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| ==Clinical Studies== | | ==Nonclinical Toxicology== |
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| ====14.1 Mania==== | | ====13.1 Carcinogenesis, Mutagenesis, and Impairment of Fertility==== |
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| The effectiveness of Depakote for the treatment of acute mania was demonstrated in two 3-week, placebo controlled, parallel group studies.
| | ======Carcinogenesis====== |
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| (1) Study 1: The first study enrolled adult patients who met DSM-III-R criteria for bipolar disorder and who were hospitalized for acute mania. In addition, they had a history of failing to respond to or not tolerating previous lithium carbonate treatment. Depakote was initiated at a dose of 250 mg tid and adjusted to achieve serum valproate concentrations in a range of 50-100 mcg/mL by day 7. Mean Depakote doses for completers in this study were 1,118, 1,525, and 2,402 mg/day at Days 7, 14, and 21, respectively. Patients were assessed on the Young Mania Rating Scale (YMRS; score ranges from 0-60), an augmented Brief Psychiatric Rating Scale (BPRS-A), and the Global Assessment Scale (GAS). Baseline scores and change from baseline in the Week 3 endpoint (last-observation-carry-forward) analysis were as follows:
| | Valproate was administered orally to rats and mice at doses of 80 and 170 mg/kg/day (less than the maximum recommended human dose on a mg/m2 basis) for two years. The primary findings were an increase in the incidence of subcutaneous fibrosarcomas in high dose male rats receiving valproate and a dose-related trend for benign pulmonary adenomas in male mice receiving valproate. The significance of these findings for humans is unknown. |
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| | ======Mutagenesis====== |
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| Depakote was statistically significantly superior to placebo on all three measures of outcome.
| | Valproate was not mutagenic in an in vitro bacterial assay (Ames test), did not produce dominant lethal effects in mice, and did not increase chromosome aberration frequency in an in vivo cytogenetic study in rats. Increased frequencies of sister chromatid exchange (SCE) have been reported in a study of epileptic children taking valproate, but this association was not observed in another study conducted in adults. There is some evidence that increased SCE frequencies may be associated with epilepsy. The biological significance of an increase in SCE frequency is not known. |
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| (2) Study 2: The second study enrolled adult patients who met Research Diagnostic Criteria for manic disorder and who were hospitalized for acute mania. Depakote was initiated at a dose of 250 mg tid and adjusted within a dose range of 750-2,500 mg/day to achieve serum valproate concentrations in a range of 40-150 mcg/mL. Mean Depakote doses for completers in this study were 1,116, 1,683, and 2,006 mg/day at Days 7, 14, and 21, respectively. Study 2 also included a lithium group for which lithium doses for completers were 1,312, 1,869, and 1,984 mg/day at Days 7, 14, and 21, respectively. Patients were assessed on the Manic Rating Scale (MRS; score ranges from 11-63), and the primary outcome measures were the total MRS score, and scores for two subscales of the MRS, i.e., the Manic Syndrome Scale (MSS) and the Behavior and Ideation Scale (BIS). Baseline scores and change from baseline in the Week 3 endpoint (last-observation-carry-forward) analysis were as follows:
| | ======Fertility====== |
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| | Chronic toxicity studies of valproate in juvenile and adult rats and dogs demonstrated reduced spermatogenesis and testicular atrophy at oral doses of 400 mg/kg/day or greater in rats (approximately equivalent to or greater than the maximum recommended human dose (MRHD) on a mg/m2 basis) and 150 mg/kg/day or greater in dogs (approximately 1.4 times the MRHD or greater on a mg/m2 basis). Fertility studies in rats have shown no effect on fertility at oral doses of valproate up to 350 mg/kg/day (approximately equal to the MRHD on a mg/m2 basis) for 60 days. The effect of valproate on testicular development and on sperm production and fertility in humans is unknown.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = DEPAKOTE (DIVALPROEX SODIUM) TABLET, DELAYED RELEASE [ABBVIE INC.] | url =http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=08a65cf4-7749-4ceb-6895-8f4805e2b01f | publisher = | date = | accessdate = }}</ref> |
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| Depakote was statistically significantly superior to placebo on all three measures of outcome. An exploratory analysis for age and gender effects on outcome did not suggest any differential responsiveness on the basis of age or gender.
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| A comparison of the percentage of patients showing ≥ 30% reduction in the symptom score from baseline in each treatment group, separated by study, is shown in Figure 1.
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| ====14.2 Epilepsy====
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| The efficacy of valproate in reducing the incidence of complex partial seizures (CPS) that occur in isolation or in association with other seizure types was established in two controlled trials.
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| In one, multiclinic, placebo controlled study employing an add-on design, (adjunctive therapy) 144 patients who continued to suffer eight or more CPS per 8 weeks during an 8 week period of monotherapy with doses of either carbamazepine or phenytoin sufficient to assure plasma concentrations within the "therapeutic range" were randomized to receive, in addition to their original antiepilepsy drug (AED), either Depakote or placebo. Randomized patients were to be followed for a total of 16 weeks. The following Table presents the findings.
