Systemic absorption of oxytocin and vasopressin through eyes in rabbits.

In order to avoid injections, oxytocin and vasopressin were systemically administered through ocular route. Although oxytocin and vasopressin are small peptide drugs with only 9 amino acids, their absorptions were relatively poor. The systemic absorption of these peptides through eyes was markedly enhanced by the addition of an absorption enhancer, 0.5% Brij-78 (polyoxyethylene-20-stearyl ether), in the eyedrops of these peptides. It is concluded that it is feasible to administer oxytocin and vasopressin as eyedrops to avoid parenteral injections.