Evaluation of Perampanel in the Presence of its Degradation Products and Process-Related Impurities by Validated Stability-Indicating Reverse Phase High Performance Liquid Chromatography Method.

A novel stability-indicating isocratic reverse phase high-performance liquid chromatographic method was developed for the quantitative determination of perampanel in the presence of degradation products and its process-related impurities. Good resolution was achieved between the peaks corresponding to process-related impurities and degradation products from the analyte using Shim-pack GIST C18 column with mobile phase, potassium dihydrogen phosphate (pH 2.5; 30 mM)-acetonitrile (45: 55, v/v) at a wavelength of 294 nm. Perampanel and its impurities were well-separated within a run time of 7 min. To show the stability-indicating power of the method, forced degradation studies were performed on bulk samples of perampanel as per ICH prescribed stress condition using acid, base, hydrolytic, oxidative and photolytic degradation conditions. The degradation products were resolved from main peak and its impurities. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision and robustness. This method was also applied for assay and related substances determination of perampanel in bulk and pharmaceutical dosage form.

Development and validation of a liquid chromatography/ mass spectrometry method for the simultaneous quantitation of rosuvastatin and ezetimibe in human plasma.

A simple, rapid, and sensitive LC/electrospray ionization (ESI)-MS method was developed and validated for the simultaneous determination of rosuvastatin (ROS) and ezetimibe (EZE) in human plasma. Following liquid-liquid extraction, the analytes and an internal standard, atorvastatin (ATO), were separated using an isocratic mobile phase comprising 0.1% (v/v) formic acid-methanol (20 + 80, v/v) on an RP-C18 column. Detection was performed on a mass spectrometer by selected ion monitoring using their respective [M-H]- ions, m/z 480 for ROS, m/z 408 for EZE, and m/z 557 for ATO. For both analytes, the method was linear in the range of 0.1 to 10 nglmL. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 4 min made it possible to determine many plasma samples/day. The validated LC/ESI-MS method can be used to study pharmacokinetics, bioavailability, and bioequivalence of combined dosage forms of ROS and EZE.

In vitro interaction study of retinoic acid isomers with telmisartan and amlodipine by equilibrium dialysis method using UV spectroscopy.

The in vitro protein binding of retinoic acid isomers (isotretinoin and tretinoin) and the antihypertensive drugs (amlodipine and telmisartan) was studied by equilibrium dialysis method. In this study, free fraction of drugs and the % of binding of drugs in the mixture to bovine serum albumin (BSA) were calculated. The influence of retinoic acid isomers on the % of protein binding of telmisartan and amlodipine at physiological pH (7.4) and temperature (37±0.5°C) was also evaluated. The in vitro displacement interaction study of drugs telmisartan and amlodipine on retinoic acid isomers and also interaction of retinoic acid isomers on telmisartan and amlodipine were carried out.

Stability-indicating high-performance column liquid chromatography and high-performance thin-layer chromatography methods for the determination of olopatadine hydrochloride in tablet dosage form.

This paper describes two simple, specific, accurate, and precise methods for estimation of olopatadine hydrochloride (OLO) in tablet dosage form. The first method is a stability-indicating isocratic RP-HPLC method. The analysis is performed on an RP-18 column using 0.1% orthophosphoric acid (adjusted to pH 4.5 with triethylamine)-acetonitrile (75 + 25, v/v) mobile phase at a flow rate of 1 mL/min. Paracetamol (PAR) was selected as the internal standard. Retention times of OLO and PAR were 11.30 +/- 0.02 and 4.70 +/- 0.03 min, respectively. For the HPTLC method, precoated silica gel 60 F254 aluminum sheets were used as the stationary phase; the mobile phase was methanol-chloroform-ammonia (8 + 2 + 0.1, v/v/v). The detection of the analyte band was carried out at 301 nm, and its Rf value was 0.46 +/- 0.03. The analytical methods were validated according to International Conference on Harmonization guidelines. Linear regression analysis data for the calibration plots showed a good linear relationship between response and concentration in the range of 0.1-1 microg/mL and 0.1-0.9 microg/band for HPLC and HPTLC, respectively.

Determination of rosuvastatin and ezetimibe in a combined tablet dosage form using high-performance column liquid chromatography and high-performance thin-layer chromatography.

This paper describes validated HPLC and HPTLC methods for the simultaneous determination of rosuvastatin (ROS) and ezetimibe (EZE) in a combined tablet dosage form. The isocratic RP-HPLC analysis was performed on a Chromolith C18 column (100 x 6 mm id) using 0.1% (v/v) orthophosphoric acid solution (pH 3.5)-acetonitrile (63 + 37, v/v) mobile phase at a flow rate of 1 mL/min at ambient temperature. Quantification was carried out using a photodiode array UV detector at 245 nm over the concentration range of 0.5-10 microg/mL for ROS and EZE. The HPTLC separation was carried out on an aluminum-backed sheet of silica gel 60F(254) layers using n-butyl acetate-chloroform-glacial acetic acid (1 + 8 + 1, v/v/v) mobile phase. Quantification was achieved with UV densitometry at 245 nm over a concentration range of 0.1-0.9 micro/spot for ROS and EZE. The analytical methods were validated according to International Conference on Harmonization guidelines. Low RSD values indicated good precision. Both methods were successfully applied for the analysis of the drugs in laboratory-prepared mixtures and commercial tablets. No chromatographic interference from the tablet excipients was found. These methods are simple, precise, and sensitive, and are applicable for simultaneous determination of ROS and EZE in pure powder and tablets.

Simultaneous LC determination of tizanidine and rofecoxib in tablets.

A reverse phase high performance liquid chromatographic method to determine tizanidine (TZ) and rofecoxib (RF) in combination is proposed and applied to the pharmaceuticals. This method allows the determination of 0.1-0.5 microg/ml of TZ and 1.2-6.0 microg/ml of RF along with 10 microg/ml of nimesulide (internal standard), in a mobile phase consisting of 1% (v/v) triethylamine (pH adjusted to 2.5 using dilute orthophosphoric acid):acetonitrile in the ratio 55:45% (v/v). Detection wavelength of 303 nm and flow rate of 0.8 ml/min were fixed for the study. The limit of detection (LOD) for TZ and RF were found to be 10 and 1 ng/ml, respectively. The limit of quantification (LOQ) for TZ and RF were found to be 80 and 12 ng/ml, respectively. The amount of drug present in the tablet and the recovery studies were also carried out. The % R.S.D. of recovery studies for TZ and RF were found to be 0.0673 and 0.0146, respectively. The method is validated for accuracy, precision, ruggedness and robustness.