Current and emerging second-generation triptans in acute migraine therapy: a comparative review

Drug interactions and risks associated with the use of triptans, ditans and monoclonal antibodies in migraine

PURPOSE OF REVIEW

The aim of this study was to review current evidence concerning potential risks and interactions associated with concomitant use of drugs indicated for the abortive treatment of migraine, namely triptans and ditans, and more recently developed drugs used for the preventive treatment. The latter drug class encompasses monoclonal antibodies (mAbs), which target either calcitonin gene-related peptide (CGRP) or its receptor.

RECENT FINDINGS

To date, no pharmacokinetic interactions between these drug classes have been reported. However, patients who suffer from triptan- (or ditan-) induced medication overuse headache or those who are nonresponders to triptans might respond less effectively to mAbs. Caution is warranted when coadministrating these drugs in migraine patients with comorbid cardiovascular disease or with an increased cardiovascular risk profile.

SUMMARY

In this review, the main mechanisms of action of triptans, ditans and mAbs targeting CGRP or its receptor are summarized as well as the current evidence on their individual risks. Studies on risks and interactions in case of concomitant use of triptans, ditans and mAbs in migraine patients are relatively scarce. Therefore, these aspects have been considered from a theoretical and hypothetical point of view by taking both their overlapping target, CGRP, and contraindications into account.

Targeting the 5-HT1B/1D and 5-HT1F receptors for acute migraine treatment

Migraine is a common and highly disabling headache disorder associated with a substantial socioeconomic burden. Migraine treatments can be categorized as preventive treatment, aimed at reducing the frequency and severity of migraine attacks, and acute therapy, intended to abort attacks. Traditionally, acute treatment can be classified as specific (ergot derivatives and triptans) or nonspecific (analgesics and nonsteroidal anti-inflammatory drugs). Triptans, a class of 5-HT1B/1D receptor agonists with some affinity for the 5-HT1F receptor subtype, have been proven to be efficacious for acute treatment of moderate to severe migraine and have been deemed the gold standard. The availability of triptans in non-oral formulations, such as subcutaneous (SC) and intranasal forms, can be beneficial for patients who suffer from prominent nausea or vomiting, have a suboptimal response to oral agents, and/or seek a more rapid onset of treatment effects. However, triptans are contraindicated in patients with preexisting cardiovascular and/or cerebrovascular diseases due to their 5-HT1B-mediated vasoconstrictive action. For this reason, studies have focused on the development of ditans, a group of antimigraine drugs targeting 5-HT1D and 5-HT1F receptors. Unfortunately, 5-HT1D receptor agonists have been shown to be ineffective in the acute treatment of migraine. Several ditans targeting the 5-HT1F receptor have been developed and have shown no vasoconstrictive effect in preclinical studies, but only two of them, lasmiditan and LY334370, have been tested in clinical trials for migraine, and only lasmiditan has reached to Phase III clinical trials. These Phase III trials have demonstrated the efficacy and safety of lasmiditan, a selective 5-HT1F receptor agonist, in acute migraine treatment. Lasmiditan might offer an alternative migraine therapy without cardiovascular risks. This review will summarize the development of agents targeting the 5-HT1B/1D and 5-HT1F receptors and the clinical evidence supporting the use of these agents for acute migraine treatment.

Is selective 5-HT1F receptor agonism an entity apart from that of the triptans in antimigraine therapy?

Migraine is a neurovascular disorder that involves activation of the trigeminovascular system and cranial vasodilation mediated by release of calcitonin gene-related peptide (CGRP). The gold standard for acute migraine treatment are the triptans, 5-HT1B/1D/(1F) receptor agonists. Their actions are thought to be mediated through activation of: (i) 5-HT1B receptors in cranial blood vessels with subsequent cranial vasoconstriction; (ii) prejunctional 5-HT1D receptors on trigeminal fibers that inhibit trigeminal CGRP release; and (iii) 5-HT1B/1D/1F receptors in central nervous system involved in (anti)nociceptive modulation. Unfortunately, coronary arteries also express 5-HT1B receptors whose activation would produce coronary vasoconstriction; hence, triptans are contraindicated in patients with cardiovascular disease. In addition, since migraineurs have an increased cardiovascular risk, it is important to develop antimigraine drugs devoid of vascular (side) effects. Ditans, here defined as selective 5-HT1F receptor agonists, were developed on the basis that most of the triptans activate trigeminal 5-HT1F receptors, which may explain part of the triptans' antimigraine action. Amongst the ditans, lasmiditan: (i) fails to constrict human coronary arteries; and (ii) is effective for the acute treatment of migraine in preliminary Phase III clinical trials. Admittedly, the exact site of action is still unknown, but lasmiditan possess a high lipophilicity, which suggests a direct action on the central descending antinociceptive pathways. Furthermore, since 5-HT1F receptors are located on trigeminal fibers, they could modulate CGRP release. This review will be particularly focussed on the similarities and differences between the triptans and the ditans, their proposed sites of action, side effects and their cardiovascular risk profile.

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.

Thermoreversible nanoethosomal gel for the intranasal delivery of Eletriptan hydrobromide

The objective of the current study was to formulate and characterize thermoreversible gel of Eletriptan Hydrobromide for brain targeting via the intranasal route. Ethosomes were prepared by 3(2) factorial design with two independent variables (concentration of soya lecithin and ethanol) and two response variables [percent entrapment efficiency and vesicle size (nm)] using ethanol injection method. Formulated ethosomes were evaluated for preliminary microscopic examination followed by percent drug entrapment efficiency, vesicle size analysis, zeta potential, polydispersibility index and Transmission electron microscopy (TEM). TEM confirms spherical morphology of ethosomes, whereas Malvern zeta sizer confirms that the vesicle size was in the range of 191 ± 6.55-381.3 ± 61.0 nm. Ethosomes were incorporated in gel using poloxamer 407 and carbopol 934 as thermoreversible and mucoadhesive polymers, respectively. Ethosomal gels were evaluated for their pH, viscosity, mucoadhesive strength, in vitro drug release and ex vivo drug permeation through the sheep nasal mucosa. Mucoadhesive strength and pH was found to be 4400 ± 45 to 5500 ± 78.10 dynes/cm(2) and 6.0 ± 0.3 to 6.2 ± 0.1, respectively. In-vitro drug release from the optimized ethosomal gel formulation (G4) was found to be almost 100 % and ex vivo permeation of 4980 µg/ml with a permeability coefficient of 11.94 ± 0.04 × 10(-5) cm/s after 24 h. Histopathological study of the nasal mucosa confirmed non-toxic nature of ethosomal gels. Formulated EH loaded ethosomal thermoreversible gel could serve as the better alternative for the brain targeting via the intranasal route which in turn could subsequently improve its bioavailability.

