Chest symptoms after sumatriptan: a two-year clinical practice review in 735 consecutive migraine patients

The recent advancement of low-dimensional nanostructured materials for drug delivery and drug sensing application: A brief review

In this review article, we have presented a detailed analysis of the recent advancement of quantum mechanical calculations in the applications of the low-dimensional nanomaterials (LDNs) into biomedical fields like biosensors and drug delivery systems development. Biosensors play an essential role for many communities, e.g. law enforcing agencies to sense illicit drugs, medical communities to remove overdosed medications from the human and animal body etc. Besides, drug delivery systems are theoretically being proposed for many years and experimentally found to deliver the drug to the targeted sites by reducing the harmful side effects significantly. In current COVID-19 pandemic, biosensors can play significant roles, e.g. to remove experimental drugs during the human trials if they show any unwanted adverse effect etc. where the drug delivery systems can be potentially applied to reduce the side effects. But before proceeding to these noble and expensive translational research works, advanced theoretical calculations can provide the possible outcomes with considerable accuracy. Hence in this review article, we have analyzed how theoretical calculations can be used to investigate LDNs as potential biosensor devices or drug delivery systems. We have also made a very brief discussion on the properties of biosensors or drug delivery systems which should be investigated for the biomedical applications and how to calculate them theoretically. Finally, we have made a detailed analysis of a large number of recently published research works where theoretical calculations were used to propose different LDNs for bio-sensing and drug delivery applications.

Sumatriptan activates TRPA1

Background:

Migraine therapy with sumatriptan may cause adverse side effects like pain at the injection site, muscle pain, and transient aggravation of headaches. In animal experiments, sumatriptan excited or sensitized slowly conducting meningeal afferents. We hypothesized that sumatriptan may activate transduction channels of the “irritant receptor,” the transient receptor potential ankyrin type (TRPA1) expressed in nociceptive neurons.

Methods:

Calcium microfluorometry was performed in HEK293t cells transfected with human TRPA1 (hTRPA1) or a mutated channel (TRPA1-3C) and in dissociated trigeminal ganglion neurons. Membrane currents were recorded in the whole-cell patch clamp configuration.

Results:

Sumatriptan (10 and 400 µM) evoked calcium transients in hTRPA1-expressing HEK293t cells also activated by the TRPA1 agonist carvacrol (100 µM). In TRPA1-3C-expressing HEK293t cells, sumatriptan had hardly any effect. In rat trigeminal ganglion neurons, sumatriptan, carvacrol, and the transient receptor potential vanillod type 1 agonist capsaicin (1 µM) generated robust calcium signals. All sumatriptan-sensitive neurons (8% of the sample) were also activated by carvacrol (14%) and capsaicin (48%). In HEK293-hTRPA1 cells, sumatriptan (100 µM) evoked outwardly rectifying currents, which were almost completely inhibited by the TRPA1 antagonist HC-030031 (10 µM).

Conclusion:

Sumatriptan activates TRPA1 channels inducing calcium inflow and membrane currents. TRPA1-dependent activation of primary afferents may explain the painful side effects of sumatriptan.

Lasmiditan for the treatment of acute migraine: a review and potential role in clinical practice

Now that the vascular hypothesis of migraine is no longer the prevailing theory of migraine pathogenesis, there is interest in developing acute migraine treatments that act exclusively on non-vascular targets. There is a large percentage of non-responders to current acute migraine treatments and the vasoconstriction associated with triptans limit their use in patients with pre-existing cardiovascular risk factors. Preferential 5-HT_1F agonists have shown promising results in in vitro and early proof-of-concept trials. Lasmiditan, a highly selective 5-HT_1F agonist, has completed two Phase III randomized, double blind, placebo-controlled clinical trials, with a third - a long-term, open-label safety study - still underway. Research to date suggests lasmiditan lacks vasoconstrictive properties and may be a safe and effective treatment option in patients refractory to current acute migraine medications or who have cardiovascular risk factors.

Efficacy and safety of DFN-11 (sumatriptan injection, 3 mg) in adults with episodic migraine: an 8-week open-label extension study

BACKGROUND

DFN-11, a 3 mg sumatriptan subcutaneous (SC) autoinjector for acute treatment of migraine, has not been assessed previously in multiple attacks. The objective of this study was to evaluate the efficacy, tolerability, and safety of DFN-11 in the acute treatment of multiple migraine attacks.

METHODS

This was an 8-week open-label extension of multicenter, randomized, double-blind, placebo-controlled US study. Subjects averaging 2 to 6 episodic migraine attacks per month were randomized to DFN-11 or placebo to treat a single attack of moderate-to-severe intensity and then entered the extension study to assess the efficacy, tolerability, and safety of DFN-11 in multiple attacks of any pain intensity.

RESULTS

Overall, 234 subjects enrolled in the open-label period, and 29 (12.4%) discontinued early. A total of 848 migraine episodes were treated with 1042 doses of open-label DFN-11 and subjects treated a mean (SD) of 3.9 (2.3) attacks. At 2 h postdose in attacks 1 (N = 216), 2 (N = 186), 3 (N = 142) and 4 (N = 110), respectively, pain freedom rates were 57.6%, 64.6%, 61.6%, and 66.3%; pain relief rates were 83.4%, 88.4%, 84.1%, and 81.7%; most bothersome symptom (MBS)-free rates were 69.0%, 76.5%, 77.7%, and 74.7%; nausea-free rates were 78.1%, 84.6%, 86.5%, and 85.7%; photophobia-free rates were 75.3%, 76.4%, 72.3%, and 77.5%; and phonophobia-free rates were 75.2%, 77.5%, 73.6%, and 76.0%. Overall, 40.6% (89/219) of subjects reported treatment-emergent adverse events (TEAE), the most common of which were associated with the injection site: swelling (12.8%), pain (11.4%), irritation (6.4%), and bruising (6.4%). Most subjects (65.2%, 58/89) had mild TEAEs; severe TEAEs were reported by 1 subject (treatment-related jaw tightness). Five subjects (2.1%) discontinued due to adverse events, which included mild throat tightness (n = 2), moderate hernia pain (n = 1), moderate hypersensitivity (n = 1), and 1 subject with mild nausea and moderate injection site swelling. There were no serious TEAEs and no new or unexpected safety findings.

CONCLUSION

DFN-11 was effective, tolerable, and safe in the acute treatment of 4 migraine attacks over 8 weeks, with consistent responses on pain and associated symptoms. Most TEAEs were mild, with a very low incidence of triptan-related TEAEs. DFN-11 is potentially an effective and safe alternative for the acute treatment of migraine.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02569853 . Registered 07 October 2015.

