Aims of Study: Conventional oxybutynin is safe and effective for the treatment of overactive bladder (OB),
but discontinuation of treatment due to dry mouth often precludes long-term
treatment. Controlled-release
oxybutynin has been shown to be comparably effective with less dry mouth
than conventional oxybutynin in short-term studies.
In a long-term, open-label study, we assessed improvement in
the bothersomeness of the condition, patient satisfaction with treatment,
and discontinuation of treatment due to dry mouth in over 1000 community-based
patients using controlled-release oxybutynin for 12 months.
Methods: This was an open-label, non-randomized study
enrolling adults with OB. Patients received their individual optimum
dose of controlled-release oxybutynin ranging from 5-30 mg/day. Adverse
effects and reasons for discontinuation of treatment were recorded.
At baseline and after 3, 6, or 12 months of treatment with controlled-release
oxybutynin, patients completed four instruments to assess different
aspects of quality of life: General Health and Bothersome Scale, Sleep
Impact Question, Individual Incontinence Impact Questionnaire, and Patient
Satisfaction Scale.
Results: Overall
1069 patients enrolled in the study, and 558 had 12-month data available
as of September 30, 1999. At baseline the mean level of bothersomeness
of the condition was 70.8 on a scale from 0 (not bothersome at all)
to 100 (as bothersome as I can imagine). Patients reported a 41.5% improvement over
baseline in the bothersomeness of the condition after 3 months, a 45.2%
improvement after 9 months, and a 49.7% improvement after 12 mos of
treatment (p<0.0001 for each comparison with baseline). At baseline
69.6% of patients reported that nighttime awakenings due to UI interfered
with daily activities some, most or all the time compared with 31.3%
of patients after 3 months of treatment. At baseline 39.5% of patients indicated that
at least 5 of 9 daily activities (household chores, relationships, exercise,
work, etc.) were impacted by urine loss frequently or all the time;
after 3 months of treatment, the percentage decreased to only 13.4%
of patients. Adverse effects were the most common cause for discontinuation
during the first 3 months and included dry mouth and other anticholinergic
effects. Adverse effects were less frequently the cause
for discontinuation after 9 months.
The total rate of discontinuation over the 12 months due to adverse
effects was 22.9%, including 8.1% for dry mouth and 6.3% for other anticholinergic
effects.
Reasons for discontinuation:
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Adverse effects (total)
Dry mouth
Other anticholinergic
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Discontinuation of treatment due to lack of efficacy was low (3.8%) prior
to 3 months and did not occur after 9 months. After 3 and 6 months of
treatment, 74.7% and 80.3% of patients, respectively, reported the drug
worked well, very well or excellent, and 79.2% and 86.8%, respectively,
were pleased, very pleased or extremely pleased with treatment.
Conclusions: In this
long-term, community-based study, discontinuation of controlled-release
oxybutynin treatment due to dry mouth was much lower than that reported
in the literature for conventional oxybutynin and occurred mostly in
the first 3 months. Treatment of overactive bladder with controlled-release
oxybutynin substantially improved the quality of life of patients as
assessed by four different instruments.
Funding: ALZA Corp. on behalf of Crescendo Pharmaceuticals
Corp., Mountain View, CA
