Injection therapy for BPH: Three routes to successful Tx

July 1, 2005

Three routes have been used with some success and are favored one over the other on the basis of perceived risk to surrounding structures.

Part of this quest is the attempt to understand and manipulate the pathophysiology of this disease and its relationship with lower urinary tract symptoms. The ultimate goal of therapy is to reduce or eliminate lower urinary tract symptoms and to minimize the adverse effects of treatment.

Current best efforts in the medical management realm involve the use of combined alpha-adrenergic blockade with 5-alpha reductase inhibitors, as suggested by results of the landmark Medical Therapy of Prostatic Symptoms (MTOPS) study. From a surgical perspective, impressive progress in outpatient resective procedures of the prostate (photoselective vaporization, Holmium laser ablation, and Holmium laser enucleation) appear to challenge the traditional TURP.

Historical perspectives The concept of administering injections into the prostate has been pursued since the late 19th century. Stoll has been credited with performing the first intraprostatic "injection" in 1877 by puncturing a prostatic abscess transperineally with a curved trocar, leaving a hollow cannula to drain the infection (J Urol 1936; 35:75).

Nearly 20 years later, Hoffman injected a 3% solution of carbolic acid into prostatic abscesses via the transperineal route (J Urol 2004; 172:20-6). BPH wasn't the target for intraprostatic injection until 1936 (Trans Am Urol Assoc 1930; 177-9).

Up to the last decade, urinary retention was the main indication for the use of intraprostatic injection to treat BPH. Since 1999, most reports of injection treatment have been primarily about patients with lower urinary tract symptoms. Most patient groups deemed appropriate to receive intraprostatic injections have been those considered high-risk candidates with multiple pre-existing comorbidities or those who do not have ready access to common medical therapies or high-priced minimally invasive technologies.

Many different agents have been used over the years, including 10% sodium hydroxide; 2% phenol; mixtures of carbolic acid, acetic acid, glycerin, and ethanol; Lugol's solution; 1% iodine with pepsin; silver nitrate; various antibiotics; and mixtures of collagenase, hyaluronidase, and octoxynol. More recently used agents include absolute ethanol liquid and gel; hot agarose/enzyme solution; hyperosmolar glucose; hypertonic saline liquid and gel; and botulinum toxin A (Botox).

In more contemporary reports, most agents reportedly induce some degree of inflammation with subsequent coagulative necrosis, leading to debulking of the enlarged gland and improvement in voiding function.

Three routes of delivery Although blind, digitally guided injection would be feasible, ultrasound-guided injection has the added advantage of placing the agent in the particular location where it might best effect its action. Three routes have been used with some success and are favored one over the other on the basis of perceived risk to surrounding structures. Historically, the transperineal route was first explored and remains the most studied route. However, problems with extravasation of the injectant, reports of necrosis of sphincter, bladder, and urethra in animal studies, and complaints of perineal pain in humans have led to the investigation and increased interest of both the transrectal and transurethral routes.