Antisense oligonucleotides were recently proposed for the treatment of cytomegalovirus (CMV) infection. Treatment of CMV infection is usually given by the systemic route. However, systemic administration of antivial drugs in ophthalmic therapy has serious drawbacks, such as renal and hematological toxicity. For these reasons, intravitreal injection may be considered as an interesting alternative to systemic delivery. This administration route is however very delicate to handle since the needle must penetrate the vitreous humor without causing retinal disruption or detachement. Moreover, the patient must remain under local anesthesia during injection. Therefore, an ideal intravitreal drug delivery system should prolong the duration of action of antiviral drugs and also improve drug activity and avoid toxicity. In thi contrext, we have designed a new drug delivery system, which consist in sterically stabilized liposomes dispersed within a thermosensitive poloxamer 407 gel. Poloxamer 407 at high concentration and above 18 deg C undergo a transition from a solution to a gel In the present study, we have compared the ocular tissue distribution of a model oligonucleotide (pdT16) injected intravitreally as a simple solution, encapsulated in liposomes or in liposomes dispersed within a thermosensitive gel.
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