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Mecamylamine Dosage

Applies to the following strength(s): 2.5 mg

The information at is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for:

Additional dosage information:

Usual Adult Dose for Hypertension

Moderately severe to severe essential hypertension or uncomplicated malignant hypertension:

Initial dose: usually 2.5 mg orally twice a day. The initial regulation of dosage should be determined by blood pressure readings in the erect position at the time of maximal effect of the drug, as well as by other signs and symptoms of orthostatic hypotension.

Maintenance dose: Increase dose as needed in increments of 2.5 mg at intervals of not less than 2 days until the desired blood pressure is achieved. In severe or urgent cases, larger increments at smaller intervals may be needed. The maintenance dosage should be just below that which causes signs of mild postural hypotension. The average total daily dosage is 25 mg orally in divided doses (generally 2 to 4 doses, but more if necessary in severe cases when smooth control is difficult to obtain). However, as little as 2.5 mg daily may be adequate in some patients.

Renal Dose Adjustments

The manufacturer recommends caution when administering mecamylamine to patients with renal dysfunction manifested by a rising or elevated BUN. Mecamylamine is contraindicated in uremia.

Liver Dose Adjustments

Data not available

Dose Adjustments

Partial tolerance may develop in some patients, requiring an increase in the daily dosage of mecamylamine.

When given with other antihypertensive drugs, the dosage of the other drugs, as well as that of mecamylamine, should be reduced to avoid excessive hypotension. However, thiazides should be continued at their usual dosage, while the dosage of mecamylamine should be decreased by at least 50 percent.


When mecamylamine is discontinued, it should be done gradually and other antihypertensive therapy usually must be substituted. In some patients, particularly those with malignant hypertension, abrupt withdrawal of mecamylamine can lead to fatal cerebral vascular accidents or acute congestive heart failure due to a sudden return of hypertensive levels.

Mecamylamine should be immediately discontinued and remedial steps taken in the presence of paralytic ileus, which may be indicated by frequent loose bowel movements with abdominal distention and decreased borborygmi.

The action of mecamylamine may be potentiated by excessive heat, fever, infection, hemorrhage, pregnancy, anesthesia, surgery, exercise, other antihypertensive drugs, alcohol, and salt depletion due to reduced intake, diarrhea, vomiting, sweating, or diuretics.

During therapy with mecamylamine, sodium should not be restricted, but if necessary, the dosage of mecamylamine should be adjusted.

Safety and effectiveness have not been established in pediatric patients (less than 18 years of age).


Data not available

Other Comments

The effective maintenance dose should be regulated by blood pressure readings in the erect position. If the patient regularly monitors blood pressure at home, instructions may be given by the physician to reduce or omit a dose if readings fall below a designated level or if faintness or lightheadedness occurs. However, no change should be instituted without the knowledge of the physician.

Administration of mecamylamine after meals may cause a more gradual absorption and smoother control of excessively high blood pressure. The timing of doses should be consistent in relation to meals. Since blood pressure response to antihypertensive drugs is increased in the early morning, the morning dose should generally be small or even omitted, and the larger doses should be given at noon or in the evening.