Flow-induced delivery from a drug mass

An apparatus, comprising:

• a drug reservoir configured for implantation in the body cavity of a living human and having a drug reservoir cavity, the drug reservoir cavity containing solid basic form gacyclidine not bound to a biodegradable polymer, the drug reservoir cavity configured to receive a substantially continuous flow of a fluid having an acid concentration corresponding to a desired gacyclidine dosage, the drug reservoir cavity further configured to output the substantially continuous flow of fluid entraining gacyclidine in the desired dosage;
• a catheter configured for implantation into the body cavity of a living human with the drug reservoir, the catheter including a lumen forming a conduit for the substantially continuous flow of fluid entraining gacyclidine in the desired dosage;
• and
• a terminal component coupled to the catheter and including at least one outlet in fluid communication with the catheter lumen, at least a portion of the terminal component including the outlet being configured for direct implantation into the inner ear tissue of a living human into the body cavity of which the drug reservoir and catheter have been implanted, and wherein
• the apparatus is configured to change the acid concentration, after initial placement of gacyclidine in the drug reservoir, without removal of gacyclidine from the drug reservoir, and without removal of the apparatus from the body cavity of the living human.