A two-part bioactive agent delivery system includes a disposable part, a reusable part, and a solvent removal element. The disposable part includes an agent reservoir, a transdermal patch communicating with the agent reservoir and adapted to transdermally deliver the bioactive agent to a user. The transdermal patch has a bottom surface adapted to contact skin of the user, a top surface opposite the bottom surface, and a gas permeable membrane disposed over the top surface of the transdermal patch. The reusable part includes a power source and control electronics that are adapted to deliver bioactive agent dissolved in a solvent from the agent reservoir to the transdermal patch. The solvent removal element includes a gap disposed between the disposable part and the reusable part to create a flow path for gaseous solvent to flow from the gas permeable membrane to ambient air around the bioactive agent delivery system.