Influence of beta-adrenoceptor antagonists on the pharmacokinetics of rizatriptan, a 5-HT1B/1D agonist: differential effects of propranolol, nadolol and metoprolol

Rizatriptan as an Over-the-Counter Triptan in the Treatment of Migraine Attacks

Around 91% of migraine patients use over-the-counter medicines to treat attacks, often without further treatment or medical consultation. This therapeutic principle is established in most countries, regardless of how the healthcare system is otherwise structured or financed. Using Germany as an example, the basis for an expansion of attack therapy with rizatriptan as an over-the-counter triptan is described. To achieve the best possible tolerability and safety in the context of self-medication, the lowest possible dose should be selected to provide the most favourable tolerability and safety profile in the context of self-medication through low dosages. The lowest approved dose of rizatriptan is 5 mg. This was investigated in three randomized controlled trials with 752 patients. The results show that rizatriptan at a dose of 5 mg is more effective than the triptans naratriptan 2.5 mg, almotriptan 12.5 mg and sumatriptan 50 mg, which were previously available for self-medication in Germany. There was no significant difference in the frequency of adverse events with rizatriptan 5 mg compared to placebo. Rizatriptan 5 mg does not have a higher side effect potential than sumatriptan 50 mg, which is already exempt from the prescription requirement. The reasons given show that rizatriptan in a dose of 5 mg for the treatment of acute migraine attacks fulfils the requirements for a transfer from prescription to pharmacy-only status at least as well as sumatriptan 50 mg, naratriptan 2.5 mg and almotriptan 12.5 mg. From a clinical care perspective, it is desirable for affected patients to have other options available for self-medication. Non-responders to other substances also have a further treatment option with rizatriptan 5 mg, with the same or even better risk-benefit profile, to treat migraine attacks safely, effectively and in a tolerable manner as part of self-medication.

QuEChERS-assisted ion pair chromatography/fluorescence detection method for determination of antimigraine combination therapy in rabbit plasma samples: Application to a pharmacokinetic study

Antimigraine combination therapy has shown significant effectiveness in relieving pain, as well as reducing the frequency, duration, and severity of migraine attacks if compared to a single migraine medication. This work represents the first analytical investigation for emphasizing the synergistic effect of combining ophthalmic beta blockers with triptans in migraine treatment. The presented study was conducted to investigate the pharmacokinetic profile of almotriptan (ALM), a serotonin (5-HT1B/1D) receptor agonist used to treat migraine, when coadministered with timolol (TIM) or verapamil (VER) which are considered as an adjuvant therapy in migraine prevention. Ion pair chromatography (IPC) with online fluorescence detection was applied to simultaneously detect and quantify the binary mixtures of ALM/TIM and ALM/VER in rabbit plasma samples. The separation was achieved using a Platinum C18 analytical column with a mobile phase composed of methanol: 35 mmol L-1 phosphate buffer solution containing 10 mmol L-1 SDS at pH = 6.8 (60:40 v/v). Several parameters were evaluated during the optimization of separation conditions including mobile phase composition, buffer concentration, buffer pH and concentration of ion pair reagent. A thorough investigation of the retention mechanism was performed, and the results showed that Coulomb forces were the main contributors to the overall retention mechanism, which may be hydrophobically assisted. QuEChERS extraction technique was utilized to extract the investigated drugs from plasma samples and a detailed study was carried out to optimize partition/extraction solvents, pH, extraction salts, sample volume and clean-up step. The method had a limit of detection and quantitation of 5.6 and 16.9 ng mL-1 for ALM in ALM/TIM mixture and 2.5 and 7.6 ng mL-1 for ALM in ALM/VER mixture, with an overall recovery not less than 95.22%. This newly proposed method offers a faster alternative to existing chromatographic methods for extraction and determination of ALM in binary mixtures with TIM or VER in rabbit plasma and provides a platform for studying pharmacokinetic parameters. The coadministration of either TIM or VER with ALM resulted in a notable rise in Cmax (maximum plasma concentration) and AUC (area under the plasma concentration-time curve) of ALM, implying possible alterations in the absorption and overall exposure of ALM.

