Different elemental infant formulas show equivalent phosphorus and calcium bioavailability in healthy volunteers

Abstract

Retrospective chart reviews have reported hypophosphatemia associated with elemental formula use in infants and children with systemic disease involving multiple diagnoses. The present study aims to evaluate the bioavailability of phosphorus from 2 commercial elemental formulas and to test our hypothesis of bioequivalence of the 2 products in healthy volunteers receiving gastric acid-suppressive medication. A single-center, double-blind, randomized, cross-over study was conducted in healthy volunteers with esomeprazole-induced hypochlorhydria. After a standardized low phosphorus meal followed by overnight fasting, subjects consumed 1 gram of phosphorus in a single oral dose of 1217 kcal of Product A (Neocate) or Product B (Elecare). The alternate product was given following a 1-week washout period. Blood and urine were collected at baseline and different time-points for up to 6 hours after product consumption. Area-under-the-curve (AUC) and peak values (C_peak) for serum phosphate and calcium and urinary creatinine-corrected phosphate and calcium were assessed for bioequivalence of Products A and B. Results show that the geometric mean ratio (GMR) and 90% CI for serum phosphate were 1.041 (0.998-1.086) and 1.020 (0.963-1.080) for AUC_0-360 and C_peak, respectively, meeting the predetermined criteria for bioequivalence. Urinary creatinine-corrected phosphate followed a similar pattern after intake of Product A and B, but did not reach bioequivalence criteria (GMR: AUC_70-370 = 1.105 (0.918-1.330); C_peak = 1.182 (1.040-1.343)). Serum calcium concentrations (GMR: AUC_0-360 = 1.002 (0.996-1.009); C_peak = 0.991 (0.983-0.999)) and urinary creatinine-corrected calcium excretion (GMR: AUC_70-370 = 1.117 (1.023-1.219); C_peak = 1.157 (1.073-1.247)) demonstrated bioequivalence of the products. In conclusion, both elemental infant formulas showed equivalent serum phosphorus and calcium bioavailability in healthy volunteers even if combined with treatment with acid-suppressive medication.

Keywords: Amino acid-based formula; Cow's milk allergy; Cross-over study; Neocate; Phosphate.