Disposição cinética do atenolol em pacientes coronarianos submetidos a revascularização do miocárdio

Myocardium ischemia is an important factor of risk for mortality and cardiovascular events in the perioperative period of cardiac and non cardiac surgeries. However, the prophylactic administration of β-blocker agents could reduce these risks. Physiologic changes, occurred during the coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB), could alter plasma concentration and pharmacokinetics of many drugs. This study investigated the pharmacokinetics of atenolol in patients with unstable angina and without renal dysfunction, submitted to CABG surgery and treated chronically with atenolol PO. For pharmacokinetic analysis, 13 blood samples were collected after doses administrated pre- and post-operatively. Compared to the pre-operative period, it was verified a non-significant reduction in the apparent volume of distribution and plasma clearance after the surgery, remaining unchanged the biological half-life, p>0.05 (NS). A negative linear correlation between plasma clearance and elimination half-life was demonstrated in both periods of the study (r: -0.77 p=0.06, pre-surgery and r: -0.89, p=0.06, post-surgery), while a correlation between volume of distribution and biological half-life was established only before revascularization (r: 0.54 p=0.03, pre-surgery and r: 0.09, p=0.03, post-surgery). We suggest that the CABG surgery leads to the normalization of the extension of distribution of atenolol.