Anzemet Injection（dolasetron mesylate） - America[美国药品]

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Anzemet Injection（dolasetron mesylate）

2016-12-13 04:13:28 来源: 作者: 【大中小】浏览:486次评论:0条

DESCRIPTION

ANZEMET (dolasetron mesylate) is an antinauseant and antiemetic agent. Chemically, dolasetron mesylate is (2α,6α,8α,9aβ)-octahydro-3-oxo-2,6-methano-2H-quinolizin-8-yl-1H-indole-3-carboxylate monomethanesulfonate, monohydrate. It is a highly specific and selective serotonin subtype 3 (5-HT3) receptor antagonist both in vitro and in vivo. Dolasetron mesylate has the following structural formula:

The empirical formula is C19H20N2O3 • CH3SO3H • H2O, with a molecular weight of 438.50. Approximately 74% of dolasetron mesylate monohydrate is dolasetron base.

Dolasetron mesylate monohydrate is a white to off-white powder that is freely soluble in water and propylene glycol, slightly soluble in ethanol, and slightly soluble in normal saline.

ANZEMET Injection is a clear, colorless, nonpyrogenic, sterile solution for intravenous administration. Each milliliter of ANZEMET Injection contains 20 mg of dolasetron mesylate and 38.2 mg mannitol, USP, with an acetate buffer in water for injection. The pH of the resulting solution is 3.2 to 3.8.

ANZEMET Injection multidose vials contain a clear, colorless, nonpyrogenic, sterile solution for intravenous administration. Each ANZEMET multidose vial contains 25 mL (500 mg) dolasetron mesylate. Each milliliter contains 20 mg dolasetron mesylate, 29 mg mannitol, USP, and 5 mg phenol, USP, with an acetate buffer in water for injection. The pH of the resulting solution is 3.2 to 3.7.

CLINICAL PHARMACOLOGY

Dolasetron mesylate and its active metabolite, hydrodolasetron (MDL 74,156), are selective serotonin 5-HT3 receptor antagonists not shown to have activity at other known serotonin receptors and with low affinity for dopamine receptors. The serotonin 5-HT3 receptors are located on the nerve terminals of the vagus in the periphery and centrally in the chemoreceptor trigger zone of the area postrema.

In healthy volunteers (N=64), dolasetron mesylate in single intravenous doses up to 5 mg/kg produced no effect on pupil size or meaningful changes in EEG tracings. Results from neuropsychiatric tests revealed that dolasetron mesylate did not alter mood or concentration. Multiple daily doses of dolasetron have had no effect on colonic transit in humans. Dolasetron mesylate has no effect on plasma prolactin concentrations.

Effects on Electrocardiogram

QTcF interval was eva luated in a randomized, placebo and active (moxifloxacin 400 mg once-daily) controlled crossover study in 80 healthy adults, with 14 measurements over 24 hours on Day 4. The maximum mean (95% upper confidence bound) differences in QTcF from placebo after baseline-correction were 14.1 (16.1) and 36.6 (38.6) ms for 100 mg and supratherapeutic 300 mg ANZEMET administered intravenously, respectively. ANZEMET 300 mg once daily resulted in approximately 3-fold higher mean Cmax values of dolasetron mesylate and its active metabolite hydrodolasetron on Day 4 compared to those observed with the therapeutic 100 mg ANZEMET dose.

Based on exposure-response analyses in healthy volunteers, QTc interval prolongation appears to be associated with concentrations of hydrodolasetron. Using the established exposure-response relationship, the mean predicted increase (95% upper prediction interval) in QTcF intervals were 22.5 (23.9) and 21.2 (22.6) ms in pediatric and adult cancer patients following a single intravenous dose of 1.8 mg/kg.

In the thorough QT study, exposure dependent prolongation of the PR and QRS interval was also noted in healthy subjects receiving ANZEMET. The maximum mean (95% upper confidence bound) difference in PR from placebo after baseline-correction was 9.8 (11.6) ms and 33.1 (34.9) ms for 100 mg and supratherapeutic 300 mg ANZEMET, respectively. The maximum mean (95% upper confidence bound) difference in QRS from placebo after baseline-correction was 3.5 (4.5) ms and 13 (14.5) ms for 100 mg and supratherapeutic 300 mg ANZEMET, respectively. Over one-fourth of the subjects treated with the 300 mg dose had an absolute PR over 200 ms and absolute QRS of over 110 ms post-treatment. A change from baseline ≥ 25% was noted in several of these subjects. (see CONTRAINDICATIONS and WARNINGS)

Pharmacokinetics in Humans

Intravenous dolasetron mesylate is rapidly eliminated (t1/2<10 min) and completely metabolized to the most clinically relevant species, hydrodolasetron.

The reduction of dolasetron to hydrodolasetron is mediated by a ubiquitous enzyme, carbonyl reductase. Cytochrome P-450 (CYP)2D6 is primarily responsible for the subsequent hydroxylation of hydrodolasetron and both CYP3A and flavin monooxygenase are responsible for the N-oxidation of hydrodolasetron.

Hydrodolasetron is excreted in the urine unchanged (53.0% of administered intravenous dose). Other urinary metabolites include hydroxylated glucuronides and N-oxide.

Hydrodolasetron appeared rapidly in plasma, with a maximum concentration occurring approximately 0.6 hour after the end of intravenous treatment, and was eliminated with a mean half-life of 7.3 hours (%CV=24) and an apparent clearance of 9.4 mL/min/kg (%CV