Adult: Initially, 0.5 mg daily. Adjust dosage upward or downward according to response. Dosage range: 0.1-1 mg daily.
Oral Hypertension
Adult: Initially, up to 0.5 mg daily for 1-2 wk, subsequently reduced to the lowest dose necessary to maintain response. Maintenance: 0.1-0.25 mg daily. Max: 0.5 mg daily.
Administration
Should be taken with food.
Contraindications
Active peptic ulcer or ulcerative colitis; history of mental depression; phaeochromocytoma, Parkinson’s disease. Patient receiving electroconvulsive therapy (ECT).
Asses/monitor BP and cardiac status prior to starting therapy, during first doses, when changing dose and regularly, thereafter.
Overdosage
Symptoms: Impaired consciousness ranging from drowsiness to coma, flushing, conjunctival injection, pupillary constriction, hypotension, hypothermia, central resp depresson, bradycardia, increased salivary and gastric secretion, diarrhoea. Management: Symptomatic and supportive treatment. Administer activated charcoal w/in 1 hr of ingestion. Place patient in supine position w/ feet raised for severe hypotension or give direct-acting sympathomimetics.
Drug Interactions
Enhanced hypotensive effects w/ thiazide diuretics and other antihypertensives. May cause excitation and HTN in patients receiving MAOIs. Risk of cardiac arrhythmias w/ digitalis or quinidine. May enhance the effects of CNS depressants. May inhibit the action of indirect-acting amines (e.g. ephedrine). May prolong the action of direct-acting amines (epinephrine). Decreased antihypertensive effect w/ TCAs.
Action
Description: Mechanism of Action: Reserpine is an antihypertensive drug that causes depletion of norepinephrine, catecholamine and serotonin stores resulting in a reduction in BP, bradycardia and CNS depression. Decrease in cardiac output and peripheral resistance result in hypotensive effect. Onset: Antihypertensive: 3-6 days. Duration: 2-6 wk. Pharmacokinetics: Absorption: Absorbed from the GI tract. Bioavailability: 50%. Distribution: Crosses the placenta and blood-brain barrier and enters breast milk. Plasma protein binding: 96%. Metabolism: Extensively metabolised in the liver (>90%). Excretion: Via faeces (approx 60% as unchanged drug) and urine (approx 8% as metabolites). Elimination half-life: Approx 50-100 hr.