Abstract: The in situ gel loaded with phosphodiesterase Type V (PDE5) inhibitors nanoemulsion was prepared using an innovative approach to reformulate the PDE5 inhibitors in a nanoemulsion, and then loading the nanoemulsion into an in situ gel base. These preparations are administered by intramuscular injection in order to give a depot effect for a period of time that exceeds 15 days. The in situ gel composition gives slow, controlled release of the PDE5 inhibitor. The in situ gel composition is useful for prophylaxis and treatment of some important chronic diseases, such as diabetic complications, benign prostatic hyperplasia, erectile dysfunction, and diseases associated with endothelial dysfunction.