Effect of Concomitant Medications on the Safety and Efficacy of Extended-Release Carbidopa-Levodopa (IPX066) in Patients With Advanced Parkinson Disease: A Post Hoc Analysis.

OBJECTIVES: Extended-release (ER) carbidopa-levodopa (CD-LD) (IPX066/RYTARY/NUMIENT) produces improvements in "off" time, "on" time without troublesome dyskinesia, and Unified Parkinson Disease Rating Scale scores compared with immediate-release (IR) CD-LD or IR CD-LD plus entacapone (CLE). Post hoc analyses of 2 ER CD-LD phase 3 trials evaluated whether the efficacy and safety of ER CD-LD relative to the respective active comparators were altered by concomitant medications (dopaminergic agonists, monoamine oxidase B [MAO-B] inhibitors, or amantadine). METHODS: ADVANCE-PD (n = 393) assessed safety and efficacy of ER CD-LD versus IR CD-LD. ASCEND-PD (n = 91) evaluated ER CD-LD versus CLE. In both studies, IR- and CLE-experienced patients underwent a 6-week, open-label dose-conversion period to ER CD-LD prior to randomization. For analysis, the randomized population was divided into 3 subgroups: dopaminergic agonists, rasagiline or selegiline, and amantadine. For each subgroup, changes from baseline in PD diary measures ("off" time and "on" time with and without troublesome dyskinesia), Unified Parkinson Disease Rating Scale Parts II + III scores, and adverse events were analyzed, comparing ER CD-LD with the active comparator. RESULTS AND CONCLUSIONS: Concomitant dopaminergic agonist or MAO-B inhibitor use did not diminish the efficacy (improvement in "off" time and "on" time without troublesome dyskinesia) of ER CD-LD compared with IR CD-LD or CLE, whereas the improvement with concomitant amantadine failed to reach significance. Safety and tolerability were similar among the subgroups, and ER CD-LD did not increase troublesome dyskinesia. For patients on oral LD regimens and taking a dopaminergic agonist, and/or a MAO-B inhibitor, changing from an IR to an ER CD-LD formulation provides approximately an additional hour of "good" on time.

Conversion to carbidopa and levodopa extended-release (IPX066) followed by its extended use in patients previously taking controlled-release carbidopa-levodopa for advanced Parkinson's disease.

BACKGROUND: IPX066 (Rytary®; carbidopa and levodopa [CD-LD] extended-release capsules) was designed to achieve therapeutic LD plasma concentrations within 1h of dosing and maintain LD concentrations for a prolonged duration in early or advanced Parkinson's disease (PD). METHODS: In this open-label study, patients underwent 6weeks of conversion to IPX066 from their prior controlled-release (CR)±immediate-release (IR) CD-LD therapy and 6months of maintenance (with an additional 6months of IPX066 at some sites). Clinical utility was assessed at both the end of conversion and maintenance. RESULTS: Among 43 patients initiated on IPX066, 33 completed conversion. The mean LD conversion ratio was 1.8 among 30 patients previously on CR plus IR (and 1.5 among 3 previously taking CR alone). The mean IPX066 dosing frequency was 3.5times/day compared with 2.6times/day for CR plus 4.6times/day for IR previously (and 4.7times/day for CR alone). By patient and clinician global improvement ratings after 6-month maintenance, ≥43.8% of patients were much or very much improved from their previous treatment, and ≥68.8% were at least minimally improved. Adverse events were consistent with those reported in prior IPX066 studies. CONCLUSIONS: These results suggest that advanced PD patients using CR CD-LD±IR can be safely converted to IPX066, with high likelihood of achieving a stable regimen, less frequent LD dosing, and improved overall clinical benefit. TRIAL REGISTRATION: Clinicaltrials.govNCT01411137.

Conversion to IPX066 from Standard Levodopa Formulations in Advanced Parkinson's Disease: Experience in Clinical Trials.

