Clonidine Hydrochloride

Indications

Clonidine Hydrochloride is used for: Hypertension, Anxiety disorders, Migraine, Panic disorder, Menopausal flushing, Hypertensive crisis, Cancer pain

Adult Dose

Oral Hypertension Adult: Initially, 50-100 mcg tid, increased every 2nd or 3rd day according to response. Maintenance: 300-1,200 mcg daily, some may require >1,800 mcg daily. Max: 2,400 mcg daily. Prophylaxis of migraine; Menopausal flushing Adult: 50 mcg bid, increased to 75 mcg bid if no remission after 2 wk.

Child Dose

<12 years old: Safety and efficacy not established

Renal Dose

Renal impairment: Supplemental doses after haemodialysis are not necessary. CrCl (ml/min) <10 50-75% of usual dose.

Administration

May be taken with or without food.

Contra Indications

Hypersensitivity. Disorders of cardiac pacemaker activity and conduction. Pregnancy and lactation.

Precautions

Withdraw gradually, renal impairment, tasks that require mental alertness. Cerebrovascular disease, ischaemic heart disease, MI. IV inj should be administered slowly. Occlusive peripheral vascular disorders, history of depression. Lactation: Distributed in breast milk; caution advised

Pregnancy-Lactation

Pregnancy category: C Lactation: Distributed in breast milk; caution advised

Interactions

Hypotensive action may be potentiated by diuretics and vasodilators. Effects of clonidine antagonised by TCAs and centrally-acting alpha-blockers. May enhance toxicity due to digitalis, lithium. May antagonise oral hypoglycaemics. Potentially Fatal: Hypnosedatives, antihistamines and alcohol may cause excessive drowsiness in patients on clonidine. Withdrawal of clonidine in patients receiving noncardioselective ?-blockers may result in rebound BP. Acute severe hypotension following concomitant administration of clonidine and chlorpromazine or haloperidol.

Adverse Effects

Side effects of Clonidine Hydrochloride : >10% Skin reactions; patch (15-50%), Dry mouth (40%), Somnolence (19-38%), Headache (19-29%), Fatigue (13-24%), Drowsiness (33%), Dizziness (13-16%), Hypotension, epidural (45%), Postural hypotension, epidural (32%), Anxiety (11%) 1-10% Constipation (10%), Sedation (10%), Nausea/vomiting, PO (5%), Malaise (3%), Orthostatic hypotension (3%), Anorexia, PO (1%), Abnormal LFTs (1%), Rash (1%), Weight gain, PO (1%) Frequency Not Defined Children with ADHD Upper respiratory tract infection, Irritability, Throat pain, Nightmares, Insomnia, Emotional disorder, Constipation, Nasal congestion Potentially Fatal: Transient hypertension or profound hypotension, respiratory depression, convulsion. Clonidine withdrawal syndrome could be life threatening. Bradycardia, coma and disturbances in conduction (in individuals with preexisting diseases of SA/AV nodes, overdose or on digitalis).

Mechanism of Action

Clonidine stimulates alpha-2 receptors in brain stem which results in reduced sympathetic outflow from the CNS and a decrease in peripheral resistance leading to reduced BP and pulse rate. It does not alter normal haemodynamic response to exercise at recommended dosages.