New drugs for migraine

The need for new acutely acting antimigraine drugs: moving safely outside acute medication overuse

Background

The treatment of migraine is impeded by several difficulties, among which insufficient headache relief, side effects, and risk for developing medication overuse headache (MOH). Thus, new acutely acting antimigraine drugs are currently being developed, among which the small molecule CGRP receptor antagonists, gepants, and the 5-HT_1F receptor agonist lasmiditan. Whether treatment with these drugs carries the same risk for developing MOH is currently unknown.

Main body

Pathophysiological studies on MOH in animal models have suggested that decreased 5-hydroxytryptamine (5-HT, serotonin) levels, increased calcitonin-gene related peptide (CGRP) expression and changes in 5-HT receptor expression (lower 5-HT_1B/D and higher 5-HT_2A expression) may be involved in MOH. The decreased 5-HT may increase cortical spreading depression frequency and induce central sensitization in the cerebral cortex and caudal nucleus of the trigeminal tract. Additionally, low concentrations of 5-HT, a feature often observed in MOH patients, could increase CGRP expression. This provides a possible link between the pathways of 5-HT and CGRP, targets of lasmiditan and gepants, respectively. Since lasmiditan is a 5-HT_1F receptor agonist and gepants are CGRP receptor antagonists, they could have different risks for developing MOH because of the different (over) compensation mechanisms following prolonged agonist versus antagonist treatment.

Conclusion

The acute treatment of migraine will certainly improve with the advent of two novel classes of drugs, i.e., the 5-HT_1F receptor agonists (lasmiditan) and the small molecule CGRP receptor antagonists (gepants). Data on the effects of 5-HT_1F receptor agonism in relation to MOH, as well as the effects of chronic CGRP receptor blockade, are awaited with interest.

Anti-migraine effect of ∆9-tetrahydrocannabinol in the female rat

Current anti-migraine treatments have limited efficacy and many side effects. Although anecdotal evidence suggests that marijuana is useful for migraine, this hypothesis has not been tested in a controlled experiment. Thus, the present study tested whether administration of ∆⁹-tetrahydrocannabinol (THC) produces anti-migraine effects in the female rat. Microinjection of the TRPA1 agonist allyl isothiocyanate (AITC) onto the dura mater produced migraine-like pain for 3h as measured by depression of home cage wheel running. Concurrent systemic administration of 0.32 but not 0.1mg/kg of THC prevented AITC-induced depression of wheel running. However, 0.32mg/kg was ineffective when administered 90min after AITC. Administration of a higher dose of THC (1.0mg/kg) depressed wheel running whether rats were injected with AITC or not. Administration of a CB₁, but not a CB₂, receptor antagonist attenuated the anti-migraine effect of THC. These data suggest that: 1) THC reduces migraine-like pain when administered at the right dose (0.32mg/kg) and time (immediately after AITC); 2) THC's anti-migraine effect is mediated by CB₁ receptors; and 3) Wheel running is an effective method to assess migraine treatments because only treatments producing antinociception without disruptive side effects will restore normal activity. These findings support anecdotal evidence for the use of cannabinoids as a treatment for migraine in humans and implicate the CB₁ receptor as a therapeutic target for migraine.

The safety and efficacy of the 5-HT 1F receptor agonist lasmiditan in the acute treatment of migraine

INTRODUCTION

Migraine is among the most disabling disorders worldwide, with a significant therapeutic need. Triptans are drugs of choice in the acute attack treatment, but they are contraindicated in patients with vascular conditions due to their potential vasoconstrictive properties. Further limitations include side effects, inconsistency in therapeutic action and possible non-response. Lasmiditan, a highly selective 5-HT1F receptor agonist, is a novel acute anti-migraine substance devoid of vasoconstriction. Areas covered: This article reviews the clinical efficacy and safety of oral and intravenous lasmiditan as a possible acute migraine treatment. We analyze all currently available results in Phase I to III studies. Expert opinion: Lasmiditan is a promising acute migraine therapy, in particular for patients at cardiovascular risk. Phase II and the first Phase III clinical trials show a significant better headache response in comparison to placebo. The efficacy of lasmiditan proves that vasoconstriction is not essential for acute migraine therapy and thereby points, in addition to a well-established trigeminal contribution, to central neuronal mechanisms in migraine pathophysiology. Lasmiditan penetrates the blood-brain barrier and CNS associated adverse events are common, but mostly in mild to moderate severity. The results of long-term Phase III studies will determine if these adverse events represent a limitation in clinical practice.

