Tibalosin: an effective antihypertensive agent both alone and in combination with atenolol

26 outpatients aged 24·62 (mean 42.3) years with essential hypertension (diastolic BP 85·115mm Hg) received the a'antagonist tibalosin [CP 1068S; CP 804S; Monsanto] 50mg capsules, 1 in the morning and 2 at dinner, for 1 month after a l·month placebo run·in. Mean supine BP decreased significantly from 157/101 to 147/94mm Hg and mean supine heart rate from 74 to 68 beats/min after 1 month of tibalosin treatment . Four patients withdrew because of side effects, BUN levels increased and urinary aldosterone levels decreased significantly during the study.

The remaining 10 with diastolic BP uncontrolled by tibalosin continued on the drug and received placebo, atenolol 100mg or chlorthalidone 50mg for 1 month In randomised double·bltnd fashion . Compared With tibalosin + placebo, tibalosin + atenolol further lowered BP (from 148/97 to 140/90) and heart rate (from 70 to 60 beats/min). The addition of chlorthalidone did not lower BP further .

Compared with placebo, more patients receiving tibalosin alone or in combination experienced somnolence, weary legs and dry mouth. With tibalosin alone the frequency of passing stools was increased (p < 0,05 vs placebo). Compared with placebo, haemoglobin and plasma renin decreased significantly with tibalosin monotherapy; serum potassium increased significantly and plasma renin and urinary aldosterone decreased significantly with tibalosin + atenolol therapy . Haemoglobin, erythrocyte count , uric acid, plasma renin, urinary aldosterone and urinary kallikrein increased significantly and serum potassium and chloride levels decreased significantly with tibalosin + chlorthalidone therapy.

The treatments appeared well tolerated but ' ... the combination of tibalosine [tibalosin] with a beta-adrenergic blocking agent might be more eHective in reducing blood pressure than the association with a thiazide'.

Slaessen U, Fagard R, Fiocchi R. Lijnen p, M'Buyamba UR Archives InlernallOl18les de Pharmacodynamle el de TMraple 279' 162· 176. Jan 1986

6 INPHARMA'" 7 June 1986 0156·2703/ 86/ 0607.0006/ 0$0100/ 0 © ADIS Press