Naratriptan is effective and well tolerated in the acute treatment of migraine. Results of a double-blind, placebo-controlled, parallel-group study. Naratriptan S2WA3001 Study Group

A systematic review of the use of triptans in acute migraine

OBJECTIVE

A systematic review of the literature was undertaken, to consolidate evidence concerning the efficacy and safety of triptans currently available in Canada (sumatriptan, rizatriptan, naratriptan, zolmitriptan), and to provide guidelines for selection of a triptan.

METHODS

Data from published, randomized, placebo-controlled trials were pooled and a combined number needed to treat (NNT) and number needed to harm (NNH) was generated for each triptan. Direct comparative trials of triptans were also examined.

RESULTS

The lowest NNT for headache response/pain-free at one/two hours is observed with subcutaneous sumatriptan. Among the oral formulations, the lowest NNT is observed with rizatriptan and the highest NNT with naratriptan. The lowest NNH is observed with subcutaneous sumatriptan.

CONCLUSIONS

Triptans are relatively safe and effective medications for acute migraine attacks. However, differences among them are relatively small. Considerations in selecting a triptan include individual patient response/tolerance, characteristics of the attacks, relief of associated symptoms, consistency of response, headache recurrence, delivery systems and patient preference.

Pharmacokinetics of naratriptan in adolescent subjects with a history of migraine

Naratriptan is a novel 5-HT1 agonist developed to treat acute migraine. The study objective was to characterize the pharmacokinetics of oral naratriptan in adolescent migraine patients outside a migraine attack. Subjects received a single 2.5 mg naratriptan tablet. Serial serum samples for naratriptan concentrations were collected over 24 hours. Blood pressure, pulse rate, and 12-lead ECG were recorded at baseline and at regular intervals after dosing. Seven patients--3 males and 4 females, 12 to 16 years of age--received drug and completed the study. The geometric mean and 95% confidence interval maximum concentration (Cmax) was 8.0 ng/mL (5.9-10.7), elimination half-life (t1/2) was 4.9 hours (4.5-5.4), area under the concentration-time curve (AUC) was 74.6 ng.h/mL (56.6-98.2), and apparent total clearance (Cl/F) was 558.8 mL/min (424.3-735.9). The median time to maximal concentration (tmax) was 4 hours, with a range of 1.5 to 4. Blood pressure, pulse rate, and ECG parameters did not change significantly from baseline. No serious adverse events or subject withdrawal after drug administration occurred. Oral naratriptan pharmacokinetic parameters in adolescents were similar to values reported in adults. Naratriptan doses for adolescents older than 12 years of age would be expected to be similar to adult doses.

Naratriptan

Naratriptan is a selective 5-HT(1B/1D) receptor agonist, with a high affinity at the 5-HT(1B), 5-HT(1D) and 5-HT(1F) receptor subtypes. Naratriptan contracts a number of large isolated cerebral arteries from several species, and has little contractile effect on peripheral blood vessels. It has an inhibitory effect on the cranial neurogenic inflammation model. The clinically recommended dose is 2.5 mg. It was found significantly superior to placebo on headache relief and pain free at 2 and 4 hours, and in relieving nausea, photophobia and phonophobia. It also has a good within-patient consistency, and a low recurrence rate. The side-effect profile is that of the triptan class, wih an incidence no different from placebo at the 25 mg dose. The contraindications are similar to any triptan, including coronary disease. Naratriptan is unlikely to affect metabolism of other drugs. In comparison sumatriptan 100 mg, naratriptan 2.5 mg has a slower onset of action and a lower response rate at 4 h, but it has a lower recurrence rate, and is better tolerated.

The pharmacology of headache

Headache is a common problem which besets most of us at some time or the other. The pharmacology of headache is complex in an overall sense but can be understood in terms of the anatomy and physiology of the pain-producing structures. Migraine can be used as a template to understand the activation of nociceptive systems in the head and thus their neurotransmitter mediation and modulation. In recent years, the role of serotonin (5-HT) in headache pharmacology has been unravelled in the context of both understanding its role in the nociceptive systems related to headache and by exploiting its 5-HT1 receptor subtypes in headache therapeutics. The pharmacology of the head pain systems, as they are known and as they might evolve, are explored in the context of both, the anatomy and physiology of trigeminovascular nociception and in the context of clinical questions, such as those of efficacy, headache recurrence and adverse events.

