"Sept. 30, 2011 (San Diego) -- A disturbing number of people with heart problems who shouldn't be prescribed standard migraine medications like Amerge, Axert, Frova, Imitrex, Maxalt, Relpax, Treximet, and Zomig are given the drugs anyway, research"...
Mechanism of Action
Rizatriptan binds with high affinity to human cloned 5-HT1B/1D receptors. MAXALT presumably exerts its therapeutic effects in the treatment of migraine headache by binding to 5-HT1B/1D receptors located on intracranial blood vessels and sensory nerves of the trigeminal system.
Rizatriptan is completely absorbed following oral administration. The mean oral absolute bioavailability of the MAXALT Tablet is about 45%, and mean peak plasma concentrations (Cmax) are reached in approximately 1-1.5 hours (Tmax). The presence of a migraine headache did not appear to affect the absorption or pharmacokinetics of rizatriptan. Food has no significant effect on the bioavailability of rizatriptan but delays the time to reach peak concentration by an hour. In clinical trials, MAXALT was administered without regard to food.
The bioavailability and Cmax of rizatriptan were similar following administration of MAXALT Tablets and MAXALT-MLT Orally Disintegrating Tablets, but the rate of absorption is somewhat slower with MAXALT-MLT, with Tmax delayed by up to 0.7 hour. AUC of rizatriptan is approximately 30% higher in females than in males. No accumulation occurred on multiple dosing.
The mean volume of distribution is approximately 140 liters in male subjects and 110 liters in female subjects. Rizatriptan is minimally bound (14%) to plasma proteins.
The primary route of rizatriptan metabolism is via oxidative deamination by monoamine oxidase-A (MAO-A) to the indole acetic acid metabolite, which is not active at the 5-HT1B/1D receptor. N-monodesmethyl-rizatriptan, a metabolite with activity similar to that of parent compound at the 5-HT1B/1D receptor, is formed to a minor degree. Plasma concentrations of N-monodesmethyl-rizatriptan are approximately 14% of those of parent compound, and it is eliminated at a similar rate. Other minor metabolites, the N-oxide, the 6-hydroxy compound, and the sulfate conjugate of the 6-hydroxy metabolite are not active at the 5-HT1B/1D receptor.
The total radioactivity of the administered dose recovered over 120 hours in urine and feces was 82% and 12%, respectively, following a single 10 mg oral administration of 14C-rizatriptan. Following oral administration of 14C-rizatriptan, rizatriptan accounted for about 17% of circulating plasma radioactivity.
Approximately 14% of an oral dose is excreted in urine as unchanged rizatriptan while 51% is excreted as indole acetic acid metabolite, indicating substantial first pass metabolism.
The plasma half-life of rizatriptan in males and females averages 2-3 hours.
Cytochrome P450 Isoforms
Rizatriptan is not an inhibitor of the activities of human liver cytochrome P450 isoforms 3A4/5, 1A2, 2C9, 2C19, or 2E1; rizatriptan is a competitive inhibitor (K,=1400 nM) of cytochrome P450 2D6, but only at high, clinically irrelevant concentrations.
Geriatric: Rizatriptan pharmacokinetics in healthy elderly non-migraineur volunteers (age 65-77 years) were similar to those in younger non-migraineur volunteers (age 18-45 years).
Pediatric: The pharmacokinetics of rizatriptan was determined in pediatric migraineurs 6 to 17 years of age. Exposures following single dose administration of 5 mg MAXALT-MLT to pediatric patients weighing 20-39 kg (44-87 Ib) or 10 mg MAXALT-MLT to pediatric patients weighing ≥ 40 kg (88 Ib) were similar to those observed following single dose administration of 10 mg MAXALT-MLT to adults.
Gender: The mean AUC0-∞ and Cmax of rizatriptan (10 mg orally) were about 30% and 11% higher in females as compared to males, respectively, while Tmax occurred at approximately the same time.
