Parenteral vs. oral sumatriptan and naratriptan: plasma levels and efficacy in migraine. a comment

Relationship of dihydroergotamine pharmacokinetics, clinical efficacy, and nausea-A narrative review

OBJECTIVE

To assess the relationships between dihydroergotamine (DHE) pharmacokinetic (PK) parameters, clinical efficacy, and nausea incidence to determine a DHE PK profile that optimizes efficacy while minimizing adverse events (AEs), particularly nausea.

BACKGROUND

Dihydroergotamine is a widely used option for the acute treatment of migraine. Although multiple DHE dosage forms, with varying PK and AE profiles, have been evaluated in randomized controlled trials (RCTs), the relationships between PK profile, efficacy, and the common DHE-related AE, nausea, have not been comprehensively evaluated.

METHODS

A literature search identified RCTs evaluating the efficacy (2-h pain relief [2hPR]) of different DHE dosage forms. The PK profiles for these DHE dosage forms were determined from published literature. Univariate regression analyses were performed to determine the PK parameters that best predicted 2hPR across DHE dosage forms. The relationship between maximum plasma concentration (Cmax) and nausea incidence for various dosage forms was determined from published Phase 1 trials.

RESULTS

The literature search identified nine RCTs with DHE dosage forms that reported 2hPR: DHE liquid nasal spray (four studies), DHE administered subcutaneously (three), and DHE administered via oral pulmonary inhalation (two). The DHE PK parameters that best predicted 2hPR rates were Cmax and area under the curve from time zero to 0.5 h post-dose (AUC0-0.5h) (R2 = 0.59 for each). Across Phase 1 trials, nausea incidence was minimal when Cmax was <2500 pg/mL but increased in a log-linear manner when Cmax exceeded ~2500 pg/mL.

CONCLUSIONS

The maximum concentration and AUC over the first 30 min following DHE administration were associated with increasing rates of 2hPR and a Cmax below ~2500 pg/mL was associated with low incidences of nausea. We suggest that this may be an optimal profile for a DHE delivery form. Further research to test this hypothesis is warranted.

Influence of metabolic state and body composition on the action of pharmacological treatment of migraine

Migraine is a disabling neurovascular disorder among people of all ages, with the highest prevalence in the fertile years, and in women. Migraine impacts the quality of life of affected individuals tremendously and, in addition, it is associated with highly prevalent metabolic diseases, such as obesity, diabetes mellitus and thyroid dysfunction. Also, the clinical response to drugs might be affected in patients with metabolic disease due to body composition and metabolic change. Therefore, the efficacy of antimigraine drugs could be altered in patients with both migraine and metabolic disease. However, knowledge of the pharmacology and the related clinical effects of antimigraine drugs in patients with metabolic disease are limited. Therefore, and given the clinical relevance, this article provides a comprehensive overview of the current research and hypotheses related to the influence of metabolic state and body composition on the action of antimigraine drugs. In addition, the influence of antimigraine drugs on metabolic functioning and, vice versa, the influence of metabolic diseases and its hormonal modulating medication on migraine activity is outlined. Future exploration on personalizing migraine treatment to individual characteristics is necessary to enhance therapeutic strategies, especially given its increasing significance in recent decades.

Evaluation of sex differences in the pharmacokinetics of oral sumatriptan in healthy Korean subjects using population pharmacokinetic modeling

Sumatriptan was introduced in 1983, as the first of the triptans, selective 5‐hydroxytryptamine (5‐HT_1B/1D) receptor agonists, to treat moderate to severe migraine. Migraine predominates in females. Although there have been reports of sex differences in migraine‐associated features and pharmacokinetics (PKs) of some triptans, sex differences in the PKs of oral sumatriptan have never been evaluated in Korean. We conducted this study of oral sumatriptan to assess the sex differences in Korean population. Thirty‐eight healthy Korean subjects who participated in two separate clinical studies receiving a single oral dose of 50 mg sumatriptan with the same protocols were included in this analysis. A total of 532 sumatriptan concentration observations were used for a population PK modeling. Validation of final population PK model of sumatriptan was performed using bootstrap and visual predictive check. The PK profile of oral sumatriptan was adequately described by a one‐compartmental model with combined transit compartment model and a first‐order absorption. The covariate analysis showed that the clearance of oral sumatriptan was significantly higher in males than in females (male: 444 L/h, female: 281 L/h). Our results showed that there were sex differences in the clearance of oral sumatriptan. These results encourage further studies to establish the sumatriptan pharmacokinetic–pharmacodynamic model considering sex‐related PK differences, which may help to determine optimal dosing regimens for effective treatment of migraine in males and females. Clinical trial registration: CRIS Registration No. KCT0001784.

