Characterisation of the 5-HT receptor binding profile of eletriptan and kinetics of [3H]eletriptan binding at human 5-HT1B and 5-HT1D receptors

5-HT1A agonists for levodopa-induced dyskinesia in Parkinson's disease

Levodopa is the most effective agent for treating the symptoms of Parkinson's disease (PD). However, levodopa-induced dyskinesia remains a significant complication that manifests after few years of treatment, for which therapeutic options remain limited. Several agonists of the serotonin type 1A (5-HT_1A) receptor with varying levels of efficacy and interaction at other sites, have been tested in the clinic. Clinical trials testing 5-HT_1A agonists have yielded inconsistent results in alleviating dyskinesia, especially that the antidyskinetic benefit observed was often accompanied by an adverse effect on motor function. In this article, we summarize and analyze the various clinical trials performed with 5-HT_1A agonists in PD patients with dyskinesia and offer perspectives on the future of this class of agents in PD.

Comparison of New Pharmacologic Agents With Triptans for Treatment of Migraine: A Systematic Review and Meta-analysis

IMPORTANCE

New therapeutic classes of migraine-specific treatment have been developed, including 5-hydroxytryptamine1F receptor agonists (lasmiditan) and calcitonin gene-related peptide antagonists (rimegepant and ubrogepant).

OBJECTIVE

To compare outcomes associated with the use of lasmiditan, rimegepant, and ubrogepant vs triptans for acute management of migraine headaches.

DATA SOURCES

The Cochrane Register of Controlled Trials, Embase, and PubMed were searched from inception to March 5, 2020.

STUDY SELECTION

Double-blind randomized clinical trials examining current available migraine-specific acute treatments were included.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was applied to extract the data according to a predetermined list of variables of interest, and all network meta-analyses were conducted using a random-effects model.

MAIN OUTCOMES AND MEASURES

The primary outcome was the odds ratio (OR) for freedom from pain (hereafter referred to as pain freedom) at 2 hours after the dose, and the secondary outcomes were ORs for pain relief at 2 hours after the dose and any adverse events.

RESULTS

A total of 64 randomized clinical trials were included (46 442 participants; 74%-87% women; age range, 36-43 years). Most of the included treatments were associated with reduced pain at 2 hours compared with placebo. Most triptans were associated with higher ORs for pain freedom at 2 hours compared with lasmiditan (range: OR, 1.72 [95% CI, 1.06-2.80] to OR, 3.40 [95% CI, 2.12-5.44]), rimegepant (range: OR, 1.58 [95% CI, 1.07-2.33] to OR, 3.13 [95% CI, 2.16-4.52]), and ubrogepant (range: OR, 1.54 [95% CI, 1.00-2.37] to OR, 3.05 [95% CI, 2.02-4.60]). Most triptans were associated with higher ORs for pain relief at 2 hours compared with lasmiditan (range: OR, 1.46 [95% CI, 1.09-1.96] to OR, 3.31 [95% CI, 2.41-4.55]), rimegepant (range: OR, 1.33 [95% CI, 1.01-1.76] to OR, 3.01 [95% CI, 2.33-3.88]), and ubrogepant (range: OR, 1.38 [95% CI, 1.02-1.88] to OR, 3.13 [95% CI, 2.35-4.15]). The comparisons between lasmiditan, rimegepant, and ubrogepant were not statistically significant for both pain freedom and pain relief at 2 hours. Lasmiditan was associated with the highest risk of any adverse events, and certain triptans (rizatriptan, sumatriptan, and zolmitriptan) were also associated with a higher risk of any adverse events than the calcitonin gene-related peptide antagonists.

CONCLUSIONS AND RELEVANCE

For pain freedom or pain relief at 2 hours after the dose, lasmiditan, rimegepant, and ubrogepant were associated with higher ORs compared with placebo but lower ORs compared with most triptans. However, the lack of cardiovascular risks for these new classes of migraine-specific treatments may offer an alternative to triptans.

International Union of Basic and Clinical Pharmacology. CX. Classification of Receptors for 5-hydroxytryptamine; Pharmacology and Function

5-HT receptors expressed throughout the human body are targets for established therapeutics and various drugs in development. Their diversity of structure and function reflects the important role 5-HT receptors play in physiologic and pathophysiological processes. The present review offers a framework for the official receptor nomenclature and a detailed understanding of each of the 14 5-HT receptor subtypes, their roles in the systems of the body, and, where appropriate, the (potential) utility of therapeutics targeting these receptors. SIGNIFICANCE STATEMENT: This review provides a comprehensive account of the classification and function of 5-hydroxytryptamine receptors, including how they are targeted for therapeutic benefit.

Managing migraine with over-the-counter provision of triptans: the perspectives and readiness of Western Australian community pharmacists

Background

Down-scheduling one or more triptans to Schedule 3 (Pharmacist Only Medicine) from Schedule 4 (Prescription Only Medicine) has been debated in Australia for a decade. This study aimed to evaluate the perspectives and readiness of Western Australian (WA) community pharmacists to manage migraine including over-the-counter (OTC) provision of triptans.

Methods

Data were collected using a self-administered paper-based questionnaire, posted to a random sample of 178 metropolitan and 97 regional pharmacies in WA. Respondent pharmacists were surveyed regarding: knowledge of optimal migraine treatment as per current guidelines, resources required to appropriately recommend triptans and attitudes and perspective toward down-scheduling. Data were analysed using descriptive statistics and multivariate regression analysis. Pharmacist/pharmacy characteristics influencing readiness were evaluated by assigning respondents a score based on responses to Likert scale questions. These questions were assigned to five domains based on an implementation model and these scores were used in a general linear model to identify demographic characteristics associated with readiness across each domain.

Results

A total of 114 of the 275 pharmacies returned useable questionnaires (response rate: 41.5%). The two most commonly recommended first line OTC agents were a combined paracetamol/non-steroidal anti-inflammatory drugs and aspirin (44/104; 42.3% and 22/104; 21.2%, respectively) which provided context to the respondents’ knowledge of optimal migraine treatment. Responses to questions in relation to triptans and the warning signs requiring referral were in line with current guidelines, demonstrating respondents’ knowledge in these areas. Nevertheless, most respondents demonstrated uncertainty in relation to the pathogenesis of migraine. If triptans were available OTC, 66/107 (61.7%) would recommend them first-line. The majority (107/113; 94.7%) agreed that down-scheduling would improve timely access to effective migraine medication and 105/113 (92.9%) agreed that if triptans were down-scheduled, pharmacists may be better able to assist people in the treatment of migraine. Most respondents agreed that additional training and resources, including a guideline for OTC supply of triptans and the management of first-time and repeat migraine would be necessary if triptans were down-scheduled. No single demographic characteristic influenced readiness across all five domains.

Discussion

Pharmacists were knowledgeable regarding triptans and recognised symptoms requiring referral; migraine knowledge could be improved. Pharmacists supported down-scheduling of one or more triptans in Australia, however they highlighted a need for further training and resources to support migraine diagnosis and provision of OTC triptans. Professional pharmacy bodies should consider these findings when recommending drugs suitable for down-scheduling for pharmacist recommendation.

Lasmiditan is an effective acute treatment for migraine: A phase 3 randomized study

Objective

To assess the efficacy and safety of lasmiditan in the acute treatment of migraine.

