A Drug Delivery System for Treating Erectile Impotence: A Preliminary Communication
Authors: CARTER PAUL G. , JOYCE ADRIAN D. , DICKINSON IAN K. , PACKHAM DEREK A. , PRYOR JOHN P. , BRINDLEY GILE S. 
Published: October 2023

ABSTRACT: This report describes the use of a novel, implanted, intracavernosal drug delivery system for use in men with erectile failure. The first totally implanted, small volume, subcutaneous injection devices were reported in 1982 (Gyves et al, 1982; Niederhuber et al, 1982) and were used for intravascular administration of chemotherapeutic agents In malignant disease. This principle was then applied to the injection of Intracorporeal, vasoactive agents by Desai et al (1987) who described three patients in whom a subcutaneous drug delivery system had been Implanted. Later, Helmy (1991) described 37 patients successfully treated with a similar device where the injection portal was placed over the gluteal region.

The unit consists of a ceramic frame covered with silicone rubber containing a central reservoir (that has an access port for filling at the base). The frame reservoir has a tubing connector for intracorporeal Implantation. Under general anesthetic, an oblique penoscrotal incision Is made and the tunica albuginea of the corpus cavernosum on the selected side is exposed. Through a small stab corporotomy, the cannula is inserted over a metal introducing rod and embedded into the erectile tissue to a depth of 2.8 mm. A pouch is then created between the testes using blunt dissection and the reservoir inserted Into this, the pump being placed anteriorly. At this stage, the reservoir is filled with normal saline only, with a view to replacing this with vasoactive agent after 6 weeks.

After 6 weeks, the reservoir is filled (by introducing a fine needle through the scrotal skin into the self‐sealing port) and the system activated by depressing the pump between the patient's thumb and forefinger. Most patients require between two and four pumps to obtain an erection adequate for penetrative intercourse. Using a vasoactive mixture containing 3.3 mg phentolamine and 1.7 mg verapamil per ml, four activations would deliver approximately 2.2 mg phentolamine and 1.12 mg verapamil. The reservoir has an average capacity for approximately 18 erections before needing to be refilled.

Eight patients with an average age of 38 (28–64) years have received implants (between January 1990 and December 1992). Four patients have neurogenic impotence and four have no known organic cause for their impotence. The follow‐up period is between 3 and 37 months (average 13.3 months); all implants were confirmed to be working at the last visit. The average frequency of use was every 4 days (1–3 times per week), with between two and four pumps required for erection. Time to erection was between 2 and 10 minutes in the second and third months after implantation. Thereafter, it became longer (5–20 minutes), with an average duration of erection of 2.5 hours (1–5 hours). No patients reported problems with priapism or pain with activation or with erection. All said the erections were sufficient for penetrative intercourse, though one felt they were not as good as when directly injecting papaverine.