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A simple and sensitive stability-indicating HPLC-UV method was developed and validated for the determination of montelukast in the development of chewable tablet formulation. Chromatographic separation was achieved using Atlantis® T3 3µm C18 (4.6mmID X 10cm) analytical column. The mobile phase was consisted of KH 2 PO 4 (0.05mM)-ACN-TEA (450:550:1.33, v/v/v) adjusted to pH 2.0 with orthophosphoric acid. The analysis was run at a flow rate of 1.5 mL/min with detection wavelength at 255nm. Method validation was performed in accordance with ICH guideline. Stress degradation studies, comprising of acid and alkali hydrolysis (1M HCl and 1M NaOH), oxidative degradation (3% H2O2), photo degradation and heat degradation, were performed. The standard calibration curve was linear from 0.0025 - 0.375mg/mL. The LOD and LLOQ were 0.01μg/mL and 0.04μg/mL. Stress degradation result shows that montelukast sodium was sensitive to photo degradation, oxidation and acid hydrolysis. Oxidative degradation kinetic study of montelukast sodium followed first order reaction, with r 2 =0.9877, apparent degradation rate constant, k= 0.1066 h -1 , t 1/2 = 6.6151 hr and t90% = 1.0118hr. In conclusion, HPLC-UV method was successfully developed and validated for determination of montelukast sodium in chewable tablet formulation.

A stability-indicating HPLC-UV method for the simultaneous determination of sildenafil citrate and dapoxetine hydrochloride in solution and tablet was developed. The mobile phase was comprised of acetonitrile and 0.2M ammonium acetate buffer. The analyte was eluted at 3.392min and 7.255min for sildenafil citrate and dapoxetine HCl respectively using gradient system at a flow rate of 1.5mL/min. The theoretical plates count was>2000, tailing factor <.30, capacity factor 3.19-7.58 and peak asymmetry factor <.08.The method was linear from 5-180 and 1-40μg/mL with a correlation coefficient of 0.9999 and 0.9994 for sildenafil citrate and dapoxetine HCl respectively. The drug solution was stable at ambient room temperature (26˚C) for 48hours.Both drugs were found susceptible to oxidation and the drug content dropped slightly in acid and alkali condition but stable under UV light and heat. No interference from tablet excipients and degradation products was found.

The effect of deprotenizing agents on recovery of donepezil hydrochloride in the development of a simple, rapid, selective and sensitive high performance liquid chromatography method for quantification of donepezil hydrochloride in human plasma was described. The deprotenizing agents were comprised of, perchloric acid, methanol, acetonitrile, chloroform and their mixtures. The chromatographic separation was carried out using reversed phase C18 column (Agilent Eclipse Plus C18) with UV detection at 268 nm. The mobile phase was comprised of 0.01 M potassium dihydrogen phosphate buffer, methanol and acetronitrile (50:30:20, v/v) adjusted to pH 2.7 with phosphoric acid (80%). A combination of perchloric acid and methanol gave a cleaner sample with a good recovery of donepezil hydrochloride of above 96%. The method showed intraday precision and accuracy in the range of 6.82% to 1.5% and 3.13% to 1.12% respectively, while interday precision and accuracy ranged between 1.06% to 4.71% and 13.01% to 6.43% respectively. The standard calibration curve was linear from 30ng/mL to 4000ng/mL, with a correlation coefficient of 0.9965±0.0034. The retention time of donepezil was 5.9 min with a run time of 7.0 min. The method can be applied to analyze large batch plasma samples in pharmacokinetic studies.

An easy, fast and validated RV-HPLC method was invented to quantify donepezil hydrochloride in drug solution and orally disintegrating tablet. The separation was carried out using reversed phase C-18 column (Agilent Eclipse Plus C-18) with UV detection at 268 nm. Method optimization was tested using various composition of organic solvent. The mobile phase comprised of phosphate buffer (0.01M), methanol and acetonitrile (50:30:20, v/v) adjusted to pH 2.7 with phosphoric acid (80%) was found as the optimum mobile phase. The method showed intraday precision and accuracy in the range of 0.24% to -1.83% and -1.83% to 1.99% respectively, while interday precision and accuracy ranged between 1.41% to 1.81% and 0.11% to 1.90% respectively. The standard calibration curve was linear from 0.125 μg/mL to 16 μg/mL, with correlation coefficient of 0.9997±0.00016. The drug solution was stable under room temperature at least for 6 hours. System suitability studies were done. The average plate count was > 2000, tailing factor <1, and capacity factor of 3.30. The retention time was 5.6 min. The HPLC method was used to assay donepezil hydrochloride in tablet and dissolution study of in-house manufactured donepezil orally disintegrating tablet and original Aricept.

The objective of the present study was to determine the intestinal absorption of sulpiride incorporated into SMEDDS by means of single-pass intestinal perfusion method (SPIP) in rat and to compare the effective permeability coefficient obtained with that of drug solution and micellar solution. The prepared SMEDDS and micelles formulations were investigated for droplets size. SPIP experiment was performed using the three formulations in three of the secluded regions of the small intestine (duodenum, jejunum, and ileum). The amount of the drug in the samples was estimated by HPLC and the effective permeability coefficients in rats were calculated. The human intestinal permeability was predicted based on rat effective permeability coefficient value. The dilution stability of the formulations was also determined. The average droplet size of SMEDDS and micelles was 9.27 nm and 7.20 nm respectively. The effective permeability coefficient of sulpiride was appreciably lower in the ileum weighed against jejunum and duodenum when administered as a solution (P<0.05). The estimated human absorption of sulpiride for the SMEDDS dilutions was superior to that from solution (P<0.05) and similar to micellar solution. The micellar dilutions were unstable whereas the SMEDDS dilutions were stable. Based on the above results, SMEDDS can be a potential candidate for improving the peroral absorption of the sulpiride.