The bioequivalence study of folifer-Z: a new formulation of sustained-release iron and zinc

The bioequivalence of Folifer-Z tablets, a new sustained-release iron and zinc formulation was evaluated and compared to that of Fefol-Z capsules in 30 healthy male subjects. Each subject received a single oral dose of either product according to a randomized two-way crossover design. A washout period of 1 week was allowed after each treatment. Blood samples were obtained over a 24-h period, and iron and zinc concentrations were measured. The pharmacokinetic parameters of Folifer-Z were Cmax (103 +/- 46.2 micrograms/dl), Tmax (5.93 +/- 2.94 h) and AUC0-24 h (1937 +/- 706 micrograms/dl per h), whereas the corresponding Fefol-Z values were Cmax (109 +/- 41.5 micrograms/dl), Tmax (6.64 +/- 2.54) and AUC0-24 h (1865 +/- 699 micrograms/h per dl). Analysis of variance on log-transformed data for Cmax and AUC0-24 h revealed lack of significant differences among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 1.07 (90% confidence interval range: 99-115%) and for Cmax test/Cmax reference was 0.96 (90% confidence interval range: 88-105%). Regarding the zinc results, the pharmacokinetic parameters of Folifer-Z values were Cmax (101 +/- 20.7 micrograms/dl), Tmax (4.86 +/- 1.53 h) and AUC0-24 h (1944 +/- 202 micrograms/h per dl), while the corresponding Fefol-Z values were Cmax (102 +/- 20.7), Tmax (4.93 +/- 1.51) and AUC0-24 h (1953 +/- 200). Analysis of variance on log-transformed zinc data for Cmax, Tmax and AUC0-24 h revealed lack of significant difference among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 0.98 (90% confidence interval range; 95-101%) and for Cmax test/Cmax reference was 0.92 (90% confidence interval range: 89-96%). The results also indicate a possible inhibition of zinc absorption by iron content of both formulations. It is concluded that Folifer-Z product is bioequivalent to Fefol-Z product.