Emerging drugs for the preventive treatment of migraine: a review of CGRP monoclonal antibodies and gepants trials

INTRODUCTION

Migraine is a leading cause of years lived with disability and preventive strategies represent a mainstay to reduce health-related disability and improve quality of life of migraine patients. Until a few years ago, migraine prevention was based on drugs developed for other clinical indications and relocated in the migraine therapeutic armamentarium, characterized by unfavourable tolerability profiles. The advent of monoclonal antibodies against Calcitonin Gene-Related Peptide (CGRP) and gepants, CGRP receptor antagonists, has been a turning point in migraine prevention owing to advantageous efficacy, safety and tolerability profiles.Nevertheless, while in an ideal scenario a drug characterized by significant greater efficacy and tolerability compared to existing therapeutic strategies should be adopted as a first-line treatment, cost-effectiveness analyses available for monoclonal antibodies against CGRP pathway tend to limit their administration to more severe migraine phenotypes.

AREAS COVERED

The present narrative review aim to provide a critical appraisal of phase II and III CGRP-mAbs and gepants trials to analyse their use in clinical practice.

EXPERT OPINION

Despite monoclonal antibodies against CGRP pathway and gepants can be undoubtedly considered top-of-the-range treatments, there are still issues deserving to be addressed in the coming years as the risk of off-target effects as well as their economic sustainability based on the considerable migraine burden.

Roles of selected non-P450 human oxidoreductase enzymes in protective and toxic effects of chemicals: review and compilation of reactions

This is an overview of the metabolic reactions of drugs, natural products, physiological compounds, and other (general) chemicals catalyzed by flavin monooxygenase (FMO), monoamine oxidase (MAO), NAD(P)H quinone oxidoreductase (NQO), and molybdenum hydroxylase enzymes (aldehyde oxidase (AOX) and xanthine oxidoreductase (XOR)), including roles as substrates, inducers, and inhibitors of the enzymes. The metabolism and bioactivation of selected examples of each group (i.e., drugs, "general chemicals," natural products, and physiological compounds) are discussed. We identified a higher fraction of bioactivation reactions for FMO enzymes compared to other enzymes, predominately involving drugs and general chemicals. With MAO enzymes, physiological compounds predominate as substrates, and some products lead to unwanted side effects or illness. AOX and XOR enzymes are molybdenum hydroxylases that catalyze the oxidation of various heteroaromatic rings and aldehydes and the reduction of a number of different functional groups. While neither of these two enzymes contributes substantially to the metabolism of currently marketed drugs, AOX has become a frequently encountered route of metabolism among drug discovery programs in the past 10-15 years. XOR has even less of a role in the metabolism of clinical drugs and preclinical drug candidates than AOX, likely due to narrower substrate specificity.

A narrative review of the importance of pharmacokinetics and drug-drug interactions of preventive therapies in migraine management

Objective

To review the pharmacokinetics of major classes of migraine preventives and the clinical implications of drug–drug interactions (DDIs) with the use of these therapies in migraine management.

Background

Preventive treatments for migraine are recommended for a large proportion of patients with frequent migraine attacks. These patients often exhibit a number of comorbidities, which may lead to the introduction of multiple concomitant therapies. Potential DDIs must be considered when using polytherapy to avoid increased risk of adverse events (AEs) or inadequate treatment of comorbid conditions.

Methods

A literature search was performed to identify pharmacokinetic properties and potential DDIs of beta‐blockers, antiepileptic drugs, antidepressants, calcium channel blockers, gepants, and monoclonal antibody therapies targeting the calcitonin gene‐related peptide pathway with medications that may be used for comorbid conditions.

