To assess the effective duration of action of propranolol, the heart rate response to maximal exercise was determined in six healthy male volunteers before and after abrupt drug withdrawal after a steady-state dosage of 200 mg per day had been given for seven days. The maximal work load at each exercise level, determined by the speed and angle of the treadmill, was unchanged for each individual, despite the lesser maximal heart rate response seen after propranolol was determined by subtracting the maximal heart rate at each time interval from the control value and plotting the return to the control value on semilog paper. This value was calculated to be 11.6 ± 0.58 hr. The plasma drug concentrations determined from blood specimens drawn simultaneously with the stress tests were significantly less than the biologic half-life would suggest, indicating that when propranolol is discontinued, at least 36 hours must elapse before the biologic effects of the drug are effectively dissipated.
|Original language||English (US)|
|Number of pages||6|
|State||Published - Jan 1 1978|
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine