Determination of rabeprazole enantiomers in commercial tablets using immobilized cellulose-based stationary phase.

Rabeprazole is one of the latest proton-pump inhibitors used for treatment of several gastrointestinal disorders. For therapeutic applications, rabeprazole has been administered as a mixture of R-(+) and S-(-) enantiomers. Owing to pharmacological and toxicological differences between stereoisomers, chiral recognition has now become an integral part of drug research and development. A simple and rapid liquid chromatographic method for enantioselective separation and determination of R-(+) and S-(-) enantiomers of rabeprazole in bulk drug and pharmaceutical formulations was developed. Chiralpak IC (150 × 4.6 mm, 5 µm) column and µmobile phase containing hexane:ethanol:ethylenediamine (30:70:0.05 v/v) in an isocratic mode yielded baseline separation with resolution greater than 6.0 at 35 °C. Effects of additives and n-hexane were evaluated. Optimized condition was validated as per ICH guidelines. The method has good linearity, high sensitivity with LOD was 0.01 µg/mL and LOQ was 0.03 µg/mL for both enantiomers. Intra-day precision varied between 0.44 and 1.79% for S-(-) enantiomer, 0.65 and 1.97% for R-(+) enantiomer. Relative standard deviations of inter-day precision were less than 1.81% for both enantiomers. The percentage recovery for both enantiomers of rabeprazole ranged between 99.81 and 101.95%, 98.82 and 101.36% in material and tablets, respectively. The method was successfully applied to determine content of each enantiomer in commercial tablets.

Can gabapentin help reduce postoperative pain in arthroscopic rotator cuff repair? A prospective, randomized, double-blind study.

PURPOSE: The aim of the study was to determine the effect of low-dose gabapentin on postoperative pain management in patients undergoing arthroscopic rotator cuff repair. METHODS: This randomized, double-blinded, placebo-controlled study included 46 patients. The patients were divided into 2 groups according to the drug administered 2 hours before surgery, either 300 mg of gabapentin or placebo. The primary outcome measure was the visual analog scale (VAS) score at 2, 6, 12, and 24 hours postoperatively. The secondary outcome measures were fentanyl consumption and side effects during the first 2 hours in the postanesthesia care unit and then at 6 and 24 hours postoperatively. The patients were evaluated for side effects including nausea, vomiting, respiratory depression, dizziness, drowsiness, voiding difficulty, and pruritus. RESULTS: The VAS scores at 2, 6, and 12 hours postoperatively were significantly lower in the gabapentin group than in the placebo group (P = .023, P = .019, and P = .022, respectively). The consumption of fentanyl, over a period of 24 hours, was not different in the comparisons between the groups (P = .686). The incidence of side effects was similar in the 2 groups. CONCLUSIONS: A single dose of 300 mg of gabapentin reduced the VAS score during the first 24 hours postoperatively in patients undergoing shoulder arthroscopic rotator cuff repair, without significant side effects when compared with placebo. However, the fentanyl consumption did not differ between the gabapentin and placebo groups. LEVEL OF EVIDENCE: Level I, randomized controlled trial.