Validated RP-HPLC method for the assay of zalcitabine in drug substance, formulated products and human serum

A HPLC method for zalcitabine determination in bulk form, pharmaceutical dosage forms and human serum has been developed and validated. The proposed method was conducted using a reverse phase technique, and UV monitoring at 265 nm. The mobile phase consisted of methanol: 0.01 M NaH2PO4 (85:15; v/v) adjusted to pH 4.62 with 1 M NaOH. The detector response was linear in the range of 0.015-50 mug mL(-1). The limit of detection and the limit of quantification of the procedure were 0.0066 mug mL(-1) and 0.022 mug mL(-1), respectively. The retention time was 2.5 min for zalcitabine and 3.5 min for the internal standard. No interferences from tablet additives were observed and analysing tablets containing zalcitabine proved the applicability of the method. This method was also applied for the determination of zalcitabine in spiked human serum samples.