Abstract

Objective: This study was performed to evaluate serum creatine kinase (CK) levels during tocolytic therapy. Methods: A retrospective study was performed in 27 patients who were treated with intravenous tocolytic agents for more than one week. The first-line tocolytic agent was ritodrine hydrochloride, followed by concomitant magnesium sulfate (MgSO₄). The serum CK level was measured on admission and every week thereafter. The patients were divided into the normal CK (group 1) and abnormal CK (> 150 IU/L) (group 2) groups. Results: Seventeen patients received both ritodrine hydrochloride and MgSO₄. The CK levels in all patients rose significantly from 58.4 ± 30.8 IU/L on admission 116.0 ± 68.7 IU/L on day 7 (p = 0.002). Abnormal elevation of CK occurred in 7 (25.9%) of the 27 patients. Significant differences were found between groups 1 and 2 in the total doses of ritodrine and MgSO₄ (p = 0.046 and 0.0028, respectively). All patients in group 2 received ritodrine in combination with MgSO₄ (p = 0.018). Conclusion: When tocolytic therapy continued for more than 1 week, nearly one-fourth of patients showed an increase in CK level above the normal range.