Neurovascular contributions to migraine: Moving beyond vasodilation

Migraine is the third most common disease worldwide, the most common neurological disorder, and one of the most common pain conditions. Despite its prevalence, the basic physiology and underlying mechanisms contributing to the development of migraine are still poorly understood and development of new therapeutic targets is long overdue. Until recently, the major contributing pathophysiological event thought to initiate migraine was cerebral and meningeal arterial vasodilation. However, the role of vasodilation in migraine is unclear and recent findings challenge its necessity. While vasodilation itself may not contribute to migraine, it remains possible that vessels play a role in migraine pathophysiology in the absence of vasodilation. Blood vessels consist of a variety of cell types that both release and respond to numerous mediators including growth factors, cytokines, adenosine triphosphate (ATP), and nitric oxide (NO). Many of these mediators have actions on neurons that can contribute to migraine. Conversely, neurons release factors such as norepinephrine and calcitonin gene-related peptide (CGRP) that act on cells native to blood vessels. Both normal and pathological events occurring within and between vascular cells could thus mediate bi-directional communication between vessels and the nervous system, without the need for changes in vascular tone. This review will discuss the potential contribution of the vasculature, specifically endothelial cells, to current neuronal mechanisms hypothesized to play a role in migraine. Hypothalamic activity, cortical spreading depression (CSD), and dural afferent input from the cranial meninges will be reviewed with a focus on how these mechanisms can influence or be impacted by blood vessels. Together, the data discussed will provide a framework by which vessels can be viewed as important potential contributors to migraine pathophysiology, even in light of the current uncertainty over the role of vasodilation in this disorder.

Utilisation of prescription and over-the-counter triptans: a cross-sectional study in Stockholm, Sweden

PURPOSE

Triptans are widely used in acute migraine, and in some countries, they are also available over-the-counter (OTC). In Sweden, sales have increased for both prescription and OTC triptans. This study aimed to describe current prescribing and utilisation patterns of prescription and OTC triptans in Stockholm, Sweden.

METHODS

Register data from 4759 patients dispensed triptans in 2014 were used to study documented diagnosis of migraine, concomitant acute and preventive treatment for migraine, and contraindications. Survey data from 49 patients purchasing OTC triptans in three pharmacies were used to capture physician-diagnosed migraine, concomitant acute and preventive treatment for migraine, a behaviour of combining or alternating between prescription and OTC triptans, and pharmacy counselling rates.

RESULTS

Among the prescription triptan users, 52 % had a recorded diagnosis of migraine, 48 % had no other acute treatment, preventive treatment was rare (12 %) and contraindications were found in 2 % of the patients. Among the OTC triptan users, the majority (63 %) had been diagnosed by a physician and had a history of prescription triptan use, but combining or alternating between OTC and prescription triptans was rare. Concomitant acute treatment was reported in 53 % and preventive treatment was rare (4 %), despite high self-reported migraine frequencies. Some off-label use was detected, despite moderate to high counselling rates.

CONCLUSION

Triptans are prescribed with attention to safety but with poor recording of migraine diagnosis. OTC triptan users generally have a history of prescription triptan use. Preventive treatment rates are low in both groups. Strategies to discern patients who need other treatment options should be considered.

ASICs as therapeutic targets for migraine

Migraine is the most common neurological disorder and one of the most common chronic pain conditions. Despite its prevalence, the pathophysiology leading to migraine is poorly understood and the identification of new therapeutic targets has been slow. Several processes are currently thought to contribute to migraine including altered activity in the hypothalamus, cortical-spreading depression (CSD), and afferent sensory input from the cranial meninges. Decreased extracellular pH and subsequent activation of acid-sensing ion channels (ASICs) may contribute to each of these processes and may thus play a role in migraine pathophysiology. Although few studies have directly examined a role of ASICs in migraine, studies directly examining a connection have generated promising results including efficacy of ASIC blockers in both preclinical migraine models and in human migraine patients. The purpose of this review is to discuss the pathophysiology thought to contribute to migraine and findings that implicate decreased pH and/or ASICs in these events, as well as propose issues to be resolved in future studies of ASICs and migraine. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.

