Abstract
Purpose: :
To evaluate the ocular pharmacokinetics of indomethacin following topical administration of two different formulations present in the market.
Methods: :
Rabbits received a single topical instillation (30 µl) of indomethacin ophthalmic suspension (IND-S; IndomTM Alfa-Intes) or indomethacin ophthalmic solution with hydroxypropyl-β-cyclodextrin (IND-CD; IndocollirioTM Bausch & Lomb), and aqueous humor, vitreous and retina were collected from animals at fixed time intervals after dosing. Indomethacin ocular levels were measured by LC/MS/MS, and PK parameters (Cmax, Tmax, and AUC0-240) were determined. All the animals were treated according to the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.
Results: :
Peak concentrations of indomethacin in aqueous and vitreous were achieved within 30 min and 60 min after a single instillation of IND-S and IND-CD respectively. Retinal Tmax was 30 min and 120 min in IND-S-treated group and IND-CD-treated group respectively. Higher levels of indomethacin were found in retina after IND-S administration compared to IND-CD (AUC0-240 272.9 ng/g/min vs. AUC0-240 73.5 ng/g/min respectively; p<0.01). Also in the aqueous and vitreous the drug levels were statistically higher (p<0.01) in the IND-S group in comparison with the IND-CD group (AUC0-240 2039 ng/ml/min vs. AUC0-240 427.3 ng/ml/min, AUC0-240 53.8 ng/ml/min vs. AUC0-240 12.5 ng/ml/min respectively). Highest drug levels in the ocular tissues were found following IND-S administration compared with IND-CD (retina: Cmax 73.7 ± 6.4 ng/g vs. 25.5 ± 1.73 ng/g; aqueous: Cmax 952 ± 6.8 ng/ml vs. 163 ± 4.1 ng/ml; vitreous Cmax 31 ± 3.5 ng/ml vs. 6.37 ± 3.6 ng/ml).
Conclusions: :
IND-S treatment demonstrates a nonclinical ocular PK profile of indomethacin characterized by higher concentrations of drug in ocular tissues (4.7-, 4.3- and 3.7-fold higher in aqueous, vitreous and retina, respectively) compared to IND-CD-treated group. Taken together these data seem to indicate that IND-S formulation has good ocular distribution reaching relevant retinal indomethacin levels, and suggesting that this formulation may be useful in clinical practice for macular edema treatment.
Keywords: inflammation • retina • macula/fovea