title: Pharmacokinetics of famotidine in infants.
abstract: BACKGROUND
  Although famotidine pharmacokinetics are similar in adults and children older than 1 year of age, they differ in neonates owing to developmental immaturity in renal function. Little is currently known about the pharmacokinetics of famotidine in infants aged between 1 month and 1 year, a period when renal function is maturing.
  
  
  OBJECTIVE
  To characterise the pharmacokinetics of famotidine in infants.
  
  
  METHODS
  This was a two-part multicentre study with both single dose (Part I, open-label) and multiple dose (Part II, randomised) arms.
  
  
  METHODS
  Thirty-six infants (20 females and 16 males) who required treatment with famotidine and who had an indwelling arterial or venous catheter for reasons unrelated to the study.
  
  
  METHODS
  Infants in Part I were administered a single dose of famotidine 0.5 mg/kg; the dose was intravenous or oral according to the judgement of the attending physician. Infants receiving 0.5 mg/kg intravenously were divided into two groups by age, and pharmacokinetic parameters in infants 0-3 months and >3 to 12 months of age were compared. Infants in Part II were randomised to one of the following treatments: 0.25 mg/kg/dose intravenously or 0.5 mg/kg/dose orally on day 1 and subsequent days, or 0.25 mg/kg/dose intravenously or 0.5 mg/kg/dose orally on day 1 followed by doses of either 0.5 mg/kg/dose intravenously or 1 mg/kg/dose orally on subsequent days. From day 2 onwards, age-adjusted dose administration regimens (once daily in infants <3 months of age and every 12 hours in infants >3 months of age) were used; the total number of famotidine doses ranged from 3 to 11 and the total number of days of dose administration ranged from two to eight.
  
  
  RESULTS
  In infants <3 months of age, plasma and renal clearance of famotidine were decreased compared with infants >3 months of age. Pharmacokinetic parameters for the older infants (i.e. those >3 months) were similar to those previously reported for children and adults. Approximate dose-proportionality, no accumulation on multiple dosing and an estimated bioavailability similar to adult values were also observed.
  
  
  CONCLUSIONS
  A short course of famotidine therapy in infants appears generally well tolerated, and the characteristics of famotidine pharmacokinetics during the first year of life are explained to a great degree by the development of renal function, the primary route of elimination for this drug.
authors.affiliation: Merck Research Laboratories, West Point, Pennslyvania, USA. larissa_wenning@merck.com
authors.forename: Larissa A
authors.initials: LA
authors.lastname: Wenning
authors.forename: M Gail
authors.initials: MG
authors.lastname: Murphy
authors.forename: Laura P
authors.initials: LP
authors.lastname: James
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Blumer
authors.forename: James D
authors.initials: JD
authors.lastname: Marshall
authors.forename: John
authors.initials: J
authors.lastname: Baier
authors.forename: Ann O
authors.initials: AO
authors.lastname: Scheimann
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Panebianco
authors.forename: Ling
authors.initials: L
authors.lastname: Zhong
authors.forename: Roy
authors.initials: R
authors.lastname: Eisenhandler
authors.forename: Kuang C
authors.initials: KC
authors.lastname: Yeh
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Kearns
mesh_terms: D000284:Administration, Oral; D019540:Area Under Curve; D001682:Biological Availability; D015738:Famotidine / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D005260:Female; D005764:Gastroesophageal Reflux / Q000188:drug therapy; D006207:Half-Life; D006635:Histamine H2 Antagonists / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007275:Injections, Intravenous; D008297:Male; D008657:Metabolic Clearance Rate
chemical_list: D006635:Histamine H2 Antagonists; D015738:Famotidine