Comparative in vitro study of the antimicrobial activities of different commercial antibiotic products of vancomycin

In vitro equivalence of generic and branded amoxicillin tablet by microbiological assay method

Background Indonesian Ministry of Health advocate doctors, especially in government-owned healthcare facility, to prescribe generic drugs including amoxicillin. Although BPOM (the National Agency of Drug and Food Control) already guarantees that the generic amoxicillin and the branded one were interchangeable, lack of confidence in generic drugs still remains among patients, pharmacists, and doctors. This issue supported by lack of publication confirmed the therapeutic equivalence of branded and generic drugs. This study aims to evaluate and compare the in vitro microbiological assay of different generic and branded amoxicillin that are available in Indonesian market, especially those used in government-owned healthcare facilities. Methods Microbiological assays for five samples of amoxicillin tablet containing 500 mg amoxicillin available in Indonesia were determined using a method from Indonesia Pharmacopeia. Samples were coded as Products A to E. The assay was carried out by measuring the diameter of the inhibition zones in the plate agar incubated with Escherichia coli and Staphylococcus aureus. The obtained data were evaluated to determine the sample potency and compared with the amoxicillin reference standard. Results Minor and insignificant differences (p > 0.05) were found in the diameters of the inhibition zones. Potency ratio measured both in E. coli and S. aureus were all between 95% and 105%. The lowest of the tested samples were from Product C, which resulted to ratio potencies of 96.3% and 95.5% in E. coli and S. aureus, respectively. Conclusions All five samples were in the range of the acceptance criteria. Therefore, from the view of the microbiological assay, these products are in equivalence in quality and are interchangeable.

Compatibility of linezolid with commercial peritoneal dialysis solutions

PURPOSE

Results of a compatibility and stability study of linezolid admixed in commercial peritoneal dialysis (PD) solutions stored at various temperatures are reported.

METHODS

Test samples were prepared by adding linezolid i.v. injection (2 mg/mL) to infusion bags of 4 PD solutions (Extraneal, Nutrineal, Physioneal 40 Glucose 1.36%, and Physioneal 40 Glucose 2.27%, all from Baxter Healthcare Corporation). Assessments were conducted at various time points during storage of test samples at refrigeration temperature (6 °C) or room temperature (25 °C) for 14 days and at body temperature (37 °C) for 24 hours. Linezolid concentrations over time were determined by high-performance liquid chromatography, physical compatibility was determined by pH measurement and visual inspection, and antimicrobial activity was monitored by a disk diffusion method. The influence of solution warming by heating plate on drug stability was investigated.

RESULTS

Linezolid was stable in all tested solutions for 14 days at refrigeration and room temperatures and for 24 hours at body temperature. No linezolid adsorption to container material was detected. There were only minor variations in pH values, and visual inspection revealed no diluent abnormalities. With 1 exception, antimicrobial activity of >90% was retained in all PD solution samples for the duration of the study under all temperature conditions.

CONCLUSION

Linezolid injection 2 mg/mL remained stable and was compatible with the PD solutions studied for up to 2 weeks at refrigeration or room temperature and up to 24 hours at body temperature.