Use of famotidine in pediatric patients <1 year of age is supported by evidence from adequate and well-controlled studies of famotidine in adults, and by the following studies in pediatric patients <1 year of age.   
  
Two pharmacokinetic studies in pediatric patients <1 year of age (N=48) demonstrated that clearance of famotidine in patients >3 months to 1 year of age is similar to that seen in older pediatric patients (1 to 15 years of age) and adults. In contrast, pediatric patients 0 to 3 months of age had famotidine clearance values that were 2- to 4-fold less than those in older pediatric patients and adults. These studies also show that the mean bioavailability in pediatric patients <1 year of age after oral dosing is similar to older pediatric patients and adults. Pharmacodynamic data in pediatric patients 0 to 3 months of age suggest that the duration of acid suppression is longer compared with older pediatric patients, consistent with the longer famotidine half-life in pediatric patients 0 to 3 months of age. (See CLINICAL PHARMACOLOGY IN PEDIATRIC PATIENTS, Pharmacokinetics and Pharmacodynamics. )   
  
In a double-blind, randomized, treatment-withdrawal study, 35 pediatric patients <1 year of age who were diagnosed as having gastroesophageal reflux disease were treated for up to 4 weeks with famotidine oral suspension (0.5 mg/kg/dose or 1 mg/kg/dose). Although an intravenous famotidine formulation was available, no patients were treated with intravenous famotidine in this study. Also, caregivers were instructed to provide conservative treatment including thickened feedings. Enrolled patients were diagnosed primarily by history of vomiting (spitting up) and irritability (fussiness). The famotidine dosing regimen was once daily for patients <3 months of age and twice daily for patients ≥3 months of age. After 4 weeks of treatment, patients were randomly withdrawn from the treatment and followed an additional 4 weeks for adverse events and symptomatology. Patients were evaluated for vomiting (spitting up), irritability (fussiness) and global assessments of improvement. The study patients ranged in age at entry from 1.3 to 10.5 months (mean 5.6 ± 2.9 months), 57% were female, 91% were white and 6% were black. Most patients (27/35) continued into the treatment-withdrawal phase of the study. Two patients discontinued famotidine due to adverse events. Most patients improved during the initial treatment phase of the study. Results of the treatment-withdrawal phase were difficult to interpret because of small numbers of patients. Of the 35 patients enrolled in the study, agitation was observed in 5 patients on famotidine that resolved when the medication was discontinued; agitation was not observed in patients on placebo (see ADVERSE REACTIONS,  Pediatric Patients).   
  
These studies suggest that a starting dose of 0.5 mg/kg/dose of famotidine oral suspension may be of benefit for the treatment of GERD for up to 4 weeks once daily in patients <3 months of age and twice daily in patients 3 months to <1 year of age; the safety and benefit of famotidine treatment beyond 4 weeks have not been established. Famotidine should be considered for the treatment of GERD only if conservative measures (e.g., thickened feedings) are used concurrently and if the potential benefit outweighs the risk.