Hepatic impairment: Following oral administration in patients with hepatic impairment caused by mild to moderate alcoholic cirrhosis of the liver, plasma concentrations of rizatriptan were similar in patients with mild hepatic insufficiency compared to a control group of subjects with normal hepatic function; plasma concentrations of rizatriptan were approximately 30% greater in patients with moderate hepatic insufficiency.
Renal impairment: In patients with renal impairment (creatinine clearance 10-60 mL/min/1.73 m2), the AUC0-∞, of rizatriptan was not significantly different from that in subjects with normal renal function. In hemodialysis patients, (creatinine clearance < 2 mL/min/1.73 m2), however, the AUC for rizatriptan was approximately 44% greater than that in patients with normal renal function.
Race: Pharmacokinetic data revealed no significant differences between African American and Caucasian subjects.
[See also DRUG INTERACTIONS.]
Monoamine oxidase inhibitors: Rizatriptan is principally metabolized via monoamine oxidase, 'A' subtype (MAO-A). Plasma concentrations of rizatriptan may be increased by drugs that are selective MAO-A inhibitors (e.g., moclobemide) or nonselective MAO inhibitors [type A and B] (e.g., isocarboxazid, phenelzine, tranylcypromine, and pargyline). In a drug interaction study, when MAXALT 10mg was administered to subjects (n=12) receiving concomitant therapy with the selective, reversible MAO-A inhibitor, moclobemide 150 mg t.i.d., there were mean increases in rizatriptan AUC and Cmax of 119% and 41% respectively; and the AUC of the active N-monodesmethyl metabolite of rizatriptan was increased more than 400%. The interaction would be expected to be greater with irreversible MAO inhibitors. No pharmacokinetic interaction is anticipated in patients receiving selective MAO-B inhibitors [see CONTRAINDICATIONS and DRUG INTERACTIONS].
Propranolol: In a study of concurrent administration of propranolol 240 mg/day and a single dose of rizatriptan 10 mg in healthy adult subjects (n=11), mean plasma AUC for rizatriptan was increased by 70% during propranolol administration, and a four-fold increase was observed in one subject. The AUC of the active N-monodesmethyl metabolite of rizatriptan was not affected by propranolol [see DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS].
Nadolol/Metoprolol: In a drug interactions study, effects of multiple doses of nadolol 80 mg or metoprolol 100 mg every 12 hours on the pharmacokinetics of a single dose of 10 mg rizatriptan were evaluated in healthy subjects (n=12). No pharmacokinetic interactions were observed.
Paroxetine: In a study of the interaction between the selective serotonin reuptake inhibitor (SSRI) paroxetine 20 mg/day for two weeks and a single dose of MAXALT 10 mg in healthy subjects (n=12), neither the plasma concentrations of rizatriptan nor its safety profile were affected by paroxetine [see WARNINGS AND PRECAUTIONS, DRUG INTERACTIONS, and PATIENT INFORMATION].
Oral contraceptives: In a study of concurrent administration of an oral contraceptive during 6 days of administration of MAXALT (10-30 mg/day) in healthy female volunteers (n=18), rizatriptan did not affect plasma concentrations of ethinyl estradiol or norethindrone.
The efficacy of MAXALT Tablets was established in four multicenter, randomized, placebo-controlled trials. Patients enrolled in these studies were primarily female (84%) and Caucasian (88%), with a mean age of 40 years (range of 18 to 71). Patients were instructed to treat a moderate to severe headache. Headache response, defined as a reduction of moderate or severe headache pain to no or mild headache pain, was assessed for up to 2 hours (Study 1) or up to 4 hours after dosing (Studies 2, 3 and 4). Associated symptoms of nausea, photophobia, and phonophobia and maintenance of response up to 24 hours post-dose were evaluated. A second dose of MAXALT Tablets was allowed 2 to 24 hours after dosing for treatment of recurrent headache in Studies 1 and 2. Additional analgesics and/or antiemetics were allowed 2 hours after initial treatment for rescue in all four studies.
In all studies, the percentage of patients achieving headache response 2 hours after treatment was significantly greater in patients who received either MAXALT 5 or 10 mg compared to those who received placebo. In a separate study, doses of 2.5 mg were not different from placebo. Doses greater than 10 mg were associated with an increased incidence of adverse effects. The results from the four controlled studies are summarized in Table 2.