Naratriptan is as effective as sumatriptan for the treatment of migraine attacks when used properly. A mini-review

BACKGROUND

Naratriptan, marketed in a low oral dose of 2.5 mg, is generally regarded as a less-effective triptan with a slower onset of action than most other triptans in the treatment of migraine attacks. In this review, naratriptan will be compared with sumatriptan, the standard triptan.

METHODS

Papers on pharmacodynamics and pharmacokinetics and results from comparative clinical trials with oral and subcutaneous naratriptan versus other triptans were retrieved from PubMed.

RESULTS

Naratriptan and sumatriptan have similar effects in relevant animal models. In a randomized controlled trial, oral naratriptan 2.5 mg is less effective than oral sumatriptan 100 mg after both 2 h and 4 h. In contrast, oral naratriptan 10 mg has a similar time-effect curve as oral sumatriptan 100 mg, in both its steepness and the efficacy at 2 h and 4 h. Subcutaneous naratriptan 10 mg (88% pain free at 2 h) was in one trial superior to subcutaneous sumatriptan 6 mg (55% pain free at 2 h).

CONCLUSION

Naratriptan was marketed for the treatment of migraine attacks as the "gentle triptan" in a low oral dose of 2.5 mg, a dose with no more adverse events than placebo. This low dose results in the slow onset of action and low efficacy of oral naratriptan, but in high doses oral naratriptan is similar to oral sumatriptan. Based on one randomized controlled trial, subcutaneous naratriptan has probably the greatest effect of any triptan.

Pharmacological strategies to treat attacks of episodic migraine in adults

INTRODUCTION

Migraine patients prioritize early complete relief of headache and associated symptoms, sustained freedom of pain, and good tolerability. One major obstacle for the successful use of drug treatment of migraine attack is that the speed of action of triptans, 5-HT_1B/1D receptor agonists, is delayed.

AREAS COVERED

In this review, the author discusses the following features of acute migraine drugs: pharmacology; pharmacokinetics, and absorption of drugs during migraine attacks. Next, dose-response curves for effect; and the delayed onset of action is reviewed. In the more clinical part of the review, the following items are discussed: overall clinical judgments; comparison of triptans; comparison of triptans with NSAIDs; early intervention with triptans; medication-overuse headache; comments on the effect of gepants; and the general principle of acute migraine therapy.

EXPERT OPINION

The delay in the onset of effect of acute migraine drugs is likely due to a complex antimigraine system involving more than one site of action. Investigations into the mechanisms of the delay should have a high priority, both in studies with animals, migraine models, and in migraine patients during attacks. Non-oral administration of antimigraine drugs resulting in early absorption of drugs should be developed as they possibly also can increase E_max.

Evaluation of 2-Hour Post-Dose Efficacy of Lasmiditan for the Acute Treatment of Difficult-to-Treat Migraine Attacks

OBJECTIVE

To identify factors predicting response (2-hour headache pain freedom or most bothersome symptom freedom) to lasmiditan based on individual patient characteristics, migraine disease characteristics, and migraine attack characteristics. Further, efficacy specifically in difficult-to-treat patient/migraine disease characteristics or attack characteristics (ie, historically considered less responsive to certain acute therapies) subgroups was analyzed.

BACKGROUND

Knowledge of factors associated with a positive or negative response to acute treatment would be useful to practitioners prescribing acute treatments for migraine. Additionally, practitioners and patients would benefit from understanding the efficacy of lasmiditan specifically in subgroups of patients with migraine disease characteristics and migraine attack characteristics historically associated with decreased pain threshold, reduced efficacy of acute treatment, or increased burden of migraine.

METHODS

Pooled analyses were completed from 2 Phase 3 double-blind clinical trials, SPARTAN and SAMURAI. Data from baseline to 2 hours after taking lasmiditan (50, 100, or 200 mg) or placebo were analyzed to assess efficacy based on patient characteristics, migraine disease characteristics, and migraine attack characteristics. A total of 3981 patients comprising the intent-to-treat population were treated with placebo (N = 1130), lasmiditan 50 mg (N = 598), lasmiditan 100 mg (N = 1133), or lasmiditan 200 mg (N = 1120). Data were analyzed for the following efficacy measures at 2 hours: headache pain freedom and most bothersome symptom freedom.

