Verapamil: Drug Effects, Side Effects, Dosage and Uses

Products

Verapamil is commercially available in the form of film-coated tablets and sustained-release tablets (Isoptin, generic). It has been approved in many countries since 1964. Verapamil is also combined fixed with trandolapril (Tarka).

Structure and properties

Verapamil (C27H38N2O4, Mr = 454.60 g/mol) is a racemate consisting of the – and -enantiomer. It is an analog of the open-chain derivatives of papaverine, for example, mebeverine, and belongs to the phenylalkylamines. Verapamil is present in drugs as verapamil hydrochloride, a white, crystalline, odorless powder with a bitter taste that is soluble in water.

Effects

Verapamil (ATC C08DA01) has antihypertensive, vasodilator, antiarrhythmic, antiischemic, antianginal, and negative dromotropic properties. It dilates coronary arteries, reduces oxygen consumption by the heart muscle and promotes its blood flow. It lowers blood pressure, afterload and heart rate. The effects are based on inhibition of calcium influx into the muscle cells of the heart and blood vessels. The molecular drug target is L-type voltage-gated calcium channels. Verapamil has low bioavailability due to high first-pass metabolism. The half-life is comparatively short, ranging from 3 to 7 hours.

Indications

  • Coronary artery disease: angina pectoris, Prinzmetal’s angina, coronary spasm, post-myocardial infarction.
  • Hypertrophic cardiomyopathy
  • Tachycardic arrhythmia
  • High blood pressure (essential hypertension)

Dosage

According to the professional information. The tablets are taken – depending on the dosage form and indication – between one to four times a day with or shortly after food.

Contraindications

  • Hypersensitivity
  • Certain cardiovascular diseases (see FI).
  • Combination with ivabradine (due to the reduction of heart rate).

For complete precautions, see the drug label.

Interactions

Verapamil is a substrate of CYP450 isoenzymes (CYP3A4, CYP1A2, CYP2C8, CYP2C9, and CYP2C18), an inhibitor of CYP3A4 of P-glycoprotein. It has a high potential for drug-drug interactions.

Adverse effects

The most common potential adverse effects include headache, dizziness, gastrointestinal distress, bradycardia, tachycardia, palpitations, hypertension, flushing, peripheral edema, and fatigue.