Overactive bladder dry patients benefit from lower-dose botulinum

October 1, 2008

When oral antimuscarinic therapy fails for overactive bladder patients who don't leak, intra-detrusor botulinum toxin A (Botox) injection is effective, and costs can be kept down with a lower dose.

That's what Angelo Gousse, MD, and colleagues at the University of Miami concluded after they compared 100-U with 150-U dosages for these patients.

"We didn't believe five injections more was really going to make a difference," said Dr. Gousse, professor of urology and gynecology at the University of Miami's Miller School of Medicine.

At 12 weeks after injection, all 20 idiopathic OAB dry patients in this prospective randomized trial had significant improvement in frequency. But the two groups of patients showed essentially the same results. Urinary frequency was 13.5/day among the 10 patients who received 100 U and 12.6/day among the 10 who received 150 U. Even among responders, the percentage improvements were neck and neck. The groups also showed no significant difference in postvoid residual volumes, maximum cystometric capacity, maximum detrusor pressure, or maximum flow.

"We wanted to see if we could use the lowest dose possible because it would be less expensive, and that would have an important impact on health care," Dr. Gousse told Urology Times.

With each 100-U vial costing $500 to $600, an additional five injections would cost $250 to $300 per patient. Those savings would add up, since OAB dry is more common than OAB wet. In fact, he said, approximately two-thirds of a urologist's typical OAB patients are OAB dry.

Interestingly, Dr. Gousse pointed out, their previous studies showed that, although antimuscarinics may be clinically effective, they don't produce significant urodynamic changes, but botulinum toxin does. It should be noted that botulinum toxin is not FDA-approved for the treatment of OAB.

Dr. Gousse also uses a technique that spares both the dome and trigone. Avoiding the dome of the urinary bladder helps avoid accidental injection into the peritoneal cavity. That makes for a straightforward technique that's easy to implement.

The in-office technique can be performed in men and women with flexible cystoscopy, takes only about 5 minutes, and causes little pain for patients (who rate it at a 2 on a 0- to 10-point scale).

"This has a huge clinical application, and certainly a very significant population can benefit from this therapy," he concluded.

Dr. Gousse is an investigator and consultant for Allergan.