Results

Most DDIs occur through alterations in cytochrome P450 isoenzyme activity and may be complicated by genetic polymorphism for metabolic enzymes. Additionally, drug metabolism may be altered by grapefruit juice ingestion and smoking. The use of migraine preventive therapies may exacerbate symptoms of comorbid conditions or increase the risk of AEs associated with comorbid conditions as a result of DDIs.

Conclusions

DDIs are important to consider in patients with migraine who use multiple medications. The development of migraine‐specific evidence‐based preventive treatments allows for tailored clinical management that reduces the risk of DDIs and associated AEs in patients with comorbidities.

Potential Herb-Drug Interactions in the Management of Age-Related Cognitive Dysfunction

Late-life mild cognitive impairment and dementia represent a significant burden on healthcare systems and a unique challenge to medicine due to the currently limited treatment options. Plant phytochemicals have been considered in alternative, or complementary, prevention and treatment strategies. Herbals are consumed as such, or as food supplements, whose consumption has recently increased. However, these products are not exempt from adverse effects and pharmacological interactions, presenting a special risk in aged, polymedicated individuals. Understanding pharmacokinetic and pharmacodynamic interactions is warranted to avoid undesirable adverse drug reactions, which may result in unwanted side-effects or therapeutic failure. The present study reviews the potential interactions between selected bioactive compounds (170) used by seniors for cognitive enhancement and representative drugs of 10 pharmacotherapeutic classes commonly prescribed to the middle-aged adults, often multimorbid and polymedicated, to anticipate and prevent risks arising from their co-administration. A literature review was conducted to identify mutual targets affected (inhibition/induction/substrate), the frequency of which was taken as a measure of potential interaction. Although a limited number of drugs were studied, from this work, interaction with other drugs affecting the same targets may be anticipated and prevented, constituting a valuable tool for healthcare professionals in clinical practice.

Effects of Lasmiditan on Cardiovascular Parameters and Pharmacokinetics in Healthy Subjects Receiving Oral Doses of Propranolol

Lasmiditan (LY573144/COL‐144) is a high‐affinity, centrally penetrant, selective 5‐HT_1F receptor agonist currently under investigation for acute treatment of migraine. Although lasmiditan is not known to induce vasoconstriction, it remains important to understand its effect on cardiovascular parameters because it is likely to be coadministered with β‐adrenergic receptor antagonists used for migraine prophylaxis, such as propranolol. This phase 1, single‐center, open‐label, fixed‐sequence study evaluated the cardiovascular and pharmacokinetic effects of 200 mg lasmiditan in 44 healthy subjects receiving repeated oral doses of twice‐daily 80 mg propranolol under fasting conditions. Coadministration caused statistically significant decreases in mean hourly heart rate relative to propranolol alone, but the maximum magnitude of this effect was –6.5 bpm and recovered to predose levels by 3 to 4 hours before stabilizing. Additionally, short‐lived (≤2.5 hours) statistically significant increases in systolic blood pressure (8.3 mm Hg) and diastolic blood pressure (6.4 mm Hg) were observed following coadministration. Consistent with the largely nonoverlapping metabolic pathways of lasmiditan and propranolol, exposure to either drug was not affected by coadministration. Overall, compared with administration of either drug alone, coadministration was generally well tolerated.

β-blockers: Their new life from hypertension to cancer and migraine

The pharmacological class of β-blockers includes a plea of molecules with largely different pharmacokinetic and pharmacodynamic characteristics with a protective effect that may span far beyond the cardiovascular system. Although all these compounds share the pharmacological blockade of the adrenergic receptors, each of them is characterized by specific pharmacological properties, including selectivity of action depending on the adrenergic receptors subtypes, intrinsic sympathomimetic activity (ISA), lipid solubility, pharmacokinetic profile, and also other ancillary properties that impact their clinical effect. Their use in the treatment of hypertension has been extensively debated and at the moment a class indication is not present. However, in specific niche of patients, such as in those young individuals in which hypertension is mainly driven by a sympathetic hyperactivation, strong evidence pose β-Blockers as a highly reasonable first-line treatment. Lipophilic β-blockers, specifically propranolol and metoprolol, can cross the Blood Brain Barrier and have a Class A indication for the prophylactic treatment of migraine attacks. Moreover, since β-adrenergic receptors affect the proliferative process of both cancer and immune cells, their blockade has been associated with metastasis reduction in several epithelial and solid organ tumors posing β-Blockers as a new attractive, inexpensive and relatively safe therapeutic strategy in patients with several types of cancer. However, further dedicated prospective, randomized, placebo-controlled studies are needed to determine the real efficacy of these compounds.