Migraine in the era of precision medicine

Migraine is a common neurovascular disorder in the neurologic clinics whose mechanisms have been explored for several years. The aura has been considered to be attributed to cortical spreading depression (CSD) and dysfunction of the trigeminovascular system is the key factor that has been considered in the pathogenesis of migraine pain. Moreover, three genes (CACNA1A, ATP1A2, and SCN1A) have come from studies performed in individuals with familial hemiplegic migraine (FHM), a monogenic form of migraine with aura. Therapies targeting on the neuropeptids and genes may be helpful in the precision medicine of migraineurs. 5-hydroxytryptamine (5-HT) receptor agonists and calcitonin gene-related peptide (CGRP) receptor antagonists have demonstrated efficacy in the acute specific treatment of migraine attacks. Therefore, ongoing and future efforts to find new vulnerabilities of migraine, unravel the complexity of drug therapy, and perform biomarker-driven clinical trials are necessary to improve outcomes for patients with migraine.

Poloxamer 407-based intranasal thermoreversible gel of zolmitriptan-loaded nanoethosomes: formulation, optimization, evaluation and permeation studies

Zolmitriptan is the drug of choice for migraine, but low oral bioavailability (<50%) and recurrence of migraine lead to frequent dosing and increase in associated side effects. Increase in the residence time of drug at the site of drug absorption along with direct nose to brain targeting of zolmitriptan can be a solution to the existing problems. Hence, in the present investigation, thermoreversible intranasal gel of zolmitriptan-loaded nanoethosomes was formulated by using mucoadhesive polymers to increase the residence of the drug into the nasal cavity. The preparation of ethosomes was optimized by using 3(2) factorial design for percent drug entrapment efficiency, vesicle size, zeta potential, and polydispersity index. Optimized formulation E6 showed the vesicle size (171.67 nm) and entrapment efficiency (66%) when compared with the other formulations. Thermoreversible gels prepared by using poloxamer 407 showed the phase transition temperature at 32-33 °C which was in line with the nasal physiological temperature. The optimized ethosomes were loaded into the thermoreversible mucoadhesive gel optimized by varying concentrations of poloxamer 407, carbopol 934, HPMC K100, and evaluated for gel strength, gelation temperature, mucoadhesive strength, in vitro drug release, and ex vivo drug permeation, where G3 and G6 were found to be optimized formulations. In vitro drug release was studied by different kinetic models suggested that G3 (n = 0.582) and G6 (n = 0.648) showed Korsemeyer-Peppas (KKP) model indicating non-Fickian release profiles. A permeation coefficient of 5.92 and 5.9 µg/cm(2) for G3 and G6, respectively, revealed very little difference in release rate after 24 h between both the formulations. Non-toxic nature of the gels on columnar epithelial cells was confirmed by histopathological evaluation.

Experimental public speaking: contributions to the understanding of the serotonergic modulation of fear

Public speaking is widely used as a model of experimental fear and anxiety. This review aimed to evaluate the effects of pharmacological challenges on public speaking responses and their implications for the understanding of the neurobiology of normal and pathological anxiety, specifically panic disorder. We also describe methodological features of experimental paradigms using public speaking as an inducer of fear and stress. Public speaking is a potent stressor that can provoke significant subjective and physiological responses. However, variations in the manners in which public speaking is modelled can lead to different responses that need to be considered when interpreting the results. Results from pharmacological studies with healthy volunteers submitted to simulated public speaking tests have similarities with the pharmacological responses of panic patients observed in clinical practice and panic patients differ from controls in the response to the public speaking test. These data are compatible with the Deakin and Graeff hypothesis that serotonin inhibits fear, as accessed by public speaking tasks, and that this inhibition is likely related to the actions of serotonin in the dorsal periaqueductal grey matter.

Recurrent headaches may be caused by cerebral toxoplasmosis

AIM

To establish seroprevalence and provide characteristics of Toxoplasma gondii (TG) infection in children with recurrent headaches.

METHODS

The study was performed in 178 children aged 7-17 years admitted consecutively to the Department of Pediatric Neurology from November 2009 to July 2011. The children were surveyed with a questionnaire with the help and assistance of their parents and blood samples taken on admission were studied for the presence of specific anti-TG IgM, IgG antibodies and IgG avidity using enzyme immunoassay Platelia Toxo IgM, IgG.

RESULTS

The study showed that 19 children (8 boys, 11 girls; 8-17 years old, mean age 14.36 years) had high serum anti-TG IgG antibody levels (range: 32.2 > 240 UI/mL, mean 120.18 UI/mL; positive value for IgG was ≥ 9 UI/mL). The avidity index (AI) ranged from 0.202 to 0.925 (scale: ≥ 0.5 high AI). The results for IgM antibodies were all negative and the obtained results ranged from 0.113 to 0.25 U/mL (mean = 0.191 IU/mL) and all values below 0.8 IU/mL were considered negative. The most frequent complaints found in the seropositive patients were headaches that affected the frontal (13 children), occipital (4) and parietal areas (5). Headaches usually had a pulsating (in 7 patients) and squeezing (6) character and rarely were piercing, dull or expanding. Interestingly, 8 children did not feel discomfort during the headaches, probably because they did not have sufficiently increased intracranial pressure yet. The headaches usually appeared 1-2 times/mo, lasted for 2-6 h, and had a mean intensity of 5.5 points in a 10 point subjective scale. The comorbidities included epilepsy (5 patients), various infections in 3 children (chronic eustachitis, chronic rhinitis, chronic purulent tonsillitis, streptococcal pharyngitis, meningitis, allergic diseases), disturbances of behavior, deficits of attention, and ocular and motor concentration disorders in 1 child. The electroencephalographic and neuroimaging studies performed in our patients had a very limited value in establishing cerebral toxoplasmosis.

CONCLUSION

Ten point six seven percent of the studied children had markedly increased serum anti-TG IgG antibodies and high AI indicated chronic infestation. It is suggested that tests for TG infection should be introduced to routine diagnostics in patients with recurrent headaches.