BACKGROUND: Due to the short half-life of levodopa, immediate-release carbidopa-levodopa (IR CD-LD) produces fluctuating LD concentrations, contributing to a risk of eventual motor complications. IPX066 was designed to rapidly attain therapeutic LD concentrations and maintain them to allow a dosing interval of ∼6 hours. OBJECTIVE: To extensively analyze the dosing data collected in IPX066 studies during open-label conversions from IR CD-LD alone or with entacapone (CLE) and identify patterns relevant for managing conversion in the clinical setting. METHODS: Patients had ≥2.5 hours/day of "off" time despite a stable IR or CLE regimen. Suggested initial dosing conversion tables based on prior LD daily dosage were provided. RESULTS: Of 450 patients previously treated with IR CD-LD and 110 with CLE, 87.3% and 82.7% completed conversion to IPX066, respectively. At the end of conversion, average IPX066 LD daily dosages were higher than pre-conversion dosages, with a mean conversion ratio of 2.1±0.6 for IR CD-LD and 2.8±0.8 for CLE; >90% of patients took IPX066 3 or 4 times/day, compared with a median of 5 times/day at baseline in both studies. After conversion, daily "off" time significantly decreased, with no significant increase in troublesome dyskinesia. The most common adverse event reported during conversion was nausea, with an incidence of 5.3% for conversion from IR and 7.3% from CLE. CONCLUSIONS: Among PD patients with substantial "off" time, a majority were safely converted to IPX066. The sustained LD profile from the IPX066 formulation allowed an increase in LD dose accompanied by improved motor functions, without increased troublesome dyskinesia.

Long-Term Treatment with Extended-Release Carbidopa-Levodopa (IPX066) in Early and Advanced Parkinson's Disease: A 9-Month Open-Label Extension Trial.

BACKGROUND AND OBJECTIVE: IPX066 is a multiparticulate extended-release formulation of carbidopa-levodopa, designed to produce prolonged therapeutic levodopa plasma concentrations. This 9-month open-label extension study assessed its long-term safety and clinical utility in early and advanced Parkinson's disease (PD). METHODS: Participants were enrolled from two phase III IPX066 studies and one open-label phase II study. Early PD patients were titrated to an appropriate dosing regimen while advanced patients started with regimens established in the antecedent studies. Adjustment was allowed throughout the extension. Clinical utility measures included the Unified Parkinson's Disease Rating Scale (UPDRS) and Patient Global Impression (PGI) ratings. RESULTS: Among 268 early PD patients, 53.4 % reported adverse events (AEs) and 1.1 % (three patients) discontinued due to AEs; the most frequent AEs were nausea (5.6 %) and insomnia (5.6 %). Among 349 advanced patients, 60.2 % reported AEs and 3.7 % (13 patients) discontinued due to AEs; the most frequent AEs were dyskinesia (6.9 %) and fall (6.6 %). At month 9 (or early termination), 78.3 % of early patients were taking IPX066 three times daily (median: 720 mg/day) and 87.7 % of advanced patients were taking IPX066 three or four times daily (median: 1450 mg/day). Adjusting for 70 % bioavailability relative to immediate-release (IR) carbidopa-levodopa, the median dosages correspond to ~500 and ~1015 mg/day of IR levodopa in early and advanced PD, respectively. Based on the plasma profiles previously observed in PD patients, the IPX066 regimens in the extension can be estimated to provide a levodopa Cmax (maximum plasma drug concentration) similar to or lower than that provided by IR regimens during the antecedent trials. UPDRS and PGI findings showed sustained treatment effects throughout the extension. CONCLUSION: During 9 months of extended use, IPX066 exhibited a safety/tolerability profile consistent with dopaminergic PD therapy.

Comparison of IPX066 with carbidopa-levodopa plus entacapone in advanced PD patients.