Triptans in migraine: a comparative review of pharmacology, pharmacokinetics and efficacy

Triptans are a new class of compounds developed for the treatment of migraine attacks. The first of the class, sumatriptan, and the newer triptans (zolmitriptan, naratriptan, rizatriptan, eletriptan, almotriptan and frovatriptan) display high agonist activity at mainly the serotonin 5-HT1B and 5-HT1D receptor subtypes. As expected for a class of compounds developed for affinity at a specific receptor, there are minor pharmacodynamic differences between the triptans. Sumatriptan has a low oral bioavailability (14%) and all the newer triptans have an improved oral bioavailability and for one, risatriptan, the rate of absorption is faster. The half-lives of naratriptan, eletriptan and, in particular, frovatriptan (26 to 30h) are longer than that of sumatriptan (2h). These pharmacokinetic improvements of the newer triptans so far seem to have only resulted in minor differences in their efficacy in migraine. Double-blind, randomised clinical trials (RCTs) comparing the different triptans and triptans with other medication should ideally be the basis for judging their place in migraine therapy. In only 15 of the 83 reported RCTs were 2 triptans compared, and in 11 trials triptans were compared with other drugs. Therefore, in all placebo-controlled randomised clinical trials, the relative efficacy of the triptans was also judged by calculating the therapeutic gain (i.e. percentage response for active minus percentage response for placebo). The mean therapeutic gain with subcutaneous sumatriptan 6mg (51%) was more than that for all other dosage forms of triptans (oral sumatriptan 100mg 32%; oral sumatriptan 50mg 29%: intranasal sumatriptan 20mg 30%; rectal sumatriptan 25mg 31%; oral zolmitriptan 2.5mg 32%; oral rizatriptan 10mg 37%; oral eletriptan 40mg 37%; oral almotriptan 12.5mg 26%). Compared with oral sumatriptan 100mg (32%), the mean therapeutic gain was higher with oral eletriptan 80mg (42%) but lower with oral naratriptan 2.5mg (22%) or oral frovatriptan 2.5mg (16%). The few direct comparative randomised clinical trials with oral triptans reveal the same picture. Recurrence of headache within 24 hours after an initial successful response occurs in 30 to 40% of sumatriptan-treated patients. Apart from naratriptan, which has a tendency towards less recurrence, there appears to be no consistent difference in recurrence rates between the newer triptans and sumatriptan. Rizatriptan with its shorter time to maximum concentration (tmax) tended to produce a quicker onset of headache relief than sumatriptan and zolmitriptan. The place of triptans compared with non-triptan drugs in migraine therapy remains to be established and further RCTs are required.

Efficacy of naratriptan tablets in the acute treatment of migraine: a dose-ranging study. Naratriptan S2WB2004 Study Group

OBJECTIVE

This study sought to compare the efficacy of several doses of naratriptan tablets with that of sumatriptan tablets and placebo in the acute treatment of a single migraine attack.

METHODS

This was a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study. Patients received either naratriptan tablets (1, 2.5, 5, 7.5, or 10 mg), sumatriptan tablets (100 mg), or placebo.

RESULTS

A total of 643 patients took part in the study. Two hours after dosing, headache relief was reported by significantly more patients treated with any dose of naratriptan (52%-69%) or sumatriptan (60%) than with placebo (31%) (P < 0.05). Four hours after dosing, headache relief was reported by significantly more patients treated with any dose of naratriptan (63%-80%) or sumatriptan (80%) than with placebo (39%) and by significantly more patients treated with sumatriptan 100 mg (80%) than with naratriptan 1 mg (64%), 2.5 mg (63%), or 5 mg (65%) (P < 0.05). Twenty-four-hour overall efficacy (headache relief maintained through 24 hours postdose with no worsening, no use of rescue medication, and no recurrence) was reported by more patients treated with any dose of naratriptan (39%-58%) or sumatriptan (44%) than with placebo (22%). Headache recurrence was reported in 17% to 32% of naratriptan-treated patients, 44% of sumatriptan-treated patients, and 36% of placebo recipients. The overall incidence of adverse events was similar in patients treated with naratriptan 1 mg (20%), naratriptan 2.5 mg (21%), and placebo (23%). For naratriptan 5, 7.5, and 10 mg, the incidence of adverse events was 32%, 37%, and 35%, respectively, and for sumatriptan 100 mg it was 26%.