Serotonin receptor agonists in the acute treatment of migraine: a review on their therapeutic potential

Migraine is an important socioeconomic burden and is ranked the sixth cause of years of life lost because of disability in the general population and the third cause of years of life lost in people younger than 50 years. The cornerstone of pharmacological treatment is represented by the acute therapy. The serotonin (5-hydroxytryptamine [5-HT]) receptor subtype 1_B/1_D agonists, called triptans, are nowadays the first-line acute therapy for patients who experience moderate-to-severe migraine attacks. Unfortunately, a high percentage of patients are not satisfied with this acute treatment, either for lack of response or side effects. Moreover, their mechanism of action based on vasoconstriction makes them unsuitable for patients with previous cardio- and cerebrovascular diseases and for those with uncontrolled hypertension. Since the introduction of triptans, no other acute drug class has passed all developmental stages. The research for a new drug lacking vasoconstrictive effects led to the development of lasmiditan, a highly selective 5-HT1_F receptor agonist with minimized interactions with other 5-HT receptor subtypes. Lasmiditan is considered to be the first member of a new drug category, the neurally acting anti-migraine agent (NAAMA). Phase II and III trials had shown superiority compared to placebo and absence of typical triptan-associated adverse events (AEs). Most of the AEs were related to the central nervous system, depending on the high permeability through the blood–brain barrier and mild to moderate severity. The results of ongoing long-term Phase III trials will determine whether lasmiditan will become available in the market, and then active triptan comparator studies will assess patients’ preference. Future studies could then explore the safety during pregnancy and breastfeeding or the risk that overuse of lasmiditan leads to medication overuse headache.

A review of clinical safety data for sumatriptan nasal powder administered by a breath powered exhalation delivery system in the acute treatment of migraine

INTRODUCTION

AVP-825 (sumatriptan nasal powder) is an FDA-approved intranasal medication delivery system containing low-dose sumatriptan powder for acute treatment of migraine with or without aura in adults. AVP-825 utilizes unique nasal anatomy features to avoid limitations of other intranasal delivery methods. Areas covered: Literature search terms: 'AVP-825', 'sumatriptan nasal powder', 'intranasal sumatriptan', 'sumatriptan safety', 'sumatriptan acute migraine'. Pharmacokinetic, Phase 2/3 studies, reviews (AVP-825) and metanalyses/reviews (sumatriptan) were evaluated. Expert opinion: AVP-825 provides a more efficient sumatriptan delivery method versus other formulations. Pharmacokinetics showed that a single dose of AVP-825 (22 mg) delivers 15-16 mg sumatriptan and produces significantly lower exposure than oral or injectable formulations, which may translate into a better safety/tolerability profile. AVP-825 was well tolerated in controlled trials, with the most common adverse events localized at the administration-site (abnormal taste, nasal discomfort); these were mostly mild, leading to only one discontinuation. Compared to 100 mg oral sumatriptan, AVP-825 had a significantly lower rate of atypical sensations across multiple attacks. AVP-825 has the advantage of early efficacy onset associated with faster absorption at a lower delivered dose than liquid nasal spray or oral formulations. AVP-825 provided earlier efficacy (within 30 min) vs. 100 mg oral sumatriptan and similar sustained efficacy. AVP-825 offers the benefits of a non-oral, low-dose, tolerable acute migraine medication.

Randomized, double-blind, crossover study comparing DFN-11 injection (3 mg subcutaneous sumatriptan) with 6 mg subcutaneous sumatriptan for the treatment of rapidly-escalating attacks of episodic migraine

Background

A 6-mg dose of SC sumatriptan is the most efficacious and fast-acting acute treatment for migraine, but a 3-mg dose of SC sumatriptan may improve tolerability while maintaining efficacy.

Methods

This randomized, double-blind, crossover study compared the efficacy and tolerability of 3 mg subcutaneous (SC) sumatriptan (DFN-11) with 6 mg SC sumatriptan in 20 adults with rapidly-escalating migraine attacks. Eligible subjects were randomized (1:1) to treat 1 attack with DFN-11 and matching placebo autoinjector consecutively or 2 DFN-11 autoinjectors consecutively and a second attack similarly but with the alternative dose (3 mg or 6 mg).

Results

The proportions of subjects who were pain-free at 60 min postdose, the primary endpoint, were similar following treatment with 3 mg SC sumatriptan and 6 mg SC sumatriptan (50% vs 52.6%, P  =  .87). The proportions of subjects experiencing pain relief (P  ≥  .48); reductions in migraine pain intensity (P  ≥  .78); and relief from nausea, photophobia, or phonophobia (P  ≥  .88) with 3 mg SC sumatriptan and 6 mg SC sumatriptan were similar, as were the mean scores for satisfaction with treatment (M  =  2.6 vs M  =  2.4, P  =  .81) and the mean number of rescue medications used (M  =  .11 vs M  =  .26, P  =  .32). The most common adverse events with the 3- and 6-mg doses were triptan sensations — paresthesia, neck pain, flushing, and involuntary muscle contractions of the neck — and the incidence of adverse events with both doses was similar (32 events total: 3 mg, n  =  14 [44%]; 6 mg, n  =  18 [56%], P  =  .60). Triptan sensations affected 4 subjects with the 6-mg dose only, 1 subject with the 3-mg dose only, and 7 subjects with both sumatriptan doses. Chest pain affected 2 subjects (10%) treated with the 6-mg dose and no subjects (0%) treated with the 3-mg dose of DFN-11. There were no serious adverse events.

Conclusions

The 3-mg SC dose of sumatriptan in DFN-11 provided relief of migraine pain and associated symptoms comparable to a 6-mg SC dose of sumatriptan. Tolerability was similar with both study medications; DFN-11 treatment was associated with fewer triptan sensations than the 6-mg dose. DFN-11, with its 3-mg dose of sumatriptan, may be a clinically useful alternative to higher-dose autoinjectors.

Cardiovascular Events, Conditions, and Procedures Among People With Episodic Migraine in the US Population: Results from the American Migraine Prevalence and Prevention (AMPP) Study

BACKGROUND

Though migraine, particularly migraine with aura, is a cardiovascular (CV) risk factor, the scope and distribution of cardiovascular disease in representative samples of people with migraine are not known. This is important because many widely used acute migraine treatments, including triptans, ergot alkaloids, and nonsteroidal anti-inflammatory drugs, carry precautions, warnings, or contraindications for use in persons with CV disease.

OBJECTIVES

To assess the scope and distribution of cardiovascular events, conditions, and procedures in persons with episodic migraine in a representative sample of the US population, using data from the American Migraine Prevalence and Prevention (AMPP) Study.

METHODS

Eligible subjects completed the 2009 AMPP survey, met ICHD-3beta criteria for migraine, and had a headache frequency of less than 15 days per month (episodic migraine). A survey on cardiovascular events (ie, myocardial infarction), conditions (ie, angina), and procedures (ie, carotid endarterectomy) was adopted from the Women's Health Study and the Physician's Health Studies. Cardiovascular events and conditions were defined by participant reports of having both experienced and received a physician diagnosis for a particular event or condition. The distribution of CV events, conditions, and procedures was summarized for the entire migraine sample and in groups defined by gender and age (22-39, 40-59, and ≥60). To assess the numbers of persons with episodic migraine in the US, we applied age and gender stratified estimates of migraine prevalence to the 2015 Census data. To estimate the number of cardiovascular events, conditions, and procedures in the US migraine population, we applied age and gender stratified event rates to the number of persons with episodic migraine in each stratum.

