An evaluation of the pharmaceutical quality and antimicrobial effectiveness of some frequently used eye drop products available for sale in Nigeria

Aim: Eye drop products must be properly packaged and must be sterile throughout the period of use. For this reason, we evaluated eye drops offered for sale and used for the treatment of eye diseases in Nigeria for their pharmaceutical quality and antimicrobial effectiveness. Materials and Methods: Eleven different sterile eye-drop product samples containing gentamicin, chloramphenicol, timolol, tropicamide, tetrahydrozoline, pilocarpine, antazoline-tetryzoline, diclofenac, dexamethasone, and flubiprofen were opened and tested for bacterial contamination after exposure to air over 56 days. To assess the possibility of contaminations by pathogens due to repeated handling during use about 10(7)-10(8) cells of Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Candida albicans were added to other newly opened eye drops and incubated at room temperature. Samples were collected and the number of viable organisms was estimated. Eye-drop product samples were also investigated for packaging, pH, and clarity. Results: No viable microorganisms were detected in the eye drops during and at the end of the 56 days exposure to air. All the samples exhibited rapid bactericidal and fungicidal activities at a rate which depended on the species of pathogens and the content of the sample. The anti-infective samples demonstrated the highest rapidity in microbicidal activities. There were no microbial survivors in any of the samples after 4 h of inoculation by pathogens. Conclusions: The study concluded that generally multi-dose eye drop products offered for sale in Nigeria were of acceptable microbial quality and possessed good antimicrobial effectiveness.