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| Figure 2 presents the proportion of patients (X axis) whose percentage reduction from baseline in complex partial seizure rates was at least as great as that indicated on the Y axis in the adjunctive therapy study. A positive percent reduction indicates an improvement (i.e., a decrease in seizure frequency), while a negative percent reduction indicates worsening. Thus, in a display of this type, the curve for an effective treatment is shifted to the left of the curve for placebo. This Figure shows that the proportion of patients achieving any particular level of improvement was consistently higher for valproate than for placebo. For example, 45% of patients treated with valproate had a ≥ 50% reduction in complex partial seizure rate compared to 23% of patients treated with placebo.
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| The second study assessed the capacity of valproate to reduce the incidence of CPS when administered as the sole AED. The study compared the incidence of CPS among patients randomized to either a high or low dose treatment arm. Patients qualified for entry into the randomized comparison phase of this study only if 1) they continued to experience 2 or more CPS per 4 weeks during an 8 to 12 week long period of monotherapy with adequate doses of an AED (i.e., phenytoin, carbamazepine, phenobarbital, or primidone) and 2) they made a successful transition over a two week interval to valproate. Patients entering the randomized phase were then brought to their assigned target dose, gradually tapered off their concomitant AED and followed for an interval as long as 22 weeks. Less than 50% of the patients randomized, however, completed the study. In patients converted to Depakote monotherapy, the mean total valproate concentrations during monotherapy were 71 and 123 mcg/mL in the low dose and high dose groups, respectively.
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| The following Table presents the findings for all patients randomized who had at least one post-randomization assessment.
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| Figure 3 presents the proportion of patients (X axis) whose percentage reduction from baseline in complex partial seizure rates was at least as great as that indicated on the Y axis in the monotherapy study. A positive percent reduction indicates an improvement (i.e., a decrease in seizure frequency), while a negative percent reduction indicates worsening. Thus, in a display of this type, the curve for a more effective treatment is shifted to the left of the curve for a less effective treatment. This Figure shows that the proportion of patients achieving any particular level of reduction was consistently higher for high dose valproate than for low dose valproate. For example, when switching from carbamazepine, phenytoin, phenobarbital or primidone monotherapy to high dose valproate monotherapy, 63% of patients experienced no change or a reduction in complex partial seizure rates compared to 54% of patients receiving low dose valproate.
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| ====14.3 Migraine====
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| The results of two multicenter, randomized, double-blind, placebo-controlled clinical trials established the effectiveness of Depakote in the prophylactic treatment of migraine headache.
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| Both studies employed essentially identical designs and recruited patients with a history of migraine with or without aura (of at least 6 months in duration) who were experiencing at least 2 migraine headaches a month during the 3 months prior to enrollment. Patients with cluster headaches were excluded. Women of childbearing potential were excluded entirely from one study, but were permitted in the other if they were deemed to be practicing an effective method of contraception.
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| In each study following a 4-week single-blind placebo baseline period, patients were randomized, under double blind conditions, to Depakote or placebo for a 12-week treatment phase, comprised of a 4-week dose titration period followed by an 8-week maintenance period. Treatment outcome was assessed on the basis of 4-week migraine headache rates during the treatment phase.
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| In the first study, a total of 107 patients (24 M, 83 F), ranging in age from 26 to 73 were randomized 2:1, Depakote to placebo. Ninety patients completed the 8-week maintenance period. Drug dose titration, using 250 mg tablets, was individualized at the investigator's discretion. Adjustments were guided by actual/sham trough total serum valproate levels in order to maintain the study blind. In patients on Depakote doses ranged from 500 to 2,500 mg a day. Doses over 500 mg were given in three divided doses (TID). The mean dose during the treatment phase was 1,087 mg/day resulting in a mean trough total valproate level of 72.5 mcg/mL, with a range of 31 to 133 mcg/mL.
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| The mean 4-week migraine headache rate during the treatment phase was 5.7 in the placebo group compared to 3.5 in the Depakote group (see Figure 4). These rates were significantly different.
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| In the second study, a total of 176 patients (19 males and 157 females), ranging in age from 17 to 76 years, were randomized equally to one of three Depakote dose groups (500, 1,000, or 1,500 mg/day) or placebo. The treatments were given in two divided doses (BID). One hundred thirty-seven patients completed the 8-week maintenance period. Efficacy was to be determined by a comparison of the 4-week migraine headache rate in the combined 1,000/1,500 mg/day group and placebo group.
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| The initial dose was 250 mg daily. The regimen was advanced by 250 mg every 4 days (8 days for 500 mg/day group), until the randomized dose was achieved. The mean trough total valproate levels during the treatment phase were 39.6, 62.5, and 72.5 mcg/mL in the Depakote 500, 1,000, and 1,500 mg/day groups, respectively.
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| The mean 4-week migraine headache rates during the treatment phase, adjusted for differences in baseline rates, were 4.5 in the placebo group, compared to 3.3, 3.0, and 3.3 in the Depakote 500, 1,000, and 1,500 mg/day groups, respectively, based on intent-to-treat results (see Figure 4). Migraine headache rates in the combined Depakote 1,000/1,500 mg group were significantly lower than in the placebo group.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = DEPAKOTE (DIVALPROEX SODIUM) TABLET, DELAYED RELEASE [ABBVIE INC.] | url =http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=08a65cf4-7749-4ceb-6895-8f4805e2b01f | publisher = | date = | accessdate = }}</ref>
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| ==References== | | ==References== |