CONCLUSIONS

Our results suggest that the 2.5-mg dose of naratriptan tablets offers the optimal efficacy-to-tolerability ratio at the dose range between 1 and 10 mg. Although naratriptan 2.5 mg was less effective than sumatriptan 100 mg at 4 hours after dosing, the 2 medications showed similar efficacy at 24 hours.

Comparison of naratriptan and sumatriptan in recurrence-prone migraine patients. Naratriptan International Recurrence Study Group

OBJECTIVE

This randomized, double-blind, crossover study was undertaken to compare the incidence of headache recurrence after treatment with naratriptan or sumatriptan in migraine patients with a history of frequent headache recurrence (recurrence in > or =50% of successfully treated attacks).

BACKGROUND

Although the selective 5-hydroxytryptamine, (5-HT1) agonist sumatriptan is effective and well tolerated for acute treatment of migraine in most patients, headache recurrence within 24 hours of initial successful treatment with sumatriptan and other medications has been reported in approximately 35% of patients. The novel 5-HT1 agonist naratriptan possesses pharmacologic and pharmacokinetic characteristics that may address the issue of headache recurrence.

METHODS

Men and women aged 18 to 65 years with a > or =1-year history of migraine with or without aura were randomly assigned to treat 1 moderate or severe migraine attack in a nonclinical setting with one 2.5-mg naratriptan tablet and 1 attack with one 100-mg sumatriptan tablet. A pain-free interval of > or =24 hours was required between attacks. At 4 hours, patients not using rescue medication and experiencing headache recurrence could take a second, identical dose of study medication to treat recurrence. No more than 2 tablets of study medication were permitted in any 24-hour period.

RESULTS

A total of 253 patients treated > or =1 migrane attack and were included in the safety analysis; the 225 patients who treated both attacks were included in the efficacy analysis. Of the 164 naratriptan-treated and 181 sumatriptan-treated patients experiencing headache relief after > or =1 attack, headache recurrence 4 to 24 hours after treatment was reported by 74 naratriptan-treated patients (45%) and 101 sumatriptan-treated patients (57%; not statistically significant). (One naratriptan- and 3 sumatriptan-treated patients who experienced headache relief did not record recurrence status and were not included in the denominator for the percentage calculation.) In a subset of patients experiencing headache relief after 2 attacks, headache recurrence 4 to 24 hours after initial dosing was reported by 55 naratriptan- and 77 sumatriptan-treated patients (41% and 57%, respectively; P = 0.005). The overall incidence of adverse events was 22% after treatment with naratriptan and 33% after treatment with sumatriptan. This incidence did not increase after use of a second dose of naratriptan (20%) or sumatriptan (31%).

CONCLUSION

These data suggest that naratriptan is a long-acting and well-tolerated addition to currently available medications for the treatment of acute migraine.

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

Sterile neurogenic inflammation within cephalic tissue, involving vasodilation and plasma protein extravasation, has been proposed as a pathophysiological mechanism in acute migraine. The action of 5-hydroxytryptamine (5-HT1B/1D) agonists--so-called triptans--on receptors located in meningeal arteries (5-HT1B) and trigeminovascular fiber endings (5-HT1D) has an inhibitory effect on this neurogenic inflammation. Recently, a series of second-generation 5-HT1B/1D agonists (almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan, and zolmitriptan) have been developed and are reviewed in this article. Their in vitro pharmacological properties, pharmacokinetics, clinical efficacy, drug interactions, and adverse effects are evaluated and compared to the golden standard in the treatment of acute migraine, sumatriptan.

Naratriptan efficacy in migraineurs who respond poorly to oral sumatriptan

OBJECTIVES

To determine whether 347 patients would respond to a 50-mg oral dose of sumatriptan, even though they considered themselves poor responders to this acute therapy for migraine, and to investigate whether oral naratriptan can be an effective acute therapy for migraine in the subset of patients who did not respond to sumatriptan under double-blind, well-controlled conditions.

