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1

A new TLC densitometric method for stability assessment of modafinil

Faisal M. S., Naz Z., Shakeel F., Ahmed S., Kohli K., Khar R. K.

Chemia Analityczna

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2009

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Vol. 54, No. 1

77-88

EN

TLC densitometric method for simple and sensitive stability assessment of modafinil has -been developed. The objective was to provide a rapid, precise, robust, and reproducible technique for the analysis of modafinil. The method was validated for bulk drug and tablet , formulations. It could be used to separate the drug from its degradation products. The pro- cedure employed TLC aluminum plates precoated with 60F-254 silica gel as the stationary phase. The solvent system consisted of toluene-chloroform-methanol (1:1:0.5, v/v/v) 'o'o mixture. It provided well-resolved compact spots for modafinil (Rr value 0.46 š 0.01) and allowed for separation of the excipients and degradation products. Densitometric scanning interegation was performed at the wavelength of 220 nm. Calibration plot was linear , (r2 = 0.999) in the analyte concentration range 100-5000 ng per spot. The method was validated with respect to linearity, accuracy recovery, precision, ruggedness, and specificity. The limit of detection and quantification were 20.54 ng per spot and 62.26 ng per spot, respectively. The determined drug content was within the š5% range of the labeled content. The drug was analyzed under different stress conditions in order to study its degradation in the presence of acid, base, and peroxide.

PL

Opracowano densytometryczną metodę TLC pozwalającą na proste i czułe badanie stabilności modafinilu. Opracowana technika była szybka, precyzyjna, odporna na warunki zewnętrzne i powtarzalna. Metodę zwalidowano dla substancji farmaceutycznej i tabletek. Można ją stosować do oddzielenia leku od produktów rozkładu. Jako fazę stacjonarną użyto żel krzemionkowy 60F-254 naniesiony na płytki aluminiowe. Fazę ruchomą stanowiła '"' mieszanina: toluen-chlorofbrm-metanol (1:1:0,5; v/v/v). Otrzymywano dobrze rozdzielone, zwarte plamki modafinilu (wartość Rf 0.46 š 0.01), oddzielone od substancji pomocniczych i produktów rozkładu. Skanowanie densytometryczne prowadzono przy długości fali 220 nm. Krzywa kalibracyjna miała charakter liniowy (r2 = 0,999) w zakresie stężeń analitu 100-5000 ng na plamkę. Metodę zwalidowano w zakresie liniowości, dokładności, odzysku, precyzji, odporności na czynniki zewnętrzne i specyficzności. Granica wykrywalności i oznaczalności ilościowej wynosiły odpowiednio 20,54 ng i 62.26 ng na plamkę. Oznaczana zawartość leku mieściła się w granicach š 5% ilości deklarowanej. Lek analizowano w różnych warunkach stresowych w celu zbadania jego degradacji w obecności kwasów, zasad i nadtlenków.

2

Development and validation of a stability-indicating LC-UV method for rapid analysis of buspirone in pharmaceutical dosage forms

Azeem A., Rizwan M., Ahmad F. J., Iqbal Z., Khar R. K., Aqil M, Talegaonkar S.

Acta Chromatographica

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2009

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Vol. 21, no. 2

283--297

EN

An accurate, sensitive, precise, rapid and isocratic reversed-phase HPLC (RPHPLC) method for analysis of buspirone in the bulk drug and in solid dosage formulations has been developed and validated. The best separation was achieved on a 250 mm × 4.6 mm i.d., 5-μm particle, RP C 18 column with 70:30 ( υ/υ ) methanol-0.01 M sodium dihydrogen phosphate buffer (pH 3.5) as mobile phase at a flow rate of 0.8 mL min -1. UV detection was at 244 nm. Response was a linear function of concentration over the range 0.05–20 μg mL -1 ( r = 0.9998) and the limits of detection and quantitation were 3.7 and 11.3 ng mL -1, respectively. The method was validated in accordance with ICH guidelines. The drug was subjected to oxidative, hydrolytic, photolytic, and thermal stress. Degradation products produced as a result of this stress did not interfere with detection of buspirone and the assay can thus be regarded as stability-indicating. The method was used for quantification of buspirone in commercial buspirone tablets and to check content uniformity. The excipients present in the formulation did not interfere with the assay. The method is suitable for application in quality-control laboratories, because it is simple and rapid with good accuracy and precision.

3

Development and validation of a stability-indicating method for determination of ropinirole in the bulk drug and in pharmaceutical dosage forms

Azeem A., Iqbal Z., Ahmad F. J., Khar R. K., Talegaonkar S.

Acta Chromatographica

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2008

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Vol. 20, no. 1

95-107

EN

An accurate, sensitive, precise, rapid, and isocratic reversed phase HPLC (RP-HPLC) method for analysis of ropinirole in the bulk drug and in pharmaceutical preparations has been developed and validated. The best separation was achieved on a 250 mm × 4.6 mm i.d, 5-µm particle, C18 reversed-phase column with methanol-0.05 M ammonium acetate buffer (pH 7) 80:20 (v/v) as mobile phase, at a flow rate of 1 mL min-1. UV detection was performed at 250 nm. The method was linear over the concentration range 0.2-100 µg mL-1 (r = 0.9998), with limits of detection and quantitation of 0.061 and 0.184 µg mL-1, respectively. The drug was subjected to oxidation, hydrolysis, photolysis, and heat as stress conditions. Degradation products resulting from the stress did not interfere with detection and assay of ropinirole and thus the method can be regarded as stability-indicating. The method can be used for quality-control assay of ropinirole.

4

Development and validation of an HPTLC method for determination of minocycline in human plasma

Jain G. K., Jain N., Iqbal Z., Talegaonkar S., Ahmad F. J., Khar R. K.

Acta Chromatographica

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2007

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No. 19

197-205

EN

A new high-performance thin-layer chromatographic (HPTLC) method has been established for determination of minocycline in human plasma. Chromatography was performed on aluminium plates coated with silica gel 60F254; the mobile phase was methanol–acetonitrile–isopropanol–water 5:4:0.5:0.5 (v/v). Densitometric analysis was performed at 345 nm. The method is rapid (single-step extraction with methanol), sensitive (limit of quantification 15.4 ng per zone), precise (CV ≤ 4.61 %), accurate (drug recovery 95.08–100.6%), and linear over the range 100–1200 ng per zone. Recovery of minocycline from plasma samples was 95.8 ± 4.5%. The halflife of minocycline in plasma was 9.9 h at 4°C and 6.3 h at 20°C. Minocycline is stable in human plasma for at least two months at -20°C and can tolerate two freeze–thaw cycles with losses <10%. The method was successfully used to determine therapeutic levels of minocycline.