RESULTS

The 2009 AMPP Study survey was returned by 11,792 study participants out of 16,983 (64.9% response rate), including 6723 individuals who met study criteria for episodic migraine (5227 women and 1496 men). Among 22-39 year olds with episodic migraine, 3.4% reported having received a physician diagnosis of CV events or conditions and 1.1% reported undergoing CV related procedures. Among 40-59 year olds, 10.2% reported having received a physician diagnosis of CV events or conditions and 3.5% reported CV related procedures. For those age 60 or older, 22.3% reported CV events or conditions and 8.8% reported CV procedures. Prevalence of events, conditions, and procedures was higher in men than women and also in older age groups. However, the absolute number of CV events, procedures, and conditions was greater for women than men due to the higher population prevalence of episodic migraine in women. We projected that 2.0 million women and 665,000 men in the US had episodic migraine and a history of one or more CV event, condition, or procedure. By age group, it is estimated that 579,000 among those aged 22-39, 1.37 million of those aged 40-59, and 696,000 of those 60 and older with episodic migraine have ever had at least one CV event, procedure, or condition.

CONCLUSION

Based on these analyses, we estimate that there are roughly 2.6 million people with episodic migraine aged 22 and older in the US with one or more prior CV event, condition, or procedure. For this group, cardiovascular contraindications to many migraine-specific acute migraine therapies may make treatment challenging.

Clinical Profile and Practice Experience of Almotriptan

Patients expect their acute migraine treatment to have a rapid onset of action, achieve complete pain relief that is sustained for 24 h, and to have a good tolerability profile. Almotriptan has a favourable pharmacokinetic profile that translates clinically to a rapid onset of action and consistent absorption regardless of age, sex, food intake and status of the acute migraine attack. In addition, almotriptan is not associated with any clinically relevant drug-drug interactions. Pain-free status at 2 h postdose is achieved by approximately 39% of patients receiving almotriptan in clinical trials. Recurrence of headaches within 24 h is low with almotriptan (< 22%). Almotriptan has a sustained pain-free rate of 25-27%, which in a meta-analysis of triptans was superior to sumatriptan 100 mg. Almotriptan therapy is associated with a low incidence of adverse events, including those affecting the central nervous system and chest.

Triptans and Chest Symptoms: The Role of Pulmonary Vasoconstriction

Triptans are effective and well tolerated in the treatment of acute migraine. Chest symptoms are a common adverse effect unrelated to coronary vasoconstriction in most patients. Although the aetiology of chest symptoms remains to be fully defined, pulmonary vasoconstriction is a possible underlying mechanism. Preclinical studies of isolated human blood vessels were used to identify the cerebral selectivity of triptans and ascertain if selectivity vs the pulmonary vasculature predicts a lower rate of chest symptoms. Controlled clinical trials and post-marketing surveillance studies were reviewed to document the incidence of chest symptoms after triptan therapy. In clinical trials, the incidence of chest symptoms at usual therapeutic doses ranged from 1 to 4% depending on the triptan and study design, whereas in post-marketing surveillance studies, up to 41% of patients specifically asked about chest symptoms reported them. A comparative clinical trial showed that almotriptan was associated with lower incidence of chest symptoms than sumatriptan (0.3 vs 2.2%). The intrinsic activity of almotriptan, a second-generation triptan, on human pulmonary arteries and veins was lower than that of sumatriptan. Pre-clinical studies of isolated pulmonary blood vessels may predict the clinical likelihood of chest symptoms; however, additional comparisons are needed.

Blockade of CGRP Receptors in the Intracranial Vasculature: A New Target in the Treatment of Headache

In primary headaches, there is a clear association between the headache and the release of calcitonin gene-related peptide (CGRP) but not with any of the other neuronal messengers. The purpose of this review is to describe the role of CGRP in the intracranial circulation and to elucidate a possible role for a specific CGRP receptor antagonist in the treatment of primary headaches. Acute treatment with a 5-HT1B/1D agonist (triptan) results in alleviation of the headache and normalization of the cranial venous CGRP levels, in part due to a presynaptic inhibitory effect on sensory nerves. The central role of CGRP in migraine and cluster headache pathophysiology has led to the search for small molecule CGRP antagonists with few cardiovascular side-effects. The initial pharmacological profile of such a group of compounds has recently been disclosed. One of these compounds has been found to be efficacious in the relief of acute attacks of migraine.

Triptans and serious adverse vascular events: data mining of the FDA Adverse Event Reporting System database

AIM

The aim of this article is to investigate the vascular safety profile of triptans through an analysis of the United States Food and Drug Administration Adverse Event Reporting System (FDA_AERS) database with a special focus on serious and unexpected adverse events.

METHODS

A CASE/NON-CASE analysis was performed on the reports entered in the FDA_AERS from 2004 to 2010: CASES were reports with at least one event included in the MedDRA system organ classes 'Cardiac disorder' or 'Vascular disorders', whereas NON-CASES were all the remaining reports. Co-reported cardiovascular drugs were used as a proxy of cardiovascular risk and the adjusted reporting odds ratio (adj.ROR) with 95% confidence intervals (95% CI) was calculated. Disproportionality signals were defined as adj.ROR value >1. Adverse events were considered unexpected if not mentioned on the relevant label.

RESULTS

Among 2,131,688 reports, 7808 concerned triptans. CASES were 2593 among triptans and 665,940 for all other drugs. Unexpected disproportionality signals were found in the following high-level terms of the MedDRA hierarchy: 'Cerebrovascular and spinal necrosis and vascular insufficiency' (103 triptan cases), 'Aneurysms and dissections non-site specific' (15), 'Pregnancy-associated hypertension' (10), 'Reproductive system necrosis and vascular insufficiency' (3).

DISCUSSION

Our analysis revealed three main groups of unexpected associations between triptans and serious vascular events: ischaemic cerebrovascular events, aneurysms and artery dissections, and pregnancy-related vascular events. A case-by-case assessment is needed to confirm or disprove their plausibility and large-scale analytical studies should be planned for risk rate estimation. In the meantime, clinicians should pay special attention to migraine diagnosis and vascular risk assessment before prescribing a triptan, also promptly reporting any unexpected event to pharmacovigilance systems.

Subcutaneous delivery of sumatriptan in the treatment of migraine and primary headache

Subcutaneous sumatriptan is an effective treatment for pain from acute migraine headache, and can be used in patients with known migraine syndrome and in patients with primary headaches when secondary causes have been excluded. In limited comparative trials, subcutaneous sumatriptan performed in a manner comparable with oral eletriptan and intravenous metoclopramide, was superior to intravenous aspirin and intramuscular trimethobenzamide-diphenhydramine, and was inferior to intravenous prochlorperazine for pain relief. The most common side effects seen with subcutaneous sumatriptan are injection site reactions and triptan sensations. As with all triptans, there is a risk of rare cardiovascular events with subcutaneous sumatriptan and its use should be limited to those without known cerebrovascular disease and limited in those with known cardiovascular risk factors and unknown disease status. In studies of patient preference and tolerability, the subcutaneous formulation has a faster time of onset and high rate of efficacy when compared with the oral formulation, but the oral formulation appears to be better tolerated. It is important to consider the needs of the patient, their past medical history, and what aspects of migraine treatment are most important to the patient when considering treatment of acute migraine or primary headache. Subcutaneous sumatriptan is a good first-line agent for the treatment of pain from acute migraine headaches and primary headaches.