Table 2: Response Rates 2 Hours Following Treatment of Initial
Headache in Studies 1,2, 3, and 4
|Study||Placebo|| MAXALT Tablets
| MAXALT Tablets
|1||35% (n=304)||62%* (n=458)||71%*,† (n=456)|
|2‡||37% (n=82)||-||77%* (n=320)|
|3||23% (n=80)||63%* (n=352)||-|
|4||40% (n=159)||60%* (n=164)||67%* (n=385)|
| * p-value < 0.05 in comparison with placebo
†p-value < 0.05 in comparison with 5 mg
‡Results for initial headache only.
Comparisons of drug performance based upon results obtained in different clinical trials may not be reliable. Because studies are conducted at different times, with different samples of patients, by different investigators, employing different criteria and/or different interpretations of the same criteria, under different conditions (dose, dosing regimen, etc.), quantitative estimates of treatment response and the timing of response may be expected to vary considerably from study to study.
The estimated probability of achieving an initial headache response within 2 hours following treatment in pooled Studies 1, 2, 3, and 4 is depicted in Figure 1.
Figure 1: Estimated Probability of Achieving an Initial Headache
Response by 2 Hours in Pooled Studies 1, 2, 3, and 4††
††Figure 1 shows the Kaplan-Meier plot of the probability over time of obtaining headache response (no or mild pain) following treatment with MAXALT or placebo. The averages displayed are based on pooled data from 4 placebo-controlled, outpatient trials providing evidence of efficacy (Studies 1, 2, 3, and 4). Patients taking additional treatment or not achieving headache response prior to 2 hours were censored at 2 hours.
For patients with migraine-associated photophobia, phonophobia, and nausea at baseline, there was a decreased incidence of these symptoms following administration of MAXALT compared to placebo.
Two to 24 hours following the initial dose of study treatment, patients were allowed to use additional treatment for pain response in the form of a second dose of study treatment or other medication. The estimated probability of patients taking a second dose or other medication for migraine over the 24 hours following the initial dose of study treatment is summarized in Figure 2.
Figure 2: Estimated Probability of Patients Taking a Second
Dose of MAXALT Tablets or Other Medication for Migraines Over the 24 Hours Following
the Initial Dose of Study Treatment in Pooled Studies 1, 2, 3, and 4†††
†††This Kaplan-Meier plot is based on data obtained in 4 placebo-controlled outpatient clinical trials (Studies 1, 2, 3, and 4). Patients not using additional treatments were censored at 24 hours. The plot includes both patients who had headache response at 2 hours and those who had no response to the initial dose. Remedication was not allowed within 2 hours post-dose.
Efficacy was unaffected by the presence of aura; by the gender, or age of the patient; or by concomitant use of common migraine prophylactic drugs (e.g., beta-blockers, calcium channel blockers, tricyclic antidepressants) or oral contraceptives. In two additional similar studies, efficacy was unaffected by relationship to menses. There were insufficient data to assess the impact of race on efficacy.
MAXALT-MLT Orally Disintegrating Tablets
The efficacy of MAXALT-MLT was established in two multicenter, randomized, placebo-controlled trials that were similar in design to the trials of MAXALT Tablets (Studies 5 and 6). Patients were instructed to treat a moderate to severe headache. Patients treated in these studies were primarily female (88%) and Caucasian (95%), with a mean age of 42 years (range 18-72).
In both studies, the percentage of patients achieving headache response 2 hours after treatment was significantly greater in patients who received either MAXALT-MLT 5 or 10 mg compared to those who received placebo. The results from Studies 5 and 6 are summarized in Table 3.
Table 3: Response Rates 2 Hours Following Treatment of Initial
Headache in Studies 5 and 6
|5||47% (n=98)||66%* (n=100)||66%* (n=113)|
|6||28% (n=180)||59%* (n=181)||74%*;† (n=186)|
| * p-value < 0.01 in comparison with placebo
†p-value < 0.01 in comparison with 5 mg
The estimated probability of achieving an initial headache response by 2 hours following treatment with MAXALT-MLT in pooled Studies 5 and 6 is depicted in Figure 3.