Methods

Adult patients with migraine were randomized (1:1:1) to a double-blind dose of oral lasmiditan 200 mg, lasmiditan 100 mg, or placebo and were asked to treat their next migraine attack within 4 hours of onset. Over 48 hours after dosing, patients used an electronic diary to record headache pain and the presence of nausea, phonophobia, and photophobia, one of which was designated their most bothersome symptom (MBS).

Results

Of the 1,856 patients who treated an attack, 77.9% had ≥1 cardiovascular risk factors in addition to migraine. Compared with placebo, more patients dosed with lasmiditan 200 mg were free of headache pain at 2 hours after dosing (32.2% vs 15.3%; odds ratio [OR] 2.6, 95% confidence interval [CI] 2.0–3.6, p< 0.001), similar to those dosed with lasmiditan 100 mg (28.2%; OR 2.2, 95% CI 1.6–3.0, p< 0.001). Furthermore, compared with those dosed with placebo, more patients dosed with lasmiditan 200 mg (40.7% vs 29.5%; OR 1.6, 95% CI 1.3–2.1, p< 0.001) and lasmiditan 100 mg (40.9%; OR 1.7, 95% CI, 1.3–2.2, p< 0.001) were free of their MBS at 2 hours after dosing. Adverse events were mostly mild or moderate in intensity.

Conclusions

Lasmiditan dosed at 200 and 100 mg was efficacious and well tolerated in the treatment of acute migraine among patients with a high level of cardiovascular risk factors.

ClinicalTrials.gov identifier

NCT02439320.

Classification of evidence

This study provides Class I evidence that for adult patients with migraine, lasmiditan increases the proportion of subjects who are headache pain free at 2 hours after treating a migraine attack.

Pharmacokinetics and tolerability of eletriptan hydrobromide in healthy Korean subjects

Background

Migraine is one of the most common headache disorders that greatly affect the quality of life. Selective serotonin (5-HT) receptor agonists such as triptamine-based drugs called triptans are used for treatment of migraine.

Purpose

This study aimed to evaluate the pharmacokinetic (PK) and tolerability profiles of eletriptan hydrobromide (eletriptan HBr), a selective 5-hydroxytryptamine (also known as serotonin) 1B/1D receptor agonist, in Koreans and compare the results to those observed in non-Koreans in a previously published study.

Patients and methods

A randomized, open-label, single, and repeated-dose study was conducted in 16 healthy Korean male subjects using a four-treatment, four-period, and four-sequence crossover design (NCT01139515). The subjects received one of the following four treatments in each period: a single dose of 20, 40, 80 mg eletriptan HBr or a repeated oral dose of 40 mg 2 h apart. Blood samples were collected before and up to 26 h after dosing for quantification of plasma eletriptan concentration by high-performance liquid chromatography tandem–mass spectrometry. The PK parameters were estimated using noncompartmental methods. Ethnicity differences between Korean and non-Korean subjects were identified using geometric mean ratios and 90% confidence intervals (CIs) of dose-normalized maximum plasma concentration (C_max) and dose-normalized area under the plasma concentration versus time curve from 0 h to the last measurable concentration (AUC_0–t).

Results

After single-dose administration of eletriptan HBr to Korean subjects, the mean C_max and AUC_0–t increased linearly with dose. Comparable total systemic exposures were observed in the 2 h apart 40 mg repeated and single 80 mg dose. The geometric mean ratios (90% CIs) of the dose-normalized C_max and AUC_0–t of Korean subjects were similar to those of non-Korean subjects reported in the literature. The adverse events observed were transient and mild in severity.

Conclusion

Eletriptan HBr showed linear PK and was well tolerated in Korean subjects. The PK and tolerability of eletriptan HBr did not differ between Korean and non-Korean subjects.

From the Promiscuous Asenapine to Potent Fluorescent Ligands Acting at a Series of Aminergic G-Protein-Coupled Receptors

Monoamine neurotransmitters such as serotonin, dopamine, histamine, and noradrenaline have important and varied physiological functions and similar chemical structures. Representing important pharmaceutical drug targets, the corresponding G-protein-coupled receptors (termed aminergic GPCRs) belong to the class of cell membrane receptors and share many levels of similarity as well. Given their pharmacological and structural closeness, one could hypothesize the possibility to derivatize a ubiquitous ligand to afford rapidly fluorescent probes for a large set of GPCRs to be used for instance in FRET-based binding assays. Here we report fluorescent derivatives of the nonselective agent asenapine which were designed, synthesized, and evaluated as ligands of 34 serotonin, dopamine, histamine, melatonin, acetylcholine, and adrenergic receptors. It appears that this strategy led rapidly to the discovery and development of nanomolar affinity fluorescent probes for 14 aminergic GPCRs. Selected probes were tested in competition binding assays with unlabeled competitors in order to demonstrate their suitability for drug discovery purposes.

Insights Into the Molecular Mechanism of Triptan Transport by P-glycoprotein

The P-glycoprotein (Pgp) transporter reduces the penetration of a chemically diverse range of neurotherapeutics at the blood-brain barrier, but the molecular features of drugs and drug-Pgp interactions that drive transport remain to be clarified. In particular, the triptan neurotherapeutics, eletriptan (ETT) and sumatriptan (STT), were identified to have a >10-fold difference in transport rates despite being from the same drug class. Consistent with these transport differences, ETT activated Pgp-mediated ATP hydrolysis ∼2-fold, whereas STT slightly inhibited Pgp-mediated ATP hydrolysis by ∼10%. The interactions between them were also noncompetitive, suggesting that they occupy different binding sites on the transporter. Despite these differences, protein fluorescence spectroscopy revealed that the drugs have similar affinity to the transporter. NMR with Pgp and the drugs showed that they have distinct interactions with the transporter. Tertiary conformational changes probed by acrylamide quenching of Pgp tryptophan fluorescence with the drugs and a nonhydrolyzable ATP analog implied that the STT-bound Pgp must undergo larger conformational changes to hydrolyze ATP than ETT-bound Pgp. These results and previous transport studies were used to build a conformationally driven model for triptan transport with Pgp where STT presents a higher conformational barrier for ATP hydrolysis and transport than ETT.

Network meta-analysis of migraine disorder treatment by NSAIDs and triptans

Background

Migraine is a neurological disorder resulting in large socioeconomic burden. This network meta-analysis (NMA) is designed to compare the relative efficacy and tolerability of non-steroidal anti-inflammatory agents (NSAIDs) and triptans.

Methods

We conducted systematic searches in database PubMed and Embase. Treatment effectiveness was compared by synthesizing direct and indirect evidences using NMA. The surface under curve ranking area (SUCRA) was created to rank those interventions.

Results

Eletriptan and rizatriptan are superior to sumatriptan, zolmitriptan, almotriptan, ibuprofen and aspirin with respect to pain-relief. When analyzing 2 h-nausea-absence, rizatriptan has a better efficacy than sumatriptan, while other treatments indicate no distinctive difference compared with placebo. Furthermore, sumatriptan demonstrates a higher incidence of all-adverse-event compared with diclofenac-potassium, ibuprofen and almotriptan.

Conclusion

This study suggests that eletriptan may be the most suitable therapy for migraine from a comprehensive point of view. In the meantime ibuprofen may also be a good choice for its excellent tolerability. Multi-component medication also attracts attention and may be a promising avenue for the next generation of migraine treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s10194-016-0703-0) contains supplementary material, which is available to authorized users.