BACKGROUND: IPX066, an investigational extended-release carbidopa-levodopa (CD-LD) preparation, has demonstrated a rapid attainment and prolonged maintenance of therapeutic LD plasma concentrations in advanced Parkinson's disease (PD). This phase-3 crossover study assessed its efficacy and safety vs. CD-LD plus entacapone (CL + E). METHODS: At baseline, all patients had motor fluctuations despite a stable regimen of CL + E or CD-LD-entacapone combination tablets (CLE). The study included a 6-week conversion from CL + E or CLE to IPX066, followed by two 2-week, double-blind crossover treatment periods in randomized order, one on IPX066 (and placebo CL + E), the other on CL + E (and placebo IPX066), separated by 1-week open-label IPX066 treatment. The primary efficacy measure was mean percent daily "off" time during waking hours (from patient diaries). RESULTS: Of 91 randomized patients, 84 completed the study. Their median daily LD dosage was 1495 mg from IPX066 and 600 mg from CL + E, corresponding, after correction for bioavailability, to an approximately 22% higher LD exposure on IPX066. Compared with CL + E, IPX066 demonstrated a lower percent "off" time (24.0% vs. 32.5%; p < 0.0001), lower "off" time (3.8 vs. 5.2 h/day; p < 0.0001), and higher "on" time without troublesome dyskinesia (11.4 vs. 10.0 h/day; p < 0.0001). Other endpoints, including patient-reported treatment preference, also favored IPX066 (p < 0.05). During double-blind treatment, 20.2% and 13.6% of patients reported adverse events on IPX066 and CL + E, respectively. The most common were dyskinesia (4 patients), insomnia (3), and confusional state (3) for IPX066, and fall (2) for CL + E. CONCLUSIONS: In advanced PD, IPX066 showed improved efficacy, compared with CL + E, and appeared to be well tolerated.

Randomized trial of IPX066, carbidopa/levodopa extended release, in early Parkinson's disease.

OBJECTIVE: IPX066 is an extended release carbidopa/levodopa formulation designed to rapidly attain and maintain therapeutic plasma concentrations for a prolonged duration, allowing dosing intervals of approximately 6 h. The objective was to assess the efficacy, safety, and impact on quality of life of IPX066 in the treatment of levodopa-naive Parkinson's disease (PD) patients. METHODS: This was a randomized, double-blind, placebo-controlled, 30-week study of 381 levodopa-naïve patients assigned to placebo or IPX066 containing 145, 245 or 390 mg of levodopa administered three times daily (TID). The primary efficacy measure was change from Baseline in Unified Parkinson's Disease Rating Scale (UPDRS) activities of daily living (Part II) + motor scores (Part III), at 30 weeks. Secondary outcome measures included UPDRS total and subscores, patient and clinician global impressions (PGI-I, CGI-I), and the Parkinson's Disease Questionnaire (PDQ-39). RESULTS: All IPX066 dosages were superior to placebo throughout the study and at 30 weeks (P < 0.0001). The mean improvement in UPDRS Parts II + III at 30 weeks compared to baseline was 11.7, 12.9, and 14.9 points for the three dosages and 0.6 points for placebo (P < 0.0001, all dosages). PDQ-39 total scores improved with IPX066 (P ≤ 0.034, all dosages). The most commonly reported adverse events with IPX066 included nausea, dizziness, and headache. No unexpected drug-related serious adverse events were reported. CONCLUSION: IPX066 provided significant clinical benefits at the three dosages tested compared to placebo and was well tolerated in levodopa-naive PD patients. Of the dosages tested, IPX066 145 mg TID appeared to provide the best overall balance between efficacy and safety.

Extended-release carbidopa-levodopa (IPX066) compared with immediate-release carbidopa-levodopa in patients with Parkinson's disease and motor fluctuations: a phase 3 randomised, double-blind trial.

