Subcutaneous histamine versus topiramate in migraine prophylaxis: a double-blind study

Migraine, Allergy, and Histamine: Is There a Link?

The relationship between migraines and allergies is controversial. Though they are epidemiologically linked, the underlying pathophysiological connection between them remains unclear. Migraines and allergic disorders have various underlying genetic and biological causes. As per the literature, these conditions are epidemiologically linked, and some common pathophysiological pathways have been hypothesized. The histaminergic system may be the clue to understanding the correlation among these diseases. As a neurotransmitter in the central nervous system with a vasodilatory effect, histamine has a well-documented influence on the allergic response and could be involved in the pathophysiology of migraines. Histamine may influence hypothalamic activity, which may play a major role in migraines or may simply influence their severity. In both cases, antihistamine drugs could prove useful. This review examines whether the histaminergic system, particularly H3 and H4 receptors, may provide a mechanistic link between the pathophysiology of migraines and allergic disorders, two common and debilitating conditions. Identifying their connection could help identify novel therapeutic strategies.

Histamine and migraine revisited: mechanisms and possible drug targets

OBJECTIVE

To review the existing literature on histamine and migraine with a focus on the molecule, its receptors, its use in inducing migraine, and antihistamines in the treatment of migraine.

BACKGROUND

Histamine has been known to cause a vascular type headache for almost a hundred years. Research has focused on antihistamines as a possible treatment and histamine as a migraine provoking agent but there has been little interest in this field for the last 25 years. In recent years two additional histamine (H3 and H4) receptors have been discovered and a series of non-sedating antihistamines have been developed. It is therefore timely to review the field again.

METHODS

For this review the PubMed/MEDLINE database was searched for eligible studies. We searched carefully for all articles on histamine, antihistamines and histamine receptors in relation to migraine and the nervous system. The following search terms were used: histamine, migraine disorders, migraine, headache, antihistamines, histamine antagonists, clinical trials, induced headache, histamine H3 receptor, histamine H4 receptor and pharmacology. Four hundred thirty-six titles were read, 135 abstracts were read, 112 articles were read in full and 53 articles were used in this review. Review process resulted in 12 articles added to a total of 65.

FINDINGS

Early studies of H1 and H2 antihistamines lack scientific strength and show conflicting results. Most of the antihistaminic drugs used in these trials bind also to other receptors which makes it difficult to conclude on the antihistaminic effect. Histamine is an efficient inducer of migraine attacks in migraine patients by an H1 mechanism most likely extracerebrally. These findings merit further investigation of antihistamines in clinical drug trials. The H3 and H4 receptors are found in primarily in CNS and immune tissues, respectively. H3 is likely to be involved in antinociception and has been linked with cognitive, neurodegenerative and sleep disorders. The only marketed H3 agent, pitolisant, is a brain penetrant H3 antagonist/inverse agonist which increases central histamine and causes headache. The experimental H3 agonist Nα-methylhistamine has shown promising results as a migraine preventative in studies of uncertain quality. With the current limited knowledge of the H4 receptor it is questionable whether or not the receptor is involved in migraine.

CONCLUSION

There is insufficient support for first generation antihistamines (both H1 and H2) as preventive migraine medications and sedation and weight gain are unacceptable side effects. Non-sedating H1 antihistamines need to be appropriately tested. Central H3 receptors seem to have a role in migraine that merit further investigation. The histaminergic system may be a goal for novel migraine drugs.

Histamine and Migraine

BACKGROUND

Histamine is an ancient "tissue amine" preceding multicellular organisms. In the central nervous system (CNS), its fibers originate solely from the tuberomammillary nucleus and travel throughout the brain. It is mainly responsible for wakefulness, energy homeostasis, and memory consolidation. Recently, several studies suggest a potential role of histamine in migraine pathogenesis and management.

METHODS

Narrative review of current literature regarding histamine and migraine.

