tailieunhanh - Handbook of clinical drug data - part 5

Hai hiệu ứng serotonergic này làm cho nó khác nhau từ SSRI và (Xem biểu đồ so sánh thuốc chống trầm cảm.) Quản lý và Liều dùng cho người lớn. PO trầm cảm 100 mg thầu ban đầu (50 mg thầu ở người già), tăng q 4-7 ngày | Antidepressants 453 NEFAZODONE Serzone Pharmacology. Nefazodone is a postsynaptic serotonin 5-HT2A antagonist and presynaptic serotonin reuptake inhibitor. These two serotonergic effects make it different from SSRIs and 156 See Antidepressants Comparison Chart. Administration and Adult Dosage. PO for depression 100 mg bid initially 50 mg bid in the elderly increasing q 4-7 days to the effective dosage range of 150 300 mg bid. After initial dosage titration once-daily bedtime administration is preferred to minimize daytime Dosage Forms. Tab 50 100 150 200 250 mg. Pharmacokinetics. Nefazodone has an oral bioavailability of about 20 . Singledose studies in the elderly have shown a 100 larger AUC with multiple doses the AUC differences decreased to 10 20 above those in younger populations. It is 99 protein bound and extensively metabolized with a dose-dependent elimination half-life of about 1 hr in young patients modestly prolonged in the elderly and 2 3 times longer in hepatic disease. The major active metabolite hydroxynefazodone has a half-life of hr in young and elderly patients increasing to 2 4 hr with hepatic disease. Renal impairment does not markedly affect nefazodone pharmacokinetics. Adverse Reactions. Although chemically similar to trazodone it causes less sedation and orthostatic hypotension and its lower a-adrenergic blockade makes priapism much less likely no cases reported . Frequent adverse effects include sedation dry mouth nausea and dizziness. Unlike SSRIs nefazodone s effects on sexual function agitation tremor insomnia and weight are no different from placebo. Drug Interactions. Nefazodone is a potent inhibitor of the CYP3A4 isoenzyme and a weak inhibitor of the CYP2D6 isoenzyme. Drug interactions of particular concern include the triazolobenzodiazepines ie alprazolam triazolam midazolam . a 1- to 2-week washout period is recommended when converting a patient to or from a MAOI and nefazodone. PAROXETINE Paxil .