlled trial evaluated the efficacy and safety of a single dose of eletriptan 20 mg, 40 mg and 80 mg in Japanese migraineurs. A total of 402 adult Japanese migraineurs were diagnosed using International Headache Society (IHS) criteria. At 2 h after a single dose, the headache response rates of eletriptan 20 mg, 40 mg, 80 mg and placebo were 64%, 67%, 76% and 51%, respectively, with all doses significantly superior to placebo (P<0.05). Eletriptan had a statistically significant dose response for headache relief and pain-free response at 2 h post-dose (P=0.0011 and P=0.0291, respectively). Most all-causality adverse events were mild and there were no deaths or discontinuations. Saliva samples were used to assess serum eletriptan levels 2 h post-dose. Pharmacokinetic evaluations showed no clinically significant differences between Japanese and Western subjects. Eletriptan was shown to be efficacious, safe, and well tolerated in Japanese migraineurs.

Impact of chest pain on cost of migraine treatment with almotriptan and sumatriptan

Chest-related symptoms occur with all triptans; up to 41% of patients with migraine who receive sumatriptan experience chest symptoms, and 10% of patients discontinue treatment. Thus, the cost of chest pain-related care was estimated in migraineurs receiving almotriptan 12.5 mg versus sumatriptan 50 mg. A population-based, retrospective cohort study used data to quantify the incidence and costs of chest pain-related diagnoses and procedures. An economic model was constructed to estimate annual cost savings per 1000 patients receiving almotriptan versus sumatriptan based on the reported rates of chest pain. Annual direct medical cost avoided was calculated for a hypothetical health plan covering 1 million lives. Among a cohort of 1390 patients, the incidence of chest pain-related diagnoses increased significantly by 43.6% with sumatriptan (P=.003). Aggregate costs for chest pain-related diagnoses and procedures increased from $22,713 to $30,234. Payments for inpatient hospital services, costs for primary care visits, and costs for outpatient hospital visits increased by over 100%, 53.1%, and 14.4%, respectively. The model predicted $11,215 in direct medical cost savings annually per 1000 patients treated with almotriptan versus sumatriptan. Annual direct medical costs avoided totaled $194,358, and when applied to recent estimates of 86 million lives currently covered by almotriptan treatment, translates into an annual cost savings of just under $17 million for chest pain and associated care. Thus, using almotriptan in place of sumatriptan will likely reduce the cost of chest pain-related care.

A long-term open-label study of oral almotriptan 12.5 mg for the treatment of acute migraine

OBJECTIVE

Evaluate the long-term tolerability of almotriptan 12.5 mg for the treatment of acute migraine attacks occurring over a 6-month period.

BACKGROUND

Almotriptan is a second-generation 5-HT(1B/1D) agonist that exhibits vascular selectivity for meningeal arteries and has demonstrated efficacy for the treatment of acute migraine in short-term controlled trials.

METHODS

This was a 6-month open-label study. Adults (18 years of age or older) were required to have a diagnosis of acute migraine with or without aura (according to the diagnostic criteria of the International Headache Society), a history of at least 1 year of moderate-to-severe migraine pain with at least two and a maximum of six migraines per month, and at least 24 hours of freedom from head pain between attacks. Patients were instructed to take a single 12.5-mg dose of almotriptan at the onset of a migraine attack. If migraine pain did not disappear in 2 hours, escape medication could be taken; if relapse occurred in less than 24 hours, a second 12.5-mg dose could be taken. Tolerability was assessed from the nature and incidence of all adverse events, and efficacy was assessed according to the end point of pain relief 2 hours following almotriptan administration.

RESULTS

Of 585 patients treated, 582 were included in the intent-to-treat population. The most frequent drug-related adverse events were nausea (3.1%) and dizziness (2.4%). No serious drug-related adverse events were reported, and no deaths occurred. Adverse events led to discontinuation of treatment in 36 patients (6.2%). Drug-related chest pain was reported in 9 patients (1.5%). Seventy-six percent of patients achieved pain relief at 2 hours for all attacks treated, and 49% were pain-free at 2 hours. After a second dose of almotriptan 12.5 mg, pain relief was achieved in 87% of attacks, and 59% were pain-free. Pain relief and pain-free rates were higher among those with moderate baseline pain.

CONCLUSIONS

When taken at attack onset, almotriptan 12.5 mg is well tolerated, safe, and effective for the long-term treatment of acute migraine.

Tripstar: a comprehensive patient-based approach to compare triptans

Several second-generation triptans have been introduced that differ in their pharmacologic profiles relative to each other and to sumatriptan. As therapeutic options multiply, clinicians must be able to distinguish among these compounds. Recently, a meta-analysis was conducted on data from 53 double-blind, randomized, placebo- or active-controlled trials involving over 24,000 patients receiving oral triptans. Results indicated that almotriptan 12.5 mg, rizatriptan 10 mg, and eletriptan 80 mg are generally superior to sumatriptan 100 mg based on individual treatment attributes, such as pain relief, sustained pain freedom, consistency of response, and tolerability. Meta-analyses are limited, however, as the analysis can only be performed for individual end points, whereas patients and prescribers balance a variety of treatment attributes when assessing drug acceptability. A flexible overall scoring system ("Tripstar") is proposed that compares triptans to a hypothetical "ideal" using meta-analysis data combined with ratings of the relative importance of clinically relevant treatment criteria. An informal test of the Tripstar model indicated that sumatriptan is most similar to a hypothetical ideal for both mild and severe migraine, primarily due to its high worldwide clinical exposure. However, after exclusion of worldwide exposure as a contributing factor, almotriptan 12.5 mg is most similar to the ideal, principally because of its good tolerability. Further tests of the Tripstar model are planned that will gauge the relative importance of a broader range of attributes.

