A small-scale method of sample preparation suitable for simultaneous HPLC-UV assay of capecitabine and its 5'-DFCR metabolite in mouse blood plasma

Abstract The objective of the study was to develop an easy, cheap, effective, and safe, small-scale method for sample preparation suitable for the simultaneous high-performance liquid chromatography (HPLC)-ultraviolet (UV) assay of capecitabine and its 5′-deoxy-5-fluorocytidine (5′-DFCR) metabolite in mouse blood plasma. The suitability of the proposed method of sample preparation was verified by the optimal effectiveness and efficiency achieved in the overall analytical workflow. The chromatographic separation of capecitabine and its first metabolite was performed on a Hypersil GOLD aQ column with a mobile phase consisting of 1% formic acid, methanol, and water, and run in a gradient elution mode. The absence of interfering endogenous components at the retention times of each analyte was confirmed by the chromatographic analysis of blank matrices and matrices spiked with the corresponding standards. The absence of any tactile matrix effect was also recorded. For the first time, the effect of the vacutainer's anticoagulant on the extraction efficiency of both analytes was evaluated. The method was found to be accurate, precise, and specific. The estimated mean "extraction" efficiencies were ≥90% for each analyte. The lower limit of quantitation for both capecitabine and 5′-DFCR was 0.05 μg/mL.

In vitro and ex vivo studies on diltiazem hydrochloride-loaded microsponges in rectal gels for chronic anal fissures treatment.

Diltiazem hydrochloride, topically applied at 2% concentration, is considered effective for the treatment of chronic anal fissures, although it involves several side effects among which anal pruritus and postural hypotension. To test the hypothesis that a sustained delivery system of diltiazem hydrochloride may be helpful for the treatment of chronic anal fissures, in the present study we evaluated the potential of gels containing diltiazem hydrochloride entrapped in microsponges. Such microsponges were based on Eudragit RS 100 and the effect of some formulation variables was assessed by a 23 full factorial screening design. An optimized formulation of diltiazem hydrochloride microsponges was dispersed in Methylcellulose 2% or Poloxamer 407 20% and the resulting gels (micro-l-diltiazem hydrochloride 2%) were subjected to in vitro drug release, ex vivo permeability and drug deposition after application on porcine rectal mucosa. The results showed a prolonged release up to 24 h from micro-l-diltiazem hydrochloride at 2% in the gels. The permeation tests revealed up to 18% higher drug retention on the mucosal tissue after 24 h by the micro-l-diltiazem hydrochloride 2% gels compared to conventional diltiazem hydrochloride gels at 2%. These results suggest that diltiazem hydrochloride-loaded microsponges dispersed in rectal gels may be useful to overcome some limitations of conventional local chronic anal fissure therapy.