Abstract
Purpose: :
The formulation of topical lipophilic drugs in ophthalmology is a very difficult challenge. The aim of our study was to develop and characterize a new drug delivery system (DDS) capable of carrying out latanoprost for topical ophthalmic use.
Methods: :
The new nanoemulsion (LAT-DDS) was prepared adding 0.005% latanoprost and 0.1% hyaluronic acid (HA) to the DDS composed by a phosphate buffered water containing Medium Chain Triglycerides (MCT) and VIT E TPGS. To characterize and to investigate the mechanism that stabilize latanoprost we prepared the DDS in D2O and 1H NMR spectra were registered; a 0.005% latanoprost in D2O solution (LAT) was also prepared for comparison. We have also prepared a 0.005% latanoprost solution in water (LAT). D2O was used for both LAT-DDS and LAT. 1H NMR Spectroscopy, Dynamic Light Scattering and Electrophoretic Mobility measurements were performed. Latanoprost chemical stability in (LAT-DDS) was controlled under different ICH recommended conditions.
Results: :
1H NMR signals of LAT-DDS system were different from those obtained in the D2O formulation of LAT. In particular, the signals of the phenyl protons in ortho, meta and para and the signals of protons of the isopropyl ester group of latanoprost shifted upfield (the Δ in chemical shifts were 0.19 ppm, 0.26 ppm, 0.27 ppm and 0.10 ppm, respectively). The shifts showed the protective effect of DDS on the latanoprost. Moreover we were able to demonstrate by Dynamic Light Scattering and Electrophoretic Mobility measurements that the particle size of the stable nanoemulsion was 10nm±2 and that HA binds with DDS, as indicated by the change of particle size and by the net increase of the Z potential from less than -4mV without HA to about -15mV after adding HA. As showed by stability study addition of HA in DDS did not affect latanoprost stability.
Conclusions: :
In the LAT-DDS latanoprost is stable at room temperature. The supramolecular binding between HA and the other components of LAT-DDS furnishes to the nanoemulsion the mucoadhesive ability which may represents a strong advantage in the ocular penetration (aqueous bioavailability) of latanoprost in the treatment of glaucoma and ocular hypertension.
Keywords: intraocular pressure • aqueous