From the Department of Pharmaccutics, Faculty of Pharmacy, University of Karachi, Karachi 75270, Pakistan.
Abstract: (3630 Views)
Zinc sulphate and boric acid ophthalmic preparations, containing benzalkonium
chloride as preservative, have been investigated against gram-negative and
positive bacteria. Viability of bacteria was found after 7 days, although it was
completely suppressed after 24 hours of inoculation. Zinc sulphate generally
increases the antimicrobial activity of benzalkonium chloride, whereas boric acid
or its combination with zinc sulphate reduce it. Pseudomonas aeruginosa was
shown to be viable against zinc sulphate, boric acid, and their combination at a
concentration of 0.0 I % to 0.005% of the preservative. Escherichia coli and
Staphylococcus aureus were also found to be resistant but to a lesser extent than
Pseudomonas aeruginosa. This viability may be dangerous in case of multidose
ophthalmic preparations.