A class experiment in clinical pharmacology using beta‐adrenoceptor antagonist drugs.

Abstract

Cardiac beta‐adrenoceptor blocking activity was evaluated in a between‐ subject study carried out as a class experiment with pre‐clinical medical students participating in a practical pharmacology course. From each of 10 groups of students, three healthy male volunteers, took oral propranolol 80 mg, pindolol 10 mg or placebo, according to a double‐ blind randomised protocol. Pre‐treatment, and 45‐60 min (1 h) and 105‐ 120 min (2 h) post‐treatment heart rate (HR) was determined electrocardiographically in the last 15 s during periods of rest (sitting for 5 min), isometric exercise (applying a standardized hand grip to a rolled sphygmomanometer cuff to elevate pressure from 50 to 150 mm Hg; 2 min) and dynamic exercise (bicycle ergometry with a load of 150 W for 3 min). Reductions from pre‐treatment HR yielded statistically significant differences during exercise (isometric and dynamic) between all corresponding changes on placebo and active drugs (P less than 0.05‐0.01), except with the 1 h post‐propranolol hand grip HR. At rest, only the difference between 2 h HR changes on placebo and propranolol achieved statistical significance (P = 0.05); presumably, the partial agonist activity of pindolol overcame any minimal HR slowing liable to occur at rest. Cardiac beta‐adrenoceptor blocking activity as judged by reductions in HR from pretreatment values, was more evident during cycling than during hand grip; and during hand grip than at rest. 1985 The British Pharmacological Society