Studies on improved corneal permeability to bunazosin.

Various factors influencing corneal permeability to bunazosin were investigated. The permeability of the cornea to bunazosin increased with increasing pH, either in the presence or absence of caprylic acid; the permeability to bunazosin and the partition of bunazosin were both enhanced by caprylic acid and both enhancements became maximal when the molar ratio of bunazosin: caprylic acid became unity; the permeability to methylparaben, a non-ionic permeant, was not increased by caprylic acid or capric acid and the permeability was not increased by the pretreatment of the cornea with caprylic acid. Furthermore, protein-bunazosin interaction was not affected by caprylic acid. The present results suggest that the enhancement of permeability caused by caprylic acid is attributable only to the increased partition of bunazosin to the corneal membrane.