BACKGROUND

Although most migraineurs respond to sumatriptan, there remains a need for an effective alternative for those who do not respond. Naratriptan is a more potent and more lipophilic member of this class of agent and could prove beneficial in such patients. This is the first well-controlled study to assess the value of another 5-HT1B/1D agonist in this difficult patient subset.

METHODS

This study comprised two migraine attacks. The first (attack 1) was a single-blind assessment of the efficacy of sumatriptan (50 mg orally) in patients with a history of poor response to the drug. The second (attack 2) was a randomized, parallel group, double-blind, placebo-controlled trial of naratriptan (2.5 mg orally) in nonresponders to oral sumatriptan.

RESULTS

Attack 1: About two thirds of this selected migraine population did not respond to sumatriptan. Attack 2: Naratriptan was statistically superior to placebo for headache relief at 2 hours and 4 hours, as well as for most other features of migraine attacks. These data suggest an intrinsic efficacy of naratriptan in this patient subset and not a coincidental response. No unexpected tolerability issues arose.

CONCLUSIONS

Naratriptan is an alternative therapy for migraineurs who respond poorly to oral sumatriptan. No response to one "triptan" does not necessarily predict no response to them all.

Emergency department management of pediatric migraine

Migraine is a common pediatric emergency department problem. Since its pathophysiology is unclear and possibly multifactorial, a single treatment strategy is unlikely to be successful for all patients. A specific treatment that has been successful for a particular patient should be strongly considered. Otherwise, it is best to start with simple therapies such as acetaminophen, aspirin, or an NSAID if not already tried at home. For patients requiring more specific therapy, reasonable choices would be dihydroergotamine or a dopamine antagonist such as prochlorperazine. There are several newer agents studied in adults with examples being sumatriptan and naratriptan. These probably have a role in the adolescent and should be considered in the younger age group when other therapies have failed. When the headache has been prolonged, dexamethasone may be useful in decreasing inflammation and relieving pain. As illustrated in many of the above studies, monotherapy is often inadequate in achieving complete relief of headache pain in all patients. Most of the drugs discussed here address only one of the three etiologies thought to be involved in migraine pathogenesis, namely; the dopaminergic system. the serotonin system or inflammation. Presumably, therapy directed toward more than one of these etiologies at the same time may be more effective (11).

Low migraine headache recurrence with naratriptan: clinical parameters related to recurrence

OBJECTIVE

To evaluate clinical parameters that may affect the incidence of headache recurrence or the time to headache recurrence, or both, in migraineurs treated with naratriptan, 2.5-mg tablets.

BACKGROUND

The incidence of headache recurrence within 24 hours of treatment with naratriptan, 2.5-mg tablets (17%-28%), is lower than that reported for other currently available selective serotonin agonists. Identifying clinical parameters that influence headache recurrence may further reduce the incidence of headache recurrence or prolong the time to recurrence, or both, for naratriptan-treated patients.

METHODS

We examined the effects of three clinical parameters (predose pain severity, headache duration prior to treatment, and relief status 4 hours post dose) on the incidence of and time to headache recurrence across four placebo-controlled naratriptan clinical trials. The impact of these parameters on headache recurrence was examined individually and in combination.

RESULTS

Predose pain severity had no effect on the incidence of headache recurrence (overall 23%; moderate 22%, severe 23%). The median time to recurrence was longer for patients with moderate pain before treatment compared with patients with severe pain before treatment (14.5 hours versus 9.3 hours, respectively). Overall time to headache recurrence was 11.8 hours. Patients with headache recurrence reported a longer time until they treated the headache compared with patients without headache recurrence (median, 145 minutes versus 97.5 minutes). Patients who treated headache pain within 3 hours of onset had a lower incidence of headache recurrence (20%) than patients who treated their headache more than 3 hours after onset (28%). Patients with no pain 4 hours post dose had a lower incidence of and a longer time to headache recurrence compared with patients with mild pain 4 hours post dose (17% versus 32%; median, 17.8 hours versus 8.1 hours, respectively). The interaction of all three clinical parameters was significant in predicting headache recurrence.