Distribution of 5-HT1F Receptors in Monkey Vestibular and Trigeminal Ganglion Cells

Background

Evidence of serotonergic involvement in vestibular pathway contributions to migraine and balance disorders is compelling. Serotonergic 5-HT_1B and 5-HT_1D receptors are expressed extensively in inner ear ganglia of monkeys and rats. The serotonergic 5-HT_1F receptor is also a target of triptans. This study describes its distribution in vestibular and trigeminal ganglia of monkeys.

Methods

Using primary polyclonal antibodies raised against oligopeptides specific for the human 5-HT_1F receptor, neuronal somatic area and intensity of immunoreactive vestibular and trigeminal ganglia were quantified.

Results and Discussion

Virtually all vestibular and considerable trigeminal ganglia showed positive 5-HT_1F receptor immunoreactivity. Inferior and superior vestibular ganglia staining appeared confined to distinct cell regions, varying considerably among cells of different sizes: more intense in small, punctate in some medium and regionally polarized in some large cells. Analyses of average somatic vestibular neuronal immunoreactive intensity identified mainly medium sized cells with high standard deviation of intensity corresponding to punctately stained cells. Less variability occurred in somatic intensity staining and cellular distribution among 5-HT_1F receptor immunopositive trigeminal ganglia. Most exhibited similar punctate staining patterns, higher mean somatic immunoreactive intensity and larger neuronal somatic size proportions per size distribution subpopulation compared to vestibular ganglia size distribution populations. Centrally directed vestibular ganglion neuronal processes, cochlear inner hair cells, vestibular hair cells and blood vessels in vestibular maculae and cristae were immunoreactive. The 5-HT_1F receptor expression in vestibular ganglia shows complex variable staining intensity patterns associated with cell size of immunopositive neurons, not seen in immunopositive trigeminal ganglia and not previously evident with 5-HT_1B and 5-HT_1D receptor subtype immunoreactivity in vestibular ganglia. These data motivate exploration of 5-HT₁ receptor oligomerization and ligand functional selectivity in differential serotonergic involvement in co-morbidity of migraine and balance disorders. Similar findings in cochlear inner hair cell afferents are applicable to migraine-related tinnitus or hypercusis (phonophobia).

Eletriptan Treatment of Migraine in Patients Switching from Barbiturate-Containing Analgesics: Results from a Multiple-Attack Study

The aim of this study was to examine efficacy and tolerability of eletriptan in patients switched from barbiturate-containing combinations (Fiorinal®, Fioricet®). Migraineurs ( n = 160) meeting IHS criteria, with unsatisfactory response in the past year to butalbital-containing combinations, treated up to 16 attacks over 3 months with eletriptan 40 mg. Assessments included headache response and pain-free rates and functional impairment at baseline and 2 h postdose, and global ratings of treatment satisfaction at 24 h. At 2 h postdose, average headache response and pain-free rates were 71% (95% CI, 69-74%) and 37% (95% CI, 35-40%), respectively; 68.5% of patients (95% CI, 65-72%) reported functional response. Within-patient analysis found no efficacy diminution over time (no tolerance). Average headache recurrence rate was 20% (95% CI, 18-23%). Eletriptan was well-tolerated; 6 (3.7%) patients discontinued due to adverse events. There were no serious treatment-related adverse events. We conclude that in poor responders to butalbital-caffeine combinations, switching to eletriptan 40 mg was well-tolerated and efficacious.

Theory-based analysis of clinical efficacy of triptans using receptor occupancy

BACKGROUND

Triptans, serotonin 5-HT1B/1D receptor agonists, exert their action by targeting serotonin 5-HT1B/1D receptors, are used for treatment of migraine attack. Presently, 5 different triptans, namely sumatriptan, zolmitriptan, eletriptan, rizatriptan, and naratriptan, are marketed in Japan. In the present study, we retrospectively analyzed the relationships of clinical efficacy (headache relief) in Japanese and 5-HT1B/1D receptor occupancy (Φ1B and Φ1D). Receptor occupancies were calculated from both the pharmacokinetic and pharmacodynamic data of triptans.

METHODS

To evaluate the total amount of exposure to drug, we calculated the area under the plasma concentration-time curve (AUCcp) and the areas under the time curves for Ф1B and Ф1D (AUCФ1B and AUCФ1D). Moreover, parameters expressing drug transfer and binding rates (Acp, AФ1B, AФ1D) were calculated.

RESULTS

Our calculations showed that Фmax1B and Фmax1D were relatively high at 32.0-89.4% and 68.4-96.2%, respectively, suggesting that it is likely that a high occupancy is necessary to attain the clinical effect. In addition, the relationships between therapeutic effect and AUCcp, AUCΦ1B, AUCΦ1D, and Acp · AUCcp differed with each drug and administered form, whereas a significant relationship was found between the therapeutic effect and AΦ1B · AUCΦ1B or AΦ1D · AUCΦ1D that was not affected by the drug and the form of administration.

CONCLUSIONS

These results suggest that receptor occupancy can be used as a parameter for a common index to evaluate the therapeutic effect. We considered that the present findings provide useful information to support the proper use of triptans.

Myocardial infarction after taking eletriptan

We report the case of a 53-year-old male patient with a medical history significant for paroxysmal atrial fibrillation, migraines with visual aura and non-obstructive coronary artery disease, who sustained a non-ST-elevation myocardial infarction a few hours after taking eletriptan as abortive therapy for migraine headaches. We believe this case implies a causal association between eletriptan and myocardial infarction, considering the timing of both drug intake and symptom onset. To the best of our knowledge this is the first reported myocardial infarction attributable to eletriptan overdose in a patient without obstructive coronary artery disease.

Dihydroergotamine and sumatriptan in isolated human coronary artery, middle meningeal artery and saphenous vein

BACKGROUND

Dihydroergotamine (DHE) and sumatriptan are contraindicated in patients with cardiovascular disease because of their vasoconstricting properties, which have originally been explored in proximal coronary arteries. Our aim was to investigate DHE and sumatriptan in the proximal and distal coronary artery, middle meningeal artery and saphenous vein.

METHODS

Blood vessel segments were mounted in organ baths and concentration response curves for DHE and sumatriptan were constructed.

RESULTS

In the proximal coronary artery, meningeal artery and saphenous vein, maximal contractions to DHE (proximal: 8 ± 4%; meningeal: 32 ± 7%; saphenous: 52 ± 11%) and sumatriptan (proximal: 17 ± 7%; meningeal: 61 ± 18%, saphenous: 37 ± 8%) were not significantly different. In the distal coronary artery, contractions to DHE (5 ± 2%) were significantly smaller than those to sumatriptan (17 ± 9%). At clinically relevant concentrations, mean contractions to DHE and sumatriptan were below 3% in proximal coronary arteries and below 6% in distal coronary arteries. Contractions in the meningeal artery and saphenous vein were higher (7%-38%).

CONCLUSIONS

Contractions to DHE in distal coronary arteries are smaller than those to sumatriptan, while at clinical concentrations they both induce only slight contractions. In meningeal arteries contractions to DHE and sumatriptan are significantly larger, showing their cranioselectivity. Contractions to DHE in the saphenous vein are higher than those in the arteries, confirming its venous contractile properties.

The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors

The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.

