Verapamil

Verapamil(中文:維拉帕米) is a phenylalkylamine calcium-channel blocker. It is used for:

a. Prevention and long-term treatment of angina.

b. Treatment of mild to moderate hypertension.

c. Treatment of supraventricular arrhythmias

Pronunciation

Verapamil 40mg

Generic Name:	Verapamil
Class:	Cardiovascular Drug
Subclass:	Calcium-channel Blocker, CCB
Legal Classification:	P1S1S3

Drug Names

Generic Name 藥物化學名稱	HA Code 藥物代碼	Legal Classification法律藥物分類
Verapamil HCL Tablet 40mg	VERA01	P1S1S3

Mechanism of Action

Verapamil is a peripheral and coronary vasodilator. It also slows conduction through the AV node, and thus slows the increased ventricular response rate that occurs in atrial fibrillation and flutter. Verapamil works by lowering your blood pressure and makes it easier for your heart to pump blood around your body. In angina, verapamil works by improving the blood and oxygen supply to your heart. Angina is chest pain that comes on when not enough blood gets to the muscles of the heart. This usually happens because the arteries going to the heart become hardened and narrowed.

Route of Administration

Verapamil may be given intravenously or orally, as the hydrochloride; doses are expressed in terms of verapamil hydrochloride.

Dosage

Your dose of diltiazem depends on why you need the medicine and what kind your doctor has prescribed. It is important to keep taking the same brand of diltiazem once you have started.

Agina

• BY MOUTH
• Adult: 80 – 120 mg 3 times a day

Hypertension

• BY MOUTH
• Adult: initially 120 mg twice daily increasing to 160 mg twice daily where necessary. In some cases, doses of up to 480 mg daily, in divided doses, have been used.

Supraventricular Arrhythmias

• BY MOUTH
• Adult:40 – 120 mg 3 times daily.

Side Effects

The following definitions of frequencies are used:

Very common ≥ 1/10

Common ≥ 1/100 to < 1/10

Uncommon ≥ 1/1,000 to < 1/100

Rare ≥ 1/10,000 to < 1/1,000

Very rare < 1/10,000

System Organ Class	Frequency	Adverse reactions
Nervous system disorder	Common	Headache, dizziness
Cardiac disorders	Common	Atrioventricular block, bradycardia
Vascular disorders	Common	Flushing, orthostatic hypotension
Gastro-intestinal disorders	Common	Gastric pain, dyspepsia, nausea, constipation
General disorders	Common	Peripheral oedema, notably of ankles

Pharmacokinetics

Absorption

Verapamil is 90% absorbed from the gastrointestinal tract after oral doses, but undergoes extensive first-pass hepatic metabolism resulting in a bioavailability of about 20%.

Peak plasma concentrations occur about 1 to 2 hours after an oral dose.

Distribution

Verapamil is about 90% bound to plasma proteins. It is distributed into breast milk.

Metabolism

It is extensively metabolized in the liver, mainly by the cytochrome P450 isoenzymes.

Elimination

Following oral administration, the elimination half-life is 3 to 7 hours.