Efficacy and safety of lasmiditan in patients using concomitant migraine preventive medications: findings from SAMURAI and SPARTAN, two randomized phase 3 trials

OBJECTIVE

To study the efficacy and safety of lasmiditan for acute treatment of migraine in patients using migraine preventive medications.

BACKGROUND

While lasmiditan has been proven to be an effective acute treatment for migraine, its effectiveness has not been examined when used concurrently with migraine preventives.

METHODS

SAMURAI and SPARTAN were similarly designed, double-blind, phase 3, placebo-controlled studies of patients 18 years or older with 3 to 8 migraine attacks per month. Patients were randomized to treat a migraine attack with oral lasmiditan 50 mg (SPARTAN only), 100 mg, 200 mg, or placebo. Migraine preventives were allowed as long as doses were stable for 3 months prior to screening and were unchanged during the study. Preventive medications with established or probable efficacy, as recommended by the American Academy of Neurology, the American Headache Society, and the European Headache Federation, plus botulinum toxin type A and candesartan, were included. Within the subgroups of patients using and not using preventive therapies, lasmiditan and placebo groups were analyzed for the outcome of pain-free at 2 h and other efficacy outcomes. The subgroups of patients using and not using preventive therapies were compared and interaction p-values were calculated for safety and efficacy outcomes.

RESULTS

In these trials, 698 of 3981 patients (17.5%) used migraine preventive treatments. Among patients using preventives, all lasmiditan doses resulted in significantly more patients being pain-free at 2 h, compared to placebo (p < 0.05). Primary efficacy outcome (pain-free at 2 h), key secondary outcome (most bothersome symptom-free at 2 h) and all other efficacy outcomes were not significantly different between patients using or not using migraine preventives (all interaction p-values ≥0.1). Rates of adverse events were similar for patients using and not using preventive medications.

CONCLUSIONS

Lasmiditan was more effective than placebo for the acute treatment of migraine in patients concurrently using migraine preventive medications. Lasmiditan efficacy and safety measures were similar for patients using and not using preventive medications.

TRIAL REGISTRATION

SAMURAI (NCT02439320) and SPARTAN (NCT02605174). Registered 18 March 2015.

Medication overuse and chronic migraine: a critical review according to clinical pharmacology

INTRODUCTION

Chronic migraine is often complicated by medication-overuse headache (MOH), a headache due to excessive intake of acute medications. Chronic migraine and MOH are serious and disabling disorders. Since chronic migraine derives from the progression of originally episodic migraine, the fundamental therapeutic strategy is prevention. This narrative review describes how to try to prevent the development of MOH and how to manage it once it has appeared.

AREAS COVERED

A PubMed database search (from 1988 to January 2015) and a review of published studies on chronic migraine and MOH were conducted.

EXPERT OPINION

In spite of progress in migraine treatment, the prevalence of chronic headaches and MOH has not changed in the course of time. Today, a large number of migraine patients have turned to numerous expert physicians and experienced all sorts of prophylactic treatments without decisive benefits. Their condition seems to have crystallized even more as chronic and intractable. This means that to prevent chronification and MOH, we need more effective drugs and better strategies to use them. In particular, we must detect disease biomarkers and predictive factors for drug response that allow for personalized treatment when migraine is still episodic and make analgesic overuse pointless.

