@article {49, title = {Newly Developed and Validated Method of Montelukast Sodium Estimation in Tablet Dosage Form by Ultraviolet Spectroscopy and Reverse Phase - High Performance Liquid Chromatography}, journal = {PTB Reports}, volume = {2}, year = {2016}, month = {May 2016}, pages = {27-30}, type = {Original Article}, chapter = {27}, abstract = {

Objective: Simple high performance liquid chromatographic (HPLC) and ultraviolet (UV) methods were newly developed and validated for the quantitative estimation of Montelukast (ML) in pharmaceutical dosage form. Material and Methods: HPLC was carried out by reverse phase-HPLC technique on a C18 column with a good mobile phase consist of 10 mM ammonium acetate and acetonitrile [(pH 5.5 adjusted with orthophosphoric acid (25:75, v/v)]. UV method was developed with the wavelength at 280 nm. Two methods showed good linearity, reproducibility and precision. Both the methods (UV and HPLC) showed no spectral or chromatographic interferences from the tablet excipients. Results: The developed methods were successfully applied to dosage forms. Validation parameters were carried out such as linearity, precision, accuracy, and specificity. The HPLC LOD and LOQ for montelukast were found to be 150 ng/ml and 500 ng/ml. The UV LOD and LOQ for montelukast were found to be 1 μg/ml and 5 μg/ ml. Both the results were statistically differentiated using one-way analysis of variance (ANOVA). The developed and validated economical methods could be applicable for analysis of ML and monitoring of the quality of available drugs.

}, keywords = {Estimation, HPLC, Montelukast, Tablets, UV, Validation}, doi = {10.5530/PTB.2016.2.2}, author = {Selvadurai Muralidharan and Low Jia Qi and Lai Ting Yi and Narvinder Kaur and Subramani Parasuraman and Jayaraja Kumar and Vijayan Venugopal and Palanimuthu Vasanth Raj} } @article {52, title = {Simple and Effective HPLC Method Development and its Validation for Ursolic acid in Drug Free plasma: Application to bioanalytical studies}, journal = {Pharmacology, Toxicology and Biomedical Reports}, volume = {2}, year = {2016}, month = {August 2016}, pages = {52-55}, type = {Original Article}, chapter = {52}, abstract = {

Objective: Simple and effective high performance liquid chromatographic (HPLC) method was developed for estimation of ursolic acid in drug free human drug free blank plasma. Material and Methods: The current method was used protein precipitating extraction of ursolic acid from blank plasma. Separation was achieved on reversed-phase C18 column (250{\texttimes}4.6 mm, 5μ) and the detection was monitored by UV detector at 220 nm. The optimized mobile phase was used acetonitrile: 0.5\% triethyl amine (pH 4.0), in the ratio of 70:30 \% v/v at a flow rate of 1.0 mL/min. This linearity was achieved in this method range of 25.0{\textendash}150.0 ng/ml with regression coefficient range is 0.99. Results: The present method is suitable in terms of precise, accurate and specific during the study. The simplicity of the method allows for application in laboratories that lack sophisticated analytical instruments such as GC{\textendash}MS/MS or LC{\textendash}MS/MS that are costly, time consuming and complicated rather than a simple HPLC{\textendash}UV method. The present method was successfully applied for bioanalytical studies.

}, keywords = {Bioanalytical studies, HPLC, Method Development and Validation., Ursolic acid}, doi = {10.5530/PTB.2016.2.8}, author = {Selvadurai Muralidharan and Jayaraja Kumar and Venugopal Vijayan} } @article {65, title = {The Importance of Pharmacokinetic and Pharmacodynamic Models in Sustained Release Formulation}, journal = {Pharmacology, Toxicology and Biomedical Reports}, volume = {1}, year = {2015}, month = {27th Feb, 2015}, pages = {5-9}, type = {Review Article}, chapter = {5}, abstract = {

The main role of preclinical pharmacokinetics and pharmacodynamics in drug discovery and development is to optimize candidate selection for the target therapeutic area, taking into consideration the type of agent required, and to predict the dose and dosing regimen for initial clinical trials with due concern to the requirements for effective treatment in the target therapeutic area. In order for this approach to be successful, a clear understanding is required for both the pharmacological target and drug disposition (absorption, clearance and distribution) of new chemical entities. A fundamental tenet in linking the pharmacokinetic and pharmacodynamic phases is that free drug in the systemic circulation is in equilibrium with the receptors. In the pharmacokinetic phase, only free drug can be cleared and drug is reversibly bound to tissues and blood. The pharmacodynamic phase is further subdivided into the interaction with the drug receptor triggering postreceptor events, eventually leading to actual drug effect. In this phase, only free drug can exert pharmacological effect and the free concentration of drug in plasma is in direct equilibrium with the interstitial fluid bathing most cells, since the capillary wall contains sufficient aqueous pores to allow the rapid passage of relatively small molecules, regardless of physicochemistry. Most receptor targets are accessed extracellularly. Therefore, one can expect that all drugs regardless of physicochemistry will be in direct equilibrium, at these targets, with free drug in plasma.

Key words: Bioavailability, Drug discovery, Formulations, PK-PD models, Sustained release dosage form.

}, keywords = {Bioavailability, Drug discovery, Formulations, PK-PD models, Sustained release dosage form.}, doi = {10.5530/PTB.1.1.3}, author = {Selvadurai Muralidharan and Kalaimani Jayaraja Kumar} }