Optimum dosage of lidocaine.

Lidocaine dosage recommendations vary widely. Severe heart failure adds to risk factors when attempting to reach the optimal therapeutic blood level. Fifty-two coronary care unit (CCU) patients, who were treated with lidocaine infusion after an initial bolus injection of 100 mg, were randomly selected for the study. Blood samples were drawn at 2, 6 and 18 h. The material was divided into four groups according to infusion rates: Group A (n = 15) 4 mg/min for 3 h and then 3 mg/min for 15 h, Group B (n = 10) 4 mg/min for 3 h and then 2 mg/min for 15 h, Group C (n = 9) 2 mg/min for 18 h and Group D (n = 18) according to clinical situation by a mean rate of 3.3 mg/min for 2 h, 2.5 mg/min for 4 h and 2.15 mg/min for 12 h. The mean serum lidocaine concentrations were in optimum therapeutic range of 2-4 mg/l in Groups A, B and D at every sampling time point. Percentage of the patients whose lidocaine concentrations at each sampling time were within the optimum range as follows: Group A 72, 67 and 52, Group B 70, 70 and 56%, Group C 0, 38 and 63% and Group D 38, 38 and 30%. Our material indicates that the optimal lidocaine infusion rate for CCU patients should be as in Group B.