Drug delivery devices and methods of controlled drug delivery to a patient are provided. The drug delivery device may include one or two microchip elements, each of which has a body portion with one or more drug release apertures in fluid communication with at least one containment reservoir. The drug release apertures are closed off by one or more reservoir caps which can be electrically activated to open the drug release apertures. The drug delivery device also includes (i) a drug formulation disposed in the at least one containment reservoir, and (ii) at least one drug-permeable membrane. In some cases, an outer housing is spaced a distance from an exterior wall of the body portion of the microchip element, the outer housing includes the at least one drug-permeable membrane, and a depot space is defined between the drug-permeable membrane and the exterior wall of the body portion of the microchip element.