A comparison of the effects on saliva output of oxybutynin chloride and tolterodine tartrate.
BACKGROUND
Oxybutynin chloride and tolterodine tartrate are anticholinergic agents used to suppress involuntary bladder contractions in urinary incontinence. They act by inhibiting binding of acetylcholine to the muscarinic receptors in the detrusor muscle of the bladder. The same types of muscarinic receptors are found in the salivary glands; thus anticholinergic agents may decrease saliva production and cause dry mouth, a commonly cited reason for discontinuation of therapy.


OBJECTIVE
The primary objective of this study was to compare saliva output, which is an objective measure of dry mouth, in subjects taking immediate- or extended-release oxybutynin, tolterodine, or placebo.


METHODS
This was a single-site, single-dose, randomized, double-blind, 4-treatment, 4-period crossover study. Subjects were randomly assigned to 1 of 4 treatment sequences that included extended-release oxybutynin 10 mg, tolterodine 2 mg, immediate-release oxybutynin 5 mg, and placebo. Saliva output was measured objectively before dosing with each treatment and at 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 hours after dosing.


RESULTS
Thirty-six healthy adult volunteers (22 women and 14 men) participated in the study. They ranged in age from 19 to 42 years (mean, 27 years). Thirty-one were white, 3 Asian, and 2 black. There were no significant differences in predose saliva output between the 4 study groups. With placebo, saliva output increased throughout the day. Saliva output was maintained at predose levels throughout the day with extended-release oxybutynin. Two hours after dosing with tolterodine and immediate-release oxybutynin, saliva output decreased nearly 0.5 g in specimens collected over 2 minutes. All 3 active treatments were associated with lower saliva output compared with placebo. Extended-release oxybutynin and tolterodine were similar with respect to area under the saliva concentration-time curve but were associated with significantly greater saliva output than was immediate-release oxybutynin (P < 0.01). There were no serious adverse events (AEs) in this study. AEs were similar between treatments, although the incidence of headache was higher in the active-treatment groups than with placebo.


CONCLUSIONS
Objective assessment of saliva output in healthy adult volunteers indicated that extended-release oxybutynin and tolterodine had less impact on saliva output than did conventional immediate-release oxybutynin, suggesting that they may yield lower levels of dry mouth.
Chancellor
M B
MB
Department of Urology, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA. chancellormb@msx.upmc.edu
Appell
R A
RA
Sathyan
G
G
Gupta
S K
SK
D000328:Adult; D019540:Area Under Curve; D001559:Benzhydryl Compounds / Q000009:adverse effects / Q000494:pharmacology*; D018680:Cholinergic Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D003408:Cresols / Q000009:adverse effects / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006261:Headache / Q000139:chemically induced; D006801:Humans; D008297:Male; D008333:Mandelic Acids / Q000009:adverse effects / Q000494:pharmacology*; D010665:Phenylpropanolamine; D012463:Saliva / Q000378:metabolism; D012472:Salivation / Q000187:drug effects*; D013644:Tartrates / Q000009:adverse effects / Q000494:pharmacology*; D000068737:Tolterodine Tartrate
D001559:Benzhydryl Compounds; D018680:Cholinergic Antagonists; D003408:Cresols; D008333:Mandelic Acids; D013644:Tartrates; D010665:Phenylpropanolamine; D000068737:Tolterodine Tartrate; C005419:oxybutynin