The 5-HT1D/1B receptor agonist sumatriptan enhances fear of simulated speaking and reduces plasma levels of prolactin

This study measured the effects of the preferential 5-HT1D/1B receptor agonist sumatriptan in healthy volunteers who performed the Simulated Public Speaking Test (SPST), which recruits the neural network involved in panic disorder and social anxiety disorder. In a double-blind, randomised experiment, 36 males received placebo (12), 50 mg (12) or 100 mg (12) of sumatriptan 2 h before the SPST. Subjective, physiological and hormonal measures were taken before, during and after the test. The dose of 100 mg of sumatriptan increased speech-induced fear more than either a 50mg dose of the drug or placebo. The largest dose of sumatriptan also enhanced vigilance more than placebo, without any change in blood pressure, heart rate or electrical skin conductance. Sumatriptan decreased plasma levels of prolactin. A significant but moderate increase in plasma cortisol after SPST occurred, independent of treatment. Because sumatriptan decreases 5-HT release into the extracellular space, the potentiation of SPST-induced fear caused by the drug supports the hypothesis that 5-HT attenuates this emotional state. As acute administration of antidepressants has also been shown to enhance speaking fear and increase plasma prolactin, in contrast to sumatriptan, the 5-HT regulation of stress-hormone release is likely to be different from that of emotion.

Activation of 5-hydroxytryptamine1B/1D/1F receptors as a mechanism of action of antimigraine drugs

INTRODUCTION

The introduction of the triptans (5-hydroxytryptamine (5-HT)1B/1D receptor agonists) was a great improvement in the acute treatment of migraine. However, shortcomings of the triptans have prompted research on novel serotonergic targets for the treatment of migraine.

AREAS COVERED

In this review the different types of antimigraine drugs acting at 5-HT receptors, their discovery and development are discussed. The first specific antimigraine drugs were the ergot alkaloids, consisting of ergotamine, dihydroergotamine and methysergide, which are agonists at 5-HT receptors, but can also bind α-adrenoceptors and dopamine receptors. In the 1990s, the triptans became available on the market. They are 5-HT1B/1D receptor agonists, showing fewer side effects due to their receptor specificity. In the last years, compounds that bind specifically to 5-HT1D, 5-HT1F and 5-HT7 receptors have been explored for their antimigraine potential. Furthermore, the serotonergic system seems to act in tight connection with the glutamatergic as well as the CGRP-ergic systems, which may open novel therapeutic avenues.

EXPERT OPINION

Although the triptans are very effective in treating migraine attacks, their shortcomings have stimulated the search for novel drugs. Currently, the focus is on 5-HT1F receptor agonists, which seem devoid of vascular side effects. Moreover, novel compounds that affect multiple transmitter and/or neuropeptide systems that are involved in migraine could be of therapeutic relevance.

Application of a Reliable LC-MS/MS Method for Determination of Rizatriptan in Healthy Subject Samples: Demonstration of Assay Reproducibility by Incurred Sample Reanalysis

A reliable, rapid, and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been proposed for the determination of rizatriptan in human plasma using sumatriptan as internal standard (IS). The analyte and IS were extracted from 300 μL human plasma via liquid-liquid extraction and the chromatography was achieved on Hypurity C18 (50 mm × 4.6 mm, 5 μm) column under isocratic conditions. Detection of rizatriptan and IS was done by tandem mass spectrometry, operating in positive ionization and multiple-reaction monitoring mode. The limit of detection and lower limit of quantitation of the method were 0.04 and 0.20 ng/mL, respectively, with a linear dynamic range of 0.20–60.0 ng/mL. The intrabatch and interbatch precision (% CV) was ≤8.4% while the mean extraction recovery was >78% across quality control levels. Bench top stability, freeze and thaw stability, processed sample stability, and long-term stability in plasma were evaluated at two quality control levels. It was successfully applied to a bioequivalence study of 10 mg rizatriptan orally disintegrating tablet formulation in 40 and 32 healthy Indian male subjects under fasting and fed conditions, respectively. The reproducibility in the measurement of study data was demonstrated by reanalysis of 254 incurred samples.

Improved patient satisfaction and pain evolution with almotriptan in migraine: a primary care study

BACKGROUND/OBJECTIVE

The START study was a large general practice observational study involving 400 patients with migraine. Given the large sample size, a sub-analysis was planned to ascertain whether any patient characteristics/behaviors might help predict/explain the responses observed in this study, which demonstrated that almotriptan administered early when pain was mild significantly improved pain-related outcomes compared with non-early/non-mild treatment.

METHODS

This pre-planned sub-analysis assessed the impact of predictors of patient satisfaction, medication history, delayed drug intake, etc. on the primary pain endpoints of the START study.

RESULTS

Patients had previously tried an average of 2.5 drugs for migraine relief and were currently taking a mean of 1.4 drugs. Almotriptan had been tried by 21% of the sample and was still being used by 83% of this sub-group. Treatment satisfaction was higher in the subset of patients taking almotriptan than in almotriptan-naїve individuals (p < 0.001) and this may explain why this group had the highest continuation rate of all drugs evaluated. On completion of the study, patient satisfaction was higher in the early/mild treatment group than the non-early/non-mild group (p = 0.049). Many patients delayed taking almotriptan, despite being instructed otherwise. Patients reported that this was primarily because they believed that they should only take the medication in the case of a severe migraine attack and/or to ensure that the symptoms were definitely due to migraine headache. The limitations of the trial include its open, observational design, and the small number of individuals who managed to treat their migraine attack within 1 hour when it was still mild.

CONCLUSIONS

Almotriptan was associated with increased patient satisfaction, particularly when taken early. Further action is required to increase patient compliance with early treatment regimens to improve clinical outcomes.

