RESUMO
OBJECTIVE: To evaluate the cost-effectiveness of a new extended-release (XL) formulation of oxybutynin relative to tolterodine immediate release (IR), currently the most prescribed treatment for overactive bladder in the UK. METHODS: A state-transition model was developed to compare outcomes over 1 year. Effectiveness and treatment persistence data were derived from the OBJECT (Overactive Bladder: Judging Effective Control and Treatment) study, a 3-month clinical trial comparing oxybutynin XL 10 mg/day with tolterodine IR 4 mg/day. The daily costs of oxybutynin XL and tolterodine IR were pound0.82 and pound1.04, respectively. These data and information from the literature were used to project outcomes beyond the trial time. Severity-specific incontinence cost profiles were developed for the UK (2002 costings). RESULTS: After 1 year, 3.1 more patients per 100 treated attained complete continence with oxybutynin XL compared with tolterodine IR, and 5.6% more had less than seven incontinent episodes per week. Over 1 year, patients receiving oxybutynin XL had almost 17 additional incontinence-free days and 95 fewer incontinent episodes. Estimated costs were pound86 lower per patient with oxybutynin XL. If drugs are priced equally, savings decrease to pound21 per patient. Oxybutynin XL maintains its advantage over wide ranges of inputs, and outcomes are similar if analyses are limited to 3 months. CONCLUSION: Base-case analyses suggest that oxybutynin XL provides better effectiveness than tolterodine IR and reduces costs. Results indicate that oxybutynin XL is the dominant therapeutic option under a wide range of alternative inputs and assumptions.
RESUMO
After overnight drug withdrawal and in the fasting state, 11 patients with Parkinson's disease (PD) and a fluctuating response to chronic levodopa treatment were given, in random sequence on consecutive days, equivalent levodopa doses (with peripheral decarboxylase inhibitor) (a) as levodopa methyl ester (ME), (b) as Sinemet CR, or (c) as half the dose of ME together with a halved tablet of Sinemet CR. All patients turned ON rapidly after treatments a and c, but only half did so after treatment b. On period duration was longest after treatment c, intermediate after treatment a, and shortest after treatment b. Pharmacokinetic analysis in a subset of 6 patients revealed no significant difference between treatments a and c, although there was a trend for t1/2 to be longer after treatment c. We conclude that giving ME with a halved tablet of Sinemet CR provided a useful clinical balance between rapid onset and extended duration of action of at least the first levodopa intake of the day. In view of differing release profiles between whole and halved tablets of Sinemet CR, similar single-dose pharmacokinetic studies, followed by sequential-dose clinical studies, are indicated when Sinemet CR 125 tablets soon become available.
