COX Inhibition of Feline Urodynamics

Recent studies in rat and rabbit detrusor strips suggest that COX‐1 plays a major role in controlling normal micturition, while COX‐2 activity may be involved when bladder irritation occurs. Feline studies found that nonspecific COX inhibitors have greater effects on micturition than selective inhibitors. In human studies, indomethacin decreases the incident of urinary incontinence. The purpose of this study was to determine if COX inhibition facilitates collection and storage of urine, and if nonspecific COX inhibition has greater effects on the urinary collection phase than selective COX‐2 inhibition. Indomethacin (a nonspecific COX inhibitor, 1–100 mcg/kg) and meloxicam (a COX‐2 inhibitor, 0.1–10mg/kg) was administered into the cat via a lumbar colonic artery to investigate the effect of each inhibitor on several urodynamic parameters, including the frequency and time to onset of spontaneous contractions during the bladder filling, micturition volume threshold, and the duration of the micturition contractions. Data indicates that the micturition volume threshold was increased by both drugs by 62%. However these agents produced inconsistent dose dependent changes in micturition contraction amplitude and duration. Indomethacin decreased time to onset of spontaneous contractions by 31 %, while meloxicam decreased this time to onset by 55% at most doses tested. Both drugs decreased the frequency of spontaneous contractions, but the magnitude of the decrease was less, indomethacin at 9% and meloxicam at 16%. These changes in time to onset and frequency of spontaneous contractions, induced by both drugs, suggest that COX inhibitors can suppress activity, and that indomethacin is more potent than meloxicam.