Meningeal afferent signaling and the pathophysiology of migraine

Migraine is the most common neurological disorder. Attacks are complex and consist of multiple phases but are most commonly characterized by intense, unilateral, throbbing headache. The pathophysiology contributing to migraine is poorly understood and the disorder is not well managed with currently available therapeutics, often rendering patients disabled during attacks. The mechanisms most likely to contribute to the pain phase of migraine require activation of trigeminal afferent signaling from the cranial meninges and subsequent relay of nociceptive information into the central nervous system in a region of the dorsal brainstem known as the trigeminal nucleus caudalis. Events leading to activation of meningeal afferents are unclear, but nerve endings within this tissue are mechanosensitive and also express a variety of ion channels including acid-sensing ion channels and transient receptor-potential channels. These properties may provide clues into the pathophysiology of migraine by suggesting that decreased extracellular pH and environmental irritant exposure in the meninges contributes to headache. Neuroplasticity is also likely to play a role in migraine given that attacks are triggered by routine events that are typically nonnoxious in healthy patients and clear evidence of sensitization occurs during an attack. Where and how plasticity develops is also not clear but may include events directly on the afferents and/or within the TNC. Among the mediators potentially contributing to plasticity, calcitonin gene-related peptide has received the most attention within the migraine field but other mechanisms may also contribute. Ultimately, greater understanding of the molecules and mechanisms contributing to migraine will undoubtedly lead to better therapeutics and relief for the large number of patients across the globe who suffer from this highly disabling neurological disorder.

Intravenous dextromethorphan/quinidine inhibits activity of dura-sensitive spinal trigeminal neurons in rats

BACKGROUND

Migraine is a chronic neurological disorder characterized by episodes of throbbing headaches. Practically all medications currently used in migraine prophylaxis have a number of substantial disadvantages and use limitations. Therefore, the further search for principally new prophylactic antimigraine agents remains an important task. The objective of our study was to evaluate the effects of a fixed combination of dextromethorphan hydrobromide and quinidine sulphate (DM/Q) on activity of the spinal trigeminal neurons in an electrophysiological model of trigemino-durovascular nociception.

METHODS

The study was performed in 15 male Wistar rats, which were anaesthetized with urethane/α-chloralose and paralysed using pipecuronium bromide. The effects of cumulative intravenous infusions of DM/Q (three steps performed 30 min apart, 15/7.5 mg/kg of DM/Q in 0.5 mL of isotonic saline per step) on ongoing and dural electrical stimulation-induced neuronal activities were tested in a group of eight rats over 90 min. Other seven animals received cumulative infusion of equal volumes of saline and served as control.

RESULTS

Cumulative administration of DM/Q produced steady suppression of both the ongoing activity of the spinal trigeminal neurons and their responses to electrical stimulation of the dura mater.

CONCLUSIONS

It is evident that the observed DM/Q-induced suppression of trigeminal neuron excitability can lead to a reduction in nociceptive transmission from meninges to higher centres of the brain. Since the same mechanism is believed to underlie the pharmacodynamics of many well-known antimigraine drugs, results of the present study enable us to anticipate the potential efficacy of DM/Q in migraine.

Emerging therapeutic options for acute migraine: focus on the potential of lasmiditan

The serotonin receptor agonist triptan drugs (5-HT1B/1D receptor agonists) have been in use for over 20 years in the abortive management of migraine. Although clearly effective, their ability to produce vasoconstriction in cerebral and coronary arteries, thought to be mediated by their high affinity for the 5-HT1B receptor, has been a limitation to their use in certain patient populations. Variable potency triptan binding at the 5-HT1F receptor occurs in addition to binding at the 5-HT1B and 5-HT1D receptors. A more selective serotonin agonist without 5-HT1B-mediated vasoconstriction might prove efficacious yet safer. The 5-HT1F receptor has been targeted as a site of action for such a drug. In experimental models, 5-HT1F receptor agonists have been shown to block neurogenic inflammation and c-Fos expression in neural tissue and, as well, show no evidence of vasoconstriction in vascular tissue models in vitro. In clinical trials, efficacy in the abortive management of migraine has been established. Lasmiditan (LY573144), a selective 5-HT1F receptor agonist (K1=2.21 μM), showed efficacy in its primary endpoint, with a 2-hour placebo-subtracted headache response of 28.8%, though with frequent reports of dizziness, paresthesias, and vertigo. Study results support an emerging central neuronal mechanism of migraine pathophysiology. This review traces the history and use of 5-HT1F receptor agonists, now referred to as neurally acting anti-migraine agents in migraine management.