Gender and triptan efficacy: a pooled analysis of three double-blind, randomized, crossover, multicenter, Italian studies comparing frovatriptan vs. other triptans

Migraine is three times as common in females as in males, and attacks may be more severe and difficult to treat in women. However, no study specifically addressed possible gender differences in response to antimigraine therapy. The objective of this study was to review the efficacy of frovatriptan vs. other triptans, in the acute treatment of migraine in subgroups of subjects classified according to gender (men vs. women) through a pooled analysis of three individual randomized Italian studies. 414 patients suffering from migraine with or without aura were randomized to frovatriptan 2.5 mg or rizatriptan 10 mg (study 1), frovatriptan 2.5 mg or zolmitriptan 2.5 mg (study 2), frovatriptan 2.5 mg or almotriptan 12.5 mg (study 3). All studies had a multicenter, randomized, double-blind, crossover design. After treating 1–3 episodes of migraine in no more than 3 months with the first treatment, patients switched to the other treatment for the next 3 months. In this analysis, traditional migraine endpoints were compared between the 66 men and 280 women of the intent-to-treat population. At baseline, long-term and debilitating migraine attacks were more frequently reported by women than men. During the observation period, the proportion of pain-free attacks at 2 h did not significantly differ between frovatriptan and the comparators in either men (32 vs. 38 %, p = NS) or women (30 vs. 33 %, p = NS). Pain relief was also similar between treatments for both genders (men: 56 % frovatriptan vs. 57 % comparators; women: 55 vs. 57 %; p = NS for both). The rate of relapse was significantly lower with frovatriptan than with the comparators in men (24 h: 10 vs. 30 %; 48 h: 21 vs. 39 %; p < 0.05) as well as in women (24 h: 14 vs. 23 %; 48 h: 28 vs. 40 %; p < 0.05). The rate of adverse drug reactions was significantly larger with comparators, irrespectively of gender. Although migraine presents in a more severe form in women, frovatriptan seems to retain its good efficacy and favorable sustained antimigraine effect regardless of the gender.

Zolmitriptan: a novel portal hypotensive agent which synergizes with propranolol in lowering portal pressure

OBJECTIVE

Only a limited proportion of patients needing pharmacological control of portal hypertension are hemodynamic responders to propranolol. Here we analyzed the effects of zolmitriptan on portal pressure and its potential interaction with propranolol.

METHODS

ZOLMITRIPTAN, PROPRANOLOL OR BOTH WERE TESTED IN TWO RAT MODELS OF PORTAL HYPERTENSION: common bile duct ligation (CBDL) and CCl4-induced cirrhosis. In these animals we measured different hemodynamic parameters including portal venous pressure, arterial renal flow, portal blood flow and cardiac output. We also studied the changes in superior mesenteric artery perfusion pressure and in arterial wall cAMP levels induced by zolmitriptan, propranolol or both. Moreover, we determined the effect of splanchnic sympathectomy on the response of PVP to zolmitriptan.

RESULTS

In both models of portal hypertension zolmitriptan induced a dose-dependent transient descent of portal pressure accompanied by reduction of portal flow with only slight decrease in renal flow. In cirrhotic rats, splanchnic sympathectomy intensified and prolonged zolmitriptan-induced portal pressure descent. Also, propranolol caused more intense and durable portal pressure fall when combined with zolmitriptan. Mesenteric artery perfusion pressure peaked for about 1 min upon zolmitriptan administration but showed no change with propranolol. However propranolol enhanced and prolonged the elevation in mesenteric artery perfusion pressure induced by zolmitriptan. In vitro studies showed that propranolol prevented the inhibitory effects of β2-agonists on zolmitriptan-induced vasoconstriction and the combination of propranolol and zolmitriptan significantly reduced the elevation of cAMP caused by β2-agonists.

CONCLUSION

Zolmitriptan reduces portal hypertension and non-selective beta-blockers can improve this effect. Combination therapy deserves consideration for patients with portal hypertension failing to respond to non-selective beta-blockers.

Drug interactions with triptans : which are clinically significant?

