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Action/Kinetics:
Stimulates alpha-2-adrenergic receptors in the CNS, resulting in a decrease in sympathetic impulses and in sympathetic tone. It also decreases the pulse rate, but postural hypotension has not been manifested.
Onset: 60 min.
Peak effect: 2-4 hr.
Peak plasma levels: 2-5 hr.
t
1/2: 6 hr.
Duration: 8-12 hr.
Uses:
Hypertension, alone or as adjunct with thiazide diuretics.
Contraindications:
Lactation, children under 12 years of age.
Special Concerns:
Use with caution in severe coronary insufficiency, cerebrovascular disease, recent MI, hepatic or renal disease. Geriatric clients may be more sensitive to the hypotensive and sedative effects; dose reduction may be necessary due to age-related decreases in renal function. Sudden cessation may result in an increase in catecholamines and, rarely, "overshoot" hypertension.
Side Effects:
CNS: Drowsiness and sedation (common), dizziness, weakness, headache, ataxia, depression, disturbances in sleep, excitement.
GI: Dry mouth (common), N&V, diarrhea, constipation, abdominal discomfort, epigastric pain.
CV: Palpitations, chest pain, arrhythmias, AV dysfunction or block.
Dermatologic: Rash, pruritus.
Miscellaneous: Edema, blurred vision, muscle aches, dyspnea, nasal congestion, urinary frequency, gynecomastia, disturbances of sexual function, taste disorders, aches in extremities.
Overdose Management:
Symptoms: Hypotension, sleepiness, irritability, miosis, lethargy, bradycardia.
Treatment: Supportive treatment. VS and fluid balance should be monitored. Syrup of ipecac or gastric lavage followed by activated charcoal; administration of fluids, pressor agents, and atropine. Maintain an adequate airway; artificial respiration may be required.
Drug Interactions:
Additive sedation with CNS depressants.
How Supplied:
Tablet: 4 mg, 8 mg
Dosage
?Tablets
Hypertension.
Adults, initial: 4 mg b.i.d. alone or with a thiazide diuretic;
then, increase by 4-8 mg/day q 1-2 weeks until control achieved. Maximum recommended dose: 32 mg b.i.d.