CONCLUSIONS

The overall incidence of headache recurrence is low after naratriptan, 2.5 mg, compared with other currently available selective serotonin agonists. Predose pain severity, time to treatment, and 4-hour relief status appear related to the incidence of or time to headache recurrence, or both. Treating less severe migraine attacks, treating earlier within an attack, and obtaining complete relief post dose may enhance the low incidence of headache recurrence and achieve longer times to recurrence with naratriptan, 2.5 mg.

Migraine: a comprehensive review of new treatment options

Headaches are among the most common complaints reported to health care professionals and are classified by the International Headache Society as migraine, tension-type, or cluster, with additional subtypes. Classification and etiology of headache should be determined after thorough review of the patient's history. Once diagnosed, migraine can be treated by preventive or abortive measures. Recent developments add new options, including availability of drugs for intranasal administration (sumatriptan, dihydroergotamine) and 5-HT1B/1D agonists (rizatriptan, zolmitriptan, naratriptan, eletriptan). Although placebo-controlled trials are available, few comparative clinical trials of these agents have been conducted; however, important pharmacologic, pharmacokinetic, and clinical differences exist among the drugs.

Symptomatic pharmacotherapy of migraine

This review summarizes data on the effectiveness of various symptomatic migraine pharmacotherapies and makes recommendations for treatment. A wide variety of agents are available for the symptomatic treatment of migraine headache, including over-the-counter analgesics, nonsteroidal anti-inflammatory drugs (NSAIDs), combination products, opiates, ergot alkaloids, corticosteroids, dopamine antagonists, and triptans. In the stepped-care approach, simple analgesics and NSAIDs are the recommended first step for the treatment of mild-to-moderate migraine headaches. Patients who do not respond to first-step treatments may be given ergots, combination products, dopamine antagonists, or triptans as the second step. Corticosteroids or opiates may be used as rescue treatment in patients who do not respond to second-step treatment. A stratified approach to care individualizes treatment based on the severity of the headache and other patient-specific factors. In a stratified approach, dihydroergotamine or triptans may be the first-step treatment for patients who present with a history of severe migraines that have responded poorly to previous treatments. Sumatriptan was the first triptan approved for the symptomatic treatment of migraine headache; newer triptans include zolmitriptan, naratriptan, and rizatriptan. Since sumatriptan is rapidly absorbed by the subcutaneous route, its time to onset of effect is shortest. Among triptan drugs that are administered orally, the relative time to onset may be shorter with rizatriptan than sumatriptan. Naratriptan has a longer time to onset but is associated with a lower rate of migraine recurrence than other triptans. graine headache, ergot alkaloids, triptans,

Naratriptan: an alternative for migraine

OBJECTIVE

To critically evaluate the literature regarding naratriptan's clinical pharmacology, efficacy, safety, and indications.

DATA SOURCE

A MEDLINE search was conducted for the period from January 1990 to June 1998. Key words used included naratriptan, triptan, serotonin agonists, migraine, and migraine therapy. In addition, pertinent references cited in articles obtained from MEDLINE and product information for triptans were reviewed.

STUDY SELECTION AND DATA EXTRACTION

All original and review articles and abstracts pertaining to naratriptan were reviewed, as were product information extracts. Clinical trials of naratriptan were critically reviewed and compared with pertinent clinical trials of other oral triptans.

DATA SYNTHESIS

The treatment of migraine has been dramatically improved with the use of sumatriptan, other triptans, and serotonin-receptor subtype 1B and 1D agonists. Drawbacks to these medications, however, have included poorly tolerated adverse effects and the recurrence of the migraine. Naratriptan has been recently approved for acute oral migraine therapy. In two Phase III trials of naratriptan compared with placebo, relief at four hours was obtained in 60% and 68% of patients using the 2.5-mg dose, with recurrence of headache in 24 hours in 27% and 28% of patients. The data on migraine recurrence were similar to those of other oral triptans; the efficacy of naratriptan at two hours was not specifically analyzed. Adverse effects of naratriptan were similar to placebo, and its tolerability seemed superior compared with studies of other oral triptans.

CONCLUSIONS

Naratriptan is a promising new oral therapy for acute migraine; it may successfully treat patients who poorly tolerate other triptan therapies or have longer duration migraine headaches.

