Study of the population pharmacokinetic characteristics of once-daily trospium chloride 60 mg extended-release capsules in patients with overactive bladder and in healthy subjects.

BACKGROUND: Overactive bladder is a common disorder that affects approximately 34 million adults in the United States. Anticholinergic (antimuscarinic) agents are the most widely used pharmacological option for overactive bladder. OBJECTIVE: This study set out to identify and characterize the influence of a number of intrinsic characteristics on the pharmacokinetics of the anticholinergic agent trospium chloride (Sanctura(®)) 60 mg extended release (XR), and to evaluate the correlation between trospium chloride exposure and key efficacy and safety outcomes in subjects and patients. STUDY DESIGN: Pharmacokinetic data were obtained from three studies in which a total of 349 subjects received trospium chloride XR for up to 12 weeks. Plasma trospium chloride concentration data were pooled and a population pharmacokinetic model was derived using non-linear mixed-effects modelling. Demographic factors were assessed for influence on the model. The correlation between trospium chloride exposure and key efficacy variables was evaluated. Correlations between exposure and safety outcomes were also assessed. INTERVENTION: Trospium chloride XR 60 mg once daily for 10 days in healthy volunteers or trospium chloride 60 mg XR once daily for either 2 weeks or 12 weeks in patients with overactive bladder. RESULTS: The best population pharmacokinetic model was determined to be a two-compartment model with zero-order release into the depot compartment and first-order absorption. Body surface area (BSA) was the only covariate to significantly (P < 0.05) impact trospium chloride 60 mg XR pharmacokinetics. Significant relationships (P < 0.05) were observed between exposure [maximum plasma concentration (C(max)) and the area under the plasma concentration-time curve from time zero to 24 h (AUC(24))] and efficacy outcomes in the <65-year age group for change in average number of voids/day, change in number of incontinence episodes, and change in urgency severity, and in the ≥65-year age group statistical significance (P < 0.05) was achieved for C(max), but not for AUC(24), for these same three efficacy measures. Statistically significant relationships (P < 0.004) were also observed between exposure and both dry mouth and constipation, with increased benefit and increased incidence of adverse events (AEs) associated with higher concentrations; the correlation coefficients were low against the aggregate of AEs of interest (0.19 for AUC(24) and 0.18 for C(max)), indicating only mild strength of association. CONCLUSION: This population pharmacokinetic analysis demonstrated that the only demographic characteristic associated with trospium chloride pharmacokinetics was BSA. Thus, treatment of most patients with overactive bladder with once-daily trospium chloride 60 mg XR should not require consideration of key intrinsic demographic parameters. Furthermore, while efficacy and tolerability outcomes were found to be correlated with trospium chloride exposure, the strength of the association was modest in this study.

Blood-brain barrier permeation and efflux exclusion of anticholinergics used in the treatment of overactive bladder.

Overactive bladder (OAB) is a common condition, particularly in the elderly. Anticholinergic agents are the mainstay of pharmacological treatment of OAB; however, many anticholinergics can cross the blood-brain barrier (BBB) and may cause central nervous system (CNS) effects, including cognitive deficits, which can be especially detrimental in older patients. Many anticholinergics have the potential to cause adverse CNS effects due to muscarinic (M(1)) receptor binding in the brain. Of note, permeability of the BBB increases with age and can also be affected by trauma, stress, and some diseases and medications. Passive crossing of a molecule across the BBB into the brain is dependent upon its physicochemical properties. Molecular characteristics that hinder passive BBB penetration include a large molecular size, positive or negative ionic charge at physiological pH, and a hydrophilic structure. Active transport across the BBB is dependent upon protein-mediated transporter systems, such as that of permeability-glycoprotein (P-gp), which occurs only for P-gp substrates, such as trospium chloride, darifenacin and fesoterodine. Reliance on active transport can be problematic since genetic polymorphisms of P-gp exist, and many commonly used drugs and even some foods are P-gp inhibitors or are substrates themselves and, due to competition, can reduce the amount of the drug that is actively transported out of the CNS. Therefore, for drugs that are preferred not to cross into the CNS, such as potent anticholinergics intended for the bladder, it is optimal to have minimal passive crossing of the BBB, although it may also be beneficial for the drug to be a substrate for an active efflux transport system. Anticholinergics demonstrate different propensities to cross the BBB. Darifenacin, fesoterodine and trospium chloride are substrates for P-gp and, therefore, are actively transported away from the brain. In addition, trospium chloride has not been detected in cerebrospinal fluid assays and does not appear to have significant CNS penetration. This article reviews the properties of anticholinergics that affect BBB penetration and active transport out of the CNS, discusses issues of increased BBB permeability in patients with OAB, and examines the clinical implications of BBB penetration on adverse events associated with anticholinergics.

The effects of reformulation: improved therapeutic index.

Antimuscarinic agents are the treatment of choice for overactive bladder syndrome. Due to the development of novel delivery systems, extended-release formulations of oxybutynin, tolterodine, and trospium chloride are now available. In addition to the convenience of once-daily dosing, the new formulations of these commonly prescribed agents have improved their therapeutic index, striking a better balance between efficacy and tolerability.

HMG-CoA reductase inhibitors improve acute ischemic stroke outcome.

BACKGROUND AND PURPOSE: Statins reduce the risk of stroke recurrence, but the benefits of statins in improving outcome of acute stroke patients have not been well explored. METHODS: We assessed potential effects of statins initiated before or within 4 weeks of stroke on 90-day outcome. Favorable outcomes were National Institutes of Health Stroke Scale (NIHSS) score < or =2 at 12 weeks and modified Rankin Scale (mRS) < or =2. RESULTS: Before stroke, 129 patients were receiving statins, 123 initiated statins within 4 weeks, and 600 patients were not on statins. Multivariate logistic regression analysis demonstrated that poststroke statins were associated with a significant probability of a favorable outcome at 12 weeks [NIHSS (P=0.002; OR, 1.92; CI, 1.27 to 2.91) and mRS (P=0.033; OR, 1.57; CI, 1.04 to 2.38)], whereas prestroke statins demonstrated a trend toward significance. CONCLUSIONS: These preliminary results suggest that statin use may improve outcome of acute ischemic stroke.

Treatment of Obese Patients with Dexfenfluramine: A Multicenter, Placebo-Controlled Study.

This randomized, placebo-controlled, double-blind study was designed to evaluate the safety and efficacy of dexfenfluramine (Dfen). Dfen 15 mg BID, and placebo were administered for 12 weeks to 337 moderately obese patients on calorically restricted diets. Patients were monitored for an additional 4 weeks. Efficacy was evaluated in 321 patients who were an average of 52% in excess of ideal body weight. Dfen-treated patients lost significantly more weight than did those treated with placebo (p less-than-or-equal 0.001). Small nonsignificant fluctuations in body weight were observed during the 4-week posttreatment period in both groups. The most common drug-related side effects were diarrhea, asthenia, dry mouth, and thirst (p less-than-or-equal 0.05 compared with placebo). Dexfenfluramine may become a valuable addition to weight loss and weight management programs.