Long-term treatment of hypertension with labetalol.

The effect of long-term treatment with labetalol was evaluated in an open clinical investigation in a total of 32 patients (15 women, 17 men), mean age 56 years (range 18-81 years). Labetalol was used in a mean daily dose of 1356 mg (range 400-3000 mg) either as mono-therapy or in combination with other drugs. Twenty-three patients were treated for more than six months, with a mean period of treatment of forty months. Thirteen of these 23 patients continue on treatment with a mean period of treatment of fifty-one months (range 6-65 months). This study does not lend support to the idea of tolerance developing to the effects of labetalol. There were no signs of liver, kidney or bone marrow involvement, and there were no changes in the retina. In 13 of the 32 patients the treatment was discontinued following subjective complaints possibly induced by the drug, partly orthostatic hypotension, and partly side effects probably related to the beta- adrenoceptor blocking effect of labetalol. Until the incidence of subjective side effects has been carefully evaluated labetalol will be used with reservations, especially as a first choice in the treatment of hypertension.