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Published on: December 3, 2020
Pharmacokinetics of famotidine in infants
Larissa A Wenning1, M Gail Murphy, Laura P James
1Merck Research Laboratories, West Point, Pennslyvania, USA. larissa_wenning@merck.com
Insights
Famotidine pharmacokinetics in infants are primarily influenced by developing renal function. Clearance is lower in infants under 3 months, but similar to adults in older infants, indicating good tolerability.
Area of Science:
- Pharmacology
- Pediatric Medicine
- Drug Metabolism
Background:
- Famotidine pharmacokinetics differ in neonates due to immature renal function.
- Limited data exists on famotidine pharmacokinetics in infants aged 1 month to 1 year.
Purpose of the Study:
- To characterize the pharmacokinetics of famotidine in infants.
- To compare famotidine pharmacokinetics in infants aged 0-3 months versus >3 to 12 months.
Main Methods:
- A two-part multicenter study with single-dose (Part I) and multiple-dose (Part II) arms.
- Thirty-six infants received famotidine via intravenous or oral routes.
- Pharmacokinetic parameters were analyzed based on age groups and dosing regimens.
Main Results:
- Infants <3 months showed decreased plasma and renal clearance of famotidine compared to infants >3 months.
- Older infants (>3 months) exhibited pharmacokinetic parameters similar to children and adults.
- Dose-proportionality, no accumulation with multiple dosing, and adult-like bioavailability were observed.
Conclusions:
- Famotidine therapy is generally well-tolerated in infants.
- Maturation of renal function significantly impacts famotidine pharmacokinetics during infancy.
- Renal function is the primary determinant of famotidine elimination in infants.
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.
Design:
This was a two-part multicentre study with both single dose (Part I, open-label) and multiple dose (Part II, randomised) arms.
Patients:
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.
Conclusion:
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.
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