Strength of topical ophthalmic preparations of tobramycin is : September 2009

Ans. A: 3 mg/ml Tobramycin works by binding to a site on the bacterial 30S and 50S ribosome, preventing formation of the 70S complex. As a result, mRNA cannot be translated into protein and cell death ensues. Sterile Tobramycin Ophtha Solution (eye-drops) contains tobramycin concentration of 0.3%. It is mixed with 0.01% benzalkonium chloride as a preservative. This concentrations result in 3 mg per ml.