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

Statistically Optimized Polymeric Buccal Films of Eletriptan Hydrobromide and Itopride Hydrochloride: An In Vivo Pharmacokinetic Study

A migraine is a condition of severe headaches, causing a disturbance in the daily life of the patient. The current studies were designed to develop immediate-release polymeric buccal films of Eletriptan Hydrobromide (EHBR) and Itopride Hydrochloride (ITHC) to improve their bioavailability and, hence, improve compliance with the patients of migraines and its associated symptoms. The prepared films were evaluated for various in vitro parameters, including surface morphology, mechanical strength, disintegration test (DT), total dissolving time (TDT), drug release and drug permeation, etc., and in vivo pharmacokinetic parameters, such as area under curve (AUC), mean residence time (MRT), half-life (t1/2), time to reach maximum concentration (Tmax), and time to reach maximum concentration (Cmax). The outcomes have indicated the successful preparation of the films, as SEM has confirmed the smooth surface and uniform distribution of drugs throughout the polymer matrix. The films were found to be mechanically stable as indicated by folding endurance studies. Furthermore, the optimized formulations showed a DT of 13 ± 1 s and TDT of 42.6 ± 0.75 s, indicating prompt disintegration as well as the dissolution of the films. Albino rabbits were used for in vivo pharmacokinetics, and the outcomes were evident of improved pharmacokinetics. The drug was found to rapidly permeate across the buccal mucosa, leading to increased bioavailability of the drug: Cmax of 130 and 119 ng/mL of ITHC and EHBR, respectively, as compared to 96 (ITHC) and 90 ng/mL (EHBR) of oral solution. The conclusion can be drawn that possible reasons for the enhanced bioavailability could be the increased surface area in the form of buccal films, its rapid disintegration, and faster dissolution, which led toward the rapid absorption of the drug into the blood stream.

Method development and validation for simultaneous determination of Eletriptan hydrobromide and Itopride hydrochloride from fast dissolving buccal films by using RP-HPLC

One of the most effective, rapid, and simple methods reversed-phase high-performance liquid chromatography (RP-HPLC) was used for simultaneous development and validation of Eletriptan hydrobromide (ELE HBR) and Itopride hydrochloride (ITP HCL) in combination. The method was validated based on the regulations of United States Pharmacopeia (USP) and International Conference on Harmonization (ICH) guidelines. Separation of both drugs was achieved within approximately 5 min by using a mobile phase made up of a 70:30 ratio of phosphate buffer and acetonitrile having a flow rate of 1 mL min−1. Furthermore, a comprehensive study was conducted on precision, accuracy, linearity, inter-day, intra-day studies, an assay of formulated films, and stability studies of combined prepared film. Co-efficient of correlation ranged between 0.9993, and 0.9965 for ELE HBR and ITP HCL respectively. The accuracy of the developed method was accurate as drug recoveries in both cases of ITP HCL, and ELE HBR falls between (99.87, 99.96, and 99.84%) to (99.81, 99.12, and 98.44%) respectively having a concentration range of solutions between 10, 30 and 50 μg mL−1 dilution. Films developed by using both drugs in combination were then validated for assay studies, and it was found that substantial results of 99.05%, and 99.87% were found in the case of ITP HCL and ELE HBR respectively. The stability of the solution and mobile phase showed the method's accuracy as the results were 97% for ITP HCL and 99% for ELE HBR. The proposed method developed for simultaneous determination of ITP HCL and ELE HBR was developed and validation and no interaction of any excipient were found.

Differential pharmacokinetic drug-drug interaction potential of eletriptan between oral and subcutaneous routes

1. Pharmacokinetic drug-drug interaction (DDI) data is important from a label claim either in combination drug usage or in polypharmacy situation. 2. Eletriptan undergoes first pass related metabolism through CYP3A4 enzyme to form pharmacologically active N-desmethyl metabolite. 3. Differential DDI interaction of the concomitant oral dosing of ketoconazole (20.1 mg/kg), a CYP3A4 inhibitor, with oral (4.2 mg/kg) or subcutaneous dose (2.1 mg/kg) of eletriptan was evaluated in male Sprague Dawley rats. Serial pharmacokinetic samples were collected and simultaneously analysed for eletriptan/N-desmethyl eletriptan using validated assay. Non-compartmentally derived pharmacokinetic parameters for various treatments were analysed statistically. 4. After oral eletriptan in presence of ketoconazole, C_max (40 vs. 32 ng/mL alone) and AUC_inf (81 vs. 24 ng.h/mL alone) of eletriptan increased; the formation of N-desmethyl eletriptan decreased (C_max=1.1 ng/mL, 3.9%) with ketoconazole as compared to without treatment (C_max=3.7 ng/mL, 11.2%). After subcutaneous eletriptan in presence of ketoconazole, there was no change in C_max (153 vs.152 ng/mL) or AUC_inf (267 vs. 266 ng.h/mL) of eletriptan. Formation of N-desmethyl eletriptan after the subcutaneous dose was determined at few intermittent time points with/without ketoconazole. 5. Preclinical data support differential DDI of eletriptan when dosed oral vs. subcutaneous, which need to be evaluated in a clinical setting.

