Development of a liquid chromatographic method and its application in the quality assessment of stavudine-containing products
Mwagiru, Philip M
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A liquid chromatographic method for the separation of the antiretroviral agents stavudine, lamivudine and zidovudine was developed and validated for stavudine. The chromatographic method finally employed a PRP-1 8 urn (2S0 mm x 4.6 mm I.D.) column maintained at SO "c. The mobile phase consisted of acetonitrile-O.OS M potassium phosphate buffer pH 3.0-0.1 M tetrabutylammonium hydroxide pH 3.0-water (10: 10:10:70, v/v) at a flow rate of 1.0 mllmin and ultraviolet detection at 268 nm. The method's detection was linear in the range between 0.78 and 200 ug/rnl with correlation value of O.997S. The limit of detection -and the limit of quantitation were 0.8 ng and 32.0 ng, respectively The method was precise, with a within-day coefficient of variation of 1.2 % when solutions were made in the mobile phase and 1.S % when the solutions were made in Krebs-Hesenleit physiological buffer. An assessment of bioequivalence of stavudine-containing products on the Kenyan market was done by determining their content, dissolution and their absorption profiles. The developed method was used as a tool of analysis. The method was successfully used to determine content and dissolution characteristics of eleven antiretroviral products, consisting of locally manufactured and imported generics. Although there are no compendial specifications for content or dissolution for stavudine, the products had a potency range from 91.4 to 103.6 % of label claim while between 99.S and 112.8 % of label claim had dissolved in water after 30 minutes using a USPIBP paddle dissolution method. The products therefore all had good content and dissolution properties. An in vitro rat intestinal gut sac model was used to study the absorption profiles of active ingredients from the various drug products in terms of their perfusion across intestinal tissue. Four stavudine-containing products were investigated. At 90 minutes, stavudine from three products had crossed the intestinal membrane to an extent of more than 60 % while for one product the value was 48 %, despite having a potency of 97.6 % of label claim. This product was found to have a relatively poor perfusion, and therefore a poor absorption profile compared to the other three. It may not be bioquivalent to the others .