EFFECT OF COMBINED ATENOLOL AND NIFEDIPINE ADMINISTRATION ON PSYCHOMOTOR PERFORMANCE IN NORMAL SUBJECTS

The aim of the present study was to evaluate the central effects of si ngle doses of the P-adrenoceptor antagonist atenolol and the calcium a ntagonist nifedipine retard, alone and in combination, in normal subje cts. Twelve normal males received single oral doses of atenolol 100 mg , nifedipine retard 20 mg, atenolol 100 mg and nifedipine retard 20 mg in combination, diazepam 5 mg (active control), and each of two match ing placebos in a double-blind, randomised fashion. Psychomotor perfor mance was assessed using digit symbol substitution, letter cancellatio n (LCT), continuous attention, choice reaction time, finger tapping, i mmediate recall and short-term memory. Two flash fusion and critical f licker fusion thresholds were measured and subjective assessments made using visual analogue scales (VAS). Diazepam 5 mg significantly worse ned LCT scores at 4h, significantly impaired alertness at 2 h and 4 h, and tended to increase reaction time and impair continuous attention and physiological measurements. Atenolol 100 mg alone significantly re duced alertness at 2 h and 4 h, and also tended to impair physiologica l measurements. Nifedipine retard 20 mg produced no significant psycho motor effects. Combined atenolol and nifedipine retard administration produced a small but significant improvement in continuous attention a nd a reduction in body sway, with no adverse effects being evident on performance or subjective awareness. The results suggest that no signi ficant adverse effects on psychomotor performance are produced by sing le doses of atenolol 100 mg and nifedipine retard 20 mg when given tog ether in normal subjects. The combination may therefore be useful in t he treatment of hypertensive patients requiring dual therapy, and in w hom adverse central effects are of particular importance.