Oral Anorectic in short-term treatment of moderate to severe obesity
Adult: As phentermine HCl: 15-37.5 mg once daily in the morning; higher dose of 37.5 mg may be given in 2 divided doses. Individualise to achieve adequate response w/ lowest effective dose. As modified-release ion-exchange resin complex: 15-30 mg once daily in the morning.
Hyperthyroidism, history of CV disease (e.g. coronary artery disease, arrhythmias, CHF, uncontrolled HTN), glaucoma, history of alcohol/drug abuse, agitated states. Pregnancy and lactation. Concomitant or w/in 14 days of MAOI use.
Symptoms: Restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucination, panic states, fatigue, depression, arrhythmia, HTN or hypotension, circulatory collapse, nausea, vomiting, diarrhoea, abdominal cramps, insomnia. Chronic intoxication: Irritability, severe dermatoses, psychosis, hyperactivity. Management: Supportive and symptomatic treatment. Administer activated charcoal and perform gastric lavage w/in 1 hr of ingestion. Diazepam (preferably PO, cautiously by IV inj) may be given to control excitement and convulsions. Urine acidification may increase phentermine excretion.
Primary pulmonary HTN or valvular heart disease may occur when phentermine is used concurrently w/ fenfluramine or dexfenfluramine. May decrease hypotensive effect of adrenergic neuron blocking drugs (e.g. guanethidine, clonidine, methyldopa). CNS stimulant effect may be increased by thyroid hormones. Potentially Fatal: Increased risk of hypertensive crisis w/ MAOI.
False-positive result w/ urine detection of amphetamine/methamphetamine.
Description: Phentermine is a sympathomimetic amine that exerts its appetite suppressant effect through a mechanism which appears to be secondary to CNS effects, including stimulation of the hypothalamus to release norepinephrine. Pharmacokinetics: Absorption: Readily absorbed from the GI tract. Time to peak plasma concentration: Approx 3-4.4 hr. Distribution: Volume of distribution: 348 L. Plasma protein binding: 17.5%. Metabolism: Hepatically metabolised via p-hydroxylation and N-oxidation, mainly by CYP3A4 isoenzyme. Excretion: Via urine (62-85% as unchanged drug). Elimination half-life: Approx 20 hr.
A08AA01 - phentermine ; Belongs to the class of centrally acting antiobesity products. Used in the treatment of obesity.
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