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.

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.

Eletriptan in the management of acute migraine: an update on the evidence for efficacy, safety, and consistent response

Migraine is a multifactorial, neurological and disabling disorder, also characterized by several autonomic symptoms. Triptans, selective serotonin 5-HT1B/1D agonists, are the first-line treatment option for moderate-to-severe headache attacks. In this paper, we review the recent data on eletriptan clinical efficacy, safety, and tolerability, and potential clinically relevant interactions with other drugs. Among triptans, eletriptan shows a consistent and significant clinical efficacy and a good tolerability profile in the treatment of migraine, especially for patients with cardiovascular risk factors without coronary artery disease. It shows the most favorable clinical response, together with sumatriptan injections, zolmitriptan and rizatriptan. Additionally, eletriptan shows the most complex pharmacokinetic/dynamic profile compared with the other triptans. It is metabolized primarily by the CYP3A4 hepatic enzyme and therefore the concomitant administration of CYP3A4-potent inhibitors should be carefully evaluated. A relatively low risk of serotonin syndrome is given by the co-administration with serotoninergic drugs. No clinically relevant interaction has been found with drugs used for migraine prophylactic treatment or other acute drugs, with the exception of ergot derivatives that should not be co-administered with eletriptan.

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.

How First-Time-in-Human Studies Are Being Performed: A Survey of Phase I Dose-Escalation Trials in Healthy Volunteers Published Between 1995 and 2004

First-time-in-human studies are small, time-lagged dose-escalation studies including volunteer subjects evaluating safety and tolerability. There is little consensus in the design of a first-time-in-human study, and it is difficult to get an overview of studies performed. One hundred five studies comprising 3323 healthy volunteers published in the 5 major clinical pharmacology journals since 1995 were analyzed. The average trial was placebo controlled, double blind including 32 subjects at 5 dose levels but with great variation in cohort size and dose-escalation method. The parallel single-dose design was the most common design, with the crossover designs being more frequent in the early publications. Despite discussions on the optimization of phase I trials, little seems to be happening. The development of study designs and evaluation methods for cancer trials is extensive, but formal statistically based methods and more scientific study designs are unusual in phase I dose-escalation trials in healthy volunteers.

Formulation and evaluation of sublingual tablets containing Sumatriptan succinate

Objective:

Sumatriptan succinate is a selective 5-hydroxytryptamine-1 receptor agonist effective in the acute treatment of migraine headaches, having low bioavailability of about 15% orally due to first-pass metabolism. The purpose of this research was to mask the intensely bitter taste of Sumatriptan succinate and to formulate fast-acting, taste-masked sublingual tablet formulation.

Materials and Methods:

Taste masking was performed by solid dispersion method with mannitol and ion exchange with Kyron T 114 because it releases the drug in salivary pH. The resultant batches were evaluated for in-vivo taste masking as well compatability study (Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC)). For a better feel in the mouth, menthol and sweetener Na saccharine were added to the tablet formulation. The tablets were prepared by direct compression and evaluated for weight variation, thickness, friability, drug content, hardness, disintegration time, wetting time, in vitro drug release, and in vitro permeation study.

Results and Discussion:

Optimized batches disintegrated in vitro within 28-34 s. Maximum drug release could be achieved with in 10 min for the solid dispersion batches and 14-15 min for the ion-exchange batches with Kyron T 114. The optimized tablet formulation showed better taste and the formulated sublingual tablets may act as a potential alternate for the Sumatriptan succinate oral tablet.

Conclusion:

Sumatriptan succinate can be successfully taste-masked by both the solid dispersion method using mannitol by the melting method and Ion exchange resin with Kyron T114. It was also concluded that prepared formulation improve bioavailability by prevention of first pass metabolism.

Quantitative analysis of eletriptan in human plasma by HPLC-MS/MS and its application to pharmacokinetic study

Authors developed a simple, sensitive, selective, rapid, rugged, and reproducible liquid chromatography-tandem mass spectrometry method for the quantification of eletriptan (EP) in human plasma using naratriptan (NP) as an internal standard (IS). Chromatographic separation was performed on Ascentis Express C18, 50 × 4.6 mm, 2.7 μm column. Mobile phase was composed of 0.1% formic acid: methanol (40:60 v/v), with 0.5 mL/min flow rate. Drug and IS were extracted by liquid-liquid extraction. EP and NP were detected with proton adducts at m/z 383.2→84.3 and 336.2→97.8 in multiple reaction monitoring (MRM) positive mode, respectively. The method was validated with the correlation coefficients of (r(2)) ≥ 0.9963 over a linear concentration range of 0.5-250.0 ng/mL. This method demonstrated intra- and inter-day precision within 1.4-9.2% and 4.4-5.5% and accuracy within 96.8-103% and 98.5-99.8% for EP. This method is successfully applied in the bioequivalence study of 24 human volunteers.

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.