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.

mRNA expression of 5-hydroxytryptamine 1B, 1D, and 1F receptors and their role in controlling the release of calcitonin gene-related peptide in the rat trigeminovascular system

Triptans, a family of 5-hydroxytryptamine (5-HT) 1B, 1D, and 1F receptor agonists, are used in the acute treatment of migraine attacks. The site of action and subtypes of the 5-HT(1) receptor that mediate the antimigraine effect have still to be identified. This study investigated the mRNA expression of these receptors and the role of 5-HT(1) receptor subtypes in controlling the release of calcitonin gene-related peptide (CGRP) in rat dura mater, trigeminal ganglion (TG), and trigeminal nucleus caudalis (TNC). The mRNA for each receptor subtype was quantified by quantitative real-time polymerase chain reaction. A high potassium concentration was used to release CGRP from dura mater, isolated TG, and TNC in vitro. The immunoreactive CGRP (iCGRP) release was measured by enzyme-linked immunoassay. The mRNA transcripts of the 3 5-HT(1) receptor subtypes were detected in the trigeminovascular system. Sumatriptan inhibited iCGRP release by 31% in dura mater, 44% in TG, and 56% in TNC. This effect was reversed by a 5-HT(1B/1D) antagonist (GR127395). The 5-HT(1F) agonist (LY-344864) was effective in the dura mater (26% iCGRP inhibition), and the 5-HT(1D) agonist (PNU-142633) had a significant effect in the TNC (48%), whereas the 5-HT(1B) agonist (CP-94253) was unable to reduce the iCGRP release in all tissues studied. We found that sumatriptan reduced the iCGRP release via activation of 5-HT(1D) and 5-HT(1F) receptor subtypes. The 5-HT(1F) receptor agonist was effective only in peripheral terminals in dura mater, whereas the 5-HT(1D) agonist had a preferential effect on central terminals in the TNC.

Pharmacokinetic evaluation of frovatriptan

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Neurologic bases for comorbidity of balance disorders, anxiety disorders and migraine: neurotherapeutic implications

The comorbidity among balance disorders, anxiety disorders and migraine has been studied extensively from clinical and basic research perspectives. From a neurological perspective, the comorbid symptoms are viewed as the product of sensorimotor, interoceptive and cognitive adaptations that are produced by afferent interoceptive information processing, a vestibulo-parabrachial nucleus network, a cerebral cortical network (including the insula, orbitofrontal cortex, prefrontal cortex and anterior cingulate cortex), a raphe nuclear-vestibular network, a coeruleo-vestibular network and a raphe-locus coeruleus loop. As these pathways overlap extensively with pathways implicated in the generation, perception and regulation of emotions and affective states, the comorbid disorders and effective treatment modalities can be viewed within the contexts of neurological and psychopharmacological sites of action of current therapies.

Distribution of 5-HT1B and 5-HT1D receptors in the inner ear

Migraine and anxiety disorders are frequently co-morbid with balance disorders. This study examined the relative distribution of subtypes of serotonin (5-HT) receptor in the inner ear of monkeys and rats. Most vestibular ganglion cells were immunoreactive for 5-HT(1B) and 5-HT(1D) receptors in macaques and rats. In the inner ear, 5-HT(1B) and 5-HT(1D) receptor immunopositivity was associated with endothelial cells of the vestibular ganglion, spiral ganglion, vestibulocochlear nerve, spiral ligament and stria vascularis. It was noteworthy that 5-HT(1B) and 5-HT(1D) receptors are expressed in parallel sites in peripheral vestibular and trigeminal systems, which may be a factor underlying the efficacy of triptans in treating migraine and migrainous vertigo. Because the vestibular ganglion and trigeminal ganglion are both within the subarachnoid space, an interaction between 5-HT(1B) and TRPV1 receptors on blood vessel and ganglion cells may also contribute to the vasospasm and the comorbid headache, dizziness, nausea and vomiting that accompany subarachnoid hemorrhage.

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.

Rapid responders to frovatriptan in acute migraine treatment: results from a long-term, open-label study

BACKGROUND

The chronic nature of migraine and the reliance on acute treatment constitute the basis of the present long-term, open-label study.

OBJECTIVES

First, assessment of the tolerability and safety of frovatriptan, 2.5-7.5 mg taken orally over 24 hours, for the acute treatment of migraine, repeatedly over a 12-month period. Second, assessment of the efficacy and tolerability of a second, double-blind dose of 2.5-mg frovatriptan, compared with placebo, for nonresponse at 2 hours after treatment of moderate or severe headache with 2.5-mg frovatriptan.

RESULTS

With regard to the first attack treated, 173 (36%) of the 486 subjects in the study did not take a second dose at 2 hours for nonresponse. At 2 hours and 4 hours, these "rapid responders" experienced a decrease in headache intensity from moderate or severe to mild or no pain in 84% and 98%, respectively ("headache response"). Six percent of them experienced recurrence of moderate or severe headache within 24 hours following a response at 4 hours and 12% took rescue medication. The response, measured in terms of median time to "complete migraine relief," was maintained over 30 subsequent migraine attacks, treated from attack 2 onwards over the course of 12 months.

CONCLUSION

Frovatriptan provides a remarkably fast and high headache response in a subgroup of more than one-third of migraineurs, with a very low 24-hour headache recurrence and low rescue medication intake.

Spotlight on eletriptan in migraine

Eletriptan (Relpax) is an orally administered, lipophilic, highly selective serotonin 5-HT(1B/1D) receptor agonist ('triptan') that is effective in the acute treatment of moderate to severe migraine attacks in adults. It has a rapid onset of action and demonstrates superiority over placebo as early as 30 minutes after the administration of a single 40 or 80 mg oral dose. The efficacy of eletriptan 20 mg was similar to that of sumatriptan 100 mg, while eletriptan 40 and 80 mg displayed greater efficacy than sumatriptan 50 or 100 mg for most endpoints. Eletriptan 40 mg was generally superior to naratriptan 2.5 mg and equivalent to almotriptan 12.5 mg, rizatriptan 10 mg and zolmitriptan 2.5 mg, while eletriptan 80 mg was superior to zolmitriptan 2.5 mg for most efficacy parameters. Eletriptan 40 and 80 mg were consistently superior to ergotamine/caffeine. Eletriptan is generally well tolerated, reduces time lost from normal activities, improves patients' health-related quality of life and appears to be at least as, if not more, cost effective than sumatriptan. Eletriptan is therefore a useful addition to the triptan family and a first-line treatment option in the acute management of migraine attacks.

Eletriptan: a review and new perspectives

Eletriptan is a second-generation 5-hydroxytryptamine(1B/1D) receptor agonist, or triptan, indicated for the acute treatment of migraine. Eletriptan has a favorable pharmacokinetic and pharmacodynamic profile expressed by bioavailability, half-life and high selectivity for cranial arteries. It has been shown to be effective and well tolerated in a wide preapproval development program, which included over 11,000 patients and treated more than 74,000 migraine attacks. In clinical trials, eletriptan has been demonstrated to be one of the most effective oral therapies for the acute treatment of migraine and has 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.

Eletriptan in migraine

Migraine is a highly prevalent, chronic and disabling illness in which the gap between practice guideline recommendations and actual clinical practice remains wide. Eletriptan, similar to other triptans, is a potent 5-HT(1B/1D) receptor agonist with a high selectivity for cranial versus coronary artery constriction and favorable pharmacokinetic profile. An extensive program of double-blind, placebo-controlled, head-to-head comparator trials has demonstrated the superior efficacy of eletriptan compared with the combination of ergotamine and caffeine, and selected oral triptans for the acute treatment of migraine. Eletriptans tolerability profile makes it a good choice as a first-line treatment of migraine. An early treatment study suggests that treatment of mild headache is associated with unusually high sustained pain-free rates and a tolerability profile that is equivalent to placebo.