Migraine treatment outcomes with rizatriptan in triptan-naive patients: a naturalistic study

BACKGROUND

The 5-hydroxytryptamine(1B/1D) agonists, or triptans, are the newest class of drugs to become available for the acute treatment of migraine. The class currently includes sumatriptan, zolmitriptan, naratriptan, and rizatriptan. The efficacy of rizatriptan in the acute treatment of migraine has been established against placebo and other oral triptans in controlled comparative trials.

OBJECTIVE

The US Migraine Assessment Protocol (USMAP) collected data on the use of rizatriptan in a naturalistic setting reflecting clinical practice. This paper presents results for patients enrolled in the USMAP study who had never taken a triptan before the study.

METHODS

At enrollment, 216 patients completed a questionnaire describing their responses to their current nontriptan medications. They were then given specially packaged samples of 4 standard 10-mg rizatriptan tablets and 4 orally disintegrating 10-mg rizatriptan tablets (wafers) and were asked to take a different formulation for each of their next 2 attacks, the sequence to be at their discretion. Within approximately 24 hours after taking rizatriptan, patients were to call a toll-free number to report their responses to rizatriptan using an interactive voice-response system.

RESULTS

Within 2 hours after initial dosing of rizatriptan, significantly more patients taking either the rizatriptan tablet or the rizatriptan wafer reported onset of pain relief, had become largely symptom free, and were able to resume usual activities compared with their baseline responses to nontriptans (P < 0.05). In addition, compared with their baseline responses to nontriptans, significantly more patients taking either rizatriptan formulation had mild or no pain 2 hours after dosing (P < 0.05). More than twice as many patients taking the rizatriptan tablets or wafers were either somewhat or very satisfied with the medication compared with their satisfaction with nontriptans (P < 0.05).

CONCLUSIONS

In the naturalistic setting of this study, migraineurs who had not previously taken a triptan medication reported more rapid relief of pain, more effective pain relief, and more rapid resumption of normal activities when taking rizatriptan tablets or wafers than when taking a nontriptan medication. Patients dissatisfied with their current nontriptan migraine therapy may benefit from treatment with rizatriptan.

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.

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.

5-HT(1B/D) receptor agonist, SKF99101H, induces locomotor hyperactivity in the guinea pig

Previous studies in guinea pigs have shown that while a serotonin 5-HT(1B/D) receptor agonist, GR46611, does not induce locomotor activation when given alone, it markedly enhances the locomotor response to selective 5-HT(1A) receptor agonists, 8-OH-DPAT and buspirone. In these studies, we found that another 5-HT(1B/D) agonist, 3-(2-dimethylaminoethyl)-4-chloro-5-propoxyindole hemifumarate (SKF99101H), significantly elevated locomotor activity in guinea pigs when given alone. We assessed the relative contribution of 5-HT1(1A) and 5-HT(1B/D) receptors in the mediation of this effect. Activity was measured by photobeam interrupts in opaque Perspex cylinders linked to a computer. SKF99101H (20 mg/kg s. c.) significantly increased the locomotor activity in guinea pigs. The locomotor stimulant effect of SKF99101H (20 mg/kg s.c) was reversed by the selective 5-HT(1B/D) receptor antagonist N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2'-methyl-4'-(5-methyl -1,2,4-oxadiazol-3-yl)[1,1biphenyl]4-carboxamide (GR127935; 0.06-0. 25 mg/kg s.c.). The 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexanecarboxamide trihydrochloride (WAY100635; 0.05-0.25 mg/kg s.c.), slightly but significantly attenuated the hyperactivity induced by SKF99101H. These findings suggest that 5-HT(1B/D) receptor agonists may require concomitant activation of 5-HT(1A) receptors to induce locomotor activity in guinea pigs. The 5-HT(2A) receptor antagonist 6[2-[4-[bis(4-fluorophenyl)methylene]-1-piperidinyl]-ethyl]-7-methyl- 5H-thiazol[3,2-a]pyrimidin-5-one (ritanserin) had no effect on SKF99101H-induced hyperactivity, suggesting that these receptors are not involved in the mediation of SKF99101H-induced hyperactivity. SKF99101H-induced hyperactivity was significantly attenuated by the D(1) dopamine receptor antagonist SCH 23390 (0.005-025 mg/kg), but not by the D(2) dopamine receptor antagonist raclopride (0.25-1.0 mg/kg), possibly suggesting the selective involvement of D(1) dopaminergic receptors in the mediation of the stimulant actions of the 5-HT(1B/D) agonist.