Rizatriptan Benzoate (Page 5 of 7)

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis: Oral carcinogenicity studies were conducted in mice (100 weeks) and rats (106 weeks) at doses of up to 125 mg/ kg/day. There was no evidence of an increase in tumor incidence related to rizatriptan in either species. Plasma exposures (AUC) at the highest dose tested were approximately 150 (mice) and 240 times (rats) that in humans at the maximum recommended human dose (MRHD) of 30 mg/day.

Mutagenesis: Rizatriptan was neither mutagenic nor clastogenic in a battery of in vitro and in vivo genetic toxicity studies, including: the microbial mutagenesis (Ames) assay, in vitro mammalian cell mutagenesis and chromosomal aberration assays, and the in vivo chromosomal aberration assay in mouse.

Impairment of FertilityOral administration of rizatriptan (0, 2, 10, or 100 mg/kg/day) to female rats prior to and during mating and continuing throughout gestation and lactation resulted in no effect on fertility; however, altered estrous cyclicity and delays in time to mating were observed at the highest dose tested. Plasma exposure at the no-effect dose (10 mg/kg/day) for reproductive toxicity was approximately 15 times that in humans at the MRHD.

Oral administration of rizatriptan (0, 5, 35, or 250 mg/kg/day) to male rats prior to and during mating resulted in no impairment of fertility or reproductive performance. Plasma exposure (AUC) at the highest dose tested was approximately 550 times that in humans at the MRHD.

14 CLINICAL STUDIES

14.1 Adults

The efficacy of rizatriptan benzoate 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 rizatriptan benzoate 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 rizatriptan benzoate 5 mg 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

* p-value <0.05 in comparison with placebo

†p-value <0.05 in comparison with 5 mg

Results for initial headache only.

StudyPlaceboRizatriptan benzoate tablets 5 mgRizatriptan benzoate tablets 10 mg
135% (n=304)62%* (n=458)71%*,† (n=456)
2 37% (n=82)77%* (n=320)
323% (n=80)63%* (n=352)
440% (n=159)60%* (n=164)67%* (n=385)

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 *

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* Figure 1 shows the Kaplan-Meier plot of the probability over time of obtaining headache response (no or mild pain) following treatment with rizatriptan benzoate 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 rizatriptan benzoate 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 Rizatriptan Benzoate 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*

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* 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.

14.2 Pediatric Patients 6 to 17 Years of Age

The efficacy of rizatriptan benzoate orally disintegrating tablets 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 rizatriptan benzoate orally disintegrating tablets or placebo. Using a weight-based dosing strategy, patients 20 kg to <40 kg (44 lb to <88 lb) received rizatriptan benzoate orally disintegrating tablets 5 mg or placebo, and patients ≥40 kg (88 lb) received rizatriptan benzoate orally disintegrating tablets 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 rizatriptan benzoate orally disintegrating tablets, 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
EndpointNo Headache pain at 2 hours post dosePlacebo24%(n/m=34/388)Rizatriptan Benzoate Orally Disintegrating tablets33%(n/m=126/382)p-value0.01
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 rizatriptan benzoate orally disintegrating tablets is shown in Figure 5.

Figure 5: Observed Percentage of Patients Reporting No Headache Pain by 2 Hours Post-Dose in Study 7

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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 rizatriptan benzoate orally disintegrating tablets and those who received placebo.

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