BACKGROUND: IPX066 is an oral, extended-release, capsule formulation of carbidopa-levodopa. We aimed to assess this extended-release formulation versus immediate-release carbidopa-levodopa in patients with Parkinson's disease and motor fluctuations. METHODS: We did a phase 3, randomised, double-blind, double-dummy study at 68 academic and clinical centres in North America and Europe. Patients with Parkinson's disease who had at least 2·5 h per day of off-time underwent 3 weeks of open-label immediate-release carbidopa-levodopa dose adjustment followed by 6 weeks of open-label extended-release carbidopa-levodopa dose conversion. These patients were then randomly allocated (1:1), by use of an interactive web-response system, to 13 weeks of double-blind treatment with extended-release or immediate-release carbidopa-levodopa plus matched placebos. The primary efficacy measure was off-time as a percentage of waking hours in all patients randomly allocated to treatment groups, adjusted for baseline value. This study is registered with ClinicalTrials.gov, number NCT00974974. FINDINGS: Between Sept 29, 2009, and Aug 16, 2010, we enrolled 471 participants, of whom 393 (83%) were randomly allocated in the double-blind maintenance period and were included in the main efficacy analyses. As a percentage of waking hours, 201 patients treated double-blind with extended-release carbidopa-levodopa (mean 3·6 doses per day [SD 0·7]) had greater reductions in off-time than did 192 patients treated double-blind with immediate-release carbidopa-levodopa (mean 5·0 doses per day [1·2]). Covariate-adjusted end-of-study means were 23·82% (SD 14·91) for extended-release carbidopa-levodopa and 29·79% (15·81) for immediate-release carbidopa-levodopa (mean difference -5·97, 95% CI -9·05 to -2·89; p<0·0001). Extended-release carbidopa-levodopa reduced daily off-time by, on average, an extra -1·17 h (95% CI -1·69 to -0·66; p<0·0001) compared with immediate-release carbidopa-levodopa. During dose conversion with extended-release carbidopa-levodopa, 23 (5%) of 450 patients withdrew because of adverse events and 13 (3%) withdrew because of a lack of efficacy. In the maintenance period, the most common adverse events were insomnia (seven [3%] of 201 patients allocated extended-release carbidopa-levodopa vs two [1%] of 192 patients allocated immediate-release carbidopa-levodopa), nausea (six [3%] vs three [2%]), and falls (six [3%] vs four [2%]). INTERPRETATION: Extended-release carbidopa-levodopa might be a useful treatment for patients with Parkinson's disease who have motor fluctuations, with potential benefits including decreased off-time and reduced levodopa dosing frequency. FUNDING: Impax Laboratories.

A population pharmacokinetic and pharmacodynamic study of a peripheral κ-opioid receptor agonist CR665 and oxycodone.

BACKGROUND: Peripherally acting opioids, particularly peripheral κ-opioid agonists, may be effective for treating visceral pain by activating receptors expressed on afferent nerves within the gut. OBJECTIVE: The objective of this study was to investigate the pharmacokinetic/pharmacodynamic profile of a novel peripherally selective κ-opioid agonist, CR665 (JNJ-38488502), and compare it to that of oxycodone, a non-selective brain-penetrant opioid. METHODS: In a randomized, placebo-controlled, double-blind, three-way crossover study, healthy male volunteers were administered CR665 (0.36 mg/kg, intravenous), oxycodone (15 mg, oral) or placebo (intravenous and oral), followed by assessment of visceral pain tolerance thresholds (VPTT) measured as volume of water (mL) in the bag placed on an oesophageal probe. Plasma drug concentration data were used to generate pharmacokinetic models, which were then used to fit the VPTT data using NONMEM(®) VI to generate population pharmacokinetic/pharmacodynamic models. RESULTS: CR665 kinetics were optimally fitted with a two-compartment model, while oxycodone kinetics were best described by a one-compartment model with transit compartment absorption feeding directly into the central compartment. For both drugs, the plasma concentration effects on VPTT were best fit by a direct linear model, i.e. without the concentration-analgesia delay characteristic of brain-penetrant opioids. The slope of oxycodone (0.089 mL per ng/mL) was steeper than that of CR665 (0.0035 mL per ng/mL) for the plasma drug concentration acting on the VPTT. CONCLUSION: The results are consistent with the peripheral selectivity of CR665, as well as the possibility that peripheral actions of oxycodone contribute to its visceral analgesic efficacy.

Crossover comparison of IPX066 and a standard levodopa formulation in advanced Parkinson's disease.

