Various embodiments of the present invention are directed to patches for medical devices. In various embodiments, an adhesive patch of a medical device may have selective areas with adhesive material of varying adhesion strengths. In other embodiments, an adhesive patch of a medical device may include adhesive material that may be activated by a catalyst to increase or decrease the adhesion strength of the adhesive material. In further embodiments, a medical device may include a pierceable membrane containing an agent, the pierceable membrane positioned to be pierced by a needle and to cause some of the agent to be carried to the user-patient.