Diltiazem hcl

Diltiazem hydrochloride is a calcium channel blocker used in the treatment of hypertension, angina pectoris, and certain types of arrhythmia. It is a benzothiazepine derivative that works by inhibiting the influx of calcium ions during membrane depolarization of cardiac and vascular smooth muscle.

Pharmacology

Mechanism of Action

Diltiazem is a non-dihydropyridine calcium channel blocker that inhibits the influx of calcium ions through L-type calcium channels. This action results in the relaxation of vascular smooth muscle and a decrease in myocardial contractility. By reducing the calcium influx, diltiazem decreases the force of contraction of the heart muscle, leading to a reduction in blood pressure and myocardial oxygen demand.

Pharmacokinetics

Diltiazem is well absorbed from the gastrointestinal tract, but it undergoes significant first-pass metabolism, resulting in a bioavailability of approximately 40%. It is highly protein-bound (70%–80%) and is metabolized in the liver by the cytochrome P450 system, primarily CYP3A4. The elimination half-life of diltiazem is approximately 3 to 4.5 hours, and it is excreted primarily in the urine.

Clinical Uses

Hypertension

Diltiazem is used to treat hypertension by relaxing the blood vessels so that blood can flow more easily. It is often used in patients who cannot tolerate beta blockers or ACE inhibitors.

Angina Pectoris

In patients with angina pectoris, diltiazem reduces myocardial oxygen demand by decreasing heart rate and contractility, and it also dilates coronary arteries, improving oxygen delivery to the heart muscle.

Arrhythmias

Diltiazem is effective in the management of certain types of arrhythmias, such as atrial fibrillation and atrial flutter, by slowing conduction through the atrioventricular node.

Adverse Effects

Common adverse effects of diltiazem include headache, dizziness, bradycardia, edema, and constipation. Serious adverse effects may include heart failure, hypotension, and hepatic dysfunction.

Contraindications

Diltiazem is contraindicated in patients with severe hypotension, cardiogenic shock, second- or third-degree atrioventricular block (unless a functioning pacemaker is present), and in patients with known hypersensitivity to the drug.

Drug Interactions

Diltiazem can interact with other medications, including beta blockers, digoxin, and statins. It may increase the plasma concentration of these drugs, leading to enhanced effects or toxicity.

Dosage and Administration

Diltiazem is available in various formulations, including immediate-release and extended-release tablets and capsules, as well as an intravenous form. The dosage varies depending on the condition being treated and the specific formulation used.

See Also

• Calcium channel blocker
• Hypertension
• Angina pectoris
• Arrhythmia

External Links

• Drugs.com: Diltiazem
• MedlinePlus: Diltiazem