Acute treatment of migraine with the selective 5-HT1F receptor agonist lasmiditan--a randomised proof-of-concept trial

INTRODUCTION

Lasmiditan (COL-144; LY573144) is a novel, highly selective and potent agonist at 5-HT(1F) receptors that lacks vasoconstrictor activity. Preclinical and early clinical experiments predict acute antimigraine efficacy of COL-144 that is mediated through a non-vascular, primarily neural, mechanism.

SUBJECTS AND METHODS

In a randomised, multicentre, placebo-controlled, double-blind, group-sequential, adaptive treatment-assignment, proof-of-concept and dose-finding study, we treated 130 subjects in-hospital during a migraine attack. Subjects were allocated to an intravenous dose level of lasmiditan or placebo in small cohorts. The starting dose was 2.5 mg. Subsequent doses were adjusted, up or down, according to the safety and efficacy seen in the preceding cohort. The primary outcome measure was headache response defined as improvement from moderate or severe headache at baseline to mild or no headache at 2 h post-dose. The study was designed to explore the overall dose response relationship but was not powered to differentiate individual doses from placebo, nor to detect effect differences for other migraine symptoms.

RESULTS

Forty-two subjects received placebo and 88 received lasmiditan in doses of 2.5-45 mg. Subjects were observed in the clinic for 4 h after treatment and used a diary card to record symptoms and adverse events for up to 24 h. The study was terminated when the 20 mg dose met predefined efficacy stopping rules. Of subjects treated in the 10, 20, 30 and 45 mg lasmiditan dose groups, 54-75% showed a 2 h headache response, compared to 45% in the placebo group (P = 0.0126 for the linear association between response rates and dose levels). Patient global impression at 2 h and lack of need for rescue medication also showed statistically significant linear correlations with dose. Lasmiditan was generally well tolerated. Adverse events were reported by 65% of subjects on lasmiditan and by 43% on placebo and were generally mild. Dizziness, paresthesia and sensations of heaviness (usually limb) were more common on lasmiditan.

CONCLUSIONS

At intravenous doses of 20 mg and higher, lasmiditan proved effective in the acute treatment of migraine. Further studies to assess the optimal oral dose and full efficacy and tolerability profile are under way. The non-vascular, neural mechanism of action of lasmiditan may offer an alternative means to treat migraine especially in patients who have contra-indications for agents with vasoconstrictor activity. The clinicaltrials.gov identifier for this study is NCT00384774.

Preclinical pharmacological profile of the selective 5-HT1F receptor agonist lasmiditan

INTRODUCTION

Lasmiditan (also known as COL-144 and LY573144; 2,4,6-trifluoro-N-[6-[(1-methylpiperidin-4-yl)carbonyl]pyridin-2yl]benzamide) is a high-affinity, highly selective serotonin (5-HT) 5-HT(1F) receptor agonist.

RESULTS

In vitro binding studies show a K(i) value of 2.21 nM at the 5-HT(1F) receptor, compared with K(i) values of 1043 nM and 1357 nM at the 5-HT(1B) and 5-HT(1D) receptors, respectively, a selectivity ratio greater than 470-fold. Lasmiditan showed higher selectivity for the 5-HT(1F) receptor relative to other 5-HT(1) receptor subtypes than the first generation 5-HT(1F) receptor agonist LY334370. Unlike the 5-HT(1B/1D) receptor agonist sumatriptan, lasmiditan did not contract rabbit saphenous vein rings, a surrogate assay for human coronary artery constriction, at concentrations up to 100 µM. In two rodent models of migraine, oral administration of lasmiditan potently inhibited markers associated with electrical stimulation of the trigeminal ganglion (dural plasma protein extravasation, and induction of the immediate early gene c-Fos in the trigeminal nucleus caudalis).

CONCLUSIONS

Lasmiditan presents a unique pyridinoyl-piperidine scaffold not found in any other antimigraine class. Its chemical structure and pharmacological profile clearly distinguish it from the triptans. The potency and selectivity of lasmiditan make it ideally suited to definitively test the involvement of 5-HT(1F) receptors in migraine headache therapy.

Pharmacology

Headache treatment has been based primarily on experiences with non-specific drugs such as analgesics, non-steroidal anti-inflammatory drugs, or drugs that were originally developed to treat other diseases, such as beta-blockers and anticonvulsant medications. A better understanding of the basic pathophysiological mechanisms of migraine and other types of headache has led to the development over the past two decades of more target-specific drugs. Since activation of the trigeminovascular system and neurogenic inflammation are thought to play important roles in migraine pathophysiology, experimental studies modeling those events successfully predicted targets for selective development of pharmacological agents to treat migraine. Basically, there are two fundamental strategies for the treatment of migraine, abortive or preventive, based to a large degree on the frequency of attacks. The triptans, which exhibit potency towards selective serotonin (5-hydroxytryptamine, 5-HT) receptors expressed on trigeminal nerves, remain the most effective drugs for the abortive treatment of migraine. However, numerous preventive medications are currently available that modulate the excitability of the nervous system, particularly the cerebral cortex. In this chapter, the pharmacology of commercially available medications as well as drugs in development that prevent or abort headache attacks will be discussed.

Treatment Choices and Patterns in Migraine Patients With and Without a Cardiovascular Risk Profile

Treatment patterns in migraine patients with cardiovascular risk factors are largely unknown. A retrospective observational study was conducted to characterize the baseline cardiovascular risk profile of new users of specific abortive migraine drugs, and to investigate treatment choices and patterns in patients with and without a known cardiovascular risk profile. New users of a triptan, ergotamine or Migrafin® ( n = 36 839) from 1 January 1990 to 31 December 2006 were included. Approximately 90 of all new users did not have a clinically recognized cardiovascular risk profile. The percentage of new users with a cardiovascular risk profile did not differ between new users of a triptan, ergotamine or Migrafin® and also did not change during the study period of 17 years. Differences in treatment choices and patterns between migraine patients with and without a known cardiovascular risk profile reveal a certain reticence in prescribing vasoconstrictive antimigraine drugs to patients at cardiovascular risk.

Cutaneous allodynia and migraine: another view

The paradigm of early treatment of the migraine attack at mild pain intensity has become one alternative to circumventing the problem of compromised oral absorption of symptomatic drugs due to migraine-induced gastrointestinal dysmotility. Early treatment also has been proposed to be advantageous because most migraineurs could be less responsive to delayed treatment, owing to the development of central sensitization of the trigeminal pain transmission. Ranking the underlying principles, it seems that the improved response to an oral triptan formulation at mild migraine symptom intensity has more to do with less impaired gastrointestinal absorption in the early stage of the attack than decreasing the time and preventing chances for central sensitization and development of cutaneous allodynia. Furthermore, parenteral administration of a triptan is always more likely to provide relief of symptoms than conventional tablets, even when it is used later in the course of the migraine attack. Individually tailored use of the available triptan formulations will increase, without any doubt, the within-migraineur consistency of response. It also will reduce the overall proportion of migraine attacks or migraineurs not responding to triptan treatment. Notwithstanding, the recommendation of early treatment during the migraine attack when the pain is mild remains valid.

