Mecamylamine (Vecamyl) - Uses, Dose, Side effects, MOA

Mecamylamine (Vecamyl) is a centrally acting antihypertensive medication that is used in patients with mild to moderate hypertension.

Mecamylamine Uses:

  • Hypertension:

    • It is recommended for the treatment of uncomplicated malignant hypertension as well as moderately severe to severe hypertension.

Mecamylamine (Vecamyl) Dose in Adults:

Mecamylamine (Vecamyl) Dose in the treatment of Hypertension:

  • Initial: 2.5 mg orally two times a day.
  • The dose may be raised in 2.5 mg increments spaced no less than two days apart until the appropriate blood pressure response is obtained.
  • The typical dosage is three divided dosages of 25 mg/day (ranging from 2 to 4 divided doses).

Note:

  • The dosing strength should be adjusted to the timings of the day. A smaller dose should be given in the morning. The large dose should be given at noontime or in the evening.
  • When the drug is administered with concomitant antihypertensive medications such as thiazide diuretics, the dose should be reduced by 50% or more.

Use in Children:

Not indicated.


Pregnancy Risk Factor C

  • It has not been used in animal reproduction studies.
  • It can also cross the placental boundary.

Use of mecamylamine during breastfeeding

  • Breastfeeding mothers should use it with caution, as there is the possibility of serious adverse drug reactions in their infants.
  • Manufacturers recommend that you weigh the benefits and risks of drug therapy for both mother and infant.

Mecamylamine (Vecamyl) Dose in Kidney Disease:

  • There are no dosage adjustments provided in the manufacturer's labeling.
  • However, it should be used with caution as the excretion of the drug is impaired in renal impairment.
  • It is contraindicated in patients with uremia.

Dose in Liver disease:

There are no dosage adjustments provided in the manufacturer's labeling


Side effects of Mecamylamine (Vecamyl):

  • 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

Contraindication to Mecamylamine (Vecamyl):

  • Allergy to mecamylamine and any component of the formulation
  • Patients with hypertension, mild, moderate or labile (it might not be suitable to uncooperative patients).
  • Patients suffering from coronary insufficiency, recent myocardial injury or other cardiac conditions;
  • Uremia;
  • Glaucoma;
  • Pyloric stenosis
  • Coadministration of antibiotics or with sulfonamides

Warnings and precautions

  • CNS effects

    • The drug may cause side effects in the central nervous system, such as tremors and choreiform movements, convulsions, and mental aberrations.
    • This is especially true if it is given in high doses or to patients with cerebral or kidney insufficiency.
    • Patients may also experience dizziness, lightheadedness or fainting.
  • Paralytic ileus:

    • Paralytic ileus is a condition that causes the patient to stop taking medication. 
    • Paralytic ileus symptoms include frequent loose bowel movements, abdominal distension, reduced borborygmi, and abdominal pain.
  • Cardiovascular disease

    • Patients with cerebral or coronary arteriosclerosis, and patients who have had a cerebral accident should use caution.
  • Prostatic hyperplasia/urinary restriction:

    • It can cause urinary retention. Patients with bladder outlet obstruction, prostatic hyperplasia, and urethral stricture should not use it.
  • Renal impairment

    • If it is used, patients with impaired kidney function should use it with caution.
    • Because the drug is excreted unchanged in the urine, renal impairment could lead to the accumulation of the drug. Hypotension could occur.
    • If the medication is administered excessively to patients with severe renal impairment, they may develop neurological adverse effects.

Mecamylamine: Drug Interaction

Risk Factor C (Monitor therapy)

Alcohol (Ethyl)

May enhance the adverse/toxic effect of Mecamylamine.

Alfuzosin

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Alkalinizing Agents

May increase the serum concentration of Mecamylamine.

Amphetamines

May diminish the antihypertensive effect of Antihypertensive Agents.

Antipsychotic Agents (Second Generation [Atypical])

Antipsychotic drugs' hypotensive effects may be enhanced by blood pressure-lowering medications (Second Generation [Atypical]).

Barbiturates

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Benperidol

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Brigatinib

May lessen the effectiveness of antihypertensive agents. Antihypertensive Agents' bradycardic action may be strengthened by brutinib.

Brimonidine (Topical

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Dexmethylphenidate

May diminish the therapeutic effect of Antihypertensive Agents.

Diazoxide

The hypotensive effects of blood pressure-lowering medications may be strengthened.

DULoxetine

Levodopa-Containing Products' hypotensive effects may be strengthened by blood pressure-lowering medications.

Herbs (Hypertensive Properties)

May lessen the effectiveness of antihypertensive agents.

Herbs (Hypotensive Properties)

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Hypotension-Associated Agents

Levodopa-Containing Products' hypotensive effects may be strengthened by blood pressure-lowering medications.

Levodopa-Containing Products

The hypotensive action of hypotension-associated agents may be strengthened by blood pressure lowering medications.

Lormetazepam

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Methylphenidate

May lessen the effectiveness of antihypertensive agents.

Molsidomine

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Naftopidil

The hypotensive effects of blood pressure-lowering medications may be strengthened.

Nicergoline

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Nicorandil

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Nitroprusside

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

Pentoxifylline

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Pholcodine

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

Phosphodiesterase 5 Inhibitors

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Prostacyclin Analogues

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Quinagolide

May enhance the hypotensive effect of Blood Pressure Lowering Agents.

Urinary Acidifying Agents

May decrease the serum concentration of Mecamylamine.

Yohimbine

May diminish the antihypertensive effect of Antihypertensive Agents.

Risk Factor D (Consider therapy modification)

Amifostine

Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered.

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.

Risk Factor X (Avoid combination)

Aminoglycosides

May enhance the neuromuscular-blocking effect of Mecamylamine.

Bromperidol

The hypotensive impact of bromperidol may be enhanced by blood pressure lowering medications. Blood Pressure Lowering Agents' hypotensive effects may be lessened by bromperidol.

Capreomycin

Mecamylamine's ability to suppress neuromuscular activity might be enhanced.

Colistimethate

Mecamylamine's ability to suppress neuromuscular activity might be enhanced.

Lincosamide Antibiotics

Mecamylamine's ability to suppress neuromuscular activity might be enhanced.

Polymyxin B

Mecamylamine's ability to suppress neuromuscular activity might be enhanced.

Sulfonamides

Mecamylamine's harmful or poisonous effects could be amplified.

Tetracyclines

Mecamylamine's ability to suppress neuromuscular activity might be enhanced.

 

Monitoring parameters:

  • Monitor blood pressure (assess the blood pressure in the erect position before initiating treatment and with dose increases)
  • Orthostatic vital signs, and
  • Heart rate

How to administer Mecamylamine (Vecamyl)?

It should be administered after meals. Administration after meals may cause a more gradual absorption and smoother control of high blood pressure. The timing of the relationship to meals should be consistent.


Mechanism of action of Mecamylamine (Vecamyl):

  • It blocks the acetylcholine receptive at the autonomic glands. 
  • These receptors are non-selectively and not-competitively inhibited, resulting in a decrease in blood pressure.
  • Although the blood pressure-lowering effect is principally orthostatic, it is also significant for those who are supine.

Onset:

  • 0.5 to 2 hours

Duration:

  • 6 to 12 hours or more.

Absorption:

  • It is almost completely absorbed.

Excretion:

  • It is excreted in urine as an unchanged drug.
  • The rate of elimination of the drug is significantly affected by urinary PH. Acidic urine promotes its excretion while alkaline PH reduces excretion.

International Brand Names of Mecamylamine:

  • Vecamyl

Mecamylamine Brand Names in Pakistan:

No Brands Available in Pakistan.