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Mecamylamine

Medically reviewed by Drugs.com. Last updated on June 10, 2020.

Pronunciation

(mek a MIL a meen)

Index Terms

  • Mecamylamine HCl
  • Mecamylamine Hydrochloride

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product

Tablet, Oral, as hydrochloride:

Vecamyl: 2.5 mg

Brand Names: U.S.

  • Vecamyl

Pharmacologic Category

  • Ganglionic Blocking Agent

Pharmacology

Mecamylamine inhibits acetylcholine at the autonomic ganglia, causing a decrease in blood pressure. The blood pressure lowering effect is predominantly orthostatic; the supine blood pressure is also significantly decreased.

Absorption

Almost complete

Excretion

Urine (unchanged); rate of elimination is significantly affected by the pH of the urine. Acidic urine promotes excretion; alkalinization reduces excretion

Onset of Action

0.5 to 2 hours

Duration of Action

6 to ≥12 hours

Use: Labeled Indications

Hypertension: Management of moderately severe to severe hypertension and in uncomplicated malignant hypertension.

Contraindications

Hypersensitivity to mecamylamine or any component of the formulation; mild, moderate, labile hypertension (may not be suitable for uncooperative patients); coronary insufficiency or recent myocardial infarction; uremia; glaucoma; organic pyloric stenosis; coadministration with antibiotics or sulfonamides

Dosing: Adult

Hypertension: Oral: Initial: 2.5 mg twice daily; may increase in increments of 2.5 mg/day at intervals ≥2 days until desired BP response is achieved; if divided doses are not the same, give the smaller dose in the morning and larger dose(s) in the afternoon; average dose: 25 mg/day (usually in 3 divided doses, but more frequent dosing may be required). Note: Avoid abrupt discontinuation; gradual tapering is recommended.

Dosing: Geriatric

Refer to adult dosing.

Administration

Oral: The morning dose should be relatively small and, in some instances, may even be omitted; the larger dose should be given at noon time and possibly in the evening. Administration after meals may cause a more gradual absorption and smoother control of excessively high BP; timing of relationship to meals should be consistent.

Dietary Considerations

Take after meals. Concomitant use of alcohol may potentiate the effects of mecamylamine.

Storage

Store at 20°C to 25°C (68°F to 77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F)

Drug Interactions

Alcohol (Ethyl): May enhance the adverse/toxic effect of Mecamylamine. Monitor therapy

Alfuzosin: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Alkalinizing Agents: May increase the serum concentration of Mecamylamine. Monitor therapy

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When used at chemotherapy doses, hold blood pressure lowering medications for 24 hours before amifostine administration. If blood pressure lowering therapy cannot be held, do not administer amifostine. Use caution with radiotherapy doses of amifostine. Consider therapy modification

Aminoglycosides: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Brigatinib: May diminish the antihypertensive effect of Antihypertensive Agents. Brigatinib may enhance the bradycardic effect of Antihypertensive Agents. Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Bromperidol: Blood Pressure Lowering Agents may enhance the hypotensive effect of Bromperidol. Bromperidol may diminish the hypotensive effect of Blood Pressure Lowering Agents. Avoid combination

Capreomycin: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Colistimethate: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Dexmethylphenidate: May diminish the therapeutic effect of Antihypertensive Agents. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Levodopa-Containing Products: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa-Containing Products. Monitor therapy

Lincosamide Antibiotics: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Naftopidil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicergoline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Pholcodine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Pholcodine. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Polymyxin B: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Sulfonamides: May enhance the adverse/toxic effect of Mecamylamine. Avoid combination

Tetracyclines: May enhance the neuromuscular-blocking effect of Mecamylamine. Avoid combination

Thiazide and Thiazide-Like Diuretics: May enhance the adverse/toxic effect of Mecamylamine. Management: Consider avoiding the use of mecamylamine and thiazide diuretics. If combined, mecamylamine prescribing information suggests reducing the mecamylamine dose by 50% in order to avoid excessive hypotension. Consider therapy modification

Urinary Acidifying Agents: May decrease the serum concentration of Mecamylamine. Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Adverse Reactions

The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.

Frequency not defined.

Cardiovascular: Orthostatic hypotension, syncope

Central nervous system: Altered mental status, choreiform movements, convulsions, fatigue, orthostatic dizziness, paresthesia, sedation

Endocrine & metabolic: Decreased libido

Gastrointestinal: Anorexia, constipation (sometimes preceded by small, frequent stools), glossitis, intestinal obstruction, nausea, vomiting, xerostomia

Genitourinary: Impotence, urinary retention

Neuromuscular & skeletal: Tremor, weakness

Ophthalmic: Blurred vision, mydriasis

Respiratory: Pulmonary edema, pulmonary fibrosis

Warnings/Precautions

Concerns related to adverse effects:

• CNS effects: CNS effects, including tremor, choreiform movements, mental aberrations, and convulsions may occur (rarely), especially with large doses or in patients with cerebral or renal insufficiency. In addition, dizziness, lightheadedness, or fainting may also occur.

• Paralytic ileus: Discontinue if signs of paralytic ileus occur (eg, frequent loose bowel movements with abdominal distention, decreased borborygmi)

Disease-related concerns:

• Cardiovascular disease: Use with caution in patients with marked cerebral and coronary arteriosclerosis or after a recent cerebral accident.

• Prostatic hyperplasia/urinary stricture: Use with caution in patients with prostatic hyperplasia, bladder obstruction, or urethral stricture; may cause urinary retention.

• Renal impairment: Use with caution in patients with renal impairment. When renal impairment is manifested by a rising or elevated BUN, use with extreme caution, if at all. Since mecamylamine is excreted unchanged in the urine, renal impairment may reduce elimination and increase the risk of adverse effects including hypotension; the risk for neurological adverse effects is increased especially when large doses are administered to patients with renal impairment.

Other warnings/precautions:

• Abrupt discontinuation: Do not abruptly discontinue.

Monitoring Parameters

Monitor BP (assess in the erect position before initiation and with dose increases), orthostatic vital signs, and heart rate.

Pregnancy Risk Factor

C

Pregnancy Considerations

Mecamylamine crosses the placenta.

Patient Education

What is this drug used for?

• It is used to treat high blood pressure.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Fatigue

• Dry mouth

• Lack of appetite

• Nausea

• Vomiting

• Loss of strength and energy

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Blurred vision

• Burning or numbness feeling

• Decreased sex drive

• Sexual dysfunction

• Severe dizziness

• Passing out

• Diarrhea

• Abdominal swelling

• Mood changes

• Mouth irritation

• Tongue irritation

• Seizures

• Severe constipation

• Severe abdominal pain

• Shortness of breath

• Unable to pass urine

• Stiff muscles

• Tremors

• Abnormal movements

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

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