Neurovascular pharmacology of migraine

Migraine is a paroxysmal neurovascular disorder, which affects a significant proportion of the population. Since dilation of cranial blood vessels is likely to be responsible for the headache experienced in migraine, many experimental models for the study of migraine have focussed on this feature. The current review discusses a model that is based on the constriction of carotid arteriovenous anastomoses in anaesthetized pigs, which has during the last decades proven of great value in identifying potential antimigraine drugs acting via a vascular mechanism. Further, the use of human isolated blood vessels in migraine research is discussed. Thirdly, we describe an integrated neurovascular model, where dural vasodilatation in response to trigeminal perivascular nerve stimulation can be studied. Such a model not only allows an in-depth characterization of directly vascularly acting drugs, but also of drugs that are supposed to act via inhibition of vasodilator responses to endogenous neuropeptides, or of drugs that inhibit the release of these neuropeptides. We discuss the use of this model in a study on the influence of female sex hormones on migraine. Finally, the implementation of this model in mice is considered. Such a murine model allows the use of genetically modified animals, which will lead to a better understanding of the ion channel mutations that are found in migraine patients.

The risk of newly diagnosed asthma in migraineurs with or without previous triptan prescriptions

BACKGROUND

Previous observational studies reported an increased prevalence of asthma in migraine patients. Whether triptans affect the asthma risk has not yet been explored in an epidemiological study.

OBJECTIVE

To estimate the risk of newly diagnosed asthma in patients with a general practitioner-diagnosed migraine in the UK between 1994 and 2001.

METHODS

A population-based follow-up study and a nested case-control analysis were conducted using the General Practice Research Database.

RESULTS

The study encompassed 51,688 migraineurs and the same number of matched controls. In the follow-up analysis, the relative risk of developing asthma in migraineurs compared with non-migraineurs was 1.3 (95% confidence interval [CI] 1.1-1.4). In the nested case-control analysis, the adjusted odds ratio for asthma in migraineurs overall was 1.17 (95% CI 1.01-1.35), and for those with a recent triptan prescription 1.12 (95% CI 0.65-1.94).

CONCLUSION

The risk of developing asthma was not materially altered for patients with a general practitioner-recorded migraine diagnosis, regardless of triptan use.

5-HT1B receptor subtype and aging in rat resistance vessels

The effects of 5-hydroxytryptamine (5-HT), 5-carboxamidotryptamine, and sumatriptan on rat caudal arteries were examined, with the goal of finding experimental conditions useful in enhancing the 'silent' 5-HT(1B) receptor subtype. It was shown that both reserpine treatment and K(+) depolarization increased the vasoconstriction by 5-HT receptor agonists. The role of the 5-HT(2A) receptor in vasoconstriction was examined using ritanserin (50 nmol/l), a selective 5-HT(2A) antagonist, whereas that of the 'silent' 5-HT(1B) receptor was examined using SB-224289 (0.2 micromol/l), a selective 5-HT(1B) receptor antagonist. The influence of age on the 'silent' 5-HT(1B) receptor subtype was also investigated; for this, the effect of sumatriptan, a selective 5-HT(1B/1D )agonist, was tested on arterial tissues of both young and old rats which had been either K(+) depolarized or reserpine treated or both. It was found that aging strongly shifted the concentration-vasoconstriction curve generated by sumatriptan to the left, also increasing the maximum contractile response, mainly in reserpine-treated tissues. RT-PCR was used to study the expression of 5-HT(1B) and 5-HT(2A) receptors in both young and old tissues. The results support the idea that reserpine-treated and K(+)-depolarized caudal arteries from old rats can be a pharmacological model which is useful in highlighting the 'silent' 5-HT(1B) receptor subtype.

The phe-124-Cys and A-161T variants of the human 5-HT1B receptor gene are not major determinants of the clinical response to sumatriptan

BACKGROUND

The 5-HT(1B/1D) receptor agonist sumatriptan is highly effective in the treatment of migraine. However, some patients do not respond to sumatriptan or experience recurrence of the headache after initial relief. In addition, some patients report chest symptoms after the use of sumatriptan.

OBJECTIVE

To assess whether 2 genetic variants (F124C changing a phenylalanine for a cysteine and polymorphism A/T at nucleotide position -161 in the 5' regulatory region) of the 5-HT(1B) receptor play a major role in the therapeutic response to sumatriptan. The 5-HT(1B) receptor most likely mediates the therapeutic action and coronary side effects of sumatriptan, and both F124C and A-161T have relevant functional consequences on either the affinity of sumatriptan to bind to the 5-HT(1B) receptor or on receptor expression level itself, respectively.

METHOD

Genomic DNA of a relatively small but very well-characterized set of migraine patients with consistently good response to sumatriptan (n = 14), with no response (n = 12), with recurrence of the headache (n = 12), with chest symptoms (n = 13), and patients without chest symptoms (n = 27) was available for the genetic analyses and screened for the F124C variant and the A-161T polymorphism in the human 5-HT(1B) receptor gene.

RESULTS

F124C was not detected in any of the patients studied. In addition, we did not observe drastic changes in allele frequencies of the A-161T polymorphism that might hint to a causal relation with the therapeutic effect of sumatriptan.

CONCLUSION

We have not obtained any evidence that variants F124C and A-161T of the 5-HT(1B) receptor are major determinants in the clinical response to sumatriptan.

CGRP receptor antagonists: A new frontier of anti-migraine medications

Migraine is a chronic pain condition that affects 12% of the population. Currently, the most effective treatments are the triptans, but they are limited in their efficacy and have potentially deleterious cardiovascular complications. Based on basic science studies over the past decade, a new generation of anti-migraine drugs is now being developed. At the forefront of these studies is a new calcitonin gene-related peptide (CGRP) receptor antagonist that is as effective as triptans in the acute treatment of migraines, without the cardiovascular effects. This review will address the likely mechanisms and therapeutic potential of CGRP receptor antagonists.

Experimental migraine models and their relevance in migraine therapy

Although the understanding of migraine pathophysiology is incomplete, it is now well accepted that this neurovascular syndrome is mainly due to a cranial vasodilation with activation of the trigeminal system. Several experimental migraine models, based on vascular and neuronal involvement, have been developed. Obviously, the migraine models do not entail all facets of this clinically heterogeneous disorder, but their contribution at several levels (molecular, in vitro, in vivo) has been crucial in the development of novel antimigraine drugs and in the understanding of migraine pathophysiology. One important vascular in vivo model, based on an assumption that migraine headache involves cranial vasodilation, determines porcine arteriovenous anastomotic blood flow. Other models utilize electrical stimulation of the trigeminal ganglion/nerve to study neurogenic dural inflammation, while the superior sagittal sinus stimulation model takes into account the transmission of trigeminal nociceptive input in the brainstem. More recently, the introduction of integrated models, namely electrical stimulation of the trigeminal ganglion or systemic administration of capsaicin, allows studying the activation of the trigeminal system and its effect on the cranial vasculature. Studies using in vitro models have contributed enormously during the preclinical stage to characterizing the receptors in cranial blood vessels and to studying the effects of several putative antimigraine agents. The aforementioned migraine models have advantages as well as some limitations. The present review is devoted to discussing various migraine models and their relevance to antimigraine therapy.