Disposition and metabolism of almotriptan in rats, dogs and monkeys

Almotriptan is a new highly potent selective 5-HT1B/1D receptor agonist developed for the treatment of migraine, and the disposition of almotriptan in different animal species is now addressed in the current study. Almotriptan was well absorbed in rats (69.1%) and dogs (100%) following oral treatment. The absolute bioavailability was variable reflecting different degrees of absorption and first-pass metabolism (18.7-79.6%). The elimination half-life was short and ranged between 0.7 and 3 h. The main route of elimination of almotriptan was urine with 75.6% and 80.4% of the dose recovered over a 168-h period in rats and dogs, respectively. The gamma-aminobutyric acid metabolite formed by oxidation of the pyrrolidine ring was the main metabolite found in urine, faeces, bile, and plasma of rats and in monkey urine. By contrast, the unchanged drug, the indole acetic acid metabolite formed by oxidative deamination of the dimethylaminoethyl group, and the N-oxide metabolite were the main metabolites in dog.

Uptake and biodistribution of rizatriptan to blood and brain following different routes of administration in rats

The objective of the present study was to investigate the biodistribution profiles of rizatriptan in the blood and brain of Wistar rats after peroral, subcutaneous, intranasal and intratracheal administration with a particular view to determining the applicability of inhalation delivery to achieve rapid and high availability of the drug in both blood and the brain. Following the intratracheal administration of the drug (4.0mg/kg) to the rats, the absolute bioavailability was found to be 91.2%, significantly higher than those from intranasal or peroral routes, and T(max) in plasma and brain was attained within 2 min, significantly shorter than the T(max) of intranasal ( approximately 10 min in both plasma and brain), subcutaneous (16.7 min in plasma and 22.5 min in brain) and peroral (30.0 min in plasma and 45.0 min in brain) administration. In addition, other pharmacokinetic parameters associated with rapid onset of action including AUC(plasma/brain) and C(max), of intratracheal instillated rizatriptan appeared also to be comparable or superior to those of other delivered routes. Although AUC(brain)/AUC(plasma) ratios after intranasal delivery (43.4%) differed significantly from the ratios shown after intratracheal instillation (23.2%), the AUC(brain 0-120 min) via the latter routes was slightly but not significantly higher than that from the former routes. The results in the present study indicated that pulmonary delivery of rizatriptan may achieve maximum plasma and brain concentrations significantly more rapidly compared with intranasal, subcutaneous and peroral administration and be a promising delivery method with extremely rapid onset of action in the pain relief of migraine.

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.

Evaluating the triptans

The debilitating effect of migraine has fueled the search for more specific agents to treat its characteristic and associated symptoms. Second-generation oral triptans have shown an improved efficacy profile in comparison with the pioneer sumatriptan and with the over-the-counter medications and prescription analgesics that have been staples of migraine treatment. Although all triptans exert effects through the 5-hydroxytryptamine 1B/1D receptors, each triptan has distinctive pharmacokinetic properties that determine its efficacy and tolerability profile. Empirical findings based on clinical trials have led to associations between triptan pharmacology and efficacy. With the expanded treatment choices, the onus is on healthcare providers (especially primary care physicians, who see the majority of patients with migraine) to determine which treatment has an efficacy profile that best suits the individual patient's needs. Patients prefer pharmacotherapy with a rapid onset of action that facilitates complete pain relief and no recurrence. Data from published comparator trials, based on commonly used efficacy end points and pharmacokinetic properties underlying patient-preferred outcomes, are reviewed in this article.

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.

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.

Eletriptan metabolism by human hepatic CYP450 enzymes and transport by human P-glycoprotein

"Reaction phenotyping" studies were performed with eletriptan (ETT) to determine its propensity to interact with coadministered medications. Its ability to serve as a substrate for human P-glycoprotein (P-gp) was also investigated since a central mechanism of action has been proposed for this "triptan" class of drug. In studies with a characterized bank of human liver microsome preparations, a good correlation (r2 = 0.932) was obtained between formation of N-desmethyl eletriptan (DETT) and CYP3A4-catalyzed testosterone 6 beta-hydroxylation. DETT was selected to be monitored in our studies since it represents a significant ETT metabolite in humans, circulating at concentrations 10 to 20% of those observed for parent drug. ETT was metabolized to DETT by recombinant CYP2D6 (rCYP2D6) and rCYP3A4, and to a lesser extent by rCYP2C9 and rCYP2C19. The metabolism of ETT to DETT in human liver microsomes was markedly inhibited by troleandomycin, erythromycin, miconazole, and an inhibitory antibody to CYP3A4, but not by inhibitors of other major P450 enzymes. ETT had little inhibitory effect on any of the P450 enzymes investigated. ETT was determined to be a good substrate for human P-gp in vitro. In bidirectional transport studies across LLC-MDR1 and LLC-Mdr1a cell monolayers, ETT had a BA/AB transport ratio in the range 9 to 11. This finding had significance in vivo since brain exposure to ETT was reduced 40-fold in Mdr1a+/+ relative to Mdr1a-/- mice. ETT metabolism to DETT is therefore catalyzed primarily by CYP3A4, and plasma concentrations are expected to be increased when coadministered with inhibitors of CYP3A4 and P-gp activity.

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.