RESULTS

None of the analyzed subgroups based on individual patient characteristics, migraine disease characteristics, or migraine attack characteristics predicted headache pain freedom or most bothersome symptom freedom response at 2 hours following lasmiditan treatment (interaction P ≥ .1). For the difficult-to-treat patient/migraine disease characteristics subgroups (defined as those with ≥24 headache days in the past 3 months, duration of migraine history ≥20 years, severe disability [Migraine Disability Assessment score ≥21], obesity [≥30 kg/m2 ], and history of psychiatric disorder), single doses of lasmiditan (100 or 200 mg) were significantly more effective than placebo (P ≤ .002) in achieving both endpoints. Headache pain freedom response rates for higher doses of lasmiditan were numerically greater than for lower doses of lasmiditan. For the difficult-to-treat migraine attack subgroups, patients with severe headache, co-existent nausea at the time of treatment, or who delayed treatment for ≥2 hours from the time of headache onset, both endpoint response rates after lasmiditan 100 or 200 mg were significantly greater than after placebo. Among those who delayed treatment for ≥4 hours from the time of headache onset, headache pain freedom response rates for the 200 mg dose of lasmiditan met statistical significance vs placebo (32.4% vs 15.9%; odds ratio = 2.7 [1.17, 6.07]; P = .018). While the predictors of response interaction test showed similar efficacy of lasmiditan vs placebo across subgroups defined by baseline functional disability (mild, moderate, or needs complete bed rest) at the time of treatment, analyses of lasmiditan efficacy within the subgroup "needs complete bed rest" appeared to show less efficacy (eg, in the 200 mg vs placebo group, 25.9% vs 18.5%; odds ratio = 1.56 [0.96, 2.53]; P = .070).

CONCLUSIONS

Efficacy of lasmiditan 200 and 100 mg for headache pain freedom and most bothersome symptom freedom at 2 hours post-treatment was generally not influenced by the individual patient characteristics, migraine disease history, or migraine attack characteristics that were analyzed. In the analyses of difficult-to-treat subgroups, patients receiving lasmiditan achieved greater responses (2-hour headache pain freedom and most bothersome symptom freedom) vs placebo recipients.

Why is the therapeutic effect of acute antimigraine drugs delayed? A review of controlled trials and hypotheses about the delay of effect

In randomised controlled trials (RCTs) of oral drug treatment of migraine attacks, efficacy is evaluated after 2 hours. The effect of oral naratriptan 2.5 mg with a maximum blood concentration (Tmax ) at 2 hours increases from 2 to 4 hours in RCTs. To check whether such a delayed effect is also present for other oral antimigraine drugs, we hand-searched the literature for publications on RCTs reporting efficacy. Two triptans, 3 nonsteroidal anti-inflammatory drugs (NSAIDs), a triptan combined with an NSAID and a calcitonin gene-related peptide receptor antagonist were evaluated for their therapeutic gain with determination of time to maximum effect (Emax ). Emax was compared with known Tmax from pharmacokinetic studies to estimate the delay to pain-free. The delay in therapeutic gain varied from 1-2 hours for zolmitriptan 5 mg to 7 hours for naproxen 500 mg. An increase in effect from 2 to 4 hours was observed after eletriptan 40 mg, frovatriptan 2.5 mg and lasmiditan 200 mg, and after rizatriptan 10 mg (Tmax  = 1 h) from 1 to 2 hours. This strongly indicates a general delay of effect in oral antimigraine drugs. A review of 5 possible effects of triptans on the trigemino-vascular system did not yield a simple explanation for the delay. In addition, Emax for triptans probably depends partly on the rise in plasma levels and not only on its maximum. The most likely explanation for the delay in effect is that a complex antimigraine system with more than 1 site of action is involved.

