The release of gentamicin sulphate from niosomes was
determined using the membrane diffusion technique (25–27).
An accurately measured amount of gentamicin sulphate
niosomal formulations, equivalent to 1 mg drug, was
suspended in 0.3 ml phosphate buffered saline (pH 7.4) and transferred to a glass cylinder having the length of 10 cm and
diameter of 2.5 cm fitted at its lower end with presoaked
cellulose membrane (Spectra/Por dialysis membrane 12,000–
14,000 Mwt cutoff). Then, the glass tube was suspended in the
dissolution flask of a USP dissolution apparatus (Hanson
research, Chatsworth, USA) containing 50 ml simulated
lacrimal fluid (pH 7.4) (28,29). The glass tube was allowed
to rotate at a constant speed (50 rpm).