RESULTS

Histamine plays a crucial role in migraine pathogenesis: sustaining the neurogenic inflammation pathway. Interaction between mast cells (MC) and calcitonin-gene related protein (CGRP) results in sensitization of trigeminal afferents and trigeminal ganglia (TG). Histamine binds with differing affinities to four different histaminergic G-protein coupled receptors, activating protein kinases, or triggering calcium release with subsequent mode of actions. Histamine 1 receptor (H₁ R) and histamine 2 receptor (H₂ R) antagonists are frequently used for the treatment of allergy and gastric acid secretion, respectively, but their antagonism is probably ineffective for migraine. Histamine 3 receptor (H₃ R) and histamine 4 receptor (H₄ R) have a threefold higher affinity than H₁ R/H₂ R for histamine and are found almost exclusively on neurons and immune tissues, respectively. H₃ R acts as an autoreceptor or as a heteroreceptor, lowering the release of histamine and other neurotransmitters. This is a potential target for anti-nociception and anti-neurogenic inflammation. To date, several small clinical trials using low dose histamine or N^α -methylhistamine have demonstrated migraine prophylactic efficacy, probably via H₃ R or other undetermined pathways.

CONCLUSION

The histamine system interacts with multiple regions in the CNS and may hypothetically modulate the migraine response. Low dose histamine may be a promising option for migraine prevention.

General lack of use of placebo in prophylactic, randomised, controlled trials in adult migraine. A systematic review

Background

The Clinical Trials Subcommittee of the International Headache Society (IHS) recommends that a placebo arm is included in comparative randomised clinical trials (RCTs) of multiple prophylactic drugs due to the highly variable placebo response in migraine prophylaxis studies. The use of placebo control in such trials has not been systematically assessed.

Methods

We performed a systematic review of all comparative RCTs of prophylactic drug treatment of migraine published in English from 2002 to 2014. PubMed was searched using the Cochrane Highly Sensitive Search Strategy for identifying reports of RCTs.

Results

A placebo arm was used in <10% (three of 31) of prophylactic RCTs in migraine. In only 7.1% (two of 28) of the comparative RCTs without placebo was one drug superior to another drug. Thus in 26 RCTs, including one study requiring more than 75,000 patient days, no difference was identified across treatment arms and conclusions regarding drug superiority could not be drawn.

Conclusions

The majority of comparative, prophylactic migraine RCTs do not include a placebo arm. Failure to include a placebo arm may result in failure to demonstrate efficacy of potentially effective migraine-prophylactic agents. In order to benefit current and future patients, the current strong tendency to omit placebo-controls in these RCTs should be replaced by adherence to the guidelines of the IHS.

The Use of Antiepileptics in Migraine Prophylaxis

BACKGROUND

Migraine is a chronic debilitating disorder. Selected antiepileptic drugs (AEDs) are proposed as preventives for migraine. Clinical efficacy and side effects of these AEDs are discussed.

SUMMARY OF REVIEW

The American Academy of Neurology and the American Society of Headache classify topiramate (TPM) and divalproex sodium (DVPX) as Level-A medications and recommend offering them to patients for migraine prophylaxis. Their mechanism(s) of actions remains not entirely known. Their recognized action as sodium channel blockers may affect the neural component of migraine pain. TPM or DVPX can be considered an obvious choice for those patients with a concomitant seizure disorder. Care must be taken to plan their treatment with their psychiatrist if a mood disorder is present. DVPX tends not to be prescribed as first/second choice due to its potential for weight gain and hepatotoxicity. TPM is generally first choice, but bears severe contraindications. Both medications require education on teratogenesis in childbearing women. Consideration of gabapentin, acetazolamide, leviteracetam, zonisamide, and carbamazipine may be given later as empiric options and in selected patients. Patients must be made aware that there is insufficient scientific support for their use in migraine.

CONCLUSIONS

Available AEDs to prophylactically treat migraine are few but of robust clinical efficacy. Special care needs to be exerted with respect to their side effects. Future research is needed for a better understanding of their mechanisms of action in migraine. Such research has the potential of providing some insight into the pathophysiology of migraine.

