Investigation of pH dependent in situ gel forming solutions of imidazoline drug for ocular administration

Abstract

Imidazoline drugs which are antihistamines indicated for the treatment of ocular allergy are presently available as drops and has to be instilled 4-5 times a day. Hence to overcome all these disadvantages, an investigation with the purpose to increase the residence time of a solution in the cul-de-sac of the eye by increasing the viscosity of the vehicle which decreases the drainage rate thereby slowing drug release from the delivery system and minimizing the pre-corneal drug loss in in situ forming solutions of ophthalmic drugs. The current study includes the in vitro studies for the prepared formulations. The phase transition was induced by a shift in pH at physiological temperature condition. For the study, naphazoline hydrochloride was chosen. The polymers used Carbopol 940 and HPMC k₄M. All the formulations FF17, FF18, AA15 and AA20 were found to have satisfactory drug release ranging from 75 to 80 % over a time duration of 8 h. Stability studies indicated that there are no significant changes in pH, visual appearance, clarity, gelation, drug content, and in vitro release during two month of study period.