Economic impact of a triptan Rx-to-OTC switch in six EU countries

INTRODUCTION

Triptans have been safely and effectively used in the management of migraine for more than fifteen years, and it seems reasonable to wonder what would be the economic impact of moving a specific triptan to OTC availability. The objective of this study was then to examine the economic impact of payer policies of a triptan Rx-to-OTC switch in six EU countries (France, UK, Spain, Italy, Germany and Poland).

METHODS

A decision model was used to model the budgetary impact of a triptan Rx-to-OTC switch from the third-party payer (TPP) and the societal perspectives, using a one-year timeframe.

RESULTS

From the TPP perspective, it is estimated that the current overall direct spending on the management of migraine attacks across the 6 EU Member States is €582 million annually, and that the savings would reach €75 million (13% of the overall direct economic burden of migraine). From the societal perspective, €86 million annually would be added.

CONCLUSIONS

Given evidence of effectiveness and safety, and given the potential savings, a triptan Rx-to-OTC switch is a reasonable public policy decision.

Indomethacin/prochlorperazine/caffeine: a review of its use in the acute treatment of migraine and in the treatment of episodic tension-type headache

The indomethacin/prochlorperazine/caffeine fixed combination (Difmetré®) combines the NSAID indomethacin with the phenothiazine antiemetic prochlorperazine and caffeine. It is currently available as two oral (effervescent tablet and coated tablet) and two rectal (suppository and low-dose suppository) formulations. Oral and rectal formulations of indomethacin/prochlorperazine/caffeine were effective and generally well tolerated in the treatment of migraine and episodic tension-type headache (TTH) in adult patients participating in randomized, multicentre, active-comparator controlled studies. For the most part, the efficacy of oral indomethacin/prochlorperazine/caffeine did not significantly differ from that of oral sumatriptan in patients with migraine and oral nimesulide in patients with episodic TTH. With rectal administration, indomethacin/prochlorperazine/caffeine was, in general, significantly more effective than sumatriptan in patients with migraine. Thus, oral and rectal formulations of indomethacin/prochlorperazine/caffeine provide a further option in the acute treatment of migraine and in the treatment of episodic TTH in adult patients.

Combined analgesics in (headache) pain therapy: shotgun approach or precise multi-target therapeutics?

BACKGROUND

Pain in general and headache in particular are characterized by a change in activity in brain areas involved in pain processing. The therapeutic challenge is to identify drugs with molecular targets that restore the healthy state, resulting in meaningful pain relief or even freedom from pain. Different aspects of pain perception, i.e. sensory and affective components, also explain why there is not just one single target structure for therapeutic approaches to pain. A network of brain areas ("pain matrix") are involved in pain perception and pain control. This diversification of the pain system explains why a wide range of molecularly different substances can be used in the treatment of different pain states and why in recent years more and more studies have described a superior efficacy of a precise multi-target combination therapy compared to therapy with monotherapeutics.

DISCUSSION

In this article, we discuss the available literature on the effects of several fixed-dose combinations in the treatment of headaches and discuss the evidence in support of the role of combination therapy in the pharmacotherapy of pain, particularly of headaches. The scientific rationale behind multi-target combinations is the therapeutic benefit that could not be achieved by the individual constituents and that the single substances of the combinations act together additively or even multiplicatively and cooperate to achieve a completeness of the desired therapeutic effect.As an example the fixed-dose combination of acetylsalicylic acid (ASA), paracetamol (acetaminophen) and caffeine is reviewed in detail. The major advantage of using such a fixed combination is that the active ingredients act on different but distinct molecular targets and thus are able to act on more signalling cascades involved in pain than most single analgesics without adding more side effects to the therapy.