N-methyl-D-aspartate receptor-mediated modulations of the anti-allodynic effects of 5-HT1B/1D receptor stimulation in a rat model of trigeminal neuropathic pain

Previous studies showed that triptans and other 5-HT(1B/1D)-receptor agonists attenuate hyper-responsiveness to mechanical stimulation of the face in a rat model of trigeminal neuropathic pain, probably by activating 5-HT(1B/1D)-receptors on primary afferent nociceptive fibers. We now tested whether blockade of post-synaptic receptors for the excitatory amino acid glutamate released by these fibers would increase this action. We thus evaluated whether (±)1-hydroxy-3-aminopyrrolidine-2-one (HA-966), an antagonist at the glycine/D-serine site of N-methyl-D-aspartate (NMDA)-receptors, would potentiate the anti-allodynic action of dihydroergotamine and zolmitriptan in rats with chronic constriction injury to the infraorbital nerve (CCI-ION). Complementary studies were performed with other NMDA-receptor ligands and in rats with chronic constriction injury to the sciatic nerve (CCI-SN) for comparison. Injury was produced by loose ligatures of the nerves. Responsiveness to mechanical stimulation (vibrissae or hindpaw territories) with von Frey filaments was used to evaluate allodynia 2 weeks after nerve ligature. Rats received NMDA-receptor ligands or saline 20 min before dihydroergotamine (25-100 μg/kg, i.v.) or zolmitriptan (25-100 μg/kg, s.c.). HA-966 (2.5mg/kg, s.c.), inactive on its own, enhanced the anti-allodynic effects of dihydroergotamine (eightfold increase) and zolmitriptan (threefold increase) in CCI-ION rats, but these drugs exerted no effects in allodynic CCI-SN rats. NMDA-receptor blockade by memantine (5mg/kg, i.p.) also enhanced, whereas activation at glycine/NMDA site by D-cycloserine (3mg/kg, i.p.) reduced the anti-allodynic properties of zolmitriptan in CCI-ION rats. Combined administration of NMDA-receptor antagonist and 5-HT(1B/1D)-receptor agonist may be a promising approach for alleviating trigeminal neuropathic pain.

A subpopulation of serotonin 1B receptors colocalize with the AMPA receptor subunit GluR2 in the hippocampal dentate gyrus

The serotonin(1B) receptor (5-HT(1B)R) plays a role in cognitive processes that also involve glutamatergic neurotransmission via amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptors. Accumulating experimental evidence also highlights the involvement of 5-HT(1B)Rs in several neurological disorders. Consequently, the 5-HT(1B)R is increasingly implicated as a potential therapeutic target for intervention in cognitive dysfunction. Within the hippocampus, a brain region critical to cognitive processing, populations of pre- and post-synaptic 5-HT(1B)Rs have been identified. Thus, 5-HT(1B)Rs could have a role in the modulation of hippocampal pre- and post-synaptic conductance. Previously, we demonstrated colocalization of 5-HT(1B)Rs with the N-methyl-D-aspartate (NMDA) receptor subunit NR1 in a subpopulation of granule cell dendrites (Peddie et al. [53]). In this study, we have examined the cellular and subcellular distribution of 5-HT(1B)Rs with the AMPA receptor subunit GluR2. Of 5-HT(1B)R positive profiles, 28% displayed colocalization with GluR2. Of these, 87% were dendrites, corresponding to 41% and 10% of all 5-HT(1B)R labeled or GluR2 labeled dendrites, respectively. Dendritic labeling was both cytoplasmic and membranous but was not usually associated with synaptic sites. Colocalization within dendritic spines and axons was comparatively rare. These findings indicate that within the dentate gyrus molecular layer, dendritic 5-HT(1B)Rs are expressed predominantly on GluR2 negative granule cell processes. However, a subpopulation of 5-HT(1B)Rs is expressed on GluR2 positive dendrites. Here, it is suggested that activation of the 5-HT(1B)R may play a role in the modulation of AMPA receptor mediated conductance, further supporting the notion that the 5-HT(1B)R represents an interesting therapeutic target for modulation of cognitive function.

Eletriptan

Migraine is a multifactorial chronic central nervous system disorder, characterized by recurrent disabling attacks of moderate-to-severe headache. Symptomatic acute treatment of migraine should provide rapid and effective relief of the headache pain. The introduction of the 5-HT(1B/1D) receptor agonists (triptans) expanded the armamentarium for acute migraine pain treatment. Eletriptan is a second-generation triptan with favorable bioavailability and half-life, a high affinity for 5-HT(1B/1D) receptors and selectivity for cranial arteries. Eletriptan (40 and 80 mg) has been shown to be effective as early as 30 min after administration and well tolerated when compared to placebo. In comparative clinical trials, eletriptan 40 and 80 mg were superior or equivalent to other triptans and have shown a very high safety and tolerability profile across the studies performed. Eletriptan showed the most favorable cost-effectiveness profile when compared with other agents in its class.

Allodynia-associated symptoms, pain intensity and time to treatment: predicting treatment response in acute migraine intervention

OBJECTIVE

To evaluate the relationship between treatment outcomes and allodynia-associated symptoms (AAS) at the time of treatment with almotriptan.

METHODS

Analyses were performed with data collected prospectively from patients in 2 recently completed early intervention trials, AXERT Early miGraine Intervention Study (AEGIS) and AXERT 12.5 mg time vs Intensity Migraine Study (AIMS): 2-hour pain free, 2-hour pain relief (AEGIS only), sustained pain free (SPF), use of rescue medication, and median headache duration (AIMS only), in the presence and absence of pretreatment AAS, which was determined by responses to a questionnaire. Analyses were conducted to evaluate possible prognostic variables.

RESULTS

The presence of pretreatment AAS did not have a significant effect on 2-hour pain-free, 2-hour pain-relief or SPF rates, use of rescue medication, or headache duration. Significant factors for most favorable outcomes (greater 2-hour pain-free, 2-hour pain-relief and SPF rates, less use of rescue medication, and shorter headache duration) included treatment with almotriptan 12.5 mg, treatment of mild or moderate headache pain, and treatment within 1 hour of headache onset.

CONCLUSION

Almotriptan 12.5 mg was efficacious in providing 2-hour pain free, 2-hour pain relief, SPF, and reducing rescue medication use irrespective of the presence of AAS at the time of treatment. The most optimal efficacy outcomes occurred when patients treated migraine attacks early and before the onset of severe pain. The presence of AAS, which may indicate an early phase of allodynia, did not influence the efficacy of almotriptan therapy.

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

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

Triptans in pregnancy

The triptans are a class of tryptamine-based drugs indicated for in the treatment of migraine headaches. The triptans act as serotonin (5-hydroxytriptamine) (5-HT) agonists by binding to various serotonin receptors, causing vasoconstriction and neuronal inhibition to alleviate migraines. There are 7 types of triptans currently available on the U.S. market: almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, sumatriptan and zolmitriptan. The objective of this study was to examine the use and effects of triptans in pregnancy. Although three of the triptans have pregnancy registries maintained by the manufacturer, triptan use in pregnancy has not been extensively studied. Information on the use of sumatriptan during pregnancy is relatively more abundant, because it has been on the market longer than the other triptans and may also have a higher percentage of the market share. There are no data to suggest teratogenicity for any of the triptans, although preterm birth rates appear to be elevated.

