Withdrawal phenomena after atenolol and bopindolol: haemodynamic responses in healthy volunteers.

1. The effect of withdrawal of atenolol and bopindolol administration was studied in 12 normal volunteers; six on each drug. 2. Following sub-maximal cycle-ergometer exercise training six sets of base-line observations were made of heart-rate (HR) and blood pressure (BP) responses; supine, 60 degrees head-up tilt, during graduated isoprenaline infusion and sub-maximal cycle exercise. 3. The results show that withdrawal phenomena occur following both drug treatments. Atenolol produced a hypersensitivity to isoprenaline and a small overshoot of HR in response to physiological manoeuvres. In contrast bopindolol produced a prolonged state of reduced sensitivity to isoprenaline and some evidence of overshoot of HR with physiological manoeuvres. The differences between the responses may be explained by the different properties of the two beta-adrenoceptor blocking drugs. 4. Some subjects showed clear evidence of overshoot of HR and BP on exercise demonstrating that certain individuals may be more prone to have withdrawal effects than others. 5. The length of time during which withdrawal phenomena can occur is probably longer than has previously been realised. 6. Hormonal changes were found in the withdrawal period (Walden et al., 1990).

RCT Entities:   Population Interventions Outcomes