A Randomized Trial Comparing the Pharmacokinetics, Safety, and Tolerability of DFN-02, an Intranasal Sumatriptan Spray Containing a Permeation Enhancer, With Intranasal and Subcutaneous Sumatriptan in Healthy Adults

OBJECTIVE/BACKGROUND

Intranasal sumatriptan (Imitrex^® ) may be an alternative for patients who refuse injections and cannot tolerate oral agents, but due to low bioavailability and slow absorption, the clinical utility of the currently marketed formulation is limited, highlighting an unmet need for an effective non-oral migraine medication with a rapid onset of action. To overcome the slow absorption profile associated with intranasal administration, we evaluated the impact of 1-O-n-Dodecyl-β-D-Maltopyranoside (DDM, Intravail A-3™), a permeation enhancer, on sumatriptan's pharmacokinetic profile by comparing the pharmacokinetic characteristics of two commercial sumatriptan products, 4 mg subcutaneous and 6 mg subcutaneous in healthy adults, with DFN-02 - a novel intranasal agent comprised of sumatriptan 10 mg plus 0.20% DDM. We also determined the pharmacokinetic characteristics of DDM and evaluated its safety and tolerability.

METHODS

We conducted two studies: a randomized, three-way crossover study comparing monodose and multidose devices for delivery of single doses of DFN-02 with commercially available intranasal sumatriptan 20 mg in 18 healthy, fasted adults, and an open-label, randomized, single-dose, three-way crossover bioavailability study comparing DFN-02 with 4 mg and 6 mg subcutaneous sumatriptan in 78 healthy, fasted adults. In the study comparing DFN-02 with IN sumatriptan, subjects received a single dose of DFN-02 (sumatriptan 10 mg plus DDM 0.20%) via monodose and multidose delivery systems with at least 5 days between treatments. In the comparison with SC sumatriptan, subjects received a single dose of each treatment with at least 3 days between treatments. In both studies, blood was sampled for pharmacokinetic evaluation of sumatriptan and DDM through 24 hours post-dose; safety and tolerability were monitored throughout.

RESULTS

In the comparison with commercially available intranasal sumatriptan 20 mg, DFN-02 had a more rapid absorption profile; t_max was 15 minutes for DFN-02 monodose, 10.2 minutes for DFN-02 multidose, and 2.0 hours for commercially available intranasal sumatriptan 20 mg. Compared with 4 and 6 mg subcutaneous sumatriptan, DFN-02's median t_max (10 minutes) was significantly earlier (15 minutes; P < .0001). Mean sumatriptan exposure metrics were similar for DFN-02 and 4 mg sumatriptan: AUC_0-2 : 35.12 and 44.82 ng*hour/mL, respectively; AUC_0-∞ : 60.70 and 69.21 ng*hour/mL, respectively; C_max : 51.79 and 49.07 ng/mL, respectively. With 6 mg subcutaneous sumatriptan, these exposure metrics were about 50% larger (AUC_0-2 : 67.17 ng*hour/mL; AUC_0-∞ : 103.78 ng*hour/mL; C_max : 72.75 ng/mL). Inter-subject variability of AUC_0-2 , AUC_0-∞ , and C_max was 42-58% for DFN-02, 15-22% for 4 mg subcutaneous sumatriptan, and 15-25% for 6 mg subcutaneous sumatriptan. DDM exposure was low (mean C_max : 1.63 ng/mL), t_max was 30 minutes, and it was undetectable by 4 hours. There were no serious adverse events, discontinuations due to adverse events, or remarkable findings for vital signs, physical examinations (including nasal and injection site examinations), or clinical laboratory assessments. The overall incidence of adverse events was comparable across treatments, and all treatment-related events were mild in severity. Adverse events occurring in ≥10% of subjects were dysgeusia (19%), headache (18%), nausea (15%), paresthesia (15%), and dizziness (12%).

CONCLUSIONS

In healthy subjects, DFN-02, an intranasal spray containing 10 mg sumatriptan plus DDM, had a more rapid absorption profile than commercially available intranasal sumatriptan 20 mg, and systemic exposure from a single-dose administration of DFN-02 was similar to 4 mg SC sumatriptan and two-thirds that of 6 mg SC sumatriptan. With DFN-02, plasma sumatriptan peaked 5 minutes earlier than with both subcutaneous formulations. Systemic exposure to sumatriptan was similar with DFN-02 and 4 mg subcutaneous sumatriptan; both yielded lower systemic exposure than 6 mg subcutaneous sumatriptan. Systemic exposure to DFN-02's excipient DDM was short-lived. DFN-02's safety and tolerability appear to be comparable to subcutaneous sumatriptan. Addition of a permeation enhancer improved the absorption profile compared with commercially available intranasal sumatriptan 20 mg.

