Blood potassium and urine aldosterone after doxapram therapy for preterm infants

We often encounter infants who developed hypokalaemia following low-dose doxapram for apnea of prematurity (AOP). To determine changes in blood potassium (K+) levels after doxapram administration. We studied infants born before 30 weeks gestation. Doxapram (0.1–0.3 mg/kg/h) in addition to methylxanthines was used to treat AOP refractory to methylxanthines. Twenty-five infants received doxapram were studied. Fifty-two percent developed hypokalemia (<3.0 mEq/L) during doxapram administration. Time after starting doxapram to nadir blood K+ (<3.0 mEq/L) level was 11 days. Blood K+ levels normalized after 5 days of stopping doxapram administration. Data at 10 days before and after and at the time of doxapram administration were, respectively: lowest blood K+ level: 3.9, 3.0, and 3.6 mEq/L; urine aldosterone: 90, 206, and 146 pg/μg creatinine. Blood pH, blood pressure and urine volume were similar. Doxapram-induced hypokalemia may be due to an inappropriate increase in aldosterone levels.