Serum creatine phosphokinase levels during treatment with beta-adrenoreceptor blocking agents

We administered four beta-adrenoreceptor blocking agents--pindolol (15 mg/day), propranolol (60 mg/day), carteolol (15 mg/day), and labetalol (150 mg/day)--to essential hypertensive patients, and followed the changes in levels of serum creatine phosphokinase (CPK) and its isoenzymes for 1 year. Blood pressure was reduced almost equally by all drugs, but the changes in serum CPK levels differed. During treatment with pindolol, 20 of 25 patients showed a 20-760% increase in CPK compared with the pretreatment value. Studies on CPK isoenzymes revealed that the elevation was mainly in the skeletal muscle (MM type), while eight of the 25 patients also showed a slight increase in the myocardial type (MB type). Another beta-blocking agent with intrinsic sympathomimetic activity (ISA), carteolol, also increased the CPK levels significantly in 10 of 15 patients. On the other hand, such increases were observed in only four of 27 patients receiving propranolol and three of nine patients receiving labetalol. These results suggest that beta-blocking agents with ISA increase the serum CPK levels more frequently than those without ISA. Therefore, the serum CPK levels should be carefully evaluated in patients receiving beta-blocking agents, especially those with ISA.