Aim: The main aim of the present study was to characterize and perform the compatibility studies of paliperidone with its excipients. Study Design: Physico-chemical characterization and compatibility studies. Place and Duration of the Study: Chalapathi Drug Testing Laboratory, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur-522034 between December 2020 and January 2021. Methodology: Physico-chemical characterization and compatibility studies of paliperidone palmitate with its excipients like HPMC, lactose, magnesium stearate, talc, microcrystalline cellulose was done using the FTIR spectrophotometer, Scanning electron microscopy, X-ray diffraction, Differential scanning calorimeter. Results: Interaction of the paliperidone palmitate with its excipients were studied by this technique. Paliperidone palmitate showed the transition at 117.920C with the specific heat of 101.9J/g. The IR spectrum of paliperidone palmitate and excipients mixture has shown a characteristic stronger band of the N-H at 3412.75cm-1, C-H at 2921.98 cm-1, stretching vibrations of C=O at 1737.47 cm-1, C=C at 1651.94 cm-1, N-O at 1541.16 cm-1 followed by C-F at 1160.46 cm-1. XRD showed good crystalline properties with relative crystallinity index of 60.01%. The photomicrographs obtained by SEM did not evidence any interaction between paliperidone palmitate and the excipients, providing visual support for the results. Conclusion: There were no interactions of drug with selected excipients and found to be compatible. Therefore, it is a mandatory clause for the compound compatibility with various excipients in the formulation which affect the stability and efficacy of the formulation.

Aim: To design simple, rapid, new analytical method for estimation of Metronidazole, Ciprofloxacin Doxycycline by using RP-HPLC in bulk and pharmaceutical dosage form. Study Design: Estimation of Metronidazole, Ciprofloxacin Doxycycline by using RP-HPLC in bulk and pharmaceutical dosage form was planned and executed. Place and Duration of Study: Chalapathi Drug Testing Laboratory, Chalapathi Institute Of Pharmaceutical Sciences, Lam, Guntur-522034, Andhra Pradesh, India during the period of November 2019 to February 2020. Methodology: Metronidazole is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis and bacterial vaginosis. Ciprofloxacin is an antibiotic used to treat a number of bacterial infections. Doxycycline is a tetracycline antibiotic that fights bacteria in the body. The study was carried out on SHIMADZU Prominance-i, LC-2030C system equipped with Shim-pack Gist (250 x 4.6 mm, 5μm) column and mobile phase was optimized by using mixture of methanol and 0.25mM potassium phosphate buffer in the ration of 60:40 v/v at a flow rate of 0.8 ml/min. The wavelength was set as 282nm at ambient temperature by injecting 20µl of solution and the run time was fixed for 10 min. Results: Linearity plot was constructed for concentration range of 5-15µg/ml for Metronidazole,5-15µg/ml for Ciprofloxacin and 1-8µg/ml for Doxycycline standard solutions. It shows best regression coefficient and y/s values. The accuracy of the proposed method was determined by performing recovery studies and was found between 98-102%. The repeatability testing for both sample and standard solutions the %RSD was found as <2.0% which is within the acceptable limits showing that the method is precise as well. The LOD and LOQ were found to be 0.33 and 0.99 µg/ml for Metronidazole, 0.33 and 0.99 µg/ml for Ciprofloxacin, 0.08 and 0.25 µg/ml for Doxycycline respectively. The proposed method was successfully applied for the pharmaceutical dosage form of Metronidazole, Ciprofloxacin Doxycycline and it was as economic, eco-friendly with less retention time around 10.0 min. Conclusion: The proposed method was validated in terms of linearity, range, Accuracy, precision, Specificity, Robustness. Method was successfully applied to the estimation of Metronidazole, Ciprofloxacin Doxycycline in combined marketed pharmaceutical dosage form.

Aims: The main aim of the present study was to develop and validate a simple and cost- effective method for the estimation of allopurinol and its related substances by using RP-HPLC. Study Design:  Estimation of Allopurinol and its related substance in bulk and tablet dosage forms by RP-HPLC. Place and Duration of Study: Chalapathi Drug Testing Laboratory, Chalapathi Institute of Pharmaceutical Sciences, Chalapathi Nagar, Lam, Guntur-522034 between October 2020 to January 2021. Methodology: Method development was carried out by using Schimadzu, Prominence-i series LC 3D-Plus autosampler embedded with lab solutions software, equipped with PDA detector using YMC column (150 mm X 4.6 mm, 3 μm) and 0.1M Ammonium acetate buffer as a mobile phase in the ratio of 100% at a flow rate of 1.0 ml/min at a wavelength of 255nm. The developed method was validated according to ICH guidelines. Results:  The linearity was observed in the range of 20-100 µg/ml with a regression (R2) value of 0.999. Developed method was specific with no interactions and accurate with 100.11% for allopurinol and 99.54% for its related substance. The limit of detection for allopurinol was 2 µg/ml and for related substance was 0.0.1 µg/ml. The limit of quantification for allopurinol was 6 µg/ml and for related substance was 0.03 µg/ml respectively. The percentage relative standard deviation was found to be NMT 2 which indicates that the proposed method was precise and robust. Conclusion:  The developed method was simple, precise and accurate and can be successfully employed for the estimation of allopurinol in bulk and tablet dosage form.