Pharmacokinetics of mefenamic acid in preterm infants with patent ductus arteriosus.
The pharmacokinetics of mefenamic acid (MA), 2 mg/kg, were studied in 17 preterm infants with symptomatic patent ductus arteriosus. They were given this dosage orally at 24 h intervals. There were marked inter-individual differences in some of the pharmacokinetic parameters after the first dose; peak plasma concentration (Cmax) varied from 1.2 to 6.1 micrograms/mL with a mean of 3.8 micrograms/mL, time to reach Cmax (tmax) varied from 2 to 18 h with a mean of 7.7 h and plasma half-life (t1/2) varied from 3.8 to 43.6 h with a mean of 18.7 h. The group of infants (10/17) who had ductus closure after the first dose had significantly lower clearance (P < 0.01), longer t1/2 (P < 0.01) and higher 24 h plasma concentration (P < 0.001) compared to the group of infants (7/17) who had no ductus closure after the first dose. It appeared that the plasma concentration of MA had to be above 2.0 micrograms/mL and maintained at this concentration for at least 12 h for MA associated with ductus closure in preterm infants to take effect. In view of the inter-individual variation of plasma MA concentration and the effective plasma concentration, we suggest that measurement of the plasma concentration should be done 24 h after the first dose. This might be useful for safe and effective therapy for infants with ductus closure failure after the first dose.
Ito
K
K
Department of Pediatrics, Hokkaido Children's Hospital and Medical Center, Japan.
Niida
Y
Y
Sato
J
J
Owada
E
E
Ito
K
K
Umetsu
M
M
D000284:Administration, Oral; D004374:Ductus Arteriosus, Patent / Q000188:drug therapy*; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000188:drug therapy*; D008528:Mefenamic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*
D008528:Mefenamic Acid