Verapamil

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Verapamil

Verapamil (brand names: Isoptin®, Verelan®, Calan®, Bosoptin®) is a medical drug that acts as an L-type calcium channel blocker.

Indications

It is used in the treatment of hypertension, angina pectoris, and some types of arrhythmia.

Verapamil is used to treat irregular heartbeats (arrhythmias), migraines and high blood pressure. It relaxes your blood vessels so your heart does not have to pump as hard. It also increases the supply of blood and oxygen to the heart to control chest pain (angina). If taken regularly, verapamil controls chest pain, but it does not stop chest pain once it starts. Your doctor may give you a different medication to take when you have chest pain.

Verapamil is a class IV antiarrhythmic agent, and decreases conduction through the AV node.

Pharmacokinetic details

Given orally 90-100% is absorbed, but due to high first-pass metabolism bioavailability is much lower (10-35%). It is 90% plasma protein bound and has a volume of distribution of 3-5 l kg^-1. It is metabolised in the liver to at least 12 inactive metabolites. 70% is excreted in the urine as metabolites, 16% in faeces and 3-4% unchanged in urine.

Side effects

Some possible side effects of the drug are headaches, facial flushing, dizziness, swelling, increased urination, and constipation.

Uses in cell biology

Verapamil is also used in cell biology as an inhibitor of drug efflux pump proteins such as P-glycoprotein. This is useful as many tumor cell lines overexpress drug efflux pumps, limiting the effectiveness of cytotoxic drugs or fluorescent tags. It's also used in fluorescent cell sorting for DNA content, as it blocks efflux of a variety of DNA-binding fluorochromes such as Hoechst 33342.

Overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Source

Annu Rev Pharmacol Toxicol. 1996;36:161-8. P-glycoproteins and multidrug resistance. Bellamy WT.
http://emc.medicines.org.uk/emc/industry/default.asp?page=displaydoc.asp&documentid=972 Securon Summary of Product Characteristics

Antiarrhythmic agents | Calcium channel blockers