In vitro transcorneal permeation of ketorolac from oil based ocular drops and ophthalmic ointment

Transcorneal permeation of ketorolac from oil based ocular drops and ophthalmic ointments was studied in vitro, using goat cornea. Cumulative (%) permeation of ketorolac through cornea, was found to be maximum with 0.2% (w/v) ketorolac drops in sesame oil followed by formulations in corn oil and soyabean oil. Ketorolac 1% (w/v) drops in castor oil increased the quantity permeated but cumulative (%) permeation was less. Permeation profiles of ketorolac were in consistence with the partition characteristic of drug between oil and aqueous phase. Formulations favouring corneal permeation of ketorolac increased corneal hydration. Addition of benzyl alcohol, a preservative, to oil drops reduced permeation of ketorolac and corneal hydration indicating possible protective effect of benzyl alcohol against corneal damage. Permeation studies on ointment formulations containing either ketorolac acid or ketorolac tromethamine salt indicated better permeation for formulation containing ketorolac tromethamine aqueous solution. Thus for better transcorneal permeation, ketorolac 0.2% (w/v) drops, formulated in sesame oil, containing 0.5% v/v benzyl alcohol and ophthalmic ointment containing 0.5% (w/w) ketorolac tromethamine in dissolved state appear suitable.