Fluorescent, physiological and pharmacokinetic properties of fluorescein glucuronide.

When fluorescein is administered systemically, it is metabolized to form a fluorescent compound, fluorescein monoglucuronide. The molar fluorescent intensity of this compound is less than that of fluorescein but its fluorescent intensity compared to fluorescein varies considerably depending on the wavelength employed for excitation. Several hours after oral or intravenous administration the conjugate can become the dominant fluorophore in the plasma. When fluorescein is administered systemically and fluorescent intensity is measured in the eye, it is necessary to determine which compound is being measured since the time courses of the plasma concentrations and the permeability of the ocular barrier of each compound may not be the same. A technique suitable for measuring the relative concentration of each fluorophore in ocular tissues in vivo is suggested.