Safety and Efficacy of Eletriptan in the Treatment of Acute Migraine

Eletriptan is a new selective serotonin agonist approved for the treatment of acute migraine headaches. To review the pharmacologic, pharmacodynamic, pharmacokinetic, safety, and clinical efficacy data for eletriptan, we searched the literature in PubMed/MEDLINE, EMBASE, International Pharmaceutical Abstracts, and Science Direct databases to gather all published reports from January 1996-October 2004. All English-language reports (abstract or full trial reports) about the pharmacology, pharmacokinetics, clinical efficacy, and safety of eletriptan were reviewed. Eletriptan's pharmacokinetic and pharmacodynamic parameters translate into a favorable safety and efficacy profile. The drug is rapidly absorbed when administered orally, has good bioavailability and central nervous system penetration due to its lipophilicity, and has a long half-life, which contributes to its ability to prevent recurrent headaches. Compared with other serotonin agonists, eletriptan has a longer duration of action and greater lipophilicity. Eletriptan is metabolized through the cytochrome P450 3A4 system; therefore, it does have the potential for clinically significant drug interactions. In clinical trials, eletriptan demonstrated efficacy superior to that of placebo and similar or superior efficacy to that of other serotonin agonists, with limited adverse effects. With clinical use, headache and pain-free responses and headache recurrence rates were similar to those of other serotonin agonists, but the agent is superior to ergotamine tartrate-caffeine. Based on pharmaco-economic data, eletriptan is more cost-effective than other agents in its class. Eletriptan is a safe and cost-effective option for the treatment of migraine headaches.

Eletriptan

Eletriptan (Relpax) is an orally administered, lipophilic, highly selective serotonin 5-HT(1B/1D) receptor agonist ('triptan') that is effective in the acute treatment of moderate to severe migraine attacks in adults. It has a rapid onset of action and demonstrates superiority over placebo as early as 30 minutes after the administration of a single 40 or 80 mg oral dose. The efficacy of eletriptan 20 mg was similar to that of sumatriptan 100 mg, while eletriptan 40 and 80 mg displayed greater efficacy than sumatriptan 50 or 100 mg for most endpoints. Eletriptan 40 mg was generally superior to naratriptan 2.5 mg and equivalent to almotriptan 12.5 mg, rizatriptan 10 mg and zolmitriptan 2.5 mg, while eletriptan 80 mg was superior to zolmitriptan 2.5 mg for most efficacy parameters. Eletriptan 40 and 80 mg were consistently superior to ergotamine/caffeine. Eletriptan is generally well tolerated, reduces time lost from normal activities, improves patients' health-related quality of life and appears to be at least as, if not more, cost effective than sumatriptan. Eletriptan is therefore a useful addition to the triptan family and a first-line treatment option in the acute management of migraine attacks.

Eletriptan review

Eletriptan is a selective, high affinity serotonin 5-HT(1B/1D)-receptor agonist which is rapidly absorbed and has a long half-life in plasma. Eletriptan has been shown to be effective and well tolerated in randomised, double-blind, placebo-controlled acute migraine trials and long-term open-label trials. Eletriptan maintains a consistency of response across three attacks and patients continue to respond to eletriptan for at least up to 1 year. Eletriptan has been compared with sumatriptan, zolmitriptan, naratriptan and ergotamine/caffeine in placebo-controlled, randomised, head-to-head trials, and has shown better efficacy with similar adverse events. In a large triptan meta-analysis, including 53 trials and > 24,000 patients, eletriptan 80 mg showed better efficacy, similar consistency but lower tolerability compared with sumatriptan 100 mg. Eletriptan has also shown efficacy in difficult-to-treat patients who were dissatisfied with their previous treatment with sumatriptan, rizatriptan, nonsteroidal anti-inflammatory drugs or Excedrin.

Evaluating the safety and tolerability profile of acute treatments for migraine

Among the medications that have been used as acute treatments for migraine are nonspecific agents, including nonsteroidal anti-inflammatory drugs (NSAIDs), analgesics (either single or combination), and narcotics, as well as migraine-specific medications, including ergot alkaloids and triptans (5-hydroxytryptamine 1B/1D agonists). All of these drugs have side effects that vary in type and severity. Side effects of nonspecific medications, including gastrointestinal (GI) and renal effects with NSAIDs and cognitive effects and the potential for abuse with narcotics and butalbital-containing medications, have been documented over time, as these medications have been used for various indications. Side effects of the migraine-specific medications include GI and vascular symptoms with the ergots; for the triptans, they include chest and neurologic symptoms. Although adverse events are reported fairly frequently in patients receiving triptans, they are usually mild, and few patients discontinue therapy because of them. The most serious adverse events are cardiovascular. Because of potential vasoconstrictor effects--mild and transient increases in blood pressure and mild and transient effects on coronary artery tone--triptans as a class are contraindicated in patients with established or clinically suspected cardiovascular disease, specifically ischemic heart disease and uncontrolled hypertension. Other adverse events, including the potential for drug-drug interactions, are less common. Therefore, consideration should be given to the tolerability and safety of medications before their use as abortive medications for the treatment of migraine headache.

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.

The 40-mg dose of eletriptan: comparative efficacy and tolerability versus sumatriptan 100 mg

Meta-analysis provides valuable information regarding relative efficacies of triptans, but head-to-head comparator studies remain the gold standard. Three similar head-to-head trials comparing eletriptan 40 mg (E40) with sumatriptan 100 mg (S100) provide a rare opportunity and sufficient power, for robust comparisons of efficacy. Data were combined from three double-blind, placebo-controlled, first-dose, first-attack acute migraine treatment studies comparing E40 (n=1132), S100 (n=1129), and placebo (n=645). The primary outcome was headache response at 2 h. Secondary outcomes included headache response at 1 h, pain-free and functional responses, and sustained headache and pain-free responses. Odds ratios were calculated for summary estimates of probability of response. There were higher headache response rates with eletriptan versus sumatriptan at 2 h (67% vs. 57%; P<0.0001) and 1 h (34% vs. 26%; P<0.0001). Eletriptan also had higher 2 h pain-free (35% vs. 25%; P<0.0001) and functional responses (67% vs. 58%; P<0.0001). Sustained headache (42%) and pain-free (22%) response rates were higher for eletriptan versus sumatriptan (34%, P<0.0001; 15%, P<0.0001). The probability of response for eletriptan versus sumatriptan ranged from 36% higher (relief of nausea) to 64% higher (sustained pain-free rate). Combined analysis demonstrates that E40 has superior efficacy versus S100 across all clinically relevant outcomes.

Comparative efficacy of eletriptan and zolmitriptan in the acute treatment of migraine

Eletriptan 40 mg and 80 mg have shown greater efficacy in acute migraine than oral sumatriptan 100 mg and naratriptan 2.5 mg. This study continues the systematic series of active comparator trials in the eletriptan clinical development programme. In a multicentre double-blind, double-dummy, parallel-groups trial, 1587 outpatients with migraine by IHS criteria were randomised in a 3: 3 : 3: 1 ratio to eletriptan 80 mg, eletriptan 40 mg, zolmitriptan 2.5 mg or placebo. Of these, 1312 treated a single migraine attack and recorded baseline and outcome data to be included in the intention-to-treat population. The primary analysis was between eletriptan 80 mg and zolmitriptan. For the primary efficacy end-point of 2-h headache response, rates were 74% on eletriptan 80 mg, 64% on eletriptan 40 mg, 60% on zolmitriptan (P < 0.0001 vs. eletriptan 80 mg) and 22% on placebo (P < 0.0001 vs. all active treatments). Eletriptan 80 mg was superior to zolmitriptan on all secondary end-points at 1, 2 and 24 h, in most cases with statistical significance. Eletriptan 40 mg had similar efficacy to zolmitriptan 2.5 mg in earlier end-points, and significantly (P < 0.05) lower recurrence rate and need for rescue medication over 24 h. All treatments were well tolerated; 30-42% of patients on active treatments and 40% on placebo reported all-causality adverse events that were mostly mild and transient. On patients' global ratings of treatment, both eletriptan doses scored significantly better than zolmitriptan.