Preventive Migraine Treatment

PURPOSE OF REVIEW

This article reviews the evidence base for the preventive treatment of migraine.

RECENT FINDINGS

Evidence-based guidelines for the preventive treatment of migraine have recently been published by the American Academy of Neurology (AAN) and the Canadian Headache Society (CHS), providing valuable guidance for clinicians. Strong evidence exists to support the use of metoprolol, timolol, propranolol, divalproex sodium, sodium valproate, and topiramate for migraine prevention, according to the AAN. Based on best available evidence, adverse event profile, and expert consensus, topiramate, propranolol, nadolol, metoprolol, amitriptyline, gabapentin, candesartan, Petasites (butterbur), riboflavin, coenzyme Q10, and magnesium citrate received a strong recommendation for use from the CHS.

SUMMARY

Migraine preventive drug treatments are underutilized in clinical practice. Principles of preventive treatment are important to improve compliance, minimize side effects, and improve patient outcomes. Choice of preventive treatment of migraine should be based on the presence of comorbid and coexistent illness, patient preference, reproductive potential and planning, and best available evidence.

Histamine in migraine and brain

BACKGROUND

Histamine has been studied in both health and disease since the initial description a century ago. With its vasodilative effect, it was suggested early on to be involved in the pathophysiology of migraine. Over the past 25 years, much has been learned about histamine as a neurotransmitter in the central nervous system. The role of this neurotransmitter system in migraine has not been previously reviewed.

OBJECTIVE

Discuss a potential role of the brain histaminergic system in migraine.

METHODS

Unstructured literature search with a no specific hypothesis-driven approach.

RESULTS

There is substantial evidence that systemically given histamine may elicit, maintain, and aggravate headache. The mechanisms for this are not known, and histamines do not penetrate the blood-brain barrier (BBB). However, circulating histamine may influence hypothalamic activity via the circumventricular organs that lack BBB. In the rat, prolonged activation of meningeal nociceptors induced by dural mast cell degranulation has been observed. Subcutaneous injections of N-alpha-methyl histamine, a catabolite of histamine with high affinity to the histamine H3 receptor, probably have some migraine preventive effect. A negative feedback on histamine release from mast cells in proximity to C-fiber endings has been a postulated mechanism. Most antihistamines have shown to be ineffective as acute medication for migraine. Two centrally acting potent H1 receptor antagonists (cinnarizine and cyproheptadine) have been reported to be efficacious in preventing migraine. However, the proof for this is limited, and their efficacy has been ascribed other actions than the antihistaminergic. In general, lack of specificity and side effects limit the potential use of centrally acting H1 and H2 antagonists. Brain histamine is synthesized by neurons that are restricted to the posterior basal hypothalamus, more specific to the tuberomamillary nucleus (TMN), and that project practically to the whole central nervous system. The posterior hypothalamus is a suspected locus in quo in several primary headaches. Recently, a positron emission tomography study performed in the prodromal phase of migraine attacks supported the idea of initial involvement of this area. In another recent study, the thalamic nuclei receiving trigeminal output was also shown to have direct connections with the ventral TMN. The central histaminergic system plays an important role in the complex sleep-wake cycle, promoting cortical excitability during wakening and attention, and it consolidates the wake state. The period of the day, in the evenings and during the night, when there is reduced susceptibility for migraine attacks corresponds with less central histaminergic firing. Activation of both the H3 and the H4 receptor promotes inhibitory actions on neurons. The H3 receptor causes autoinhibition of the histaminergic neurons themselves, and centrally acting H3 receptor agonist prodrugs have shown to both inhibit neurogenic inflammation in dura, to induce sleep, and to produce antinociception. There are no registered ongoing studies on H3 and H4 receptor ligands in migraine.

