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The organ distribution and pharmacokinetics of DWP401, a recombinant human epidermal growth factor (rhEGF), were compared after single and repeated subcutaneous administration (50mcg/kg, 10mcCi/kg of 125I-DWP401, twice a day for 7 consecutive days) to rats. The pharmacokinetic parameters such as AUC and terminal half-life were similar between two different administration. During repeated administration, the plasma concentration of DWP401 seemed to be constant when the plasma was collected at 15 min after each dosing. The TCA-precipitated radioactivities in thyroid, liver, kidney, and stomach were higher than those of other organs studied after both single and repeated administration. The TCA-precipitated radioactivities after repeated administration in several organs, such as thyroid, stomach, prostate, adrenal, eye ball, and testis were higher than those after single administration. But, according to the observations using gel filtration chromatography and antibody binding assay, the radioactivities in thyroid and stomach were not primarily due to the intact DWP401 or its metabolites but due to the 125I-thyroxine binding protein. In conclusion, it can be suggested that DWP401 is metabolized to each amino acid or small polypeptides, and there was no significant changes in pharmacokinetics or any indications for accumulation of DWP401 in rat plasma and organs after repeated treatment.
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