Effects of a Finnish sauna on the pharmacokinetics and haemodynamic actions of propranolol and captopril in healthy volunteers

Abstract

The effects of a Finnish sauna on propranolol pharmacokinetics and on the pharmacodynamics of propranolol and captopril were studied in healthy, young volunteers (2 males, 6 females) in a double-blind, cross-over trial. The subjects received single oral doses of placebo, propranolol (40 mg) or captopril (12.5 mg) in sauna and control sessions at a one-week interval. The sauna sessions consisted of three repetitive 10-min stays in a sauna (85-100 degrees C, relative humidity 25-35%) separated by two 5-min rest periods in a cool room. Sauna bathing started 35, 50 and 65 min after ingestion of the drugs. Venous blood for plasma propranolol measurement were collected before and 15, 30, 45, 60, 75, 90 min and 2, 3, 4, 5, 7 and 24 h after drug intake. The sauna significantly increased the maximum concentration (Cmax 41 vs. 28 ng.ml-1) of propranolol and the mean plasma propranolol concentration 60 and 90 min, and 2 and 3 h after drug administration. It also significantly increased the AUC0-5h (119 vs 71 micrograms.h.l-1) of propranolol from 0 to 5 hours tmax, t1/2 beta and AUC0-24h of propranolol did not differ between the control and sauna sessions. The higher propranolol levels during and after the cessation of sauna bathing did not lead to significant changes in blood pressure or heart rate compared to the control period. Captopril had no major effects on these parameters during the post-sauna phase.(ABSTRACT TRUNCATED AT 250 WORDS)