A method for administering chemotherapy medicament, which comprises providing a closed-system drug administration kit, performing sterile catheterization on a patient by placing at least the distal tip of the catheter into the patient's bladder to drain the bladder, inserting a syringe containing the medicament into a safety adapter at a proximal end of the catheter to prevent leakage during attachment, injecting the medicament into the bladder with the injector through the adapter and the drain lumen without leakage of the medicament from the patient into an environment while assessing a pain level of the patient, removing the syringe and closing the catheter to hold the medicament in the bladder for a given treatment time, and, after the given treatment time, draining the medicament out of the bladder with a medicament pressure reservoir through the catheter and into the medicament pressure reservoir for disposal of the kit.