Cis-urocanic acid, a sunlight-induced immunosuppressive factor, activates immune suppression via the 5-HT2A receptor

Exposure to UV radiation induces skin cancer and suppresses the immune response. To induce immune suppression, the electromagnetic energy of UV radiation must be absorbed by an epidermal photoreceptor and converted into a biologically recognizable signal. Two photoreceptors have been recognized: DNA and trans-urocanic acid (UCA). Trans-UCA is normally found in the outermost layer of skin and isomerizes to the cis isomer upon exposure to UV radiation. Although UCA was identified as a UV photoreceptor years ago, and many have documented its ability to induce immune suppression, its exact mode of action remains elusive. Particularly vexing has been the identity of the molecular pathway by which cis-UCA mediates immune suppression. Here we provide evidence that cis-UCA binds to the serotonin [5-hydroxytryptamine (5-HT)] receptor with relatively high affinity (Kd = 4.6 nM). Anti-cis-UCA antibody precipitates radiolabeled 5-HT, and the binding is inhibited by excess 5-HT and/or excess cis-UCA. Similarly, anti-5-HT antibody precipitates radiolabeled cis-UCA, and the binding is inhibited by excess 5-HT or excess cis-UCA. Calcium mobilization was activated when a mouse fibroblast line, stably transfected with the human 5-HT2A receptor, was treated with cis-UCA. Cis-UCA-induced calcium mobilization was blocked with a selective 5-HT2A receptor antagonist. UV- and cis-UCA-induced immune suppression was blocked by antiserotonin antibodies or by treating the mice with 5-HT2A receptor antagonists. Our findings identify cis-UCA as a serotonin receptor ligand and indicate that the immunosuppressive effects of cis-UCA and UV radiation are mediated by activation of the 5-HT2A receptor.

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.

Rizatriptan does not change cerebral blood flow velocity during migraine attacks

Rizatriptan represents a major advance in the treatment of migraine attack: inhibition of peripheral trigeminal nerve and constriction of intracranial extracerebral blood vessels have been proposed as its main antimigraine mechanisms of action. Although many studies may suggest that rizatriptan causes highly selective vasoconstriction within intracranial extracerebral vessels (i.e., meningeal arteries), no literature data are available to date on possible cerebral hemodynamic changes in humans after treatment with rizatriptan. The aim of this study was to evaluate the effect of rizatriptan on cerebral blood flow velocity performing transcranial Doppler during spontaneous attacks of migraine without aura. Fourteen patients suffering from migraine without aura were monitored to evaluate mean flow velocity changes on both middle cerebral arteries during migraine attack 30 min before and 120 min after oral administration of rizatriptan 10mg. Monitoring was repeated for 30 min during the pain-free period. All patients turned out to be drug responders and no significant mean flow velocity changes were observed between the pain-free period and pre-treatment phase; besides no significant difference in mean flow velocity value have been detected between the periods after the drug administration during the attack versus both pre-treatment period and pain-free phase. These findings indicate that the antimigraine action of rizatriptan is not associated with clear intracranial cerebral hemodynamic changes and may support its cerebrovascular safety.

Triptans and CNS side-effects: pharmacokinetic and metabolic mechanisms

Triptans are the treatment of choice for acute migraine. While seemingly a homogenous group of drugs, results from a meta-analysis reveal significant differences in efficacy and tolerability among oral triptans. The incidence of drug-related central nervous system (CNS) side-effects with some triptans is as high as 15% and may be associated with functional impairment and reduced productivity. The occurrence of adverse events associated with triptans in general, and CNS side-effects in particular, may lead to a delay in initiating or even avoidance of an otherwise effective treatment. Potential explanations for differences among triptans in the incidence of CNS side-effects may relate to pharmacological and pharmacokinetic differences, including receptor binding, lipophilicity, and the presence of active metabolites. Of the triptans reviewed, at clinically relevant doses, almotriptan 12.5 mg, naratriptan 2.5 mg and sumatriptan 50 mg had the lowest incidence of CNS side-effects, while eletriptan 40 and 80 mg, rizatriptan 10 mg and zolmitriptan 2.5 and 5 mg had the highest incidence. The most likely explanations for the differences in CNS side-effects among triptans are the presence of active metabolites and high lipophilicity of the parent compound and active metabolites. Eletriptan, rizatriptan and zolmitriptan have active metabolites, while lipophilicity is lowest for almotriptan and sumatriptan. If CNS side-effects are a clinically relevant concern in the individual patient, use of a triptan with a low incidence of CNS side-effects may offer the potential for earlier initiation of treatment and more effective outcomes.

Receptor-Based 3D QSAR Analysis of Serotonin 5-HT1D Receptor Agonists

A three-dimensional quantitative structure-activity relationship study (3D QSAR) has been successfully applied to explain the binding affinities for the serotonin 5-HT1D receptor of a triptan series. The paper describes the development of a receptor-based 3D QSAR model of some known agonists and recently developed triptans on the 5-HT1D serotonergic receptor, showing a significant correlation between predicted and experimentally measured binding affinity (pIC50). The pIC50 values of these agonists are in the range from 5.40 to 9.50. The ligand alignment obtained from dynamic simulations was taken as basis for a 3D QSAR analysis applying the GRID/GOLPE program. 3D QSAR analysis of the ligands resulted in a model of high quality (r2 = 0.9895, q2LOO = 0.7854). This is an excellent result and proves both the validity of the proposed pharmacophore and the predictive quality of the 3D QSAR model for the triptan series of serotonin 5-HT1D receptor agonists.

