title: Relative bioavailability of carnitine supplementation in premature neonates.
abstract: BACKGROUND
  Carnitine is an important nutrient in the infant diet. We compared total plasma carnitine concentrations in premature neonates supplemented with carnitine via parenteral and enteral nutrition.
  
  
  METHODS
  This is a post hoc analysis of plasma total carnitine concentrations and carnitine intake in neonates randomized in a previous study to receive 20 mg/kg/d carnitine supplementation over 8 weeks. Neonates received l-carnitine initially via parenteral nutrition (PN). When neonates were fed enterally, oral supplementation of l-carnitine was given in divided doses with each feeding.
  
  
  RESULTS
  Sixteen neonates (27 +/- 2 weeks gestation; 2.9 +/- 1.0 days postnatal age at enrollment; 965.6 +/- 279.1 g birth weight) are included. Concentrations were below reference range (31.1-60.5 nmol/mL) at baseline and exceeded reference range from week 1 through the last study period. Concentrations were not different from week 1 (108 +/- 49) through weeks 4 (87 +/- 34) and 8 (83 +/- 31). Carnitine intakes and concentrations were compared in neonates receiving 100% parenteral carnitine at week 1 (n = 6) and 100% enteral carnitine at week 8 (n = 8). Concentrations at week 1 (100.1 +/- 27.9) were not different (p = .19) from week 8 (78.6 +/- 29.3); an estimate of relative bioavailability was 78.6%. Bioavailability with paired analysis of neonates (n = 5) receiving 100% parenteral carnitine at week 1 and 100% enteral carnitine at week 8 was 83.7% +/- 41.2% (30.1%-140.6%).
  
  
  CONCLUSIONS
  Parenteral and enteral supplementation of 20 mg/kg/d carnitine results in plasma total carnitine concentrations that exceed the reference range. Concentrations are not different between parenteral to enteral supplementation, suggesting that enteral carnitine is well absorbed when given daily in divided doses with enteral feedings.
authors.affiliation: Department of Pharmacy, Center for Pediatric Pharmacokinetics and Therapeutics at the University of Tennessee Health Science Center, Memphis, 38163, USA. ccrill@utmem.edu
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Crill
authors.forename: Michael L
authors.initials: ML
authors.lastname: Christensen
authors.forename: Michael C
authors.initials: MC
authors.lastname: Storm
authors.forename: Richard A
authors.initials: RA
authors.lastname: Helms
mesh_terms: D001682:Biological Availability; D002331:Carnitine / Q000493:pharmacokinetics*; D019587:Dietary Supplements; D004750:Enteral Nutrition; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D008297:Male; D010288:Parenteral Nutrition; D016896:Treatment Outcome; D014803:Vitamin B Complex / Q000493:pharmacokinetics*
chemical_list: D014803:Vitamin B Complex; D002331:Carnitine