Sumatriptan: a review of its pharmacokinetics, pharmacodynamics and efficacy in the acute treatment of migraine

INTRODUCTION

Sumatriptan was developed more than 20 years ago as a 5-HT1B/1D receptor agonist, the first drug in a new class of specific anti-migraine drugs, the triptans. A large amount of information and experience has been gained from the clinical trials undertaken as well the various formulations of sumatriptan used over this period of time.

AREAS COVERED

This evaluation specifically reviews the pharmacokinetics, pharmacodynamics, clinical efficacy, and safety of different formulations and dosages of sumatriptan used for the acute treatment of migraines. Special clinical trials of the timing of dosage and sumatriptan in combination with other triptans as well as non-triptan drugs are also included.

EXPERT OPINION

Oral sumatriptan is effective, but not in a convincing majority (60%) of patients in clinical trials. Sumatriptan has failed to show superiority over more standard and cheaper treatment such as aspirin or aspirin plus metoclopramide. In addition, migraine patients want to quickly become pain free, and to remain pain free, but oral sumatriptan at 100 mg managed to keep patients pain free for 24 h is only 20% of cases. Even though sumatriptan has been a major step forward in providing a new specific therapy for the treatment of migraines, there are still are limitations in its use. There is still an unmet need to develop new non-triptan, anti-migraine drugs which act as effective treatment for those who suffer with migraines.

Taking the negative view of current migraine treatments: the unmet needs

Acute migraine treatment is given to abolish ongoing attacks, while prophylactic migraine treatment is given on a daily basis to prevent the occurrence of migraine attacks as far as possible. The majority of migraine patients do not use the specific acute anti-migraine drugs, the triptans. Thus, only 10% (Denmark) to 35% (France) of migraine patients use triptans. This is most likely due to relatively low efficacy. Thus, in randomized controlled trials (RCTs) pain freedom after 2 hours ranges from 12% (frovatriptan 2.5 mg) to 40% (rizatriptan 10 mg). For prophylactic treatment (propranolol, valproate, topiramate) a response (at least a 50% reduction in migraine frequency) is observed in 40-50%. In addition, prophylactic treatment is hampered by adverse events and withdrawals. There is a need for new acute anti-migraine drugs and targets are already available and there are more to come. It has been estimated that approximately 2% of the adult population need prophylactic treatment because of frequent migraine attacks. For prophylactic migraine drugs there is an even greater need for new drugs than for acute drug treatment.

Pharmacokinetic evaluation of frovatriptan

INTRODUCTION

Migraine is the most common painful neurological disorder, affecting 13% of the general population. Triptans represent a powerful pharmacological tool in acute migraine treatment, however, a significant portion of treated patients cannot have access to this class due to possible adverse affects. Today, a total of seven triptan molecules are available, representing a commonly prescribed migraine treatment. Although there is a need of extensive use of triptans, only 25% of migraine patients are using triptans.

AREAS COVERED

This review includes triptans and evidence for the use of frovatriptan. A systematic approach is used to discuss the pharmacodynamic and pharmacokinetic aspects of frovatriptan, considering the emerging data on the clinical efficacy of frovatriptan in the treatment of migraine and cluster headaches. The data were obtained by searching the following key words in MEDLINE: pharmacokinetic, pharmacodynamic, triptans, frovatriptan, migraine, menstrual migraine, relatively to the period 1988 - 2011.

EXPERT OPINION

Frovatriptan has been developed in order to improve safety and efficacy of triptans. It shows a favorable tolerability and efficacy profile, limited to 24/48-h headache recurrence, when compared with other triptans. Preclinical data suggest that the pharmacokinetic profile of frovatriptan may differ from other available triptans. In fact, among triptans, frovatriptan showed the highest potency at the 5-HT1B receptor (8.2) and the longer half-life (26 h). These parameters determine the clinical properties of frovatriptan; in particular the lowest rate of headache recurrence in comparison with other triptans.

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.

