Comparison of sustained-release and standard preparations of clonidine in essential hypertension

The antihypertensive drug, clonidine, was administered to 18 patients, 8 females and 10 males, with WHO grade I-II essential hypertension in two forms, either as sustained-release depot capsule of 250 micrograms once daily or as standard clonidine preparation, 150 micrograms twice daily. The two drug forms were administered for 2 months each, in a double-blind, crossover outpatient study. Both preparations were equally effective in reducing blood pressure. The depot form of clonidine was preferred by the patients because of fewer side effects, which included sedation and dry mouth. The antihypertensive effect of clonidine was unrelated to pretreatment plasma renin activity. Depot forms of clonidine appear to offer the advantages of once-daily dosing and fewer side effects than standard clonidine preparations.