MECAMYLAMINE HYDROCHLORIDE
(mek-a-mill'a-meen)
Inversine
Classifications: cardiovascular agent; central acting antihypertensive
Prototype: Methyldopa
Pregnancy Category: C

Availability

2.5 mg tablets

Actions

Potent, long-acting secondary amine nondepolarizing ganglionic blocking agent. Blocks neurotransmission at both sympathetic and parasympathetic ganglia by competing with acetylcholine (Ach) for cholinergic receptor sites on postsynaptic membranes.

Therapeutic Effects

Reduces BP in both normotensive and hypertensive individuals, generally with greater decrease in standing or sitting BP than in supine BPs.

Uses

Moderately severe to severe hypertension and uncomplicated malignant hypertension.

Contraindications

Coronary insufficiency, pyloric stenosis; glaucoma; uremia, chronic pyelonephritis; recent MI; mild labile hypertension; unreliable uncooperative patients; pregnancy (category C), lactation.

Cautious Use

Rising or elevated BUN; renal, cerebral, or coronary vascular pathology; recent CVA; prostatic hypertrophy, bladder neck obstruction, urethral stricture.

Route & Dosage

Moderately Severe to Severe Hypertension
Adult: PO 2.5 mg b.i.d. p.c. for 2 d, increased by increments of 2.5 mg at intervals of 2 d until desired BP response is attained (2.5–25 mg/d in 2–4 divided doses)

Administration

Oral

Adverse Effects (1%)

CNS: Weakness, fatigue, sedation, headache, paresthesias. confusion, depression, choreiform movements, tremor. CV: Orthostatic hypotension, changes in heart rate, dizziness, syncope, precipitation of angina. Special Senses: Mydriasis, blurred vision, cycloplegia, nasal congestion, dry mouth with dysphagia, glossitis. GI: Anorexia, nausea, vomiting, constipation, diarrhea, adynamic ileus. Urogenital: Decreased libido, impotence, urinary retention.

Interactions

Drug: Alcohol, other antihypertensive agents, bethanechol, thiazide diuretics potentiate hypotensive effects; acetazolamide, sodium bicarbonate increase mecamylamine toxicity because they decrease its elimination.

Pharmacokinetics

Absorption: Almost completely absorbed from GI tract. Onset: 30 min–2 h. Peak: 3–5 h. Duration: 6–12 h. Distribution: Crosses blood-brain barrier and placenta; distributed into breast milk. Metabolism: Metabolized in liver. Elimination: Primarily excreted in urine.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug