A drug composition comprising a charged moiety coupled to a therapeutic compound is disclosed. The charged moiety is configured to interact with at least one type of component of opposite charge in a biological tissue to create an in situ depot for prolonged drug delivery. The biological tissue may be eye tissue or any tissue containing charged components. Further, a method of treating the human body is disclosed. The method is for introducing into a human body a drug composition comprising a charged moiety coupled to a therapeutic compound. Introduction may be through injection. A method of manufacturing a drug composition comprising a charged moiety coupled to a therapeutic compound is also disclosed.
