RESUMO
Erlotinib shows pH-dependent solubility and its absorption is decreased in patients receiving gastric acid suppression therapy. Here, we examined whether administration of erlotinib in acidic solutions would improve its solubility and absorption characteristics. In vitro, the solubility of erlotinib in HCl solution increased with decreasing pH, and was far higher than that in tap water. The solubility in apple juice (pH 3.7) was higher than that in HCl solution of the same pH. In vivo, the absorption of erlotinib administered in tap water was decreased in omeprazole-treated (OP) rats, used as a model of gastric acid suppression, compared to control rats. In the OP rats, the plasma concentrations in the groups given erlotinib in apple juice and in HCl (pH 3.7) were significantly higher than in the tap water group in the initial phase of absorption. AUC in OP rats given erlotinib in apple juice was 1.69-fold larger than that of control rats given erlotinib in tap water, and 2.49-fold larger than that of OP rats given erlotinib in tap water. Thus, administration of erlotinib in an acidic beverage to patients receiving gastric acid suppression therapy might be effective to increase solubility and absorption.