Time-dependent change in the effect of probucol in subjects with elevated cholesterol

A time-dependent change in the cholesterol-lowering effect of probucol has been evaluated in 20 subjects with elevated cholesterol. Probucol 500 mg was given once daily at 07.00 h (day trial) or 19.00 h (night trial) for 3 months according to a crossover design. Fasting blood samples were obtained during the control period and at the end of each treatment period. Serum concentrations of total and HDL-cholesterol were significantly decreased by both the treatments with probucol [total cholesterol (mmol.l-1): control 6.58; day trial 5.41; night trial 5.10; HDL-cholesterol (mmol.l-1): control 1.35; day trial 1.06; night trial 0.96]. These parameters were significantly lower in the night trial than in the day trial. The data indicate that the cholesterol-lowering effect of probucol varies with its time of administration in subjects with elevated cholesterol.