Effectiveness of Eletriptan in Acute Migraine: Primary Care for Excedrin Nonresponders

OBJECTIVE

To evaluate the effectiveness of eletriptan as a treatment for acute migraine in patients who were poor responders to Excedrin and had not yet been exposed to a triptan.

BACKGROUND

Self-medication with over-the-counter drugs, such as Excedrin, is the most common treatment for migraine. Guidelines, however, recommend that triptans be used as first-line treatment of moderate to severe migraine--the severity affecting approximately 80% of migraineurs. Since over-the-counter medications, such as Excedrin, continue to be used in many patients, it is important that clinicians have information on the efficacy of triptans as first-line treatment and on treatment of migraineurs who have shown poor response to over-the-counter medications.

METHODS

One hundred ten patients meeting criteria for migraine who were poor responders to Excedrin received open-label treatment with a 40-mg dose of eletriptan for one migraine attack. Efficacy assessments were made at 1, 2, 4, and 24 hours postdose and consisted of headache and pain-free response rates, absence of associated symptoms, and functional response.

RESULTS

At 1 hour, the headache response rate was 44%; at 2 hours, 81%. The pain-free response rate at 1 hour was 14% and at 2 hours, 48%. At 2 hours, relief of baseline-associated symptoms ranged from 74% to 80%. Functional response was achieved by 82% of patients by 2 hours, and 68% of patients achieved relief of migraine that was sustained across 24 hours with no need for a second dose of eletriptan or for rescue medication. Eletriptan was well tolerated with adverse events being transient and mild to moderate in intensity.

CONCLUSION

Previous studies have established the efficacy of eletriptan as a first-line treatment for migraine. The results of this open-label trial demonstrate that the 40-mg dose of eletriptan had a high degree of efficacy and tolerability among patients who were poor responders to Excedrin.

The 5-hydroxytryptamine1B/1D/1F receptor agonists eletriptan and naratriptan inhibit trigeminovascular input to the nucleus tractus solitarius in the cat

Migraine pain arises in the trigeminovascular system and is often associated with nausea and sometimes with vomiting. In this study, an in vivo cat model of trigeminovascular stimulation was used to determine first whether there is a functional connection between the trigeminovascular system and the nucleus tractus solitarius (NTS), which is involved in regulating vomiting, and second whether anti-migraine drugs have any effect on such a connection. Chloralose-anaesthetised cats (n=16) were prepared for single neuron recording. The superior sagittal sinus (SSS) was isolated and stimulated electrically. The brainstem near the obex was exposed and a metal microelectrode equipped with six glass barrels for microiontophoresis was placed in the NTS. Recordings were made from 44 NTS neurons which responded to SSS stimulation with A-delta latencies. Iontophoretic ejection (50 nA) of eletriptan or naratriptan suppressed the response in 75% (15/20) and 78% (11/14) of cells and caused an average suppression of cell firing of 42+/-5% (n=20) and 54+/-8% (n=14), respectively. This suppression could be antagonized by the concurrent ejection (20-50 nA) of the 5-HT(1B/1D) receptor antagonist GR127935. We conclude that activation of the trigeminovascular system excites cells in the NTS that can be inhibited by eletriptan and naratriptan through activation of 5-HT(1B/1D) receptors. It is possible that in patients having a migraine attack trigeminovascular activation triggers nausea and vomiting, and that the alleviation of these symptoms by anti-migraine compounds may be via an action at 5-HT(1B/1D) receptors in the NTS.

Triptans and gastric accommodation: pharmacological and therapeutic aspects

In the past decade, several studies have reported a significant delay of gastric emptying induced by the anti-migraine agent sumatriptan (a 5-hydroxytryptamine (5-HT)1B/D receptor agonist) in healthy human beings. In patients with functional dyspepsia, sumatriptan improves gastric accommodation after food consumption and reduce perception of gastric distension, hence relieving epigastric symptoms. Recent studies have established that impaired accommodation after food consumption is a major patho-physiological mechanism in functional dyspepsia and restoration of accommodation is considered to be a potential therapeutic target. The precise site of action of sumatriptan in humans is at present unknown, although recent studies carried out using a canine model indicate that sumatriptan exerts its action on gastric accommodation through 5-HT1B receptors, since both GR127935 and SB216641 (respectively, non selective 5-HT1B/D and selective 5-HT1B receptor antagonists) fully antagonised the effects of sumatriptan. Gastric relaxation and enhanced accommodation to a distending stimulus seem to be a class effect of triptans, since it occurs not only with sumatriptan, but also with second-generation triptans (rizatriptan and naratriptan), at least in a canine model. In dyspeptic patients, administration of triptans would be able to restore gastric accommodation after a meal and to improve symptoms of early satiety, confirming the therapeutic potential of 5-HT1B/D receptor agonists in functional dyspepsia.

Efficacy of Eletriptan in Migraineurs With Persistent Poor Response to Nonsteroidal Anti‐inflammatory Drugs

BACKGROUND/OBJECTIVE

Nonsteroidal anti-inflammatory drugs continue to be one of the most widely used therapies for migraine, but their efficacy in treating moderate to severe migraine headache has not been well documented. In contrast, the efficacy of triptans in this group of patients is well documented, although no systematic research is available that evaluates the effectiveness of switching to a triptan in patients who respond poorly to nonsteroidal anti-inflammatory drugs.

METHODS

One hundred thirteen patients who met International Headache Society criteria for migraine and who did not experience satisfactory response to nonsteroidal anti-inflammatory drugs, received open-label treatment with a 40-mg dose of eletriptan for one migraine attack. Efficacy assessments were made at 1, 2, 4, and 24 hours postdose and consisted of headache and pain-free response rates, absence of associated symptoms, and functional response. Global ratings of treatment effectiveness and preference were obtained at 24 hours.

RESULTS

The pain-free response rate at 2 hours postdose was 25% and at 4 hours postdose, 55%; the headache response rate at 2 hours was 66% and at 4 hours, 87%. At 2 hours postdose, relief of baseline associated symptoms was achieved by 41% of patients with nausea compared to 82% of patients at 4 hours; for patients with phonophobia, 67% were relieved at 2 hours and 93% at 4 hours, and for patients with photophobia, 70% were relieved at 2 hours and 91% at 4 hours. Functional response was achieved by 70% of patients by 2 hours postdose. The high level of acute response was maintained over 24 hours, with only 24% of patients experiencing a headache recurrence and only 10% using rescue medication. At 24 hours postdose, 74% of patients rated eletriptan as preferable to any previous treatment for migraine. The most frequent reasons cited for this treatment preference were faster headache improvement (83%) and functional response (78%). Overall, eletriptan was well tolerated; most adverse events were transient and mild to moderate in severity. No serious adverse events were reported.

CONCLUSION

Results of this open-label trial found the 40-mg dose of eletriptan to have a high degree of efficacy and tolerability among patients who responded poorly to nonsteroidal anti-inflammatory drugs.

