Reservoir-based drug delivery compositions comprise an API (e.g., raloxifene, pramipexole, or lidocaine), methods of delivering the API from an implantable composition in a therapeutically effective amount to a subject, methods of treatment, subcutaneous delivery systems, and kits regarding the same. The reservoir-based drug delivery compositions may be implanted in order to deliver a therapeutically effective amount of the API to the subject for long periods of time (e.g., at least one month, at least six months, at least one year, at least 18 months, at least two years, at least 30 months, etc.). The therapeutically effective amount of API may be delivered at a pseudo-zero order rate (e.g., zero order rate).