CONCLUSION

The role of the central histaminergic system in migraine is largely unexplored, but findings from preclinical research may be linked to several aspects of the disorder. The histaminergic system of the brain may play an important role, especially in the initial phase of an attack, and histamine H3 and H4 receptor ligands may potentially have migraine prophylactic properties. However, the basis for this is still circumstantial, and the evidence is lacking.

Chemical mediators of migraine: preclinical and clinical observations

Migraine is a neurovascular disorder, and although the pathophysiology of migraine has not been fully delineated, much has been learned in the past 50 years. This knowledge has been accompanied by significant advancements in the way migraine is viewed as a disease process and in the development therapeutic options. In this review, we will focus on 4 mediators (nitric oxide, histamine, serotonin, and calcitonin gene-related peptide) which have significantly advanced our understanding of migraine as a disease entity. For each mediator we begin by reviewing the preclinical data linking it to migraine pathophysiology, first focusing on the vascular mechanisms, then the neuronal mechanisms. The preclinical data are then followed by a review of the clinical data which support each mediator's role in migraine and highlights the pharmacological agents which target these mediators for migraine therapy.

Topiramate for the prophylaxis of episodic migraine in adults

BACKGROUND

Some antiepileptic drugs but not others are useful in clinical practice for the prophylaxis of migraine. This might be explained by the variety of actions of these drugs in the central nervous system. The present review is part of an update of a Cochrane review first published in 2004, and previously updated (conclusions not changed) in 2007.

OBJECTIVES

To describe and assess the evidence from controlled trials on the efficacy and tolerability of topiramate for preventing migraine attacks in adult patients with episodic migraine.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2012, Issue 12), PubMed/MEDLINE (1966 to 15 January 2013), MEDLINE In-Process (current week, 15 January 2013), and EMBASE (1974 to 15 January 2013) and handsearched Headache and Cephalalgia through January 2013.

SELECTION CRITERIA

Studies were required to be prospective, controlled trials of topiramate taken regularly to prevent the occurrence of migraine attacks, to improve migraine-related quality of life, or both.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies and extracted data. For headache frequency data, we calculated mean differences (MDs) between topiramate and comparator (placebo, active control, or topiramate in a different dose) for individual studies and pooled these across studies. For dichotomous data on responders (patients with ≥ 50% reduction in headache frequency), we calculated odds ratios (ORs) and, in select cases, risk ratios (RRs); we also calculated numbers needed to treat (NNTs). We calculated MDs for selected quality of life instruments. Finally, we summarised data on adverse events from placebo-controlled trials and calculated risk differences (RDs) and numbers needed to harm (NNHs).

MAIN RESULTS

Twenty papers describing 17 unique trials met the inclusion criteria. Analysis of data from nine trials (1737 participants) showed that topiramate reduced headache frequency by about 1.2 attacks per 28 days as compared to placebo (MD -1.20; 95% confidence interval (CI) -1.59 to -0.80). Data from nine trials (1190 participants) show that topiramate approximately doubled the proportion of responders relative to placebo (RR 2.02; 95% CI 1.57 to 2.60; NNT 4; 95% CI 3 to 6). Separate analysis of different topiramate doses produced similar MDs versus placebo at 50 mg (-0.95; 95% CI -1.95 to 0.04; three studies; 520 participants), 100 mg (-1.15; 95% CI -1.58 to -0.71; six studies; 1620 participants), and 200 mg (-0.94; 95% CI -1.53 to -0.36; five studies; 804 participants). All three doses significantly increased the proportion of responders relative to placebo; ORs were as follows: for 50 mg, 2.35 (95% CI 1.60 to 3.44; three studies; 519 participants); for 100 mg, 3.49 (95% CI 2.23 to 5.45; five studies; 852 participants); and for 200 mg, 2.49 (95% CI 1.61 to 3.87; six studies; 1025 participants). All three doses also significantly improved three or more domains of quality of life as compared to placebo. Meta-analysis of the three studies that included more than one dose of topiramate suggests that 200 mg is no more effective than 100 mg. With regard to mean headache frequency and/or responder rate, seven trials using active comparators found (a) no significant difference between topiramate and amitriptyline (one study, 330 participants); (b) no significant difference between topiramate and flunarizine (one study, 83 participants); (c) no significant difference between topiramate and propranolol (two studies, 342 participants); (d) no significant difference between topiramate and relaxation (one study, 61 participants); but (e) a slight significant advantage of topiramate over valproate (two studies, 120 participants). Relaxation improved migraine-specific quality of life significantly more than topiramate. In trials of topiramate against placebo, seven adverse events (AEs) were reported by at least three studies. These were usually mild and of a non-serious nature. Except for taste disturbance and weight loss, there were no significant differences in the frequency of AEs in general, or of the seven specific AEs, between placebo and topiramate 50 mg. AEs in general and all of the specific AEs except nausea were significantly more common on topiramate 100 mg than on placebo, with NNHs varying from 3 to 25, and the RDs versus placebo were even higher for topiramate 200 mg, with NNHs varying from 2 to 17.

