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Verapamil Mechanism Of Action

verapamil mechanism of action


Verapamil hydrochloride (Verapamil HCl) is a calcium ion influx inhibitor (slow-channel blocker or calcium ion antagonist) available for oral administration in film-coated tablets containing 80 mg of Verapamil hydrochloride.

Dosage & indications

For the treatment of ischemic heart disease including variant angina (Prinzmetal's angina), unstable angina, and chronic stable angina.

Oral dosage (regular-release tablets)


Initially, 80 to 120 mg PO every 8 hours. May increase up to 480 mg/day PO, administered in 3 to 4 divided doses.

Patients with hepatic disease or small stature

Initially, 40 mg PO every 8 hours.


In general, lower initial doses (e.g., 40 mg PO every 8 hours) of verapamil may be warranted. Adjust dosage based on clinical response, up to the maximum of 480 mg/day PO.

Oral dosage (Covera-HS extended-release tablets, controlled onset)


Initially, 180 mg PO once daily at bedtime. If needed, dosage may be titrated stepwise in the following manner: 240 mg/day, 360 mg/day, and then 480 mg/day, with all doses given PO once daily at bedtime. Available dosage strengths include 180 and 240 mg tablets. Up to 540 mg PO once daily has been studied.


See adult dosage. In general, use lower initial adult dosage (e.g., initially, 180 mg/day PO, given once daily at bedtime). Adjust dosage based on clinical response.

For rapid conversion of narrow-complex paroxysmal supraventricular tachycardia (PSVT) (including those associated with accessory bypass tracts such as Wolff-Parkinson-White or Lown-Ganong-Levine) to sinus rhythm.

Intravenous dosage


5 to 10 mg (0.075 to 0.15 mg/kg) IV over at least 2 minutes. If no adequate response is seen in 30 minutes, may administer an additional 10 mg (0.15 mg/kg) IV. An optimal interval for subsequent doses has not been determined and should be individualized for each patient. Clinical practice guidelines recommend 2.5 to 5 mg IV over 2 minutes. If no therapeutic response or adverse reaction is seen, may administer repeated doses of 5 to 10 mg every 15 to 30 minutes up to a total dose of 20 mg. Alternative dosing is 5 mg IV every 15 minutes, up to a total dose of 30 mg. A nondihydropyridine calcium channel blocker is suggested for PSVT if adenosine or vagal maneuvers fail to convert, if PSVT recurs after these therapies, or if these therapies disclose another SVT.

Children and Adolescents

The most commonly used initial dose is 0.1 mg/kg (up to 5 mg maximum single dose) given as an IV bolus over at least 2 minutes. However, doses of 0.2 to 0.3 mg/kg up to a maximum of 5 mg IV have also been suggested. If no response, dose may be repeated in 30 minutes, up to a maximum of 10 mg. A continuous infusion of 1 to 7 mcg/kg/minute IV following the initial loading bolus dose has also been reported.


In general, the use of verapamil in infants less than 1 year of age is not recommended and has been associated with refractory hypotension and cardiac arrest. However, initial doses of 0.1 to 0.2 mg/kg IV bolus, given over at least 2 minutes under continuous ECG monitoring has been suggested by the manufacturer. If no response, dose may be repeated in 30 minutes.


Dosage and administration

The contents of the verelan pm capsule should not be crushed or chewed. Verelan pm capsules are to be swallowed whole or the entire contents of the capsule sprinkled onto applesauce.

Essential Hypertension

Administer Verelan PM once daily at bedtime. Clinical trials studied doses of 100 mg, 200 mg, 300 mg and 400 mg. The usual daily dose of extended-release Verelan PM in clinical trials has been 200 mg given by mouth once daily at bedtime.

In rare instances, initial doses of 100 mg a day may be warranted in patients who have an increased response to verapamil [e.g. patients with impaired renal function, impaired hepatic function, elderly, low-weight patients, etc. (see Use in Specific Populations)].

Base upward titration on therapeutic efficacy and safety evaluated approximately 24 hours after dosing. The antihypertensive effects of Verelan PM are evident within the first week of therapy.

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