3. Clonidine: Wallace II

Clonidine treated patients had half as much myocardial ischemia as placebo treated patients. When the clonidine patch was removed on post operative day 4, there may have been withdrawal phenomena that led to the loss of statistically significant differences in incidence of myocardial ischemia. On post-operative days 6 and more there was once again an improvement in the incidence of myocardial ischemia in the clonidine group. In the Mivazerol study with holter monitoring (Perioperative sympatholysis. Beneficial effects of the alpha 2-adrenoceptor agonist mivazerol on hemodynamic stability and myocardial ischemia. McSPI--Europe Research Group. Anesthesiology 1997; 86: 346-63) there was evidence of withdrawal phenomena with another alpha-2 agonist (mivazerol). In the larger trial Mivazerol (Oliver MF, Goldman L, Julian DG, Holme I: Effect of mivazerol on perioperative cardiac complications during non- cardiac surgery in patients with coronary heart disease: the European Mivazerol Trial (EMIT). Anesthesiology 1999; 91: 951-61) improved survival in subgroup analysis but will not be clinically available.

Withdrawal phenomena with alpha-2 agonists is possible. Do no discontinue patients who are on preoperative clonidine in the perioperative period. If you use clonidine for perioperative cardiac risk reduction therapy (BBAC) just leave the patch on and it will autotaper as it runs out of drug.