title: Dose-response relationship of doxapram in the therapy for refractory idiopathic apnea of prematurity.
abstract: Eighteen infants with idiopathic apnea of prematurity refractory to therapeutic levels of aminophylline were treated with incremental doses of doxapram beginning at 0.5 mg/kg/h. Continuous recording of heart rate, thoracic impedance, and transcutaneous PO2 demonstrated that 47% of the infants satisfied objective response criteria at the lowest dose, 53% responded at 1.0 mg/kg/h, 65% at 1.5 mg/kg/h, 82% at 2.0 mg/kg/h, and 89% at the highest allowed dose of 2.5 mg/kg/h. The mean serum doxapram concentration at the response dose was 2.9 +/- 1.3 micrograms/mL, and all infants who responded had levels greater than 1.5 micrograms/mL. BP was significantly elevated at doses higher than 1.5 mg/kg/h (P less than .05). Minute ventilation significantly increased and PCO2 significantly decreased as the doxapram dosage was increased (P = .02). Terminal elimination half-life was 9.9 +/- 2.9 hours. When doxapram is used for treatment of refractory neonatal apnea the starting dosage should be no more than 0.5 mg/kg/h.
mesh_terms: D001049:Apnea / Q000188:drug therapy*; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004315:Doxapram / Q000097:blood / Q000627:therapeutic use*; D006207:Half-Life; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000188:drug therapy*; D012119:Respiration / Q000187:drug effects
chemical_list: D002245:Carbon Dioxide; D004315:Doxapram