Effects of sumatriptan and eletriptan on diseased epicardial coronary arteries

BACKGROUND

Triptans are contraindicated in patients with known or suspected coronary artery disease (CAD); however, few studies have evaluated triptans in patients with obstructive CAD to quantify the vasoconstrictive effect on diseased coronary vessels.

METHODS

Patients undergoing percutaneous transluminal coronary angioplasty for symptomatic single-vessel CAD were randomised to one of three parallel cohorts to receive (1) 6 mg intravenously (IV) infused eletriptan plus subcutaneous (SC) placebo, (2) IV infused placebo plus 6 mg SC sumatriptan or (3) IV infused placebo plus SC placebo, as simultaneous administrations in a double-blind manner. Serial arteriograms, hemodynamic indices, electrocardiography and triptan plasma concentrations were obtained.

RESULTS

. Fifteen minutes after triptan challenge, median (95% confidence interval) changes in coronary artery diameter (CADM) at the focal point of the stenosed segment were: dilation of 2.6% (-5.0, 11.4), eletriptan 6 mg IV (n = 18); constriction of 6.8% (-12.6, 0.4), sumatriptan 6 mg SC (n = 17), and constriction of 4.5% (-7.0, 7.9), placebo (n = 10). One patient had angiographic evidence of a new thrombus at the stenosis site, necessitating termination of study infusion and successful stenting of the lesion. There was no correlation between effects on CADM and triptan concentration, or between hemodynamic or electrocardiograph changes and the presence (n = 13) or absence (n = 33) of chest pain.

CONCLUSIONS

Triptans had very little effect on diseased epicardial coronary arteries in a small group of angina sufferers with established CAD. Results should be interpreted cautiously since there may be instances where even modest triptan-associated epicardial constriction is sufficient to precipitate myocardial ischemia in patients with severe obstructive CAD.

Triptans induce vasoconstriction of human arteries and veins from the thoracic wall

A common side effect of migraine treatment with triptans is chest symptoms. The origin of these symptoms is not known. The aim of the present study was to examine the vasocontractile effect of triptans in human arteries and veins from the thoracic wall and in coronary artery bypass grafts. In vitro pharmacology experiments showed that the 5-hydroxytryptamine (5-HT) type 1B and 1D receptor agonists, eletriptan, naratriptan, rizatriptan, sumatriptan, and zolmitriptan, induced vasoconstriction in the thoracic blood vessels from 38% to 57% of the patients. 5-carboxamidotryptamine (5-CT) and sumatriptan elicited a vasoconstriction that was antagonized by the 5-HT1B receptor antagonist SB224289, whereas the 5-HT1D receptor antagonist BRL115572 had no effect. 5-HT induced a contraction that was inhibited by the 5-HT2A receptor antagonist ketanserin. 5-HT2A, 5-HT1B, and 5-HT1D receptor mRNA levels were detected by real-time PCR in all blood vessels studied. In conclusion, triptans induce vasoconstriction in arteries and veins from the thoracic wall, most likely by activation of 5-HT1B receptors. This response could be observed in only 38% to 57% of the patients, which may provide an explanation for why a similar number of patients experience chest symptoms as a side effect of migraine treatment with triptans.

A case of myocardial infarction with sumatriptan use

Sumatriptan is widely used in the treatment of acute attacks of cluster headache. It is a serotonin-1 (5HT-1) agonist. Several studies have reported an association between sumatriptan use and myocardial infarction, possibly due to the generalized vasoconstrictive nature of this agent. We report a 16-year-old male patient presenting with acute inferior myocardial infarction after sumatriptan use without any known risk factors of coronary artery disease.

Anti-migraine action of triptans is preceded by transient aggravation of headache caused by activation of meningeal nociceptors

Consistent with previous accounts, some of the patients visiting our pain clinic during the course of a migraine attack have indicated-without solicitation-that sumatriptan injection initially intensified their headache before they were able to appreciate any pain relief. In this study, those patients who came forward complaining about pain exacerbation were asked to rate their headache intensity every 5 min. Within 5-15 min of sumatriptan injection, 17 of the 31 patients studied (55%) reported that their migraine pain intensified for 10-15 min before they started to notice any pain relief. Similar pattern of pain exacerbation was also observed in migraine attacks treated with oral formulation of almotriptan, eletriptan, rizatriptan, and zolmitriptan. To investigate the possible mechanism underlying this transient exacerbation of pain, we examined whether intravenous administration of sumatriptan can alter the response properties of C- and Adelta-meningeal nociceptors in the rat. Five to twenty minutes after intravenous administration of 300 microg/kg sumatriptan, 8/10 C-units and 2/8 Adelta-units increased their firing rate, and 6/10 C-units and 7/8 Adelta-units developed mechanical hyper-responsiveness to dural indentation. The minimal effective dose for activation and sensitization of meningeal nociceptors by sumatriptan was 3 microg/kg, suggesting that relatively low levels of triptans entering the circulation shortly after their administration can alter the physiological properties of meningeal nociceptors and produce a transient exacerbation of headache.

Pilot Study Evaluating Preference for 3‐mg Versus 6‐mg Subcutaneous Sumatriptan

BACKGROUND

Subcutaneous sumatriptan (6 mg) is undeniably an excellent treatment of migraine. However, some patients have avoided using 6 mg sumatriptan because of unpleasant or unwanted side effects.

OBJECTIVE

To evaluate the efficacy of subcutaneous sumatriptan (3 mg) during a moderate or severe migraine attack.

METHODS

Thirty subcutaneous sumatriptan-naive patients with a history of migraine with and without aura treated their next two moderate or severe migraines with either 3-mg or 6-mg sumatriptan injection. The primary endpoint was whether patients preferred the low-dose (3 mg) or the high-dose (6 mg) subcutaneous sumatriptan. Other objectives included percentage of patients pain free at 15 and 30 minutes, 1 and 2 hours; a pain-free response lasting between 2 and 24 hours, patient satisfaction, and acceptability of formulation. A new combination endpoint (efficacy and lack of significant side effects) was also evaluated.

RESULTS

Eighty percent of patients preferred 3-mg over 6-mg subcutaneous sumatriptan. At 1 hour postdose 57% of patients were pain free with 3 mg and 53% with 6 mg. At 2 hours postdose 87% were pain free with 3 mg and 80% with 6 mg. A sustained pain-free response was obtained by 70 to 80% of patients. When combining a pain-free response at 2 hours and a sustained pain-free response at 24 hours with no significant side effects, more patients met the endpoint with 3 mg (63 to 67%) than with 6 mg (33 to 50%).

CONCLUSIONS

Combining efficacy and tolerability endpoints may be clinically meaningful and reflective of real-world expectations. In some patients, a lower dose of sumatriptan injection may be beneficial.

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.

