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.
