From the Guidelines
Verapamil should be used with caution in patients with unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI), as it may be beneficial in relieving or preventing signs and symptoms of ischemia, but its use should be guided by the presence of specific clinical conditions, such as the absence of pulmonary edema or severe left ventricular dysfunction 1. When considering the use of verapamil in UA/NSTEMI, it is essential to weigh its potential benefits against its risks, particularly in patients with certain comorbidities. The medication has been shown to reduce myocardial oxygen demand and improve myocardial flow, which can be beneficial in patients with UA/NSTEMI 1. However, its use should be avoided in patients with pulmonary edema or evidence of severe left ventricular dysfunction, as it can worsen these conditions 1. Some key points to consider when using verapamil in UA/NSTEMI include:
- Verapamil can be used to control ongoing or recurring ischemia-related symptoms in patients who are already receiving adequate doses of nitrates and beta blockers, or in patients who are unable to tolerate these agents 1.
- The medication should be used with caution in patients with mild left ventricular dysfunction, as its effects in this population have not been extensively studied 1.
- Verapamil has been shown to have favorable effects on outcomes in meta-analyses that exclude nifedipine, suggesting that it may be a useful option for patients with UA/NSTEMI who require calcium channel blocker therapy 1. Overall, the use of verapamil in UA/NSTEMI should be guided by a careful consideration of the patient's individual clinical characteristics and the potential benefits and risks of the medication, as supported by the evidence from studies such as the Danish Study Group on Verapamil in Myocardial Infarction (DAVIT) and the Diltiazem Reinfarction Study (DRS) 1.
From the FDA Drug Label
Verapamil hydrochloride is a calcium ion influx inhibitor (slow-channel blocker or calcium ion antagonist) that exerts its pharmacologic effects by modulating the influx of ionic calcium across the cell membrane of the arterial smooth muscle as well as in conductile and contractile myocardial cells Verapamil hydrochloride dilates the main coronary arteries and coronary arterioles, both in normal and ischemic regions, and is a potent inhibitor of coronary artery spasm, whether spontaneous or ergonovine-induced Verapamil hydrochloride regularly reduces the total systemic resistance (afterload) against which the heart works both at rest and at a given level of exercise by dilating peripheral arterioles. The main use of Verapamil is as a calcium channel blocker to treat:
- Hypertension: by reducing systemic vascular resistance
- Angina: by dilating coronary arteries and reducing myocardial oxygen demand
- Arrhythmias: by slowing AV conduction and prolonging the effective refractory period within the AV node 2 Key warnings include:
- Heart failure: Verapamil can worsen heart failure in patients with severe left ventricular dysfunction
- Hypotension: Verapamil can cause decreases in blood pressure below normal levels, resulting in dizziness or symptomatic hypotension
- Elevated liver enzymes: Verapamil can cause elevations of transaminases, which may be transient or persistent 2
From the Research
Verapamil Overview
- Verapamil is a phenylalkylamine derivative that antagonizes calcium influx through the slow channels of vascular smooth muscle and cardiac cell membranes 3
- It causes coronary and peripheral vasodilation and depresses myocardial contractility and electrical activity in the atrioventricular and sinoatrial nodes 3
Therapeutic Use
- Verapamil is used in the treatment of hypertension, angina, cardiac arrhythmias, and cardiomyopathies 3, 4, 5, 6
- It is effective in lowering blood pressure in patients with mild to moderate essential hypertension 3
- Verapamil may be preferred as an alternative first-line antihypertensive treatment to diuretics in elderly patients due to its similar efficacy without causing adverse effects commonly linked with diuretic treatment 3
Pharmacologic Properties
- Verapamil has negative inotropic, chronotropic, and dromotropic effects, which distinguish it from other calcium channel blockers like nifedipine 4, 5
- It has a different mode of action from beta-adrenoceptor blockade, although both ultimately act on the free cytoplasmic calcium ion concentration 5
Side Effects and Interactions
- Common side effects of verapamil include constipation, while idiosyncratic side effects are rare but have been reported from the skin, mouth, musculoskeletal system, the liver, and the central nervous system 7
- Verapamil may increase serum digoxin concentrations and potentiate the effects of beta-adrenergic blocking drugs and neuromuscular blocking drugs 7