The objective of the study was to compare the pharmacokinetics, motor effects, and safety of IPX066, a novel extended-release formulation of carbidopa-levodopa, with an immediate-release carbidopa-levodopa formulation in advanced Parkinson's disease. We performed an open-label crossover study in 27 subjects with advanced Parkinson's disease experiencing motor fluctuations on levodopa therapy. Subjects were randomized 1:1 to 8 days' treatment with either immediate-release carbidopa-levodopa followed by IPX066 or IPX066 followed by immediate-release carbidopa-levodopa. Pharmacokinetic and motor assessments were undertaken on day 1 for 8 hours (following a single dose) and on day 8 for 12 hours (during multiple-dose administration). Following a single dose of IPX066 or immediate-release carbidopa-levodopa, plasma levodopa concentrations increased at a similarly rapid rate and were sustained above 50% of peak concentration for 4 hours with IPX066 versus 1.4 hours with immediate-release carbidopa-levodopa (P < .0001). Multiple-dose data showed IPX066 substantially reduced variability in plasma levodopa concentrations despite a lower dosing frequency (mean, 3.5 vs 5.4 administrations per day). In addition, total levodopa exposure during IPX066 treatment was approximately 87% higher, whereas the increase in levodopa C(max) was approximately 30% compared with immediate-release carbidopa-levodopa. Both products were well tolerated. IPX066 provided more sustained plasma levodopa concentrations than immediate-release carbidopa-levodopa. Larger, longer-term, well-controlled studies should be conducted to provide rigorous assessment of the clinical effects of IPX066.

Analgesic efficacy of peripheral kappa-opioid receptor agonist CR665 compared to oxycodone in a multi-modal, multi-tissue experimental human pain model: selective effect on visceral pain.

BACKGROUND: Peripherally selective opioids may be beneficial in visceral pain management due to absence of centrally mediated side effects. The objectives of this study were: (1) to assess the effects of a peripherally selective tetrapeptide kappa-opioid receptor agonist, CR665, on experimental pain from multi-modal stimulation of skin, muscle, and viscera, and (2) contrast these effects with those of oxycodone (centrally acting opioid). METHODS: The study was designed as a single-center, single-dose, randomized, double-blind, placebo and active-controlled, double-dummy, three-way, crossover study in healthy males. Subjects received the following treatments in randomized order: (1) CR665 (0.36 mg/kg) administered intravenously over 1 h, (2) oxycodone (15 mg) administered orally, and (3) placebo administered intravenously and orally. The following pain tests were used: (1) cutaneous pinch pain tolerance threshold, (2) pressure pain detection and tolerance thresholds, (3) cuff pressure pain tolerance threshold, and (4) pain rating thresholds to distension and thermal stimulation of the esophagus. Measurements were performed before dosing and at 30, 60, and 90 min after dosing. RESULTS: Compared to placebo, oxycodone elevated cutaneous pinch pain tolerance (P < 0.001) and cuff pressure pain tolerance threshold (P < 0.001), as well as pain rating thresholds (visual analogue scale = 7) to esophageal distension (P < 0.001) and thermal stimulation (P < 0.002). Compared to placebo, CR665 significantly increased the pain rating threshold to esophageal distension (P < 0.005) but reduced the pain tolerance threshold to skin pinching (P = 0.007). CONCLUSION: CR665 had a selective effect on visceral pain. Oxycodone exhibited a generalized effect, elevating thresholds for cutaneous, deep somatic, and visceral pain stimulation.

Efficacy and tolerability of dapoxetine in treatment of premature ejaculation: an integrated analysis of two double-blind, randomised controlled trials.