Preclinical neuropharmacology of naratriptan

The basic CNS neuropharmacology of naratriptan is reviewed here. Naratriptan is a second-generation triptan antimigraine drug, developed at a time when CNS activity was thought not to be relevant to its therapeutic effect in migraine. It was, however, developed to be a more lipid-soluble, more readily absorbed and less readily metabolized variant on preexisting triptans and these variations conferred on it a higher CNS profile. Naratriptan is a 5-HT(1B/1D) receptor agonist with a highly selective action on migraine pain and nausea, without significant effect on other pain or even other trigeminal pain. Probable sites of therapeutic action of naratriptan include any or all of: the cranial vasculature; the peripheral terminations of trigeminovascular sensory nerves; the first-order synapses of the trigeminovascular sensory system; the descending pain control system; and the nuclei of the thalamus. Naratriptan may prevent painful dilatation of intracranial vessels or reverse such painful dilatation. Naratriptan can prevent the release of sensory peptides and inhibit painful neurogenic vasodilatation of intracranial blood vessels. At the first order synapse of the trigeminal sensory system, naratriptan can selectively suppress neurotransmission from sensory fibers from dural and vascular tissue, while sparing transmission from other trigeminal fibers, probably through inhibition of neuropeptide transmitter release. In the periaqueductal gray matter and in the nucleus raphe magnus, naratriptan selectively activates inhibitory neurons which project to the trigeminal nucleus and spinal cord and which exert inhibitory influences on trigeminovascular sensory input. Naratriptan has also a therapeutic effect on the nausea of migraine, possibly exerting its action at the level of the nucleus tractus solitarius via the same mechanisms by which it inhibits trigeminovascular nociceptive input. The incidence of naratriptan-induced adverse effects in the CNS is low and it is not an analgesic for pain other than that of vascular headache. In patients receiving selective serotonin uptake inhibitors (SSRIs) naratriptan may cause serotonin syndrome-like behavioral side effects. The mechanism of action involved in the production of behavioral and other CNS side effects of naratriptan is unknown.

Eletriptan for the treatment of migraine in patients with previous poor response or tolerance to oral sumatriptan

To determine the tolerability and efficacy of eletriptan in patients who had discontinued oral sumatriptan due to lack of efficacy or intolerable adverse events (AEs) during previous clinical treatment (not a controlled trial). Eletriptan is a potent, selective 5-HT1B/1D receptor agonist with beneficial pharmacokinetic properties compared with sumatriptan. In a double-blind, parallel group, placebo-controlled multicentre study, patients with and without aura (n = 446) were randomized to 40 mg eletriptan (E40, n = 188), 80 mg eletriptan (E80, n = 171) or placebo (n = 87) for treatment of up to three migraine attacks. Two-hour headache response, based on first-dose, first-attack data, was 59% for eletriptan 40 mg, 70% for eletriptan 80 mg, and 30% for placebo (P < 0.0001 for both doses of eletriptan vs. PBO; P < 0.05 for E80 vs. E40). Onset of action was rapid, with 1-h headache response rates significantly superior for E40 and E80 vs. placebo (40%, 48%, 15%; P < 0.0005). Both E40 and E80 were significantly superior to placebo, based on first-dose, first-attack data, for 2-h pain-free response (35%, 42%, and 7%; P < 0.0001). Both E40 and E80 demonstrated significant consistency of response, with headache relief rates at 2 h on at least two of three attacks in 66% and 72% vs. 15% on placebo (P < 0.001). AEs were mild to moderate in severity and dose related. The most commonly reported AEs included nausea, vomiting, asthenia, and chest symptoms. E40 and E80 produce an effective response in patients who had previously discontinued treatment with sumatriptan due to lack of efficacy or side-effects.

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.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Therapies in development for the treatment of migraine

While oral formulations of agonists at the serotonin (5-HT) receptor subdivisions 5-HT(1B/1D)--the "triptan" class of drugs--dominate the market for migraine therapy and while still more triptans are under development, recent research efforts have also explored other pharmacological avenues, which are mostly based on our extended insights into the neuropathology and genetics of migraine. Genetic research, in particular, continues to reveal new potential drug targets, indicating that the migraine treatment options that may become available by 2010 might be substantially different from today's scenery. Meanwhile, pharmaceutical companies make increasing use of drug delivery and formulation technologies to improve the action profile and convenience of use for current triptans and this has even led to a partial revival of "old" migraine drugs, such as ergot alkaloids. The broadest potential, however, lies in a better understanding of the molecular pharmacology of migraine.

Triptans

Triptans are potent serotonin (5-HT) 1B/1D receptor agonists used to abort and treat migraine headaches. Although the triptans share pharmacodynamic characteristics at 5-HT(1B/1D) receptors, they differ pharmacokinetically. This column reviews how the triptans are metabolized. Generally, the triptans are metabolized by phase I monoamine oxidases (MAOs) and by various cytochrome p450 enzymes. However, each triptan has a unique metabolic profile, leading to significant differences in each triptan's potential for drug-drug interactions. These differences are detailed in this review.

Clinical pharmacokinetics of intranasal sumatriptan

A substantial proportion of migraine patients have gastric stasis and suffer severe nausea and/or vomiting during their migraine attack. This may lead to erratic absorption from the gastrointestinal tract and make oral treatment unsatisfactory. For such patients, an intranasal formulation may be advantageous. Sumatriptan is a potent serotonin 5HT(1B/1D) agonist widely used in the treatment of migraine; the effectiveness of the intranasal formulation (20mg) has been well established in several clinical studies. This article reviews the pharmacokinetics of intranasal sumatriptan and includes comparisons with oral and subcutaneous administration. After intranasal administration, sumatriptan is directly and rapidly absorbed, with 60% of the maximum plasma concentration (C(max)) occurring at 30 minutes after administration of a single 20mg dose. Following intranasal administration, approximately 10% more sumatriptan is absorbed probably via the nasal mucosa when compared with oral administration. Mean C(max) after a 20mg intranasal dose is approximately 13.1 to 14.4 ng/mL, with median time to C(max) approximately 1 to 1.75 hours. When given as a single dose, intranasal sumatriptan displays dose proportionality in its extent of absorption and C(max) over the dose range 5 to 10mg, but not between 5 and 20mg for C(max). The elimination phase half-life is approximately 2 hours, consistent with administration by other routes. Sumatriptan is metabolised by monoamine oxidase (MAO; predominantly the A isozyme, MAO-A) to an inactive metabolite. Coadministration with a MAO-A inhibitor, moclobemide, leads to a significant increase in sumatriptan plasma concentrations and is contraindicated. Single-dose pharmacokinetics in paediatric and adolescent patients following intranasal sumatriptan were studied to determine the effect of changes in nasal morphology during growth, and of body size, on pharmacokinetic parameters. The pharmacokinetic profile observed in adults was maintained in the adolescent population; generally, factors such as age, bodyweight or height did not significantly affect the pharmacokinetics. In children below 12 years, C(max) is comparable to that seen in adolescents and adults, but total exposure (area under the concentration-time curve from zero to infinity) was lower in children compared with older patients, especially in younger children treated with 5mg. Clinical experience suggests that intranasal sumatriptan has some advantages over the tablet (more rapid onset of effect and use in patients with gastrointestinal complaints) or subcutaneous (noninvasive and fewer adverse events) formulations.