Tolerability and Safety of Eletriptan in the Treatment of Migraine: A Comprehensive Review

OBJECTIVE

To provide a comprehensive review of the tolerability and safety of eletriptan. Background.-Eletriptan is a potent and selective 5-HT1B/1D agonist that has demonstrated significant efficacy in the acute treatment of migraine in doses of 20 mg, 40 mg, and 80 mg.

DESIGN

This review reports the tolerability and safety of eletriptan across a broad spectrum of preclinical studies and clinical trials that collectively included treatment of more than 11 000 subjects and more than 74 000 migraine attacks.

RESULTS

In clinical trials, eletriptan was well tolerated and safe across its dosing range of 20 mg to 80 mg. The adverse event profile of eletriptan 20 mg was similar to placebo, while the most commonly used dose, eletriptan 40 mg, has an adverse event profile that is only marginally higher than placebo. Eletriptan was safe and well tolerated regardless of age or gender, and for both short- and long-term treatment. Eletriptan is metabolized primarily by the CYP3A4 enzyme. Coadministration of potent CYP3A4 inhibitors was not associated with clinically meaningful change in eletriptan tolerability or safety in the population included in these clinical trials. The margin of cardiovascular safety for eletriptan was also confirmed by a well-controlled clinical study in which intravenous eletriptan in excess of an 80-mg dose was rapidly infused in patients undergoing coronary angiography; nonetheless, it is recommended that eletriptan not be coadministered with a limited list of 7 potent CYP3A4 inhibitors; in addition, the triptan class in general (including eletriptan) is contraindicated in patients with symptoms or findings consistent with ischemic heart disease or other significant underlying cardiovascular disease.

CONCLUSIONS

This comprehensive review found that eletriptan is safe and well tolerated, and that relatively large changes in dose and plasma concentration result in minimal changes in tolerability.

[Pharmacological, pharmacokinetic and clinical profile of eletriptan (Relpax), a new triptan for migraine]

Eletriptan (Relpax) is a new anti-migraine medication commonly referred to as triptans. Eletriptan is considered to reduce neuronal transmission of pain by causing vasoconstriction of dilated cranial vessels and inhibiting the release of neuropeptides from trigeminal nerves via activation of the 5-HT(1B/1D) receptors. Eletriptan showed selectivity, high affinities, and potent agonistic activity to human 5-HT(1B/1D) receptors. It selectively constricted the cranial artery relative to the coronary artery of the anesthetized dog and the isolated human specimen. The affinity to the 5-HT(1B/1D) receptors and the selectivity for the cranial artery over the coronary artery of eletriptan are higher than those of sumatriptan. Eletriptan inhibited the trigeminal nerve mediated inflammation in the rat dura mater with equal potency and efficacy to sumatriptan. Orally taken eletriptan was rapidly absorbed with good bioavailability. In clinical trials, eletriptan improved the headache response rate with rapid onset, and reduced headache recurrence. The functional impairments as well as associated symptoms such as nausea, vomiting, and photophobia were also improved by eletriptan. Eletriptan showed stable efficacy in chronic use against multiple attacks with no increase in adverse events. Eletriptan was well tolerated in patients and most adverse events were mild-to-moderate in nature.

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.

Migraine headache recurrence: relationship to clinical, pharmacological, and pharmacokinetic properties of triptans

BACKGROUND AND OBJECTIVES

Triptan use is associated with headache recurrence, and this has been cited as an important reason for patient dissatisfaction with the treatment. The mechanism by which recurrence occurs is not clear, and the incidence of recurrence varies with the triptan used. In order to explore the pharmacological and physiological interaction of triptans and migraine headache recurrence further, some specific clinical, pharmacological, and pharmacokinetic factors that might influence migraine recurrence were evaluated in a review of the major efficacy data for the drugs in the triptan class. These factors were 5-HT1B and 5-HT1D receptor activities, the pharmacokinetic elimination half-life of each triptan, and the clinical efficacy of each compound, determined by the proportion of patients with headache relief and the therapeutic gain over placebo.

METHODS

Clinical data were derived from 31 triptan, placebo-controlled, major efficacy studies used in a previous meta-analysis. The mean recurrence rate, mean headache response, and therapeutic gain were calculated using the results from the individual clinical studies. Mean headache response and therapeutic gain were calculated at the time point used to define recurrence in each study. Data for binding affinity and potency were taken from a direct-comparison in vitro pharmacology study, and the elimination half-life quoted in the data sheet for each triptan was used. Rank correlation with recurrence rate was performed for each of the test parameters.

RESULTS

Mean headache recurrence rates ranged from 17% for frovatriptan 2.5 mg to 40% for rizatriptan. Elimination half-life and recurrence were inversely correlated (r = -1.0, P =.0016). There was also a significant inverse correlation between 5-HT1B receptor potency and recurrence (r = -0.68, P =.034), but 5-HT1D receptor potency was not correlated with recurrence (r = -0.20, P =.54). In addition, the binding affinities for the 5-HT1B and 5-HT1D receptors were not correlated to headache recurrence. Importantly, it also was demonstrated that initial clinical efficacy was not correlated to headache recurrence. The correlation coefficient for headache response was 0.18 (P =.53) and for therapeutic gain, -0.11 (P =.71).

CONCLUSION

The incidence of migraine headache recurrence varies between drugs in the triptan class. Migraine recurrence does not appear to be related to initial clinical efficacy, but is influenced by the pharmacological and pharmacokinetic properties of the individual triptans. The triptans with longer half-lives and greater 5-HT1B receptor potency had the lowest rates of headache recurrence.

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.

Efficacy, safety, and tolerability of oral eletriptan for treatment of acute migraine: a multicenter, double-blind, placebo-controlled study conducted in the United States

OBJECTIVE

To investigate the efficacy, consistency, safety, and tolerability of oral eletriptan in the acute treatment of three migraine attacks.

BACKGROUND

Eletriptan is a selective 5-HT1B/1D agonist member of a class of agents known to be effective in the acute treatment of migraine.

METHODS

Thirteen hundred thirty-four patients were randomized to 20 mg, 40 mg, or 80 mg of eletriptan, or placebo and could treat up to three attacks. The primary efficacy endpoint was 2-hour headache response for the first attack. Secondary endpoints included associated symptom relief, and pain-free, sustained pain-free, and consistency of response.

RESULTS

Eletriptan 20 mg, 40 mg, and 80 mg achieved significantly (P <.0001) better headache response rates than placebo at 2 hours (47%, 62%, and 59%, respectively, versus 22%) and 4 hours (64%, 76%, and 79%, respectively, versus 25%). Headache response was observed to be rapid, showing improvement at 0.5 hour and 1 hour. Two-hour pain-free response rates for eletriptan 20 mg, 40 mg, and 80 mg were 14%, 27%, and 27%, respectively, compared with 4% for placebo. Sustained pain-free response rates were significantly (P <.001) better for eletriptan 20 mg (10%), 40 mg (20%), and 80 mg (18%) compared with placebo (3%). Eletriptan had a higher consistency of intrapatient response than placebo in two of three (68% to 82%) and three of three attacks (32% to 60%) versus 16% and 8%, respectively. All eletriptan doses yielded significant functional improvement at 2 hours. Adverse events were generally mild or moderate and transient, with eletriptan 20 mg having an adverse event profile comparable to placebo.

