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Updated 11 February 2013

Verapamil

Verapamil is the active ingredient of Calcicard SR 240, Isoptin, Micro-Verapamil, Ravamil, Sandoz Verapamil, Vasomil and VeraHexal.

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Verapamil is the active ingredient of Calcicard SR 240, Isoptin, Micro-Verapamil, Ravamil, Sandoz Verapamil, Vasomil and VeraHexal.

Verapamil is also one of multiple active ingredients found in Tarka (verapamil + trandolapril).

General information
Verapamil is a medication that widens and relaxes blood vessels, and decrease the rate at which the heart beats.

It is used to treat and prevent angina pectoris, chest pain as a result of a lack of oxygen available to the heart muscle. It is of particular use in those patients with asthma who cannot make use of other medications such as beta blockers often prescribed for angina prevention and treatment.

It is furthermore used for the treatment of high blood pressure, to treat abnormal rhythms of the heart, and to prevent acute attacks of migraine.

Verapamil does not cure any of these conditions, but merely keeps it under control. For verapamil to be effective, it has to be taken regularly, even if you do not notice any immediate effect – it may take several weeks to notice the full benefit.

Be aware that, at the start of treatment, you may feel dizzy, especially when getting up suddenly. Caution is advised.

It is advised to avoid drinking grapefruit juice while taking it, as this may increase the level of verapamil in your blood, which may lead to additional side effects.

How does verapamil work?
Calcium plays an important role in the contraction of heart muscle, as well as the smooth muscle in the walls of arteries. Blocking the channels though which calcium enters cells in these muscles, leads to relaxation of these muscles. The result is reduced workload for the heart (and a decrease in occurrence of angina), as well as widening of blood vessels, causing high blood pressure to return to normal  and safe levels. 

Fast facts
Drug schedule: Schedule 3
Available as: Tablets, slow-release tablets, injections and slow-release capsules
What does it do? Verapamil reduces high levels of blood pressure, and treats and prevents chest pains.
Overdose risk: Medium
Dependence risk: Low
Available as a generic? Yes
Available on prescription only? Yes

User information
Onset of effect: Within 2 hours.
Duration of action: Up to 8 hours.
Dietary advice: To minimise stomach irritation and adverse effects, this medication should be taken with or immediately after food; a low-salt, low-fat diet is advised; and avoid grapefruit as it may increase the level of verapamil in your blood, which may lead to additional side effects.
Stopping: Consult you prescriber before discontinuing treatment, as abrupt withdrawal may cause a return of symptoms.
Prolonged use: Although no problems are expected with long-term use, your doctor may occasionally request kidney and liver function tests.

Special precautions
Alert your doctor before using this drug if:

  • you have a liver  disease,
  • you have or have had congestive heart failure,
  • you have porphyria,
  • you are planning to have surgery, or
  • you are taking other medication.

Pregnancy: Avoid. Potential risk to the foetus has been reported. Consult your doctor before use, or if you are planning to fall pregnant.
Breastfeeding: Avoid. This medication is passed through breast milk and may affect your baby adversely. Consult your doctor before use.
Porphyria: Avoid. This medication may cause serious adverse effects. Consult your doctor before use.
Infants and children: Verapamil is not usually prescribed
Elderly: No special precautions required.
Driving and hazardous work: Caution is advised as use of this medication may lead to dizziness, light-headedness and/or sedation. Avoid such activities until you know how it affects you.
Alcohol: Avoid concomitant use of alcohol with this medication, as it is possible that the combination may cause a further drop in blood pressure adding to dizziness. Caution is advised.

Possible side effects

Side effect

Frequency

Consult your doctor

Common

Rare

Only if severe

In all cases

Headache

x

x

Constipation/ diarrhoea

x

x

Dizziness/ light-headedness

x

x

Flushing in face

x

x

Palpitations

x

x

Swelling/ weight gain

x

x

Fatigue

x

x

Drowsiness

x

x

Nausea/ abdominal pain

x

x

Irregular heartbeat

x

x

Rash

x

x

Ringing in the ears

x

x

Shortness of breath

x

x

Chest pain

x

x

Interactions
Drug interactions


ACE inhibitor drugs

Possible decrease in blood pressure

Beta blocking drugs

Increased risk of heart failure

Anaesthetics

Severe low blood pressure

Drugs affecting heart rhythm

Dangerous low heart rhythms; reduce verapamil dose by 30 percent

Benzodiazepines

Benzodiazepine effects markedly increased

Anticonvulsants

Possible anticonvulsant toxicity; reduced blood pressure lowering effect

Ciclosporin

Increased risk of ciclosporin toxicity

Digoxin

Increased risk of digoxin toxicity

Rifampicin

Reduced effect of verapamil

Ritonavir

Increased risk of verapamil toxicity

Theophylline

Increased risk of theophylline toxicity

Food interactions
A low-salt, low-fat diet is advised. Alcohol may cause a drop in blood pressure; avoid grapefruit as it may increase the level of verapamil in your blood, which may lead to additional side effects.

Disease interactions
Consult your doctor before using this drug if you have a liver or kidney disease, congestive heart failure, or if you are planning surgery.

Overdose action
A small overdose is no cause for concern. In case of intentional large overdose, seek emergency medical attention.

Recommended dosage
Adults, oral: 80-120mg 3 times daily (maximum 480mg daily).


This material is not intended to substitute medical advice, but is for informational purposes only.   Please consult a physician for specific treatment and recommendations.

 
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