SUMMARY

Multitarget therapeutics like combined analgesics broaden the array of therapeutic options, enable the completeness of the therapeutic effect, and allow doctors (and, in self-medication with OTC medications, the patients themselves) to customize treatment to the patient's specific needs. There is substantial clinical evidence that such a multi-component therapy is more effective than mono-component therapies.

Increased asymmetric dimethylarginine and nitric oxide levels in patients with migraine

Asymmetric dimethylarginine (ADMA) has been found as correlated with endothelial dysfunction and oxidative stress. There are few studies regarding ADMA and nitric oxide (NO) levels in patients with migraine and alterations of ADMA and NO levels during migraine attack are not well-known. Therefore, in present study, we aimed to measure NO and ADMA levels in patients with migraine and compare them with the control group to investigate the correlation between migraine, oxidative stress and endothelial dysfunction. The migraine group consisted of 59 patients, including 22 suffering from migraine with aura and 37 suffering from migraine without aura. The control group consisted of 31 healthy volunteers without headache. The patients in migraine group were divided into subgroups based on whether attack period was present or not and whether it was migraine with or without aura. Plasma ADMA levels were measured using an enzyme-linked immunosorbent assay method. Migraine patients had higher concentrations of NO (35.6±7.7, 31.0±6.2 μmol/L, respectively, p=0.005) and ADMA (0.409±0.028, 0.381±0.044 μmol/L, respectively, p = 0.001) levels when compared with the healthy controls. During migraine attack, NO and ADMA levels were found to be significantly higher in migraine group as compared to control group (respectively, p=0.015, p=0.014). Similarly, NO and ADMA levels in the patients with migraine in the interictal period were found to be significantly higher as compared to control group (p=0.011, p=0.003). In conclusion, higher ADMA and NO levels of patients with migraine supported that oxidative stress and endothelial dysfunction may have a role in migraine pathogenesis.

Rehabilitating chronic migraine complicated by medication overuse headaches: how can we prevent migraine relapse?

Headache is among the most common neurological symptoms in clinical practice. In some cases of episodic migraine, the headache intensifies into a chronic form, defined as chronic migraine (CM) and such a condition encompasses a headache frequency of 15 days/month, with features similar to those of migraine attacks. The assessment of CM in the US general population ranges around 1.3-2%. Migraine progression from an episodic into a chronic form is realized through a period of time involving several months or years, during which an increase attack frequency occurs. Both Topiramate and Onabotulinum toxin A can be considered to be safe as well as effective medications, therefore, representing a treatment choice. Regarding drug abusers, the initial relief step always consists of drug interruption. Only after detoxification can a new prophylaxis therapy be commenced, which otherwise would be useless from the start. The feasible diagnostic setting for the tailored treatment of CM based on the application of pharmacogenomics will allow us in predetermining the efficacy of a single old and new drugs by avoiding abuse due to non-responsivity of the abused drug.

Chronic migraine: comorbidities, risk factors, and rehabilitation

Migraine is a serious illness with a spontaneous clinical evolution into a chronic form. In some episodic migraines, increase of crises frequency modifies the headache pattern in the chronic form, defined as chronic migraine (CM), with headache frequency of 15 days/month. One-year prevalence of CM includes around 2-4% of the general population. Migraine progression from episodic to chronic form is realized through a period of time involving several months or years, during which an increase of attack frequency occurs. Migraine shows a wide spectrum of comorbidities, including cardiocerebral, vascular, psychiatric, metabolic, neurologic as well as other pathologies. The single/multiple presence of such comorbidities represents a fixed factor in the process of chronicization into CM. Risk factors including medication overuse headache (MOH), obesity, and lifestyle cooperate in the evolution process to CM. MOH is the most severe complication of CM, and similarly to CM its appearance is gradual. Both CM and MOH show particular genetic background able to favor the appearance of chronicity and abuse. Rehabilitation consists of drug withdrawal procedures, re-prophylaxis through administration of innovative drugs, such as OnabotulinumtoxinA and/or topiramate, to avoid relapsing attacks, and behavioral strategies to minimize the role of risk factors. The initial relief step for drug abusers always relies in drug withdrawal. The feasible diagnostic setting for a CM tailored treatment based on the application of pharmacogenomics will allow us to predetermine the efficacy of single old and new drugs by avoiding abuse due to non-responsivity of the acute drug.

