Mechanism of action
Antihypertensive and general anaesthetic agent.
Alpha2-adrenoreceptor agonist activates inhibitory neurons in the brainstem, reducing sympathetic outflow from the CNS.
Indications and dose
Side-effects
Bradycardia
Hypotension
May have negative inotropic effect
Constipation
Withdrawal syndrome and rebound hypertension
Depression
Dry mouth
Fatigue
Skin reactions
Delirium and hallucinations
Precautions
Caution in patients with severe cardiovascular disease or hemodynamic instability and cerebrovascular disease.
In intravenous infusion use, to avoid withdrawal syndrome and rebound hypertension, wean off gradually by 0.5 micrograms/kg/hour.
Pharmacokinetics
Routes: Oral, intravenous, transdermal
Onset of action: 0.5-1 hour (oral)
Bioavailability: 50%
Distribution: highly lipid soluble; 20-40% protein bound
Metabolism: Hepatic
Half-life of elimination: 12-16 hours
Excretion: Urine
Directions for administration
Dilute in 5% glucose or 0.9% sodium chloride.
Medicinal forms
Tablet - 1 tablet = 100 micrograms
Solution for injection - 1 vial = 1 ml (150 micrograms)
References
