Silicone adhesive, a better matrix for tolterodine patches—a research based onin vitro/in vivostudies

Lidocaine Transdermal Patch: Pharmacokinetic Modeling and In Vitro-In Vivo Correlation (IVIVC)

The present study aims to develop the correlation between in vitro and in vivo skin permeation of lidocaine in its transdermal patch. In order to minimize the run-to-run variability during in vitro skin permeation studies, release normalized cumulative percent (%Ct n) was calculated. A suitable polynomial mathematical model was used to establish a correlation between time and %Ct n. Percent in vivo absorbed was calculated by using numerical deconvolution (NDC) and non-compartmental analysis (NCA) methods. Pharmacokinetic (PK) parameters such as AUC last and C max were predicted with the established in vitro-in vivo correlation (IVIVC) models. The minimum prediction errors in NDC method for C max were found to be -30.9 and -25.4% for studies I (in vivo study in human volunteers with one batch of Lidoderm patch; internal validation) and II (in vivo study in human volunteers with another batch of Lidoderm patch; external validation), respectively, whereas minimum prediction errors in NCA method were relatively low (3.9 and 0.03% for studies I and II, respectively) compared to those in NDC method. The prediction errors for AUC last were found to be less than 2% for both methods and studies. The established method in this study could be a potential approach for predicting the bioavailability and/or bioequivalence for transdermal drug delivery systems.

Delivery methods for drugs used in the treatment of overactive bladder

INTRODUCTION

Overactive bladder affects a significant portion of the population and results in prescribing of numerous medications for its treatment. Traditional drug delivery systems used in therapy are associated with multiple commonly reported side effects. Adherence rates with use of these medications are low. It is likely that low adherence rates with the use of these drugs are due in some part to drug side effects. It is therefore important that alternate methods for drug delivery be explored to reduce side effect profiles and improve patient compliance.

AREAS COVERED

This article addresses the various forms of drug delivery for overactive bladder medications, focusing on those currently in use. Newer systems of drug delivery are also discussed. Through thorough review of research data, randomized trials and meta analyses, drug delivery systems were evaluated.

EXPERT OPINION

EXPERT OPINION favors the use of the transdermal patch and recognizes the necessity for further research and development of other delivery methods. The patch delivery method offers the most effective means of treating symptoms and minimizing drug related adverse side effects leading to treatment discontinuation. Development of OAB medications aimed at alternate receptor targets has the potential to facilitate the creation of new treatment methods to compete with the current standard of care used in OAB treatment.

A validated LC-MS/MS method for the determination of tolterodine and its metabolite in rat plasma and application to pharmacokinetic study

Liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was used for simultaneous quantification of tolterodine and its metabolite 5-hydroxy methyl tolterodine in rat plasma. Tolterodine-d6 and 5-hydroxy methyl tolterodine-d14 were used as internal standards (IS). Chromatographic separation was performed on Ascentis Express RP amide (50 mm×4.6 mm, 2.7 μm) column with an isocratic mobile phase composed of 10 mM ammonium acetate and acetonitrile in the ratio of 20:80 (v/v), at a flow-rate of 0.5 mL/min. Tolterodine, tolterodine-d6, 5-hydroxy methyl tolterodine and 5-hydroxy methyl tolterodine-d14 were detected with proton adducts at m/z 326.1→147.1, 332.3→153.1, 342.2→223.1 and 356.2→223.1 in multiple reaction monitoring (MRM) positive mode respectively. The drug, metabolite and internal standards were extracted by liquid–liquid extraction method. The method was validated over a linear concentration range of 20.00–5000.00 pg/mL for tolterodine and 20.00–5000.00 pg/mL for 5-hydroxy methyl tolterodine. This method demonstrated intra- and inter-day precision of 0.62–6.36% and 1.73–4.84% for tolterodine, 1.38–4.22% and 1.62–4.25% for 5-hydroxy methyl tolterodine respectively. This method also demonstrated intra- and inter-day accuracy of 98.75–103.56% and 99.20–104.40% for tolterodine, 98.08–104.67% and 98.73–103.06% for 5-hydroxy methyl tolterodine respectively. Both analytes were found to be stable throughout freeze–thaw cycles, bench top and postoperative stability studies. This method was successfully applied for the pharmacokinetic analysis of rat plasma samples following i.v. administration.