BACKGROUND: No drugs are approved for treatment of premature ejaculation. Our aim was to determine the efficacy and tolerability of on-demand dapoxetine in patients with severe premature ejaculation. METHODS: We determined the efficacy of dapoxetine in a prospectively predefined integrated analysis of two 12-week randomised, double-blind, placebo-controlled, phase III trials of identical design done independently, in parallel, at 121 sites in the USA. Men with moderate-to-severe premature ejaculation in stable, heterosexual relationships took placebo (n=870), 30 mg dapoxetine (874), or 60 mg dapoxetine (870) on-demand (as needed, 1-3 h before anticipated sexual activity). The primary endpoint was intravaginal ejaculatory latency time (IELT) measured by stopwatch. Safety and tolerability were assessed. All analyses were done on an intention-to-treat basis. The trials are registered at ClinicalTrials.gov, numbers NCT00211107 and NCT00211094. FINDINGS: 672, 676, and 610 patients completed in the placebo, 30 mg dapoxetine, and 60 mg dapoxetine groups, respectively. Dapoxetine significantly prolonged IELT (p<0.0001, all doses vs placebo). Mean IELT at baseline was 0.90 (SD 0.47) minute, 0.92 (0.50) minute, and 0.91 (0.48) minute, and at study endpoint (week 12 or final visit) was 1.75 (2.21) minutes for placebo, 2.78 (3.48) minutes for 30 mg dapoxetine, and 3.32 (3.68) minutes for 60 mg dapoxetine. Both dapoxetine doses were effective on the first dose. Common adverse events (30 mg and 60 mg dapoxetine, respectively) were nausea (8.7%, 20.1%), diarrhoea (3.9%, 6.8%), headache (5.9%, 6.8%), and dizziness (3.0%, 6.2%). INTERPRETATION: On-demand dapoxetine is an effective and generally well tolerated treatment for men with moderate-to-severe premature ejaculation.

Effectiveness and tolerability of extended-release oxybutynin vs extended-release tolterodine in women with or without prior anticholinergic treatment for overactive bladder.

The efficacy and the tolerability of extended-release oxybutynin chloride, 10 mg daily, and extended-release tolterodine tartrate, 4 mg daily, in women with or without prior anticholinergic treatment for overactive bladder (OAB) were compared in a post-hoc analysis of data from the Overactive Bladder: Performance of Extended Release Agents (OPERA) trial. The patient population and study methods have been described previously (Diokno et al., for the OPERA Study Group, Mayo Clin Proc 78:687-695, 2003). Among the group with anticholinergic experience, extended-release oxybutynin was significantly more effective than extended-release tolterodine in reducing micturition frequency at last observation (p=0.052). Complete freedom from urge incontinence was reported by significantly more patients taking oxybutynin than tolterodine at last observation (23.6 vs 15.1%, p=0.038). In addition, among patients completing a full 12 weeks of oxybutynin treatment, significantly greater reductions were observed compared with those taking tolterodine on the primary efficacy variable, number of urge incontinence episodes (p=0.049), and the combined total of urge and non-urge episodes (p=0.012), although the differences between treatment groups were not significant at last observation. In the anticholinergic-naïve group, efficacy and tolerability outcomes were similar across treatments, except that oxybutynin was associated with a significantly lower frequency of micturition at last observation (p=0.035). No efficacy differences favoring tolterodine were observed, and tolerability of the treatments was comparable. Dry mouth (mostly mild to moderate in severity) was reported significantly more often among participants taking extended-release oxybutynin than extended-release tolterodine (32.2 vs 19.2%, p=0.004), but only among those with previous anticholinergic experience. Discontinuation rates were comparably low across groups. The results demonstrate the appropriateness of initiating treatment for OAB with extended-release oxybutynin, particularly in women presenting with incontinence.

Pharmacokinetics and pharmacodynamics of warfarin when coadministered with pentosan polysulfate sodium.

The effect of pentosan polysulfate sodium on warfarin pharmacokinetics and pharmacodynamics was investigated in healthy subjects. Warfarin was titrated to an international normalized ratio between 1.4 and 1.8. Subjects continued their titrated dose of warfarin and received pentosan polysulfate sodium 100 mg or placebo every 8 hours for 7 days. The Cmax of R- and S-warfarin was approximately 840 to 890 ng/mL and 680 to 730 ng/mL, respectively, and was similar in the absence and presence of pentosan polysulfate sodium. The half-life for R- and S-warfarin was 52 to 56 hours and 36 to 40 hours, respectively. Prothrombin time, partial thromboplastin time, and the international normalized ratio for warfarin + placebo and warfarin + pentosan polysulfate sodium were comparable. The AUC(INR) indicated no treatment effect (P = .772); however, there was a period effect. Analysis of variance for the treatments by period indicated no treatment effect (P > .1). Adverse events were mild and included headache, epistaxis, and rash. Most adverse events were unrelated to treatment and were seen during warfarin titration. Pentosan polysulfate sodium did not affect warfarin pharmacokinetics or pharmacodynamics.