Why pharmacokinetic differences among oral triptans have little clinical importance: a comment

Triptans, selective 5-HT1B/1D receptor agonists, are specific drugs for the acute treatment of migraine that have the same mechanism of action. Here, it is discussed why the differences among kinetic parameters of oral triptans have proved not to be very important in clinical practice. There are three main reasons: (1) the differences among the kinetic parameters of oral triptans are smaller than what appears from their average values; (2) there is a large inter-subject, gender-dependent, and intra-subject (outside/during the attack) variability of kinetic parameters related to the rate and extent of absorption, i.e., those which are considered as critical for the response; (3) no dose-concentration–response curves have been defined and it is, therefore, impossible both to compare the kinetics of triptans, and to verify the objective importance of kinetic differences; (4) the importance of kinetic differences is outweighed by non-kinetic factors of variability of response to triptans. If no oral formulations are found that can allow more predictable pharmacokinetics, the same problems will probably also arise with new classes of drugs for the acute treatment of migraine.

Intranasal sumatriptan powder delivered by a novel breath-actuated bi-directional device for the acute treatment of migraine: A randomised, placebo-controlled study

Introduction: Intranasal sumatriptan is an option for the treatment of migraine; however, nasal delivery using conventional spray pumps is suboptimal.

Methods: Adult subjects ( n = 117) with migraine were enrolled in a multicentre, randomised, double-blind, parallel group, placebo-controlled study. A single migraine attack was treated in-clinic with sumatriptan 10 mg, sumatriptan 20 mg or placebo administered intranasally by a novel bi-directional powder delivery device when migraine was moderate or severe.

Results: A greater proportion of subjects who received sumatriptan were pain-free at 120 minutes compared with those who received placebo (10 mg/20 mg sumatriptan vs. placebo = 54%/57% vs. 25%, P < .05). Significant benefits were also observed for pain relief at 120 minutes (84%/80% vs. 44%, P < .001/.01) and as early as 60 minutes (73%/74% vs. 38%, P < .01) and for 48 hours sustained pain-free ( P < .05). Treatment-related adverse events were rare, with a metallic taste being the most commonly reported (10%/13%).

Conclusions: Sumatriptan nasal powder administered using the new device during a migraine attack was effective and well tolerated.

Subcutaneous sumatriptan pharmacokinetics: delimiting the monoamine oxidase inhibitor effect

BACKGROUND

The absolute bioavailability of subcutaneous (s.c.) sumatriptan is 96-100%. The decay curve for plasma concentration after 6 mg s.c. sumatriptan (ie, after T(max) = about 0.2 hours) includes a large distribution component. Metabolism by monoamine oxidase-A (MAO-A) leads to about 40% of the s.c. dose appearing in the urine as the inactive indole acetic acid. Product labeling states that co-administration of an inhibitor of MAO-A (a MAOI-A) causes a 2-fold increase in sumatriptan plasma concentrations, and a 40% increase in elimination half-life.

OBJECTIVE

The objective of this study is to determine whether MAOI-A therapy should deter the use of 6 mg s.c. sumatriptan on pharmacokinetic grounds.

METHODS

Summary pharmacokinetic data were taken from the literature and from GlaxoSmithKline (GSK) study C92-050. Half-times were converted into rate constants, which were then used in a parsimonious compartmental model (needing only 3 simultaneous differential equations). Acceptance criteria for the model included observed plasma sumatriptan concentrations at T(max), 1, 2, and 10 hours post-dose. A set of 1000 concentration measurements at a resolution of 36 seconds was generated. The model was then perturbed with elimination constants observed during concomitant moclobemide administration, creating a second set of concentration measurements. The 2 sets were then plotted, examined for their differences, and integrated for a second time to obtain and compare areas under the curve (AUCs).

RESULTS

The greatest absolute difference between the 2 sets of measurements was 2.85 ng/mL at t = 2.95 hours. A 2-fold difference between the 2 sets occurred only after t = 5.96 hours, when the concentration in the presence of the MAOI-A was 3.72 ng/mL (or <4% of C(max)). At t = 10 hours, the concentrations in both sets were <1 ng/mL (ie, below the lower limit of assay quantitation), and AUC(0-10h) was 97.4 and 117 ng.hour/mL in the absence and presence of the MAOI-A.

CONCLUSIONS

There are no pharmacokinetic grounds to deter co-administration of an MAOI-A and subcutaneous sumatriptan. The dominance of the distribution phase and completeness of absorption of a 6 mg dose of s.c. sumatriptan explains the trivial effect size of the MAOI-A on plasma sumatriptan concentrations. Importantly, these findings should not be extrapolated to other routes of administration for sumatriptan.

