A simple, sensitive and reproducible spectrophotometric method was developed for the determination of sitagliptin phosphate in bulk and in pharmaceutical formulations. The proposed method is based on condensation of the primary amino group of sitagliptin phosphate with acetyl acetone and formaldehyde producing a yellow colored product, which is measured spectrophotometrically at 430nm. The color was stable for about 1 hour. Beer's law is obeyed over a concentration range of 5-25 μg/ml. The apparent molar absorptivity and Sandell sensitivity values are 1.067 x 10 4 Lmol-1 cm-1 and 0.0471 μgcm-2 respectively. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipients. The validity of the method was tested by analyzing si-tagliptin phosphate in its pharmaceutical preparations. Good recoveries were obtained. The developed method was successfully employed for the determination of sitagliptin phosphate in various pharmaceutical preparations.

Objective: This study points to build up and validate a simple methodology to quantify the most used drug sofosbuvir for the treatment of hepatitis C virus (HCV) infection, in human plasma by using atazanavir as an Internal Standard (IS) for preclinical studies and validate as per USFDA guidelines.Methods: Sofosbuvir was isolated from plasma samples by liquid-liquid extraction method using acetonitrile; good chromatographic separation was achieved on Kromasil Column (250 mm ×4.6 mm, 5 µm). The mobile phase consisted of 0.1 % orthophosphoric acid (OPA) buffer pH 2 and acetonitrile in the ratio of (68:32, v/v), respectively. The analysis time was 7 min at a flow rate 1 ml/min. The photodiode array detector (PDA) detection was carried out at 228 nm. The suggested method was validated by performing linearity, system suitability, specificity and sensitivity, accuracy and precision, recovery, ruggedness, stability studies. The method was validated as per USFDA guidelines. Results:The developed method resulted in retention times of sofosbuvir and IS were found out to be 4.7 and 4.2 min respectively. The calibration curves are linear (r2 = 0.999) over the concentration range of 0.050-2.0 µg/ml of plasma analytes concentration. LOQ value was found to be 0.050 µg/ml with precision and accuracy. Within-batch % mean accuracy of the method ranged between 96.00% and 109.09%, and within-batch and total precision, expressed as the coefficient of variation, was 1.40-10.33%. Overall percentage mean recovery of sofosbuvir from spiked plasma was 84.14%. All the validated parameters were found to be within the limit. Conclusion:A simple, accurate, precise, linear, rugged and rapid RP-HPLC method was developed for quantitative estimation of sofosbuvir in human plasma and should be suitable for conducting pharmacokinetics studies and therapeutic drug monitoring.

The major objective of this study was to investigate the effect of biodegradable polymer type and surfactant concentration on various characteristics viz. particle size, entrapment efficiency and drug release rate constant of aqueous core nanocapsules (ACNs) containing tenofovirdisoproxil fumarate. In this study, the nanocapsules were prepared by modified multiple emulsion technique with biodegradable polymers viz. poly(lactide-co-glycolide) of two different grades (PLGA RG502H and PLGA RG503H) and poly lactic acid (PLA R203H); and the surfactant employed was span 80. The experiments were designed under response surface methodology by employing the Design Expert software. Entrapment efficiency, particle size and drug release rate constant were taken as response variables. The prepared nanocapsules were subjected to characterization studies and the obtained results were statistically analyzed by Analysis of Variance (ANOVA) for response surface 2-Factorial Interaction model. ANOVA studies showed that the influence of both factors on all the response variables were significant at p<0.05. The optimized formulation was found to have the entrapment efficiency of 71.58%, particle size of 252.41 nm and the drug release rate constant of 0.045 h-1 ; thus, indicating that the ACNs were obtained with finest characteristics. SEM studies showed that the particles were spherical.

Background: Nanoparticles made of biodegradable polymers are the most effective colloidal drug delivery systems. The in vitro characteristics as well as in vivo presentation of these nanoparticles are majorly influenced by their formulation parameters. Objectives: The principle objective of the work was to optimize various critical formulation parameters by using statistical tools in order to develop poly (lactide-co-glycolide) (PLGA) nanocapsules loaded with tenofovir disoproxil fumarate (TDF) with effective characteristic properties. Methodology: In this work, biodegradable nanocapsules with PLGA for TDF were prepared by modified double emulsification technique. Concentration of PLGA, concentration of Pluronic F-68 in secondary emulsion and concentration of glycerol in external phase were selected as the formulation factors hence, a 3 3 full factorial design in response surface methodology was chosen as an experimental design. The prepared nanocapsules were evaluated for various characteristic properties like particle size, surface morphology, entrapment efficiency, drug release studies and DSC studies. The selected formulation parameters were optimized by a mathematical model called desirability functions approach with the set desirability of high entrapment efficiency, low drug release constant and less particle size. Results and Conclusion: Particle size, entrapment efficiency and drug release constant were found in the ranges of 249.3-376.3nm, 20.95-71.35% and 0.039-0.184 hr -1 . These selected formulation parameters were found to have significant (at p < 0.05 by ANOVA) influence on various characteristics of prepared nanocapsules. The optimized formulation found to have 63.08% of entrapment efficiency, 284.53 nm of particle size with zeta potential of -26.1 mV and 0.054 h -1 of release rate constant.

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