Genetic polymorphisms related to efficacy and overuse of triptans in chronic migraine

Migraine is a common type of headache and its most severe attacks are usually treated with triptans, the efficacy of which is extremely variable. Several SNPs in genes involved in metabolism and target mechanisms of triptans have been described. To define an association between genetic profile and triptan response, we classified a migrainous population on the basis of triptan response and characterized it for polymorphisms in the genes coding for monoamine oxidase A, G protein β3 and the cytochrome CYP1A2. Analysis of the association between genotypic and allelic frequencies of the analyzed SNPs and the grade of response to triptan administration showed a significant correlation for MAOA uVNTR polymorphism. Further stratification of patients in abuser and non-abuser groups revealed a significant association with triptan overuse and, within the abusers, with drug response to the CYP1A2*1F variant.

Increased serum levels of brain-derived neurotropic factor during migraine attacks: a pilot study

There is a growing body of evidence implicating inflammatory cytokines and brain-derived neurotropic factor (BDNF) in the generation of migraine pain. No previous study evaluated BNDF levels during migraine attacks and there are conflicting results regarding tumor necrosis factor-alpha (TNF-alpha) serum levels. This study compared serum levels of TNF-alpha, soluble TNF receptors 1 and 2 (sTNF-R1 and sTNF-R2), and BDNF during migraine attacks and in headache-free periods. Nine patients with episodic migraine were clinically evaluated during a migraine attack and in a headache-free period. Blood sample of each patient in both occasions was collected and all serum was submitted to TNF-alpha, sTNF-R1, sTNF-R2, and BDNF determination by ELISA. There was no significant difference in the serum levels of TNF-alpha, sTNF-R1 and sTNF-R2 in migraine attack period and headache-free period. BDNF serum levels were significantly higher during migraine attack than in pain-free period. This is the first report showing that BDNF serum levels increase during migraine attack. This reinforces the view that BDNF may be implicated in the physiopathology of migraine.

The use of antidepressants for headache prophylaxis

The focus of this review is on the efficacy of antidepressants as preventive treatments for migraine and chronic tension-type headache (TTH). Pharmacologic prophylaxis may be indicated for patients with frequent headaches, who respond insufficiently to acute therapies, or for whom medication overuse is a concern. The well-documented efficacy of the tricyclic antidepressant amitriptyline, both for migraine and chronic TTH, has been followed by widespread use of other antidepressants for headache prophylaxis. Although antidepressants in general share comparable efficacy for the treatment of depressive disorders, their efficacy as headache preventives varies widely. Evidence supporting use of the selective serotonin reuptake inhibitors as headache preventives is poor; their use should be reserved for treating comorbid depression in a patient who also has a headache disorder. Small randomized trials of venlafaxine indicate preliminary efficacy both for migraine and tension-type headache. Evidence for other antidepressants is lacking. Although antidepressants are often prescribed to headache patients under the assumption that the prescribed agent also will be effective in reducing symptoms of comorbid depression, the majority of studies have failed to find a strong relationship between depression symptoms and headache improvement. Suggestions for future research are discussed.

Frequencies of genetic polymorphisms related to triptans metabolism in chronic migraine

Chronic migraine (CM) prevalence ranges around 1–5%. Most of these patients usually treat their acute attacks with triptans, whose efficacy is extremely variable. A genetic basis for migraine is evident and many susceptibility genes have been described, as well as gene polymorphisms possibly implied in therapy response. Several factors could be involved in the evolution of episodic migraine into a chronic form, such as natural history, psychiatric comorbidity, and the individual’s response to therapy. During a study aimed at detecting connections between genotype and response to triptans administration, we characterized a CM population for polymorphisms in the genes coding for monoamine oxidase A, g-protein beta 3 and the cytochromes CYP3A4 and CYP1A2. Alleles and genotypes distributions were compared with known frequencies of healthy Caucasian populations. A significant association with CM was found for the long allele of monoamine oxidase A 30 bp VNTR and CYP1A2*1F variant. Such genomic analysis is part of an integrated platform able to evaluate different levels of metabolic pathways of drugs in CM and their influence in the chronicization process.