Figure 3: Estimated Probability of Achieving an Initial Headache
Response with MAXALT-MLT by 2 Hours in Pooled Studies 5 and 6‡
‡Figure 3 shows the Kaplan-Meier plot of the probability over time of obtaining headache response (no or mild pain) following treatment with MAXALT-MLT or placebo. The averages displayed are based on pooled data from 2 placebo-controlled, outpatient trials providing evidence of efficacy (Studies 5 and 6). Patients taking additional treatment or not achieving headache response prior to 2 hours were censored at 2 hours.
For patients with migraine-associated photophobia and phonophobia at baseline, there was a decreased incidence of these symptoms following administration of MAXALT-MLT as compared to placebo.
Two to 24 hours following the initial dose of study treatment, patients were allowed to use additional treatment for pain response in the form of a second dose of study treatment or other medication. The estimated probability of patients taking a second dose or other medication for migraine over the 24 hours following the initial dose of study treatment is summarized in Figure 4.
Figure 4: Estimated Probability of Patients Taking a Second
Dose of MAXALT-MLT or Other Medication for Migraines Over the 24 Hours Following
the Initial Dose of Study Treatment in Pooled Studies 5 and 6‡‡
‡‡This Kaplan-Meier plot is based on data obtained in 2 placebo-controlled outpatient clinical trials (Studies 5 and 6). Patients not using additional treatments were censored at 24 hours. The plot includes both patients who had headache response at 2 hours and those who had no response to the initial dose. Remedication was not allowed within 2 hours post-dose.
Pediatric Patients 6 to 17 Years of Age
The efficacy of MAXALT-MLT in pediatric patients 6 to 17 years was evaluated in a multicenter, randomized, double-blind, placebo-controlled, parallel group clinical trial (Study 7). Patients had to have at least a 6-month history of migraine attacks (with or without aura) usually lasting 3 hours or more (when untreated). The patient population was historically non-responsive to NSAIDs and acetaminophen therapy.
Patients were instructed to treat a single migraine attack with headache pain of moderate to severe intensity. The treatment phase of the study had two stages. Stage 1 was used to identify placebo non-responders, who then entered into Stage 2, in which patients were randomized to MAXALT-MLT or placebo. Using a weight-based dosing strategy, patients 20 kg to < 40 kg (44 Ib to < 88 Ib) received MAXALT-MLT 5 mg or placebo, and patients ≥ 40 kg (88 Ib) received MAXALT-MLT 10 mg or placebo.
The mean age for the studied patient population was 13 years. Sixty-one percent of the patients were Caucasian, and fifty-six percent of the patients were female. The percentage of patients achieving the primary efficacy endpoint of no headache pain at 2 hours after treatment was significantly greater in patients who received MAXALT-MLT, compared with those who received placebo (33% vs. 24%). Study 7 results are summarized in Table 4.
Table 4: Response Rates 2 Hours Following Treatment of Initial
Headache in Pediatric Patients 6 to 17 Years of Age in Study 7
|No headache pain at 2 hours post-dose|| 24%
(n/m = 94/388)
(n/m = 126/382)
| n = Number of evaluable patients with no headache pain at 2 hours post-dose.
m = Number of evaluable patients in population.
The observed percentage of pediatric patients achieving no headache pain within 2 hours following initial treatment with MAXALT-MLT is shown in Figure 5.
Figure 5: Observed Percentage of Patients Reporting No Headache
Pain by 2 Hours Post-Dose in Study 7
The prevalence of the exploratory endpoints of absence of migraine-associated symptoms (nausea, photophobia, and phonophobia) at 2 hours after taking the dose was not statistically significantly different between patients who received MAXALT-MLT and those who received placebo.
Last reviewed on RxList: 1/5/2012
This monograph has been modified to include the generic and brand name in many instances.
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