Rapid turbidimetric assay to potency evaluation of tigecycline in lyophilized powder

Tigecycline, a first-in-class glycylcycline and an analog of the semisynthetic antibiotic minocycline, is a potent, broad-spectrum antibiotic that acts by the inhibition of protein translation in bacteria. This glycylcycline inhibits Gram-positive, Gram-negative, atypical, anaerobic and antibiotic-resistant organisms. There is no microbiological analytical method for tigecycline in lyophilized powder reported yet. Thus, this paper reports the development and validation of a simple, sensitive, accurate and reproducible turbidimetric method to quantify tigecycline in lyophilized powder, using Staphylococcus aureus as microorganism test and 3×3 parallel line assay design, with twenty tubes for each assay. The validated method showed good results of linearity in the concentration range from 3 to 4.32μg/mL (r(2)=0.9999), selectivity, precision, robustness and accuracy of 99.74%. The results demonstrated the validity of the proposed bioassay, which allows reliable quantitation of tigecycline in pharmaceutical samples and therefore can be used as a useful alternative methodology for the routine quality control of this medicine.