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Mecamylamine Hydrochloride

Pronunciation: mek-ah-MILL-oh-meen HIGH-dore-KLOR-ide
Class: Antiadrenergic

Trade Names:
- Tablets 2.5 mg


Potent ganglionic blocking agent.



Mecamylamine is almost completely absorbed.


Mecamylamine crosses the placenta and blood-brain barrier.


Slowly excreted in urine unchanged. Alkalinization of urine reduces, and acidification promotes renal excretion.


Onset is 0.5 to 2 h.


Duration is 6 to 12 h.

Indications and Usage

Treatment of moderately severe to severe essential hypertension; uncomplicated malignant hypertension.


Coronary insufficiency; recent MI; uremia; patients receiving antibiotics and sulfonamides; glaucoma; organic pyloric stenosis; mild, moderate, or labile hypertension; uncooperative patients; hypersensitivity to any component of product.

Dosage and Administration

Adults Initial dose

PO 2.5 mg twice daily. Adjust dose in increments of 2.5 mg at intervals of at least 2 days until the desired BP response occurs.


Store tablets at controlled room temperature (59° to 86°F).

Drug Interactions

Alcohol, anesthetics, other antihypertensives

May potentiate the effects of mecamylamine.

Antibiotics, sulfonamides

Patients receiving these drugs generally should not be treated with ganglionic blocking agents.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Orthostatic dizziness; syncope; postural hypotension.


Weakness; fatigue; sedation; paresthesia; tremor; choreiform movements; mental aberrations; convulsions.


Glossitis; dilated pupils; blurred vision.


Anorexia; dry mouth; nausea; vomiting; constipation; ileus.


Decreased libido; impotence; urinary retention.


Interstitial pulmonary edema; fibrosis.



Category C .


Discontinue breast-feeding or discontinue the drug.


Safety and efficacy not established.

Renal Function

Give with caution, if at all, in patients with renal function impairment manifested by a rising or elevated BUN.

CV function

Use with caution in patients with marked cerebral and coronary arteriosclerosis or after recent cerebral vascular accident.

Discontinuation of therapy

To prevent hypertension, fatal cerebral vascular accidents, or acute CHF, withdraw drug gradually, and substitute other antihypertensive therapy.

Paralytic ileus

Consider the possibility if frequent loose bowel movements with abdominal distention and decreased borborygmi occur.

Potentiation of effects

Mecamylamine's effects may be potentiated by excessive heat, fever, infection, hemorrhage, pregnancy, anesthesia, surgery, vigorous exercise, other antihypertensive agents, alcohol, salt depletion, vomiting, excessive sweating, or diuretics.

Urinary retention

Because urinary retention may occur, use with caution in patients with prostatic hypertrophy, bladder neck obstruction, and urethral stricture.



Hypotension, postural hypotension, nausea, vomiting, diarrhea, constipation, paralytic ileus, urinary retention, dizziness, anxiety, dry mouth, mydriasis, blurred vision, palpitations, increase in IOP.

Patient Information

  • Advise patient that dose may be increased slowly until max benefit is obtained.
  • Advise patient to take every day exactly as prescribed. Advise patient to take prescribed dose after meals or snacks to slow absorption of medication and provide smoother control of BP.
  • Advise patient that timing of doses in relation to meals must be consistent.
  • Caution patient not to change the dose or stop taking unless advised by health care provider.
  • Inform patient that drug controls but does not cure hypertension and to continue taking drug as prescribed even when BP is not elevated.
  • Instruct patient to continue taking other BP medications as prescribed by health care provider.
  • Instruct patient in BP and pulse measurement skills.
  • Advise patient to monitor and record BP and pulse at home in a standing position and to inform health care provider if abnormal measurements are noted. Also advise patient to take record of BP and pulse to each follow-up visit.
  • Advise patient that dizziness, lightheadedness, or fainting can occur, especially when rising from a lying or sitting position. Inform patient that getting up slowly from a lying or sitting position will reduce the chance of this occurring.
  • Caution patient that alcohol ingestion, fever, excessive heat, vigorous exercise, inadequate fluid intake, salt-depletion, and excessive perspiration, diarrhea, or vomiting can lead to excessive fall in BP resulting in dizziness, lightheadedness, or fainting.
  • Instruct patient to lie or sit down if experiencing dizziness or lightheadedness when standing.
  • Advise patient to stop taking the medication and immediately inform health care provider if any of the following occur: fainting; frequent loose bowel movements with stomach distention and “rumbling” sounds in the intestines; difficult urination; inability to urinate; mood changes or changes in thoughts; tremors or uncontrollable muscle movements.
  • Emphasize to hypertensive patient importance of other modalities on BP: weight control, regular exercise, smoking cessation, moderate intake of alcohol and salt.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.