Manidón Hta (Verapamil Hydrochloride)

Verapamil is indicated for cardiovascular conditions that involve elevated vascular tone or abnormal cardiac conduction.

• Hypertension: lowers blood pressure by causing arterial vasodilation.
• Angina pectoris: reduces myocardial oxygen demand through decreased contractility and heart rate.
• Atrial fibrillation: slows atrioventricular nodal conduction to control ventricular rate.

• Verapamil blocks L‑type calcium channels in cardiac myocytes and vascular smooth muscle, reducing intracellular calcium influx. This results in decreased myocardial contractility, slowed AV‑node conduction, and vasodilation of peripheral arteries, collectively lowering blood pressure and stabilising cardiac rhythm.

Verapamil may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Constipation: mild to moderate difficulty passing stool.
• Dizziness: sensation of light‑headedness, especially on standing.
• Headache: pressure or throbbing pain in the head.
• Flushing: transient redness of the skin.
• Peripheral edema: swelling of ankles or feet.
• Nausea: upset stomach, sometimes with mild vomiting.

Serious or Rare Side Effects

• Severe hypotension: marked drop in blood pressure requiring medical attention.
• Bradycardia or heart block: dangerously slow heart rate or conduction disturbances.
• Heart failure exacerbation: worsening of existing cardiac failure.
• Allergic reactions: rash, itching, or anaphylaxis.
• Liver enzyme elevation: potential hepatic dysfunction.
• Atrioventricular nodal dysfunction: advanced AV block.

When prescribing or dispensing Verapamil, several safety considerations are recommended.

• Monitor blood pressure: check regularly to avoid excessive hypotension.
• Assess cardiac function: use caution in patients with heart failure or conduction disorders.
• Avoid abrupt discontinuation: taper under medical supervision to prevent rebound hypertension.
• Use with caution in hepatic impairment: dose adjustments may be required.
• Pregnancy and lactation: consult a healthcare professional before use.
• Store at ambient temperature: keep in the original pack, protect from moisture and direct sunlight.

Verapamil interacts with several drug classes; awareness of the interaction level guides clinical decisions.

Major Interactions (Avoid)

• Beta‑blockers: may cause excessive bradycardia and AV‑node block.
• Digoxin: increased risk of digoxin toxicity.
• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): raise verapamil plasma concentrations.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): reduce verapamil effectiveness.
• Other antihypertensives: additive hypotensive effect, monitor blood pressure.
• Alcohol: may enhance dizziness and hypotension.