Guanadrel. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic use in hypertension.

Guanadrel sulphate is an orally active peripheral sympathetic inhibitor (adrenergic neuron-blocking drug). In comparative studies, guanadrel was comparable in efficacy with guanethidine or methyldopa in mild to moderately severe hypertension, although generally it caused fewer central nervous system side effects than methyldopa and less orthostatic dizziness and diarrhoea than guanethidine. However, its efficacy in patients whose blood pressure remains inadequately controlled by other drugs (except diuretics alone) has yet to be adequately demonstrated. Guanadrel has a rapid onset of action and a half-life of about 10 hours, thus dose titration can be achieved more rapidly than with guanethidine, and twice daily administration is appropriate. Generally, guanadrel has been well tolerated, withdrawal of treatment due to adverse effects seldom being necessary. Thus, guanadrel appears to be a suitable alternative to methyldopa for the treatment of mild to moderately severe hypertension not controlled adequately by diuretics alone.