Rate of Sterilization as a Factor in the Selection of Ophthalmic Solutions: Experimental Studies with a Proposed Method of Preparing Sterile Solutions

In the past decade many bacteriological studies have been pursued on an in vitro scale in an attempt to evaluate activity of proposed ophthalmic preservatives. These included the work of McPherson and Wood¹; Skolaut²; Scigliano and Skolaut³; Krause, Dauer, and Guth⁴; Heller and associates,⁵ and Murphy, Allen, and Mangiarcine.⁶ It is apparent from these studies that many of the authors consider bacteriostatic concentrations to be a safe level of preservation for these solutions. Murphy, Allen, and Mangiarcine directly stated that bacteriostatic and fungistatic powers were among the properties to be possessed by an ideal ophthalmic preservative. More recently, Lawrence⁷ has published a general review of chemical preservatives for ophthalmic solutions. He concludes:

A careful review of the literature reveals that in preparing and dispensing ophthalmic drugs, chlorobutanol, phenylmercuric nitrate, and benzalkonium chloride are considered the bacteriostatic agents most suitable for providing "self-sterilizing" solutions.