No abstract

A simple and reproducible high-performance thin-layer chromatographic method was developed for the simultaneous determination of bergenin and gallic acid in Bergenia ligulata. Water and methanol were used as the extracting solvents. The concentrations of bergenin and gallic acid in both of these solvents were found to be almost the same. The method involves separation of the components by thin-layer chromatography on a precoated Silica Gel 60 F254 plate with a solvent system of ethyl acetate–formic acid–acetic acid–water (100 + 11 + 11 + 27). The sensitivity of the method for bergenin was 0.30 μg, whereas for gallic acid it was 0.25 μg. The proposed method is precise and sensitive and can be used for the detection, monitoring, and simultaneous quantification of bergenin and gallic acid in B. ligulata.

The present work studies the interaction of methyl paraben (MPB) and propyl paraben (PPB), two widely used antimicrobial agents in multi-dose ophthalmic formulations, with 5 mL, low density polyethylene (LDPE) and polypropylene (PP) blow-fill-seal (BFS) packs, by subjecting the systems to accelerated stability conditions of 40°C/25% RH. The effect of pH, paraben concentration, and relative humidity (RH) on the sorption loss of both the parabens was studied. Additionally, the effects of buffer species and buffer strength on MPB sorption were studied. LDPE packs showed significantly higher loss compared to PP packs which showed< 5% loss in all cases. PPB showed a significantly higher loss (40-50%) than MPB (9-16%) in LDPE. pH (3.0, 5.0, 7.0) did not have a statistically significant effect on sorption. However, concentration, humidity and buffer at pH 7 affected paraben sorption. The application of the power law suggested that the MPB followed non-Fickian diffusion while PPB showed non-Fickian to Case II diffusion in LDPE packs. In conclusion, caution should be exercised while using parabens in LDPE BFS packs because substantial losses of the antimicrobial agent during the shelf-life can compromise the preservative effectiveness against 'in-use' contamination.

Background: Benzalkonium chloride (BKC) is the most used preservative in topical eye drops but it causes effects such as dry eye and trabecular meshwork degeneration. Polyhexamethylene biguanide (PHMB) is a polymeric biguanide is a less harmful preservative used in ophthalmic solutions. The objective of this study to com-pare the efficacy of PHMB preserved versus BKC preserved ophthalmic solutions containing brimonidine tartrate and timolol maleate on intraocular pressure (IOP) following single ocular instillation in New Zealand white (NZW) rabbits.Methods: This study was conducted on 12 normotensive male NZW rabbits (2.9-3.6 kg) between 6-9 months of age. Animals received single ocular instillation of 35 µl ophthalmic solution containing brimonidine tartrate 0.15 %w/v and timolol maleate 0.5% w/v with PHMB as preservative (n=6, test) or BKC as preservative (n=6, reference) as per the randomization. Intraocular pressure (IOP) was measured before and 2, 4, 6, 8 and 24 hours after instillation using a pneumatonometer. Percentage change in IOP from pre-instillation values were calculated. Changes in IOP were analysed using the repeated-measures analysis of variance followed by Bonferroni post-test.Results: Single ocular instillation of PHMB and BKC formulations show significant IOP reduction up to 6 hours as compared with baseline (p<0.05). Reduction in IOP was 35.8% and 32.0% at 2 hours with PHMB and BKC formulations respectively. No differences were observed between the test and reference groups for change in IOP from baseline.Conclusions: PHMB preserved brimonidine tartrate 0.15% w/v and timolol maleate 0.5% w/v ophthalmic solution was comparable to BKC preserved solution in normotensive NZW rabbits.