Abstract
Purpose :
To investigate the effect of mydrasis and ocular distribution of tropicamide and phenylephrine after a triple instillation in New Zealand white rabbit.
Methods :
A 50μl of Zhuobian® containing 0.5% tropicamide and phenylephrine eye drop was instilled into both eyes of 12 rabbits three times, every 5 minutes. The animals were divided evenly into four groups. From each group, pupil diameters were measured for both eyes by vernier gauge and blood specimens were collected at 0.5, 1, 2, 3 hours. Then the animals were sacrificed immediately to collect aqueous humor from the anterior chamber, and subsequently other eye tissues.
Results :
After a triple topical instillation, the pupil sizes reached the maximum of 11.35mm at 0.5h and the dilation was maintained for 3 hours (11.12mm). The highest concentration of tropicamide was found in aqueous humor (Cmax: 29430ng/ml), whereas in cornea for phenylephrine (Cmax: 3465ng/g), due to different permeability of the two compounds through the cornea barrier. Both drugs reached the highest concentration in iris-ciliary body at 0.5h which stayed at a steady level until 3hrs. All the ocular tissue concentrations were much higher than those of the blood (Cmax: 28.9ng/ml for tob and 3.4ng/ml for phe).
Conclusions :
Due to its quick onset and lasting effect, Zhuobian® was suitable for clinical dilation of pupils which facilitate examination of lens, vitreous body and retina. Low distribution in blood indicated Zhuobian® was minimally absorbed into systemic circulation though topical installation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.