AUTHORS' CONCLUSIONS

Meta-analysis demonstrates that topiramate in a 100 mg/day dosage is effective in reducing headache frequency and reasonably well-tolerated in adult patients with episodic migraine. This provides good evidence to support its use in routine clinical management. More studies designed specifically to compare the efficacy or safety of topiramate versus other interventions with proven efficacy in the prophylaxis of migraine are needed.

Preventive treatment in migraine and the new US guidelines

Migraine headaches are among the most common headache disorders seen in various practices. The prevalence of migraine headaches is 18% in women and 6% in men. While millions of Americans suffer from migraine headaches, roughly 3%-13% of identified migraine patients are on preventive therapy, while an estimated 38% actually need a preventive agent. The challenge among physicians is not only when to start a daily preventive agent but which preventive agent to choose. Circumstances warranting prevention have been described in the past, and in 2012, a new set of guidelines with an evidence review on preventive medications was published. A second set of guidelines provided evidence on nonsteroidal anti-inflammatory drugs, herbs, minerals, and vitamins for prevention of episodic migraine. This article describes the updated US guidelines for the prevention of migraines and also outlines the major studies from which these guidelines were derived.

A systematic review of the psychosocial difficulties relevant to patients with migraine

Migraine is a common disease which causes significant burden to individuals, in terms of personal suffering and activity reduction, and to societies, in terms of disease cost. The purpose of this study is to identify the most relevant psychosocial difficulties related to migraine, the variables associated with them and the most relevant determinants of their evolution over time. MEDLINE and PsychINFO were searched for studies published in English between 2000 and 2010 that examined psychosocial difficulties in persons with migraine with and without aura, from clinical trials and observational studies. Information on the description of each difficulty, its determinants of onset and change over time and associated variables were extracted and categorized at a higher level. In total, 34 difficulties have been collected from 51 papers: the most frequent were reduced vitality and fatigue, emotional problems, pain, difficulties at work, general physical and mental health, social functioning and global disability. Evidence exists that pharmacological treatments have an impact toward improvement in patients’ difficulties, in particular emotional problems, physical and mental health, difficulties with employment and global disability. Migraine treatments and decreased headaches frequency are the major determinants of improvements in psychosocial difficulties, while no information is available for determinants of worsening; understanding the role of such factors is of primary public health relevance, given the high prevalence and the relevant personal and societal costs of migraine.

Evidence-based guideline update: pharmacologic treatment for episodic migraine prevention in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Headache Society

OBJECTIVE

To provide updated evidence-based recommendations for the preventive treatment of migraine headache. The clinical question addressed was: What pharmacologic therapies are proven effective for migraine prevention?

METHODS

The authors analyzed published studies from June 1999 to May 2009 using a structured review process to classify the evidence relative to the efficacy of various medications available in the United States for migraine prevention.