Is there an inherent limit to the efficacy of calcitonin gene-related peptide receptor antagonists in the acute treatment of migraine? A comment

Calcitonin gene-related peptide (CGRP) receptor antagonists are a new treatment principle in acute migraine attacks. Intravenous olcegepant 2.5 mg resulted in 66% headache relief after 2 h, whereas subcutaneous sumatriptan resulted in 81–92% headache relief after 2 h. The intrinsic activity of a parenteral triptan, a 5HT_1B/1D receptor agonist, is thus higher than the maximum effect of the parenteral CGRP receptor antagonist olcegepant. For the orally bioavailable CGRP antagonist telcagepant 300 mg, the headache relief was only 55% in one phase III study. These results indicate that CGRP receptor antagonism results in success in the acute treatment of migraine in only a certain fraction of the patients.

Migraine pain: reflections against vasodilatation

The original Wolff’s vascular theory of migraine was supported by the discovery of a class of drugs, the triptans, developed as a selective cephalic vasoconstrictor agents. Even in the neurovascular hypothesis of Moskowitz, that is the neurogenic inflammation of meningeal vessels provoked by peptides released from trigeminal sensory neurons, the vasodilatation provoked by calcitonin gene-related peptide (CGRP) is considered today much more important than oedema. The role of cephalic vasodilatation as a cause of migraine pain was recently sustained by studies showing the therapeutic effect of CGRP receptor antagonists. We discuss the evidence against vasodilatation as migraine pain generator and some findings which we suggest in support of a central (brain) origin of pain.

Acute migraine in the Emergency Department: extending European principles of management

The World Health Organization (WHO) placed migraine 19th among all causes of disability (12th in women) measured in years of healthy life lost to disability (YLD). The importance of headache disorders, particularly of the primary forms, is established by their distribution worldwide, their duration (the majority being life-long conditions) and their imposition of both disability and life-style restrictions among large numbers of people. For these reasons, headache disorders should represent a public-health priority. In the Emergency Department (ED), as elsewhere, migraine is often under-diagnosed-and under-treated when it is diagnosed. The result is likely to be failure of treatment. Particular attention to diagnosis is needed in ED patients with acute headache, since there is a higher probability of secondary headache due to underlying pathologies. According to European principles of management, acute migraine treatment generally is stepwise. Of the two main steps, the first relies on symptomatic medication, preferably NSAIDs with or without antiemetics. The second step uses specific therapies, usually triptans. Modifications to routine practice are appropriate in the ED. Parenteral administration of symptomatic therapies is a preferred first choice, whilst immediate resort to triptans may be appropriate, and achieve better outcomes, in patients with severe headache and diagnostic confirmation of migraine.

Triptans vs other drugs for acute migraine. Are there differences in efficacy? A comment

The introduction of triptans in migraine treatment was apparently a revolution. Comparative randomized clinical trials (RCTs) with triptan and other drugs do not give a clear-cut picture. Oral triptans are superior to oral ergotamine most likely because the bioavailability oral of ergotamine is extremely low (<1%). Compared with NSAIDs, in most cases aspirin, triptans were not superior and in several RCTs triptans caused more adverse events than aspirin plus metoclopramide. Guidelines for treatment of migraine should be evidence-based. It is suggested that based on current evidence, effervescent aspirin should be the first-line drug for the treatment of migraine. Aspirin is also much cheaper than the triptans.

Treatment of migraine attacks based on the interaction with the trigemino-cerebrovascular system

Primary headaches such as migraine are among the most prevalent neurological disorders, affecting up to one-fifth of the adult population. The scientific work in the last decade has unraveled much of the pathophysiological background of migraine, which is now considered to be a neurovascular disorder. It has been discovered that the trigemino-cerebrovascular system plays a key role in migraine headache pathophysiology by releasing the potent vasodilator calcitonin gene-related peptide (CGRP). This neuropeptide is released in parallel with the pain and its concentration correlates well with the intensity of the headache. The development of drugs of the triptan class has provided relief for the acute attacks but at the cost of, mainly cardiovascular, side effects. Thus, the intention to improve treatment led to the development of small CGRP receptor antagonists such as olcegepant (BIBN4096BS) and MK-0974 that alleviate the acute migraine attack without acute side events. The purpose of this review is to give a short overview of the pathological background of migraine headache and to illustrate the mechanisms behind the actions of triptans and the promising CGRP receptor blockers.