CCI 2mA, 4min, 25% Ceftazidime, cathodal iontophoresis

Fig. 15.6  Vitreous and aqueous humor pharmacokinetics of ceftazidime after transscleral iontophoresis in the rabbit in relation to more frequent bacterial sensitivity. Coulomb controlled cathodal iontophoresis (CCI) was performed on pigmented rabbits (N = 8 per time points) using 25% ceftazidime, 2 mA for 4 min. Concentrations of ceftazidime (mg/mL) in the aqueous humor (AH) and in the vitreous (V) were measured at 0.5, 2, 6 and 24 h after application. Sensitivity of different bacteria is represented on the graph

MCI of the two antibiotics for different bacterial agents. Comparison with IV administration of the two antibiotics was shown only at selected time points. Interestingly, CCI was more efficient that IV administration and allowed MCI levels above therapeutic concentrations for at least 6 h (Figs. 15.5 and 15.6).

15.4.2  Transscleral Iontophoresis of Antiviral Drugs

Antiviral drugs effective against cytomegalovirus (CMV), such as ganciclovir and foscarnet have been administered by iontophoresis as an alternative to intravitreal injections. A 20% ganciclovir solution was used for a transscleral iontophoresis with a 263 mA/cm2 current density for 15 min. Therapeutic levels were obtained until 24 h after a single iontophoresis of ganciclovir in the rabbit (Lam et al. 1994). However, the pH of such a solution is greater than 11, raising serious difficulties for application on a human eye. Foscarnet was administered by a 0.19 mm2 diameter probe and the iontophoresis was performed with a current intensity of 1 mA for 10 min. Under these conditions, efficient vitreal concentrations were measured up to 60 h after a single transscleral iontophoresis of foscarnet (Sarraf et al. 1995).