Acute management of migraine: triptans and beyond

Migraine is a paroxysmal disorder characterized by attacks of headache, nausea, vomiting, photophobia and phonophobia, and malaise. This review summarizes new treatment options for the therapy of acute attacks. Sumatriptan was the first specific serotonin-1B/D agonist for the treatment of acute migraine attacks. Apart from the oral and subcutaneous formulation, it is also available as nasal spray and suppository. The other new migraine drugs zolmitriptan, naratriptan, rizatriptan and eletriptan differ in their pharmacological profiles, which translates into minor differences in efficacy, headache recurrence and side-effects. Importantly, in clinical practice individual patients may show a preference for one treatment over another. New drugs in migraine treatment include substance-P antagonists, nitric oxide synthetase inhibitors and calcitonin gene-related peptide antagonists.

Early clinical experience with subcutaneous naratriptan in the acute treatment of migraine: a dose-ranging study

Naratriptan is a novel, potent agonist at the 5HT1B/1D receptor. A total of 335 migraine patients were treated in this randomized, double-blind, placebo-controlled, dose-ranging, in-clinic study, to evaluate the efficacy, safety and tolerability of five doses of subcutaneous (sc) naratriptan (0.5, 1, 2.5, 5 or 10 mg) in comparison with sc sumatriptan (6 mg) and placebo in the acute treatment of a moderate/severe migraine attack. Headache relief [reduction of headache severity from moderate or severe (grade 2/3) to mild or none (grade 1/0)] at 1 and 2 h after each dose, was reported by a statistically significantly higher proportion of patients for all doses of sc naratriptan and sc sumatriptan (6 mg) than for placebo. The percentages of patients with headache relief at 2 h post-dose were: naratriptan (0.5 mg) 65%, (1 mg) 75%, (2.5 mg) 83%, (5 mg) 94% and (10 mg) 91%; sumatriptan (6 mg) 89%; placebo 41%, (P < 0.005). The earliest report of a statistically significant difference compared with placebo for the times assessed was with sc naratriptan (10 mg) at 10 min post-dose (P = 0.023). The percentages of patients reporting adverse events were dose-related; sc naratriptan (0.5 mg) 33%, (1 mg) 29%, (2.5 mg) 43%, (5 mg) 59% and (10 mg) 71%; sc sumatriptan 53%; placebo 22%. There were no clinically significant changes in electrocardiogram (ECG), vital signs or laboratory parameters. Systemic exposure increased proportionally to the dose, the absorption of sc naratriptan was rapid (tmax = 10 min) and the half-life was 5 h. In conclusion, sc naratriptan was an effective and well-tolerated acute treatment for migraine. Copyright 1998 Lippincott Williams & Wilkins

Tolerability and efficacy of naratriptan tablets with long-term treatment (6 months). Naratriptan Long-term Study Group

This open-label study was conducted to examine the long-term tolerability and efficacy of the novel 5HT1 agonist naratriptan tablets 2.5 mg used to treat all migraine attacks for 6 months. Patients could reduce the dose to 1 mg in the event of intolerable adverse events. The results demonstrate that the majority (median 83%) of attacks treated with naratriptan tablets 2.5 mg were not associated with an adverse event. Among attacks treated with naratriptan tablets 2.5 mg (+ optional 2.5 mg for headache recurrence), the most frequently reported adverse event was nausea (4% of attacks after a single naratriptan dose). Both the overall incidence of adverse events and the incidences of specific adverse events were no higher during months 4-6 of treatment compared with months 1-3. Only 5 of 414 patients elected to reduce their naratriptan dose to 1 mg. Headache relief 4 h postdose was reported in a mean of 68% of 6770 moderate or severe migraine attacks treated with naratriptan tablets 2.5 mg. The median number of naratriptan tablets used per attack was 1.0 (mean 1.25); patients treated only a median 7% of attacks (mean 13%) with a 2nd naratriptan tablet for headache recurrence. Patients rated naratriptan tablets as good or excellent in 61% of 7566 treated attacks. In summary, the data from this study demonstrate that naratriptan tablets 2.5 mg were very well tolerated and effective for the acute treatment of migraine for 6 months in a situation closely resembling actual clinical use.