Carvedilol

It is an arylethanolamine non-specific b-adrenoreceptor antagonist with a1-blocking activity. It exerts antihypertensive effect partly by reducing total peripheral resistance and vasodilation by blocking a1 adrenoreceptors and by inhibiting b-adrenoreceptor-mediated compensatory mechanisms.

Indications

Hypertension and congestive heart failure.

Dosage

Hypertension : Initially 6.25 mg twice daily. If tolerated, after 7-14 days, increase to 12.5mg twice daily if needed. If needed again increase the dose up to 25 mg twice daily, after 7-14 days. Max. total daily dose 50mg. Congestive heart failure : Start with 3.125 mg twice daily for 2 weeks. If tolerated, raise to 6.25mg twice daily and then double the dose every 2 weeks to the level tolerated by patients. Max. dose is 25mg and 50mg for patients weighing less than 85 kgs and more than 85 kgs respectively.

Contra-Indications

Hypersensitivity, Patients with NYHA class IV decompensated cardiac failure requiring IV inotropic therapy, bronchial asthma, second or third-degree AV block, Sick Sinus syndrome, cardiogenic shock or severe bradycardia, severe hepatic impairment, lactation.

Special Precautions

Before starting the treatment, laboratory confirmation of liver injury is very much essential. Abrupt withdrawal of b-blockers may result in exacerbation of the symptoms of hyperthyroidism. During the initiation of therapy, avoid driving or operating machinery. Pregnancy: Safety not established. Children: Safety not established.

Side Effects

Increased sweating, fatigue, oedema, bradycardia, hypotension (including postural), hyperglycaemia, hypercholesterolemia, bronchitis, insomnia, impotency, skin reactions, tinnitus, anaemia and even sudden death.

Drug Interactions

Rifampicin decrease while cimetidine increase the AUC & Cmax of carvedilol. Increase in Steady-state AUC and trough concentration of digoxin. Catecholamine-depleting agents & beta-receptors blockers results in hypotension or severe bradycardia.