Resumo

Introduction: The microbiological turbidimétric assay allows the determination of potency of the drug, by measuring the turbidity(absorbance), caused by inhibition of microorganisms by cefazolin sodium⋅ The cefazolin sodium is a semi‾synthetic β‾lactam antimicrobial for parenteral use, belonging to the first‾geration cephalosporin′s group⋅ Turbidimetric assay are described in the Brazilian Pharmacopoeia for some antibiotics, but this method is not described for cefazolin in any literature⋅ Objective: The objective of the present study was to develop and validate a microbiological assay by turbidimetry to quantify cefazolin sodium injectable⋅ Methods: Preliminary testes were performed to choose the following parameters: Staphylococcus aureus 26923, 4% of inoculum, BHI culture medium, aqueous solution at concentrations of 6⋅0; 8⋅4 and 11⋅76 μg⁄mL of cefazolin sodium⋅ To each tube was added 10⋅0 mL of sterile BHI culture medium, 0⋅2 mL of solutions (standard and finished product) and 0⋅4 mL of culture medium inoculated. The tubes were incubated in Shaker Marconi MA 420 at a temperature of 35⋅0 ^•C &#+177 2⋅0 ^•C for 4 hours⋅ The growth of microorganisms was inhibited by addition of 0⋅5 mL of 12% formaldehyde and the absorbance was determined in Quimis Q‾798DRM Spectrophotometer at a wavelength of 530 nm⋅ Results: Statistical analysis showed that there is no deviation fron linearity in the analytical curves of standard and sample⋅ The correlation coefficients were 0⋅9999 and 0⋅9995 for the standard and sample, respectively⋅ The specificity was confirmed by comparing the absorbance of the refernce substance and sample⋅ The values obtained for intraday and interday precision were 0⋅35% and 1⋅57%, repectively, which validates the accuracy of the method. The amount of cefazolin sodium present in the samples analyzed, 100⋅08%, is consistent with official compendium of 95⋅0 to 102⋅0%⋅ The accuracy was proven by the recovery test, with value of 98⋅71%⋅ The parameters veried didi not affect the analysis of cefazolin sodium, confirming the robustness of this method⋅ Conclusion: The turbidimetric assay is more versatile, fast and easier to apply agar diffusion assay⋅ The method is simple, fast and accurate and can be used in routine analysis of qualy control of formulations containing cefazolin sodium⋅