A class experiment in clinical pharmacology using beta-adrenoceptor antagonist drugs.
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.
Kumana
C R
CR
Ogle
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CW
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D010601:Pharmacology, Clinical / Q000193:education; D005082:Physical Exertion / Q000187:drug effects; D010869:Pindolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011897:Random Allocation; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D011433:Propranolol; D010869:Pindolol