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Exercise metabolism in healthy volunteers taking atenolol, high and low doses of metoprolol CR/Z0K, and placebo.
Author(s) -
Head A,
Maxwell S,
Kendall MJ,
Eagles C
Publication year - 1994
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1994.tb04390.x
Subject(s) - metoprolol , atenolol , placebo , medicine , pharmacology , blood pressure , alternative medicine , pathology
1. Exercise and beta‐adrenoceptor blockade have important roles in the prevention and treatment of cardiovascular disease, but fatigue and a reduced capacity to exercise are commonly reported side effects of beta‐ adrenoceptor blockers. The reduced capacity to exercise may be partly caused by a reduction in fat metabolism. 2. We investigated the effects of atenolol 50 mg, metoprolol CR/Z0K 50 mg, metoprolol CR/Z0K 100 mg and placebo, on heart rate, energy expenditure, fat oxidation, plasma free fatty acids, glycerol, glucose, lactate, ammonia and perceived exertion during 2 h of treadmill walking at 40% of maximal oxygen uptake in 20 healthy volunteers. 3. Compared with placebo (38.0%), total fat oxidation was significantly lower on atenolol 50 mg (30.1%) and metoprolol CR/Z0K 100 mg (31.0%), but not on metoprolol CR/Z0K 50 mg (33.7%). Reductions in fat oxidation correlated well (r2 = 0.970) with reductions in exercising heart rate, and probably reflected the degree of beta 1‐adrenoceptor blockade. Maximum plasma ammonia concentration was reached after 45 min of exercise on atenolol, 60 min on metoprolol CR/Z0K 100, and 75 min on metoprolol CR/Z0K 50, and was higher than placebo on all active drug treatments. 4. The greater reduction in fat oxidation with atenolol may be a reflection of a peak in plasma concentration, which is avoided with a controlled release preparation.