The triptans are a group of compounds with high efficacy for the acute treatment of migraine and cluster headache. They have a relatively wide therapeutic index, and although a number of minor pharmacokinetic interactions have been observed, few are likely to be clinically significant. Given the differences in principal elimination pathways, potentially interacting drugs on a pharmacokinetic basis are not common across all compounds. Of more concern than pharmacokinetic interactions are pharmacodynamic interactions. Of most concern, additive vasoconstrictor effects are likely to occur with other vasoconstrictors, especially the ergots used for migraine. Serotonin syndrome has been observed due to coadministration of triptans with selective serotonin reuptake inhibitors (SSRIs), but the absolute rate of such a clinical response to coadministration is probably low. Most patients can take triptans with other medications without dose alteration, although vigilance is required for pharmacodynamic interactions.

Triptan use in pediatric migraine: focus on rizatriptan

Migraines are a common complaint in children and can cause a significant burden to both the child and their families, with a substantial loss in both school and work days, as well as having negative effects on the child’s self-esteem and peer relations. It has become clear that migraine-specific medications are needed in this population of patients and their use may result in a significant improvement of the child’s headaches and quality of life. Rizatriptan benzoate (Maxalt®) is a selective 5-hydroxytryptamine/serotonin1B/1D (5-HT1B/1D ) agonist that was approved by the US FDA in 1998 for the acute treatment of migraine attacks in adults. Despite having been widely used in the pediatric population, rizatriptan was most recently approved in December 2011 for pediatric use in children aged 6–17 years. The advantage of rizatriptan over some other triptans is its rapid onset of action, which is thought to be beneficial in the generally shorter migraine attacks of children when compared with adults. It may also be an appealing choice for young children because it comes in an orally disintegrating form for those who may have difficulty in swallowing tablets or who have significant gastrointestinal complaints accompanying their headaches, including nausea, vomiting and abdominal pain.

Ten years of rizatriptan: from development to clinical science and future directions

The year 2008 marked the 10th anniversary since rizatriptan was first launched for the acute treatment of migraine. In this article we discuss the concepts that motivated the preclinical and clinical development of rizatriptan, the clinical evidence that has driven its use over the past decade, rizatriptan's overall contribution to the field, and future directions for research.

Pathways to the Best Fit of Triptans for Migraine Patients

Variability in drug response is a major barrier to the successful treatment of migraine, and most treatments are only optimal in a subset of patients. Although triptans provide the best therapeutic option for the treatment of acute migraine, it has not previously been possible to predict how well patients will respond to a specific triptan or whether they will experience unpleasant adverse events. Hence, it has been difficult for physicians to match individual patients with the most suitable agent to treat their migraine pain. Intrapatient variability has been associated with polymorphisms in genes encoding drug-metabolizing enzymes, drug transporters and drug targets. Pharmacogenetics provides the possibility of tailoring the therapeutic approach to individual patients, in order to maximize treatment efficacy while minimizing the potential for unwanted side-effects. This review demonstrates how almotriptan may overcome genetically determined responses by utilizing diverse metabolic pathways to provide therapeutic benefit to many migraineurs.

The pharmacological management of migraine, part 1: overview and abortive therapy

Migraine is the most common headache complaint in clinical practice. Part 1 of a two-part series presents a summary of treatments used to reduce the severity and duration of migraine and its associated symptoms and also discusses the comorbidities, clinical presentation, and risk factors associated with this affliction.