Prospective, randomized, double-blind study of the efficacy and tolerability of the extended-release formulations of oxybutynin and tolterodine for overactive bladder: results of the OPERA trial.

OBJECTIVE: To compare the efficacy and tolerability of extended-release formulations of oxybutynin chloride and tolterodine tartrate in women with overactive bladder. PATIENTS AND METHODS: The OPERA (Overactive bladder: Performance of Extended Release Agents) trial was a randomized, double-blind, active-control study performed at 71 US study centers from November 21, 2000, to October 18,2001. Extended-release formulations of oxybutynin at 10 mg/d or tolterodine at 4 mg/d were given for 12 weeks to women with 21 to 60 urge urinary incontinence (UUI) episodes per week and an average of 10 or more voids per 24 hours. Episodes of UUI (primary end point), total (urge and nonurge) incontinence, and micturition were recorded in 24-hour urinary diaries at baseline and at weeks 2, 4, 8, and 12 and compared. Adverse events were also evaluated. RESULTS: Improvements in weekly UUI episodes were similar for the 790 women who received extended-release formulations of oxybutynin (n = 391) or tolterodine (n = 399). Oxybutynin was significantly more effective than tolterodine in reducing micturition frequency (P = .003), and 23.0% of women taking oxybutynin reported no episodes of urinary incontinence compared with 16.8% of women taking tolterodine (P = .03). Dry mouth, usually mild, was more common with oxybutynin (P = .02). Adverse events were generally mild and occurred at low rates, with both groups having similar discontinuation of treatment due to adverse events. CONCLUSIONS: Reductions in weekly UUI and total incontinence episodes were similar with extended-release formulations of oxybutynin and tolterodine. In the oxybutynin group, micturition frequency was significantly lower, and the percentage of women reporting no urinary incontinence episodes was significantly higher compared with the tolterodine group. Dry mouth was more common with oxybutynin, but tolerability was otherwise comparable, including adverse events involving the central nervous system.

Oxybutynin chloride: alterations in drug delivery and improved therapeutic index.

Oxybutynin chloride (Ditropan, Alza) is widely regarded as the most efficient antimuscarinic agent for the treatment of bladder detrusor dysfunction resulting in urinary urgency, frequency and urge incontinence. Oxybutynin metabolism occurs primarily in the proximal gastrointestinal tract and the hepatic circulation and is mediated by the cytochrome P450 3A4 isozyme. The major degradation products are desethyloxybutynin, which possesses pharmacological activity, and phenylcyclohexylglycolic acid, which is metabolically inert. A major limitation to long-term compliance with immediate-release oxybutynin remains the necessity for twice- or thrice-daily dosing regimens to provide sustained pharmacological efficacy. Side effects induced by cytochrome P450 metabolism of oxybutynin into the primary metabolite desethyloxybutynin within the gut wall substantially affect the tolerability of the compound within the individual. The oral osmotic delivery system provides unique advantages for drug delivery and substantially alters the tolerability profile of the oxybutynin chloride compound. This extended-release formulation consists of a two component core encapsulated by a semi-permeable membrane. The osmotic gradient between the surrounding environment and the inner core of the delivery system remains constant and water absorption within the capsule is controlled by the semipermeable membrane causing a controlled release of drug, which is sustained over 24 h. Herein are reviewed the various pre- and post-approval trials which have documented the overall therapeutic index of the oral osmotic oxybutynin (Ortho-McNeil Pharmaceuticals). Subsequent post-market surveillance issues are reviewed as are new developments in oxybutynin delivery.