Siratiazem

Siratiazem is a calcium channel blocker used primarily in the treatment of hypertension and angina pectoris. It is a member of the benzothiazepine class of calcium channel blockers, which also includes diltiazem.

Mechanism of Action

Siratiazem works by inhibiting the influx of calcium ions through L-type calcium channels in the cardiac and smooth muscle cells. This action results in the relaxation of vascular smooth muscle, leading to vasodilation and a subsequent decrease in blood pressure. In the heart, it reduces myocardial contractility and slows down the conduction of electrical impulses through the atrioventricular node, which can help in managing arrhythmias.

Pharmacokinetics

Siratiazem is well absorbed from the gastrointestinal tract, with a bioavailability of approximately 40-60% due to first-pass metabolism in the liver. It is extensively metabolized by the cytochrome P450 enzyme system, particularly CYP3A4. The elimination half-life of Siratiazem is about 3 to 5 hours, and it is excreted primarily in the urine.

Clinical Uses

Siratiazem is indicated for the management of:

• Hypertension
• Chronic stable angina
• Variant angina (Prinzmetal's angina)
• Certain types of supraventricular tachycardia

Adverse Effects

Common side effects of Siratiazem include:

• Headache
• Dizziness
• Flushing
• Peripheral edema
• Bradycardia

Serious adverse effects may include:

• Heart failure
• Atrioventricular block
• Severe hypotension

Drug Interactions

Siratiazem can interact with other medications, including:

• Beta-blockers: May increase the risk of bradycardia and heart block.
• Digoxin: May increase digoxin levels.
• CYP3A4 inhibitors: May increase the plasma concentration of Siratiazem.

Contraindications

Siratiazem is contraindicated in patients with:

• Severe hypotension
• Second- or third-degree atrioventricular block (without a pacemaker)
• Sick sinus syndrome (without a pacemaker)

Also see

• Calcium channel blocker
• Hypertension
• Angina pectoris
• Diltiazem
• Verapamil