CONCLUSIONS

Eletriptan is efficacious, displaying high consistency of response over multiple attacks, and is well tolerated for the acute treatment of migraine.

Pharmacokinetics, pharmacodynamics, and safety of the 5-HT(1B/1D) agonist eletriptan following intravenous and oral administration

Four separate studies were conducted to examine the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of eletriptan, a 5-HT(1B/1D) receptor agonist being developed for the treatment of migraines, after oral and intravenous administration. Fifty-five males received oral (1.5-30 mg or 30-120 mg) or intravenous (1.67-50 microg/kg or 50-102 microg/kg) eletriptan in four double- and single-blind, placebo-controlled, ascending-dose crossover studies. The maximum plasma concentration (Cmax) and area under the concentration curve (AUC) appeared linear over all dose ranges, with an apparent terminal half-life of 4 to 5 hours. Clearance and volume of distribution remained constant with dose. The time to first occurrence of Cmax (tmax) for oral eletriptan was approximately 1 hour and was unaffected by dose. Comparison of AUC values suggested an absolute bioavailability of approximately 50%. A linear PK/PD model, fitted to the data, predicted small, transient elevations in diastolic blood pressure following eletriptan doses > or = 60 mg. These effects were considered unlikely to be clinically significant. Eletriptan was well tolerated, and treatment-related adverse events were mild to moderate and transient. These PK properties should result in eletriptan having a rapid onset and sustained duration of action in terms of migraine efficacy.

Efficacy, safety and tolerability of oral eletriptan in the acute treatment of migraine: results of a phase III, multicentre, placebo-controlled study across three attacks

The efficacy, safety and tolerability of the 5-HT1B/D receptor agonist eletriptan (40 mg and 80 mg) in acute treatment of migraine was evaluated in a multinational, randomized, double-blind, parallel-group, placebo-controlled, three-attack study treating 1153 patients. In the initial attack, significantly more eletriptan patients reported headache relief and complete pain relief at 2 h vs. placebo (40 mg 62% and 32%, 80 mg 65% and 34%, placebo 19% and 3%; P < 0.0001). Headache relief occurred faster after eletriptan, with more patients at both doses reporting relief 30 min (P < 0.01) and 1 h (P < 0.0001) after treatment than after placebo. There was a significantly lower recurrence rate with eletriptan 80 mg compared with placebo (P < 0.01). Adverse events for all treatments were generally mild or moderate and self-limiting. Eletriptan 40 mg and eletriptan 80 mg both appear to be effective and well-tolerated acute migraine treatments.

Eletriptan

Eletriptan (Relpax, Pfizer) is one of a group of anti-migraine medications commonly referred to as 'triptans'. It is a potent serotonin agonist at the 5-HT(1B/1D) receptor and is indicated for the acute treatment of migraine headaches. Eletriptan is administered orally. It is rapidly absorbed and has a bioavailability of 50% compared to 14% for sumatriptan. The relatively high lipophilicity of eletriptan compared to sumatriptan may explain its faster oral absorption and shorter time to onset of action. Results from comparative studies between oral eletriptan and sumatriptan indicate that eletriptan 80 mg was superior to sumatriptan 100 mg in onset of action, headache response rate, pain free response rate and relief of associated migraine symptoms at the 1 or 2 h time intervals. Although there was a modest increase in adverse events with eletriptan 80 mg than with sumatriptan 100 mg, eletriptan received a high patient acceptability rating (84%).

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

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

Serotonergic effects and extracellular brain levels of eletriptan, zolmitriptan and sumatriptan in rat brain

In vivo microdialysis was used to assess the central serotonergic effects and extracellular brain levels of the 5-HT(1B/1D) receptor agonists eletriptan, zolmitriptan and sumatriptan in rats after intravenous and intracerebral administration, while their binding affinities and functional potencies were determined at 5-HT(1B), 5-HT(1D) and 5-HT(1A) receptors. In vitro studies showed that all three triptans are high affinity, full agonists at 5-HT(1B/1D) receptors, but that sumatriptan is functionally less potent as a 5-HT(1B/1D) agonist than zolmitriptan and eletriptan. Local intracortical perfusion with the compounds via the dialysis probe decreased cortical 5-HT (5-hydroxytryptamine, serotonin) release with ED(50) values of approximately 0.1 microM for eletriptan and zolmitriptan and 0.5 microM for sumatriptan. At 3.2 mg/kg i.v., both eletriptan and zolmitriptan decreased 5-HT levels by about 35%, while sumatriptan had no effect, despite the fact that maximal sumatriptan concentrations in cortical dialysates were higher (8.8 nM at 20 min) than those of zolmitriptan (5.9 nM at 20 min) and eletriptan (2.6 nM at 40 min). The observation that eletriptan and zolmitriptan produce almost identical central serotonergic effects, after intracerebral as well as after systemic administration, is in agreement with their comparable functional 5-HT(1B/1D) receptor agonist potencies and their free levels in cortical dialysates after 3.2 mg/kg i.v. On the other hand, the lack of central serotonergic effects of 3.2 mg/kg i.v. sumatriptan is likely due to its weaker functional 5-HT(1B/1D) receptor agonist potency than eletriptan and zolmitriptan, rather than lower brain levels, consistent with sumatriptan's fivefold lower potency after intracerebral administration.

The GR127935-sensitive 5-HT(1) receptors mediating canine internal carotid vasoconstriction: resemblance to the 5-HT(1B), but not to the 5-HT(1D) or 5-ht(1F), receptor subtype

This study has further investigated the pharmacological profile of the GR127935-sensitive 5-HT(1) receptors mediating vasoconstriction in the internal carotid bed of anaesthetized vagosympathectomized dogs. One-minute intracarotid infusions of the agonists 5-hydroxytryptamine (5-HT; 0.1 - 10 microg min(-1); endogenous ligand) and sumatriptan (0.3 - 10 microg min(-1); 5-HT(1B/1D)), but not PNU-142633 (1 - 1000 microg min(-1); 5-HT(1D)) or LY344864 (1 - 1000 microg min(-1); 5-ht(1F)), produced dose-dependent decreases in internal carotid blood flow without changing blood pressure or heart rate. The responses to 5-HT were apparently resistant to blockade by i.v. administration of the antagonists SB224289 (300 microg kg(-1); 5-HT(1B)), BRL15572 (300 microg kg(-1); 5-HT(1D)) or ritanserin (100 microg kg(-1); 5-HT(2)). In contrast, the responses to sumatriptan were antagonized by SB224289, but not by BRL15572. In the animals receiving SB224289, but not those receiving BRL15572, the subsequent administration of ritanserin abolished the 5-HT-induced vasoconstriction and unmasked a vasodilator component. Similarly, in ritanserin-treated animals, the subsequent administration of SB224289, but not BRL15572, completely blocked the 5-HT-induced vasoconstriction, revealing vasodilatation. In animals receiving initially BRL15572, the subsequent administration of SB224289 did not affect (except at 10 microg min(-1)) the vasoconstrictor responses to 5-HT. Notably, in animals pretreated with 1000 microg kg(-1) of mesulergine, a 5-HT(2/7) receptor antagonist, 5-HT produced a dose-dependent vasoconstriction, which was practically abolished by SB224289. After BRL15572, no further blockade was produced and the subsequent administration of ritanserin was similarly inactive. These results suggest that the GR127935-sensitive 5-HT(1) receptors mediating canine internal carotid vasoconstriction resemble the 5-HT(1B) but not the 5-HT(1D) or 5-ht(1F), receptor subtype.