Pharmacokinetics and interactions of headache medications, part I: introduction, pharmacokinetics, metabolism and acute treatments

Recent progress in the treatment of primary headaches has made available specific, effective and safe medications for these disorders, which are widely spread among the general population. One of the negative consequences of this undoubtedly positive progress is the risk of drug-drug interactions. This review is the first in a two-part series on pharmacokinetic drug-drug interactions of headache medications. Part I addresses acute treatments. Part II focuses on prophylactic treatments. The overall aim of this series is to increase the awareness of physicians, either primary care providers or specialists, regarding this topic. Pharmacokinetic drug-drug interactions of major severity involving acute medications are a minority among those reported in literature. The main drug combinations to avoid are: i) NSAIDs plus drugs with a narrow therapeutic range (i.e., digoxin, methotrexate, etc.); ii) sumatriptan, rizatriptan or zolmitriptan plus monoamine oxidase inhibitors; iii) substrates and inhibitors of CYP2D6 (i.e., chlorpromazine, metoclopramide, etc.) and -3A4 (i.e., ergot derivatives, eletriptan, etc.), as well as other substrates or inhibitors of the same CYP isoenzymes. The risk of having clinically significant pharmacokinetic drug-drug interactions seems to be limited in patients with low frequency headaches, but could be higher in chronic headache sufferers with medication overuse.

Rizatriptan in the treatment of migraine

Migraine is a common, disabling disorder associated with considerable personal and societal burden. Current guidelines recommend triptans for the acute treatment of migraine unlikely to respond to less effective therapies. Rizatriptan is a second-generation triptan available in tablet or orally disintegrating tablet (wafer) formulations that offers several advantages over other members of its class. Rizatriptan is rapidly absorbed from the gastrointestinal tract and achieves maximum plasma concentrations more quickly than other triptans, providing rapid pain relief. Clinical trials have shown that rizatriptan is at least as effective or superior to other oral migraine-specific agents in the acute treatment of migraine, and has more consistent long-term efficacy across multiple migraine attacks. Rizatriptan has a favorable tolerability profile, and patients have reported greater satisfaction and a preference for rizatriptan over other migraine-specific agents. Improvements in quality of life reported with rizatriptan are consistent with its favorable efficacy and tolerability profiles. Notably, multi-attribute decision models that combine clinical data with patient- and physician-reported treatment preferences have identified rizatriptan as one of three triptans closest to a hypothetical "ideal". The efficacy and tolerability of rizatriptan for the acute treatment of migraine have thus been well established.

A review of rizatriptan, a quick and consistent 5-HT1B/1Dagonist for the acute treatment of migraine

Rizatriptan is a second-generation triptan marketed as 5 and 10 mg tablets and rapidly disintegrating wafer formulations. In > 5000 acute migraine patients enrolled in short-term trials and almost 1800 patients in long-term, open-label trials treating approximately 47000 attacks, rizatriptan was effective and well-tolerated. Controlled head-to-head data and a meta-analysis of 53 randomised, placebo-controlled trials of oral triptans in > 24000 patients have shown that rizatriptan 10 mg offers efficacy advantages over oral sumatriptan 50 and 100 mg and other oral triptans, both in terms of speed of onset of action and consistency. These advantages may reflect its improved pharmacological profile over sumatriptan in terms of higher oral bioavailability and a shorter time to maximum concentration. The wafer formulation offers the convenience of being administered without water. As a result of its superior efficacy profile and generally good tolerability, rizatriptan can be considered as a first-line treatment for acute migraine.

