an implantable drug delivery device comprising a microencapsulated drug contained within at least one capsule , a carrier fluid that will dissolve the drug when freed from the capsule , a drug releaser for freeing the microencapsulated drug from the capsule , a reservoir in which the carrier fluid dissolves the drug , and an electromechanical pump to convey the dissolved drug to a catheter , through which the drug is delivered to a target site within a patient .