Vertical diffusion cells (VDC) have been envisaged as in vitro surrogates for ensuring product quality and performance for topical preparations. USP General Chapter <1724> Semisolid Drug Products-Product Performance Tests describes the application of VDC as one of the apparatus required for in vitro testing of topical products. Knowledge of various operational parameters and their impact on drug release during diffusion experiments thus becomes imperative. In the present study, parameters like temperature, composition of receptor medium, speed of stirring, and filled volume of cell jacket have been evaluated for their influence on drug release rate from hydrocortisone cream employing vertical diffusion cells. The statistical analysis of the results was performed by one-way ANOVA with Bonferroni post hoc test. Results suggest that the composition of the receptor medium significantly influences drug release from cream, and slower stirring rates translate to lower release rates. On the other hand, within experimental design, the temperature of the receptor and filled condition of the cell jacket do not influence drug release significantly.

Purpose: To evaluate visual fields using Zippy Adaptive Thresholding Algorithm (ZATA) Standard and ZATA Fast among patients with glaucoma and healthy individuals. Methods: We recruited 22 healthy participants and 55 patients with glaucoma from the ophthalmology clinics at Kasturba Hospital, Manipal, India. Inclusion criteria were age 35 to 85 years, best corrected visual acuity (BCVA) 0.3 logMAR or better. Glaucoma patients had characteristic glaucomatous optic disc damage. All participants were free from any other ocular pathology except from mild cataract. Participants performed ZATA Standard and ZATA Fast tests on a Henson 9000 perimeter and Swedish Interactive Thresholding Algorithm (SITA) Standard and SITA Fast tests on a Humphrey Field Analyser. Tests were repeated within 90 days to evaluate the test-retest variability. Results: The mean difference in the mean deviation (MD) values of ZATA Standard and SITA Standard tests was 1.7 dB, and that in ZATA Fast and SITA Fast tests was 0.9 dB. The sensitivity values of ZATA and SITA tests differed by 3 dB. ZATA Standard and ZATA Fast were 30% and 6% faster than the corresponding SITA tests. Grayscale and probability maps varied slightly between the four tests but represented a similar visual field for most patients in the study. Conclusions: ZATA Standard and ZATA Fast are suitable for clinical practice. However, differences between ZATA and SITA tests suggest that they should not be used interchangeably when monitoring over time. Keywords: Visual fields, glaucoma, perimetry

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