E Prieto

Laponite as carrier for controlled in vitro delivery of dexamethasone in vitreous humor models

Laponite clay is able to retain dexamethasone by simple physisorption, presumably accomplished by hydrogen bonding formation and/or complexation with sodium counterions, as shown by solid state NMR. The physisorption can be somehow modulated by changing the solvent in the adsorption process. This simple system is able to deliver dexamethasone in a controlled manner to solutions used as models for vitreous humor. The proven biocompatibility of laponite as well as its transparency in the gel state, together with the simplicity of the preparation method, makes this system suitable for future in vivo tests of ophthalmic treatment.

Determination of Three Corticosteroids in the Biologic Matrix of Vitreous Humor by HPLC-tandem Mass Spectrometry: Method Development and Validation

ABSTRACT Purpose: To develop a simple, specific, and rapid method to determine corticosteroid concentrations in vitreous humor. Methods: An analytical method based on high-pressure liquid chromatography-tandem mass spectrometry (HPLC-MS) with a simple extraction procedure was developed. New Zealand albino rabbits (n = 54) received a single (0.1 mL) intravitreal injection of dexamethasone (DXM, 0.1 mg), methylprednisolone (MP, 2 mg), or triamcinolone acetonide (TA, 10 mg). Eyes were enucleated and mean vitreous steroid levels were quantified at 12 h and 1, 2, 3, 7, and 14 days. Results: Corticosteroids were extracted from the vitreous with acetonitrile, and TA was extracted with ethyl acetate, yielding high protein precipitation and clean solution samples. Vitreous samples were analyzed by isocratic HPLC-MS with mobile phase comprising acetonitrile and 2 mM ammonium formate buffer in water, pH 3.5. The linear range was 50–100,000 ng/g with a lower quantification limit of 45 ng/g for DXM and MP, and 50 ng/g for TA. Vitreous levels of DXM and MP were not detectable 14 days post-administration. Vitreous levels of TA were positive and stable throughout the study in both injected and control eyes. Conclusions: The HPLC-MS analytical method is an alternative to HPLC-MS/MS methods, sensitive enough for identifying and quantifying steroids in vitreous humor at a therapeutic dosage scale.

Suprachoroidal pocket to collect drugs for treatment of ocular diseases

Purpose We present the progressive improvement of a surgical procedure for suprachoroidal (sc) administration of drug, as an alternative route for drug administration to the posterior segment of the eye. Methods 25 New Zealand albino rabbit eyes were used in the study. Fifty microliters volume of different increasing viscosity formulations were tested: balanced saline solution (BSS), 0.5% sodium hyaluronate solution (SH) and a formulation with patent to be register. Catheters of several gauges (25Gs, 27 Gs and 22 Gs) and different materials: metal cannula or flexible intravenous catheter were tested. Different architecture of the scleral-sc pocket were assayed: large quadrangular area with sutures, rectangular area with small port without stitch and conic with small entrance without stitch. Results Following items were analyzed: (1) Reflux post-administration: depending on the formulation; BSS and SH 0.5% (100%) versus Formulation (73.33%), on the surgical instrument for administration; 25G and 27G (100%) vs 22G (20%), and on different pocket architecture; quadrangular and rectangular (100%) vs conic pockets (73.33%). (2) Signs of ocular irritation: higher grades of hiperemia and secretion were observed in pockets with stitches (3) Ocular perforation: 1 eye in quadrangular pocket with stitch. (4) Surgical time: longer in sutured pockets. Conclusions The possibility of perform a sc pocket with a large conic area, small port and without stitches, permits us to use it as a receptacle for high viscosity formulations or implants for sustained drug delivery, avoiding the risks of intravitreal devices and allowing an easier removal of the implant in case of adverse reactions.

Comparative analysis of changes in the macular region following cataract surgery by phacoemulsification with Ozil Intelligent Phaco technology according to different fluidics parameters

Purpose To assess the change in macular thickness values following cataract surgery by phacoemulsification with Ozil Intelligent Phaco (IP) technology comparing high and low fluidics parameters

A comparison of perimetric results with standard automated perimetry and HEP perimetry in a group of glaucomatous patients

Purpose To compare the results obtained between Humphrey Perimeter (Carl Zeiss Meditec, EEUU) and Heidelberg Edge Perimeter (HEP, Heidelberg Engineering, Alemania) tested in a group of glaucomatous patients.