Spotlight on rizatriptan in migraine

Rizatriptan is an orally active serotonin 5-HT(1) receptor agonist that potently and selectively binds to 5-HT(1B/1D) subtypes. Earlier clinical trials demonstrated that rizatriptan 5 or 10mg is more effective than placebo at providing pain relief and a pain-free state, relieving associated symptoms of migraine, normalising functional ability and improving patient quality of life, and showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recently, rizatriptan 10mg was shown to be more effective than zolmitriptan 2.5mg or naratriptan 2.5mg at producing a pain-free state 2 hours postdose. Furthermore, compared with naratriptan, significantly more patients who received rizatriptan were pain free or had pain relief from 1 hour onwards. The number of patients with normal functional ability at 2 hours was significantly higher after rizatriptan than after naratriptan or zolmitriptan. Rizatriptan was also generally more effective than zolmitriptan or naratriptan at relieving migraine-associated symptoms. Rizatriptan is generally well tolerated, and adverse events are usually mild and transient. The most common adverse events associated with rizatriptan in recent randomised trials were asthenia/fatigue, dizziness, somnolence and nausea. There was a trend towards a lower incidence of adverse events with rizatriptan compared with zolmitriptan (31.2 vs 38.8%). However, rizatriptan was associated with a significantly higher incidence of adverse events than naratriptan (39 vs 29%). The incidence of chest pain was similar after the administration of rizatriptan, zolmitriptan or naratriptan (2-4%). In conclusion, rizatriptan is an effective drug for the acute treatment of moderate or severe migraine. Oral rizatriptan 5 and 10mg have shown greater efficacy than placebo in providing pain relief, an absence of pain, relief from associated symptoms, normal functional ability and an improvement in patient quality of life. Earlier results showed that rizatriptan provides faster freedom from pain and reduces nausea to a greater extent than oral sumatriptan. More recent studies have shown that rizatriptan 10mg provides faster pain relief and a higher percentage of patients with an absence of pain and normal functional ability at 2 hours than naratriptan 2.5mg or zolmitriptan 2.5mg. The efficacy of rizatriptan is retained when used in the long term, and the drug is generally well tolerated. Although well designed studies comparing rizatriptan with almotriptan, eletriptan and frovatriptan would further define the position of rizatriptan, current data suggest that rizatriptan should be considered as a first-line treatment option in the management of migraine.

Triptans

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

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

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

CONCLUSION

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

Almotriptan: a review of its use in migraine

Almotriptan is a selective serotonin 5-HT(1B/1D) receptor agonist ('triptan'). Its efficacy and tolerability have been assessed in a number of randomised, controlled trials in over 4800 adults with moderate or severe attacks of migraine. Oral almotriptan has a rapid onset of action (significant headache relief is observed 0.5 hours after administration of a 12.5mg dose) and efficacy is sustained in most patients who respond by 2 hours. The drug is significantly more effective than placebo as measured by a number of parameters including 2-hour headache response and pain-free response rates. Other symptoms of migraine, including nausea, photophobia and phonophobia, are also alleviated by almotriptan. The efficacy of oral almotriptan appears to be maintained over repeated doses for multiple attacks of migraine treated over a long period (up to 1 year). High headache response rates were reported over all attacks without tachyphylaxis. For the relief of single attacks of migraine, oral almotriptan 12.5mg had similar efficacy to oral sumatriptan 50mg. Patients given almotriptan report less concern with adverse effects than patients given sumatriptan. The lower incidence of chest pain following treatment with almotriptan than with sumatriptan may lead to a reduction in direct costs, with fewer patients requiring management of chest pain. Almotriptan is well tolerated. Most adverse events were of mild or moderate intensity, transient, and generally resolved without intervention or the need for treatment withdrawal. The most common adverse events associated with oral almotriptan 12.5mg treatment were dizziness, paraesthesia, nausea, fatigue, headache, somnolence, skeletal pain, vomiting and chest symptoms. The incidence of adverse events did not differ from placebo and decreased in the longer term. Almotriptan can be coadministered with drugs that share a common hepatic metabolic path; in addition, dosage reduction is required only in the presence of severe renal or hepatic impairment.

CONCLUSIONS

Almotriptan is an effective drug for the acute treatment of moderate or severe attacks of migraine in adults. An oral dose of almotriptan 12.5mg has shown greater efficacy than placebo; current data indicate that efficacy is similar to that of oral sumatriptan 50mg, and is maintained in the long term (<or=1 year). Almotriptan has a good adverse event profile and a generally similar overall tolerability profile to sumatriptan; of note, almotriptan is associated with a significantly lower incidence of chest pain than sumatriptan. However, further clinical experience is required to clearly define the place of almotriptan among the other currently available triptans. Nevertheless, because triptans have an important place in various management regimens, and because the nature of individual patient response to triptans is idiosyncratic, almotriptan is likely to become a useful treatment option in the management of adults with moderate or severe migraine headaches.