Purpose:
To compare corneal and conjunctiva pharmacokinetics of CsA in rabbits following topical administration in olive oil or cationic oil-in-water emulsion.
Methods:
Rabbits received a single instillation of 2% CsA in olive oil or 0.1% CsA in emulsion. Corneal, conjunctival and whole blood CsA levels were analysed by HPLC-MS. Experimental work was performed at Iris Pharma (La Gaude, France).
Results:
Figure 1: Corneal (A) and conjunctival (B) CsA concentrations (ng/g) after instillation of 50 µL of 2% CsA in olive oil or 0.1% CsA in emulsion.Although the administered dose was 20-fold less important in the emulsion (0.05 mg) compared to the oil group (1 mg), the resultant corneal AUC1-24 (area-under-the curve between 1 and 24hr) was only 1.8-fold less (48970 and 27249 ng/g*hr respectively). After normalization by the administered dose, this results in an 11-fold improvement in ocular bioavailability.Quantifiable whole blood levels were identified only in one animal of the oil group, at the first time-point (2 ng/ml).
Conclusions:
Formulation of CsA in a cationic emulsion (NOVA22007) results in significantly (11-fold) improved corneal and conjunctival delivery compared to administration in oil, allowing a lower dose and reducing potential systemic passage. Moreover, the emulsion is expected to have a much better tolerability than the pure oil. A phase III clinical trial is currently ongoing in Europe and Mediterranean countries.
Keywords: cyclosporine • keratitis • conjunctivitis