When to Stress Over Triptans: A Markov Analysis of Cardiovascular Risk in Migraine Treatment

BACKGROUND

Migraines affect 10% of the U.S. population and the episodes are frequently associated with significant disability. Triptans, 5HT1 receptor agonists, can be highly effective in treating pain and reducing disability. However, reports of cardiac events associated with triptan ingestion have led to concerns about its use in the face of possible cardiac disease.

OBJECTIVE

Should a patient without known cardiovascular disease (CAD) and moderately severe to severe migraines undergo cardiovascular testing prior to the initiation of triptan therapy?

DESIGN

A Markov model of migraine and cardiac disease using DATA 4.0. Three strategies were compared: (1) use triptans without further evaluation (TREAT); (2) test, then treat if negative (TEST); and (3) avoid triptans (NOTRIPTAN). Triptans were prohibited if a cardiac event occurred.

DATA

Model inputs were derived from the literature and subjected to sensitivity analyses across all possible values.

TIME HORIZON

Markov cycle is 1 week.

OUTCOMES

The primary outcomes of interest were quality-adjusted life expectancy, in years (QALYs) and the impact of various cardiovascular risk levels on the preferred strategy.

RESULTS

For the base case results were TREAT 19.4 QALYs, TEST 19.2, NOTRIPTAN 19.1. When altering CAD probability: TREAT dominated from 0 to 87%, TEST 87% to 97%, and NOTRIPTAN above 97%. Results were robust during sensitivity analyses.

CONCLUSIONS

This analysis suggests that even for individuals with a relatively high risk of CAD it is not beneficial to perform cardiac testing, nor to avoid triptans. The exact level of cardiac risk at which testing should be considered is probably at or above 87%.

The genetics of migraine: implication for treatment approaches

Migraine is a paroxysmal neurological disorder affecting up to 12% of males and 24% of females in the general population, demonstrated to have a strong, but complex, genetic component. Genetic investigation of migraine bears great promise in providing new targets for drug development and optimization of individual specific therapy. Better, preferably prophylactic, treatment of migraine patients is desired because the presently used drugs are not effective in all patients, allow recurrence of the headache in a high percentage of patients and sometimes have severe adverse side effects. With the recent identification of the brain-specific P/Q-type calcium channel gene CACNA1A in the pathogenesis of migraine, the first step has been taken to identify primary biochemical pathways leading to migraine. Here, we summarize the current knowledge about the genetics of migraine and focus on the implication for treatment approaches.

Tolerability of the triptans: clinical implications

The triptans represent a relatively new class of compounds effective in the treatment of migraine. The safety and tolerability of these drugs have been extensively investigated since the first triptan (sumatriptan) became commercially available. A report on a very large population of patients tested during clinical trials and in postmarketing studies, confirms that these drugs are safe and well tolerated when correctly used. Adverse events are frequently reported, but are usually mild and only a few patients discontinue therapy because of them. These adverse events include, in particular, the so-called 'triptan symptoms' (tingling, sensation of warmth, etc.). The exact mechanism of chest symptoms reported by 20% of patients with migraine treated with triptans remains unclear, but are exceptionally related to a cardiac mechanism. CNS adverse events (i.e. somnolence) are also reported, but it is a matter of debate whether they are related to the pharmacological properties (i.e. lipophilicity) of the drug or are symptoms of the disease itself. The potential risk for drug overuse must be taken into account when the triptans are given to patients with a high frequency of migraine attacks. Clinical interaction of triptans with other drugs metabolised in the liver may theoretically influence the incidence of adverse events, but there is little evidence to support this assumption. There is no evidence of a teratogenic risk of triptans in pregnant women taking these drugs.

Almotriptan: a review of its use in migraine

Almotriptan is a selective serotonin 5-HT(1B/1D) receptor agonist ('triptan'). Its efficacy and tolerability have been assessed in a number of randomised, controlled trials in over 4800 adults with moderate or severe attacks of migraine. Oral almotriptan has a rapid onset of action (significant headache relief is observed 0.5 hours after administration of a 12.5mg dose) and efficacy is sustained in most patients who respond by 2 hours. The drug is significantly more effective than placebo as measured by a number of parameters including 2-hour headache response and pain-free response rates. Other symptoms of migraine, including nausea, photophobia and phonophobia, are also alleviated by almotriptan. The efficacy of oral almotriptan appears to be maintained over repeated doses for multiple attacks of migraine treated over a long period (up to 1 year). High headache response rates were reported over all attacks without tachyphylaxis. For the relief of single attacks of migraine, oral almotriptan 12.5mg had similar efficacy to oral sumatriptan 50mg. Patients given almotriptan report less concern with adverse effects than patients given sumatriptan. The lower incidence of chest pain following treatment with almotriptan than with sumatriptan may lead to a reduction in direct costs, with fewer patients requiring management of chest pain. Almotriptan is well tolerated. Most adverse events were of mild or moderate intensity, transient, and generally resolved without intervention or the need for treatment withdrawal. The most common adverse events associated with oral almotriptan 12.5mg treatment were dizziness, paraesthesia, nausea, fatigue, headache, somnolence, skeletal pain, vomiting and chest symptoms. The incidence of adverse events did not differ from placebo and decreased in the longer term. Almotriptan can be coadministered with drugs that share a common hepatic metabolic path; in addition, dosage reduction is required only in the presence of severe renal or hepatic impairment.

CONCLUSIONS

Almotriptan is an effective drug for the acute treatment of moderate or severe attacks of migraine in adults. An oral dose of almotriptan 12.5mg has shown greater efficacy than placebo; current data indicate that efficacy is similar to that of oral sumatriptan 50mg, and is maintained in the long term (<or=1 year). Almotriptan has a good adverse event profile and a generally similar overall tolerability profile to sumatriptan; of note, almotriptan is associated with a significantly lower incidence of chest pain than sumatriptan. However, further clinical experience is required to clearly define the place of almotriptan among the other currently available triptans. Nevertheless, because triptans have an important place in various management regimens, and because the nature of individual patient response to triptans is idiosyncratic, almotriptan is likely to become a useful treatment option in the management of adults with moderate or severe migraine headaches.

The safety of triptans in the treatment of patients with migraine

The introduction of the triptans (5-hydroxytryptophan [5-HT] (1B/1D) agonists) in the past decade has brought migraine-specific pain relief to those suffering from migraine. These drugs activate the serotonin receptors 5-HT(1B) and 5-HT(1D) on cerebral vessels. Concerns about their safety, particularly in patients with vascular risk factors, have been raised because triptans also activate the 5-HT(1B) receptors on coronary arteries. Although triptans are contraindicated in patients with cardiac or cerebrovascular disease, they are safer than many other medications used to treat patients with migraine, including the nonspecific serotonin-agonist ergot preparations.