RESULTS AND RECOMMENDATIONS

The author panel reviewed 284 abstracts, which ultimately yielded 29 Class I or Class II articles that are reviewed herein. Divalproex sodium, sodium valproate, topiramate, metoprolol, propranolol, and timolol are effective for migraine prevention and should be offered to patients with migraine to reduce migraine attack frequency and severity (Level A). Frovatriptan is effective for prevention of menstrual migraine (Level A). Lamotrigine is ineffective for migraine prevention (Level A).

Evidence-based guideline update: NSAIDs and other complementary treatments for episodic migraine prevention in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Headache Society

OBJECTIVE

To provide updated evidence-based recommendations for the preventive treatment of migraine headache. The clinical question addressed was: Are nonsteroidal anti-inflammatory drugs (NSAIDs) or other complementary treatments effective for migraine prevention?

METHODS

The authors analyzed published studies from June 1999 to May 2009 using a structured review process to classify the evidence relative to the efficacy of various medications for migraine prevention.

RESULTS

The author panel reviewed 284 abstracts, which ultimately yielded 49 Class I or Class II articles on migraine prevention; of these 49, 15 were classified as involving nontraditional therapies, NSAIDs, and other complementary therapies that are reviewed herein.

RECOMMENDATIONS

Petasites (butterbur) is effective for migraine prevention and should be offered to patients with migraine to reduce the frequency and severity of migraine attacks (Level A). Fenoprofen, ibuprofen, ketoprofen, naproxen, naproxen sodium, MIG-99 (feverfew), magnesium, riboflavin, and subcutaneous histamine are probably effective for migraine prevention (Level B). Treatments considered possibly effective are cyproheptadine, Co-Q10, estrogen, mefenamic acid, and flurbiprofen (Level C). Data are conflicting or inadequate to support or refute use of aspirin, indomethacin, omega-3, or hyperbaric oxygen for migraine prevention. Montelukast is established as probably ineffective for migraine prevention (Level B).

Clinical pharmacology of topiramate in migraine prevention

INTRODUCTION

Migraine is a widespread disorder. Migraine patients experience worse health-related quality of life than the general population. The availability of effective and tolerable treatments for this disorder is an important medical need. This narrative review focuses on the clinical pharmacology of topiramate, an antiepileptic drug that was approved for the prophylaxis of migraine where it should act as a neuromodulator.

AREAS COVERED

A PubMed database search (from 2000 to 24 January 2011) and a review of the human studies published on topiramate and migraine was conducted.

EXPERT OPINION

Topiramate is an important option for the prophylaxis of migraine and is of proven efficacy and tolerability. It has also been studied in chronic migraine with encouraging results, even in patients with medication overuse. However, in migraine prevention its efficacy is comparable to the other first-line drugs and there are no published trials with a superiority design which can establish topiramate's role in the available therapeutic armamentarium.

Are the current IHS guidelines for migraine drug trials being followed?

In 2000, the Clinical Trials Subcommittee of the International Headache Society (IHS) published the second edition of its guidelines for controlled trials of drugs in migraine. The purpose of this publication was to improve the quality of such trials by increasing the awareness amongst investigators of the methodological issues specific to this particular illness. Until now the adherence to these guidelines has not been systematically assessed. We reviewed all published controlled trials of drugs in migraine from 2002 to 2008. Eligible trials were scored for compliance with the IHS guidelines by using grading scales based on the most essential recommendations of the guidelines. The primary efficacy measure of each trial was also recorded. A total of 145 trials of acute treatment and 52 trials of prophylactic treatment were eligible for review. Of the randomized, double-blind trials, acute trials scored an average of 4.7 out of 7 while prophylactic trials scored an average of 5.6 out of 9 for compliance. Thirty-one percent of acute trials and 72% of prophylactic trials used the recommended primary efficacy measure. Fourteen percent of the reviewed trials were either not randomized or not double-blinded. Adherence to international guidelines like these of IHS is important to ensure that only high-quality trials are performed, and to provide the consensus that is required for meta analyses. The primary efficacy measure for trials of acute treatment should be “pain free” and not “headache relief”. Open-label or non-randomized trials generally have no place in the study of migraine drugs.

