Stimuli-sensitive hydrogels: A novel ophthalmic drug delivery system.

Background: Stimuli-sensitive hydrogels are three-dimensional, hydrophilic, polymeric networks capable of imbibing large amounts of water or biological fluids on stimulation, such as pH, temperature and ionic change. Aim: To develop hydrogels that are sensitive to stimuli, i.e. pH, in the cul-de-sac of the eye for providing a prolonged effect and increased bioavailability with reduction in frequency of administration. Materials and Methods: Hydrogels were formulated by using timolol maleate as the model drug, polyacrylic acid as the gelling agents, hydroxyl ethyl cellulose as the viscolizer and sodium chloride as the isotonic agent. Stirring of ingredients in pH 4 phosphate buffer at high speed was carried out. The dynamic dialysis technique was used for drug release studies. In vivo study for reduction in intraocular pressure was carried out by using albino rabbits. Statistical Analysis: Drug release studies data were used for statistical analysis in first-order plots, Higuchi plots and Peppas exponential plots. Student t-test was performed for in vivo study. Results: Viscosity of the hydrogel increases from 3.84 cps to 9.54 cps due to change in pH 4 to pH 7.4. The slope value of the Peppas equation was found to be 0.3081, 0.3743 and 0.2964. Up to 80% of drug was released in an 8 h drug release study. Sterile hydrogels with no ocular irritation were obtained. Conclusions: Hydrogels show increase in viscosity due to change in pH. Hydrogels were therapeutically effacious, stable, non-irritant and showed Fickian diffusion. In vivo results clearly show a prolonged reduction in intraocular pressure, which was helpful for reduction in the frequency of administration.

Farmacologia oftalmologica. Revision bibliografica / Opthalmologic pharmacology. A review of the literature

Se realiza una revision bibliografica de las caracteristicas farmacologicas mas relevantes de algunos medicamentos utilizados en Oftalmologia. De forma general se abarcan particularidades farmacocineticas y farmacodinamicas del ojo. Se hace referencia a quellas drogas que ejercen su accion por medio de las respuestas fisiologicas del ojo a los mecanismos de transmision en las uniones neuroefectoras del Sistema Nervioso Autonomo y que tienen un amplio uso en el diagnostico y tratamiento de afecciones propias de esta area de la Medicina

Eficacia y seguridad de la solución oftálmica de hidrocloruro de apraclonidina al 1 por ciento en pacientes sometidos a cirugía del segmento anterior con láser / Evaluate the efficacy of apraclonidine chlorhidrate 1 por ciento in patients who were undergone anterior segment laser surgery

Se realizó un estudio prospectivo, descriptivo y longitudinal, para evaluar el efecto de la solución oftálmica de clorhidrato de apraclonidina al 1 por ciento en pacientes sometidos a cirugía del segmento anterior con láser. Se incluyeron 61 sujetos candidatos a trabeculoplastia con láser de argón y capsulotomía o iridotomía con láser de nodinimun: YAG, en tres instituciones hospitalarias de atención oftalmológica en la ciudad de México. Las elevaciones postoperatorias de la presión intraocular fueron controladas de forma eficaz por la apraclonidina, sin reportarse eventos adversos y sistémicos. Este fármaco puede integrarse en las medidas de tratamiento preventivo de la hipertensión ocular en el postoperatorio en pacientes con y sin glaucoma.

Evaluación prospectiva de los colirios de tobramicina-dexametasona versus ciprofloxacino-dexametasona en cuanto a penetración y tolerancia ocular / Prospective evaluation of tobramycin-dexametasone eye drops versus ciprofloxacin-dexametasone in the ocular penetration and tolerance

El colirio de tobramicina-dexametasona se utiliza frecuentemente en el postoperatorio de la catarata y la combinación de ciprofloxacino-dexametasona parece una combinación interesante por el amplio espectro del antibiótico, sin embargo nomse encuentra disponible actualmente en el mercado. El objetivo de este trabajo fue comparar la capacidad de penetración de ambos antibióticos a cámara anterior y la tolerancia postoperatoria evaluando el grado de conjuntivitis, queratitis e inflamación intraocular. Se obtuvieron muestras de 0.1 cc de humor acuoso media hora después de instilar 2 gotas de uno u otro colirio sobre la córnea y sólo se logró detectar ciprofloxacino con un promedio de 0,35 microgramos por ml. No fue posible detectar niveles de Tobramicina en ninguna de las muestras. la evaluación postoperatoria no demostró diferencias estadísticamente significativas en cuanto a tolerancia, grado de conjuntivitis, queratitis e inflamación intraocular entre ambos colirios con un P<0.05

Formulation and stability of atropine sulfate eye drops

Atropine sulfate was formulated in ophthalmic solutions using methylcellulose, sodium carboxymethylcellulose, polyvinyl alcohol, polyethylene glycol 6000, and polyvinyl-pyrrolidone K25. The formulations were subjected to stability studies. The obtained results revealed that, no degradation or complexion occur among the tested preparations with the exception of that contained methylcellulose. A significant decrease of drug content and viscosity of the solution was appeared after storage for the first month. Furthermore, the degradation in drug concentration was reached more than 60% after storage at 70C for two years. Also, TLC revealed a chemical decomposition of atropine sulfate in methylcellulose solution

Systemic absorption of chloramphenicol eye drops

Chloramphenicol blood levels were measured in 11 patients receiving chloramphenicol eye drops for a period from 9-19 days. Peripheral blood counts were also examined before and after therapy. Chloramphenicol was detected in the plasma of all the 11 patients. Levels above the lower limit of laboratory measurements were found in 7 of the 11 patients [Range 2.5-5 mg/mI]. There was no change in the peripheral blood count following the use of the drug. The bone marrow aplasia reported with topical chloramphenicol drops is most likely to be due to idiosyncratic reaction rather than direct dose related reaction