Rizatriptan: an update of its use in the management of migraine

Rizatriptan is an orally active serotonin 5-HT(1) receptor agonist that potently and selectively binds to 5-HT(1B/1D) subtypes. Earlier clinical trials demonstrated that rizatriptan 5 or 10mg is more effective than placebo at providing pain relief and a pain-free state, relieving associated symptoms of migraine, normalising functional ability and improving patient quality of life, and showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recently, rizatriptan 10mg was shown to be more effective than zolmitriptan 2.5mg or naratriptan 2.5mg at producing a pain-free state 2 hours postdose. Furthermore, compared with naratriptan, significantly more patients who received rizatriptan were pain free or had pain relief from 1 hour onwards. The number of patients with normal functional ability at 2 hours was significantly higher after rizatriptan than after naratriptan or zolmitriptan. Rizatriptan was also generally more effective than zolmitriptan or naratriptan at relieving migraine-associated symptoms. Rizatriptan is generally well tolerated and adverse events are usually mild and transient. The most common adverse events associated with rizatriptan in recent randomised trials were asthenia/fatigue, dizziness, somnolence and nausea. There was a trend towards a lower incidence of adverse events with rizatriptan compared with zolmitriptan (31.2 vs 38.8%). However, rizatriptan was associated with a significantly higher incidence of adverse events than naratriptan (39 vs 29%). The incidence of chest pain was similar after the administration of rizatriptan, zolmitriptan or naratriptan (2 to 4%).

CONCLUSION

Rizatriptan is an effective drug for the acute treatment of moderate or severe migraine. Oral rizatriptan 5 and 10mg have shown greater efficacy than placebo in providing pain relief, an absence of pain, relief from associated symptoms, normal functional ability and an improvement in patient quality of life. Earlier results showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recent studies have shown that rizatriptan 10mg provides faster pain relief and a higher percentage of patients with an absence of pain and normal functional ability at 2 hours than naratriptan 2.5mg or zolmitriptan 2.5mg. The efficacy of rizatriptan is retained when used in the long term and the drug is generally well tolerated. Although well designed studies comparing rizatriptan with almotriptan, eletriptan and frovatriptan would further define the position of rizatriptan, current data suggest rizatriptan should be considered as a first-line treatment option in the management of migraine.

Comparison of contractile responses to donitriptan and sumatriptan in the human middle meningeal and coronary arteries

Donitriptan is a potent, high efficacy agonist at 5-HT(1B/1D) receptors. We investigated the contractile effects of donitriptan and sumatriptan on human isolated blood vessels of relevance to therapeutic efficacy in migraine (middle meningeal artery) and coronary adverse events (coronary artery). Furthermore, using the concentration-response curves in the middle meningeal artery, we predicted the plasma concentration needed for the therapeutic effect of donitriptan. Both donitriptan and sumatriptan contracted the middle meningeal artery with similar apparent efficacy (E(max): 103+/-8% and 110+/-12%, respectively), but the potency of donitriptan (pEC(50): 9.07+/-0.14) was significantly higher than that of sumatriptan (pEC(50): 7.41+/-0.08). In the coronary artery, the contraction to donitriptan was biphasic with a significantly higher maximal response (E(max): 29+/-6%) than sumatriptan (E(max): 14+/-2%; pEC(50): 5.71+/-0.16), yielding two distinct pEC(50) values (8.25+/-0.16 and 5.60+/-0.24). Incubation with the 5-HT(2) receptor antagonist ketanserin (10 microM) eliminated the low affinity component of the concentration-response curve of donitriptan and the resultant E(max) and pEC(50) were 9+/-2% and 7.33+/-0.21, respectively. Ketanserin was without effect on the sumatriptan-induced contraction. Based on the middle meningeal artery contraction, concentrations (C(max)) of donitriptan that may be expected to have a therapeutic efficacy equivalent to that of 50 and 100 mg sumatriptan are predicted to be around 2.5 and 4.3 nM, respectively. Such concentrations are likely to induce only a small coronary artery contraction of 2.9+/-1.5% and 3.8+/-2.0%, respectively; these are not different from those by C(max) concentrations of sumatriptan (1.7+/-0.4% or 2.2+/-0.4%). The present results suggest that, like sumatriptan, donitriptan exhibits cranioselectivity and would be effective in aborting migraine attacks with a similar coronary side-effect profile as sumatriptan.

The medical benefit of 5-HT research

5-HT research is now more than 50 years old, and it has generated a wealth of therapeutic agents, some of which have had a major impact on disease management. The 5-HT reuptake inhibitors (SSRIs) are among the most widely prescribed drugs for treating depression and a variety of other disorders including anxiety, social phobia and premenstrual dysphoria (PMD). The other major success stories of 5-HT research are the discovery of 5-HT1B/D receptor agonists for treating migraine and 5-HT3 receptor antagonists for chemotherapy and radiation-induced emesis. The role of 5-HT in the mechanism of action of antipsychotic agents remains a topic of intense research, which promises better treatments for schizophrenia in the future. Compounds interacting with 5-HT1F, 5-HT2C, 5-HT6 and 5-HT7 receptors are currently under investigation and may prove to have important therapeutic applications in the future.

Use of rescue medication in trials of almotriptan versus placebo in the treatment of acute migraine

BACKGROUND

Almotriptan malate is a recently marketed triptan for the treatment of acute migraine. Results from controlled clinical trials demonstrate efficacy superior to placebo and an adverse event rate comparable to that with placebo.

OBJECTIVE

The goal of this study was to assess the effect of oral almotriptan on the use of rescue medication in the treatment of acute migraine attacks.

METHODS

Three Phase II and III, placebo-controlled, randomized, double-blind studies of almotriptan used as the basis for regulatory approval of the drug were included in the analysis. Two studies (1 single dose, 1 multiple dose) assessed almotriptan 6.25 mg and 12.5 mg and a third compared almotriptan 12.5 mg and sumatriptan 100 mg. Primary results from all 3 trials were previously published. Rescue medication was permitted if migraine pain had not decreased to mild severity or to no pain at 2 hours after study medication. The primary end point of this analysis was use of rescue medication.

