No abstract

The aim of this study was to investigate the use of liquisolid technique in improving the dissolution of glyburide in a solid dosage form. This study was designed to evaluate the effects of different formulation variables, i.e. type of non-volatile liquid vehicles and drug concentrations, on drug dissolution rates. The liquisolid tablets were formulated with Propylene glycol, as liquid vehicle. Microcrystalline cellulose was used as a carrier material, silica as a coating material and croscaremellose as a disintegrant. In vitro drug dissolution profiles of the liquisolid formulations were studied and compared with direct compressed non-micronized and micronized tablets of glyburide using USP II, paddle apparatus at 50 rpm for 60 min using 900 ml of 0.05 M Phosphate Buffer, pH 7.5. The stability studies showed that the dissolution profiles of liquisolid tablets prepared with propylene glycol were not affected by ageing significantly, as f2 value found between aged and fresh samples was 51.92. Differential scanning calorimetry revealed that the drug has got solubilized in the liquid vehicle. This was further supported by the powder X-ray diffraction studies of pure drug and the liquisolid powder system. It can be concluded that it is possible to load poorly soluble drug into liquisolid tablets by addition of PVP to the liquid vehicle. This is valuable for the preparation of liquisolid tablets of poorly soluble drugs. The liquisolid tablets prepared with PVP showed a remarkably improved dissolution rate in comparison with DC tablet and other formulations.

Glyburide, a sulfonylurea derivative, widely used as hypoglycaemic agent. In the present study, an attempt has been made to investigate the most effective third component which can be used with hydroxylpropyl-β-cyclodextrin (HPβCd) to form a ternary complex with glyburide in order to enhance its dissolution rate, as well as reduce the amount of HPβCd used for formulating the binary complex with glyburide. Moreover, the objective of this study was also to develop a discriminatory dissolution media in order to discriminate the effect of the different solubilizing agents used for formulating the ternary complex system. Sodium lauryl sulphate, Poloxamer-188, Polyvinylpyrrolidone K-30, lactose and L-arginine were used to formulate ternary system along with HPβCd and glyburide. The ternary system formulated with glyburide:HPβCd:L-arginine in a proportion of 1:1:0.5 has shown the fastest dissolution rate when compared to other solubilizing agents. Unbuffered aqueous media with stirring speed 50 rpm has produced the most discriminatory dissolution profiles. The DSC thermograms and the powder X-ray analysis revealed the decrease in crystallinity of the drug. This was an indication of amorphous solid dispersion or molecular encapsulation of the drug into the cyclodextrin cavity.

Simultaneous quantification of nebivolol hydrochloride (NEB-H) and hydrochlorothiazide (HCT) in tablets by UV spectroscopy, RP-HPLC and HPTLC methods were developed. In UV spectrophotometric determination NEB-H and HCT was quantified by simultaneous equation method and absorbance ratio method. In simultaneous equation method absorbance measurements at 282.5 nm (λmaxNEB-H) and 271.5 nm (λmaxHCT), in absorbance ratio method absorbance measurements at 282.5 nm and 275 nm (iso absorptive point) in methanol. In RP-HPLC method, the drugs were resolved using a mobile phase of 30 mM phosphate buffer (K2HPO4), acetonitrile and triethylamine (50:50:0.1 % v/v) with pH 5.5 using orthophosphoric acid on a C18-ODS- Phenomenex (5 μm, 250 mm x 4.6 mm) column in isocratic mode, Atorvastatin (ATR) used as a internal standard. The retention time of HCT, NEB-H and ATR was 3.31, 4.30 and 6.93 min respectively. In the HPTLC method, the chromatograms were developed using a mobile phase of ethyl acetate: methanol: ammonia (8.5:1:0.5 v/v) on precoated plate of silica gel 60 F254and quantified by densitometric absorbance mode at 285 nm. The Rf of HCT and NEB-H were 0.21 and 0.41 respectively. Recovery studies of 98.88-102.41%, percentage relative std deviation of not more than 0.8 and correlation coefficient (linearity range) of 0.9954-0.9999 shows that developed methods were accurate and precise. These methods can be employed for the routine analysis of tablets containing NEB-H and HCT.

The objective of the present investigation is to develop and validate a simple, economical and reliable high performance liquid chromatography method for the quantification of quetiapine (CAS 111974-72-2) in human plasma with a quantification limit sufficiently low to support pharmacokinetic studies. Imipramine hydrochloride (CAS 113-52-0) was used as internal standard. The validated method allows quantification of quetiapine in 15-1000 ng/mL. The method was shown to be precise (< 7% coefficient of variation, CV) and accurate (< or = 10% relative error, RE). The correlation coefficient for quetiapine was > 0.9970. The simplicity of the assay and rapid liquid-liquid extraction make it an attractive procedure in high-throughput bioanalysis of quetiapine.