New paradigms in the recognition and acute treatment of migraine

It would be ideal if clinical decisions regarding acute migraine treatment could be made on the basis of three parameters: a critical appraisal of available scientific evidence, clinical experience (including knowledge of the individual patient and his/her attack characteristics), and, of course, patient preferences. Patients are likely to prefer agents that offer rapid relief, pain-free status within 2 hours, no recurrence or need for rescue medication, extended time to recurrence (if present), consistency of therapeutic effect over multiple attacks, oral administration. good tolerability, safety, and minimal drug interactions. Fortunately, a number of specific therapies now are available which place these objectives within the patient's reach. Ongoing barriers to optimal migraine care include underrecognition, underconsultation, undertreatment, restrictions imposed by insurance companies, and exaggerated concerns regarding the safety of the triptans. Overcoming these barriers is likely to prove a more important contribution to patient care than endeavoring to establish the relative merits of one triptan over another. We have described in detail a number of strategies for improving recognition and treatment of migraine. Many headache specialists now believe that recurrent episodes of disabling headache, with a stable pattern over years, should be viewed as migraine until proven otherwise. In the end, this may represent the most useful paradigm in the primary care setting, where time is of the essence. Studies to validate this approach are needed. Acute treatment intervention that is based on scientific evidence, clinical experience, and patients' needs and desires will provide better outcomes than those presently obtained. Preliminary evidence favors early intervention with oral triptans, and randomized, prospective, double-blind, placebo-controlled studies, ideally employing a crossover design, are required to confirm this. The US Consortium's evidence-based guidelines, the National Headache Foundation's standards of care, and the Canadian guidelines have applied the standards of scientific inquiry to the field of headache management and "translation" of these guidelines into practical instruments for clinicians through vehicles such as the Primary Care Network's Patient-Centered Strategies for Effective Management of Migraine should raise the general standard of care for patients with migraine. Last, but far from least, initiatives undertaken by the World Health Organization (WHO) will add credibility to the many layfolk and professionals who have struggled to present headache as a disabling disorder worthy of scientific investigation and aggressive medical management. The WHO states: "These common complaints impose a significant health burden ... Despite this, both the public and the majority of healthcare professionals tend to perceive headache as a minor or trivial complaint. As a result, the physical, emotional, social and economic burdens of headache are poorly acknowledged in comparison with those of other, less prevalent, neurologic disorders." Migraine is finally out of the closet.

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.

Pharmacokinetics and pharmacodynamics of the triptan antimigraine agents: a comparative review

The current approach to antimigraine therapy comprises potent serotonin 5-HT1B/1D receptor agonists collectively termed triptans. Sumatriptan was the first of these compounds to be developed, and offered improved efficacy and tolerability over ergot-derived compounds. The development of sumatriptan was quickly followed by a number of 'second generation' triptan compounds, characterised by improved pharmacokinetic properties and/or tolerability profiles. Triptans are believed to effect migraine relief by binding to serotonin (5-hydroxy-tryptamine) receptors in the brain, where they act to induce vasoconstriction of extracerebral blood vessels and also reduce neurogenic inflammation. Although the pharmacological mechanism of the triptans is similar, their pharmacokinetic properties are distinct. For example, bioavailability of oral formulations ranges between 14% (sumatriptan) and 74% (naratriptan), and their elimination half-life ranges from 2 hours (sumatriptan and rizatriptan) to 25 hours (frovatriptan). Clearly, such diverse pharmacokinetic properties will influence the effectiveness of the compounds and favour the prescription of one over another in different patient populations. This article reviews the pharmacological properties of the triptans (time to peak plasma concentration, half-life, bioavailability and receptor binding) and relates these properties to efficacy and time of onset. It also considers the effects of concomitant medication, food, age and disease on the pharmacokinetics of the compounds. In addition, the relative merits, such as headache recurrence, tolerability and route of administration, are discussed. Finally, the performance of the triptans is considered in the context of direct head-to-head comparative trials that have assessed the efficacy profile of the compounds.

Safety and efficacy of PNU-142633, a selective 5-HT1D agonist, in patients with acute migraine

In this randomized, double-blind, placebo-controlled, parallel-group study, patients received a single 50-mg oral dose of a 5-HT(1D) agonist, PNU-142633 (n = 34), or matching placebo (n = 35) during an acute migraine attack. No statistically significant treatment effects were observed at 1 and 2 h after dosing, even after stratifying by baseline headache intensity. At 1 and 2 h post-dose, 8.8% and 29.4% of the PNU-142633 group, respectively, and 8.6% and 40.0% of the placebo group, respectively, experienced headache relief; 2.9% and 8.8% of the PNU-142633 group and 0% and 5.7% of the placebo group were free of headache pain. Adverse events associated with PNU-142633 treatment included chest pain (two patients) and QTc prolongation (three patients). Results from this study suggest that anti-migraine efficacy is not mediated solely through the 5-HT(1D) receptor subtype, although this receptor may contribute, at least in part, to the adverse cardiovascular effects observed with 5-HT agonist medications.

Oral almotriptan in the treatment of migraine: safety and tolerability

OBJECTIVE

To summarize safety and tolerability data on orally administered almotriptan from premarketing clinical trials.

BACKGROUND

Almotriptan is a new 5-HT1B/1D receptor agonist similar to sumatriptan in mode of action and therapeutic efficacy. In addition, the safety and tolerability profile of almotriptan has been demonstrated in a number of controlled clinical trials. Sumatriptan is generally safe and well tolerated; however, in controlled clinical trials, it has been associated with chest symptoms (pressure, warmth, and other unpleasant sensations) with an incidence of 3% to 5%.

DESIGN

Three phase 1 dose-finding and pharmacokinetic studies in healthy men and women volunteers were reviewed to assess the safety and tolerability of oral almotriptan at single doses ranging from 2 to 200 mg. The objective of one study was to evaluate cardiovascular safety. Two phase 2 trials assessed the safety and tolerability of single doses of 2 to 150 mg in migraine (n=911). Two phase 3 trials assessed the safety and tolerability of a single 12.5-mg oral dose after three attacks (n=910) and repeated doses of 12.5 mg for multiple attacks over the long term (n=747). All studies were conducted in Europe. Data from the United States is currently being analyzed and will be published at a later date.

RESULTS

In phase 2 and 3 trials comprising more than 2500 patients with migraine and 15 000 attacks, adverse events were infrequent and mild. The most common events-dizziness, nausea and vomiting, headache, fatigue, paresthesia, and drowsiness-were reported in fewer than 3% of patients. At the recommended therapeutic dose of 12.5 mg, the adverse events profile was not statistically different from placebo. The incidence of chest symptoms was 0.2% in the phase 3 trials. The long-term safety and tolerability profile after treatment of more than 10 000 attacks was similar to that following the single-dose studies. In all clinical trials, almotriptan demonstrated a very favorable adverse event profile, particularly with respect to nonischemic-related chest symptoms.

CONCLUSIONS

Almotriptan was safe and well tolerated in nearly all adult patients with migraine, with and without aura, enrolled in these studies. The incidence of chest symptoms in preclinical studies was substantially lower than that reported for sumatriptan in premarketing studies, indicating that almotriptan may be better tolerated than sumatriptan at clinically anticipated doses. However, any potential difference in cardiovascular safety between almotriptan and sumatriptan cannot be determined or inferred from this data. Cardiovascular risk profiles for all drugs within this class (triptans) should be considered similar. Only extensive postmarketing data, not currently available, can potentially change this recommendation.