Cost effectiveness of pharmacotherapy for the prevention of migraine: a Markov model application

BACKGROUND

There are few data about the cost effectiveness of prophylactic medications for migraine. Clinical trials have shown several preventive agents to be useful in reducing the frequency of migraine attack while having tolerable side effects.

OBJECTIVE

To compare the cost effectiveness of adding preventive treatment to abortive therapy for acute migraine with abortive therapy for acute migraine alone in the primary care setting.

METHODS

A Markov decision analytic model with a cycle length of 1 day, a time horizon of 365 days and three health states was used to perform an analysis comparing the cost effectiveness and utility of five treatments for migraine prophylaxis (amitriptyline 75 mg/day, topiramate 100 and 200 mg/day, timolol 20 mg/day, divalproex sodium 1000 mg/day or propranolol 160 mg/day) with treatment of acute migraine alone for the management of migraine in the primary care setting. One-way and probabilistic sensitivity analyses were performed to test the robustness of the results.

RESULTS

The expected total annual cost for the use of preventive agents ranged from $US2932 to $US3887, compared with $US3960 for the use of abortive medications only. In the baseline analysis, use of each of the five preventive agents generated more quality-adjusted life-years (QALYs) and incurred lower costs compared with abortive medications only. Monte Carlo Simulation suggested that amitriptyline 75 mg/day was most likely to be considered a cost-effective option versus the other five therapies, followed by timolol 20 mg/day, topiramate 200 mg/day, topiramate 100 mg/day, divalproex sodium 1000 mg/day and propranolol 160 mg/day when the willingness-to-pay (WTP) for society is <$US18 000 per QALY gained.

CONCLUSIONS

Preventive medications appear to be a cost-effective approach to the management of migraine in the primary care setting compared with the approach of abortive treatment only. Among those preventive agents, probabilistic sensitivity analysis suggests that, when the societal WTP is <$US18 000 per QALY gained, amitriptyline 75 mg/day is most likely to be considered a cost-effective option.

Role of antiepileptic drugs as preventive agents for migraine

Migraine is a common neurological disease affecting about 12% of the population in Western Europe and North America, and causing a considerable burden both to migraineurs and to society. Severe, frequent and disabling migraine attacks, as well as those poorly responsive to acute care medication, require preventive treatment, which is often under-utilized. Antiepileptic drugs are used in the prevention of migraine. We performed a literature search of PubMed through June 2008 for controlled trials of antiepileptic drugs in the prevention of migraine. The search identified 70 papers for a full-text review. The majority of these papers referred to valproate and topiramate, and showed that these drugs are effective and well tolerated in migraine prevention and are suitable for first-line clinical use. On the other hand, acetazolamide, lamotrigine, oxcarbazepine and vigabatrin have been shown to be not effective and gabapentin requires further evaluation. For the rest of the antiepileptic drugs, no data from controlled trials are available.

New drugs for migraine

After the triptans, a calcitonin gene-related peptide blocker (telcagepant) is the first acute medicine that has been developed primarily for treatment of acute migraine. Otherwise, the new drugs have been developed first for other purposes, like anticonvulsants, antihypertensives and antidepressants used for migraine prophylaxis. For acute attacks, a new way to administer a traditional drug like dihydroergotamine is under way, and documentation of efficacy in migraine has been gained for some commonly used painkillers and anti-inflammatory drugs, and for some herbal extracts. Based on insights into the basic pathophysiological mechanisms of the disorder, some drugs have been developed which seem promising in early phase II studies (NOS inhibitors and 5HT1F-receptor agonists). In the future, development and enhancements of existing medicines must be accompanied by increased efforts to develop truly new migraine drugs based on knowledge of the pathophysiology if one wishes to reduce substantially the great burden migraine poses on patients and society.