RESULTS

A total of 1777 patients were included in the analysis. Mean patient age ranged from 39.4 to 44.0 years; approximately 87% were women, and >98% were white. Patients were well matched for demographic characteristics. Overall, use of rescue medication was significantly lower with almotriptan 6.25 mg and 12.5 mg compared with placebo (P < or = 0.05 for each group). No significant difference was noted between the almotriptan 12.5-mg and sumatriptan 100-mg groups. In 2 of the studies, patients with moderate or severe baseline pain used significantly less rescue medication in the almotriptan groups compared with placebo.

CONCLUSIONS

Oral almotriptan 6.25 mg or 12.5 mg significantly reduced use of rescue medication compared with placebo among patients with acute migraine. Use of rescue medication was comparable with almotriptan 12.5 mg and sumatriptan 100 mg.

Frovatriptan Succinate

Each month, subscribers to The Formulary® Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-ser-vices. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The April 2002 Formulary monograph topics are pegfilgrastim, fondaparinux sodium, dutasteride, aripiprazole, and ezetimibe. The DUE is on drotrecogin alfa.

How does almotriptan compare with other triptans? A review of data from placebo-controlled clinical trials

Almotriptan, the new selective 5-HT1B/1D agonist, has a higher oral bioavailability than any other triptan, with more than two thirds of the administered dose absorbed within the first hour both inside and outside of a migraine attack. Gender or the presence of food in the stomach does not affect its pharmacokinetic profile, and the compound has no clinically relevant interactions with other drugs. Among the available triptans, response rates at 2 hours range from 50% to 80%, with 20% to 50% of patients pain-free. Almotriptan 12.5 mg provides similar efficacy, with significant advantage over placebo at 30 minutes and a reliable consistency (75% in two of three attacks). Headache typically recurs in 25% to 45% of patients with most triptans. The recurrence rate with almotriptan 12.5 mg, 18% to 27%, is among the lowest reported. The tolerability of almotriptan 12.5 mg is close to that of placebo with a low incidence of central nervous system side effects and chest symptoms. In conclusion, almotriptan's consistent pharmacokinetics and good efficacy, in combination with excellent tolerability, make it an attractive choice in the acute treatment of migraine attacks.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Tripstar: a comprehensive patient-based approach to compare triptans

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

Almotriptan increases pain-free status in patients with acute migraine treated in placebo-controlled clinical trials

OBJECTIVES

Evaluate the efficacy of a single oral dose of almotriptan in achieving pain-free status during treatment of acute migraine attacks.

METHODS

This pooled analysis (N=1321) used data from two randomized, placebo-controlled, phase III trials (studies A and B) to determine the proportion of patients with migraine achieving pain-free status 2 hours after a single oral dose of study medication (almotriptan or placebo). Pain was assessed using a 4-point integer scale (0=no headache, 3=severe headache), and recorded in a patient self-assessment booklet.

RESULTS

The proportion of patients pain-free at 2 hours after study medication was significantly greater with almotriptan 6.25 mg (both studies P<or=.002) and almotriptan 12.5 mg (both studies P<or=.001) than with placebo. In study A, 11.6% of patients taking almotriptan 12.5 mg versus 2.5% of patients receiving placebo were pain-free at 1 hour (P=.016). At 1.5 hours, 26.8% of patients taking almotriptan 12.5 mg versus 8.8% receiving placebo (P=.001) were pain-free, and at 2 hours, 38.4% on almotriptan versus 11.3% on placebo were pain-free (P<.001). In study B, 23.8% of patients taking almotriptan 12.5 mg were free from pain at 1.5 hours versus 10.2% receiving placebo (P<.001). At 2 hours, 39.2% taking almotriptan 12.5 mg versus 15.3% receiving placebo were pain-free (P<.001). Increases in pain-free status with almotriptan generally occurred in a dose-dependent manner.

CONCLUSION

Compared with placebo, almotriptan 12.5 mg significantly increases the proportion of patients who are pain-free by as early as 1 hour, and consistently by 1.5 hours, after a single dose.

Clinical benefits of early triptan therapy for migraine

Although triptans have been proven effective for acute treatment of migraine, reserving them for moderate or severe pain may produce suboptimal pain relief and higher rates of recurrence. Recent evidence indicates that early intervention at the onset of pain improves outcomes. Post hoc analysis of a long-term, open-label European study of almotriptan 12.5 mg found that the percentage of attacks rendered pain-free at 2 hours was significantly greater when patients treated mild pain (84%) than when the intervention occurred during moderate or severe pain (53%). A similar pattern emerged with respect to the consistency of pain relief, with a significant advantage for early intervention (88% versus 56%, respectively). A difference in favor of early intervention was also seen with respect to recurrence, need for rescue medication, and adverse events. The recurrence rate was significantly lower in patients treating mild pain (28%) than in those delaying treatment until the pain became moderate or severe (33%), which suggests that achieving pain freedom results in less recurrence. These results were generally replicated in post hoc analysis of a subgroup of patients from a randomized, placebo-controlled trial (the Spectrum Study) of oral sumatriptan 50 mg in migraineurs. This analysis demonstrated that with early intervention, pain was less likely to intensify, fewer attacks required redosing, more attacks remained pain-free 24 hours postdose, and normal function returned more quickly. In sum, early intervention with triptans can improve outcomes, avoiding much of the pain and disability associated with treating moderate or severe attacks.

Almotriptan Malate

Each month, subscribers to The Formulary® Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late Phase III trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. The monographs are published in printed form and on diskettes that allow customization. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The October 2001 Formulary monograph topics are nesiritide, soledronic acid injection, anakinra, treprostinol sidium injection, and bosentan. The DUE is on nesiritide.

Vascular effects of the new anti-migraine agent almotriptan on human cranial and peripheral arteries

This paper describes the vascular effects of almotriptan in comparison with sumatriptan in human vessels and tissues in vitro. The contractile properties of almotriptan and sumatriptan were evaluated in vitro in the following arteries: meningeal, temporal, basilar, internal carotid, ophthalmic, pulmonary and coronary. In addition, the effects of almotriptan on the pulmonary vein and on bronchial tissues were studied. Almotriptan showed selectivity of action for migraine-related arteries (i.e. contractile EC(50) of 30 and 700 nm for meningeal and temporal arteries, respectively), whereas the effect on arteries supplying blood to the brain was lower. The contractile effect of almotriptan was lower than that of sumatriptan in pulmonary arteries, whereas in bronchial preparations no clinically relevant contractile responses were observed for either almotriptan or sumatriptan. In ophthalmic arteries the contractile effects of almotriptan and sumatriptan were similar, whereas lower contractile effects were obtained with almotriptan than with sumatriptan in coronary arteries.