Double beam uv vis spectrophotometer

The drug release rate from the prepared sublingual tablet formulations was investigated in the USP XXIV dissolution testing apparatus II (paddle method) in 500 mL phosphate buffer (pH 6.8) as the dissolution medium maintained at 37°C±0.5°C at 50 rpm. At predetermined time intervals (2, 5, 7.5, 10, 15, and 20 minutes), 5 mL of dissolution medium was withdrawn with replacement. The absorbance of the drug in each sample was measured spectrophotometrically at λ_max 272 nm using a Shimadzu UV/Vis double beam spectrophotometer, after filtration on 0.45 membrane filter. The cumulative percentage of drug release was calculated using an equation obtained from previously constructed standard calibration curve. The mean of six determinations was considered.22

Five tablets samples of each formula were separately crushed in a mortar and transferred to 100-mL volumetric flask. The flasks were brought to volume by phosphate buffer with pH 6.8 and sonicated for 10 minutes. A 1 mL of the prepared solution was filtered through a 0.45-µm filter and diluted to 25 mL with phosphate buffer. The absorbance of the solution was then measured spectrophotometrically at λ_max 272 nm using a UV/Vis double beam spectrophotometer (Shimadzu, Tokyo, Japan) and the drug content was calculated using K obtained from the slope of the constructed calibration curve of the drug in phosphate buffer with pH 6.8.20

The drug release rate from the prepared oral films was studied in the United States Pharmacopeia XXIV dissolution testing apparatus II (UDT-804 paddle dissolution apparatus; United States Pharmacopeia, North Bethesda, MD, USA). For that, film sample (2×2 cm) of each formula was added to 250 mL of phosphate buffer (pH 6.8) dissolution medium maintained at 37°C±0.5°C and stirred at 50 rpm. At predetermined time intervals (0, 5, 10, 15, 20, and 30 minutes), 5 mL sample was withdrawn with replacement. The absorbance of the drug was spectrophotometrically measured at 281 nm which was experimentally determined as the drug λ_max (Shimadzu UV/Vis double beam spectrophotometer) after filtration on 0.45 μm membrane filter. The cumulative percentage of drug release was calculated using an equation obtained from previously constructed standard calibration curve.32 For comparison, the dissolution rate of plain drug and its release rate from conventional alginate films (prepared using the same excipients) were also determined. The mean of six determinations was considered.

Comparative in vitro transcorneal permeation of bromfenac through marketed eyedrops and ChS-CS-NPs was performed in goat cornea according to a previous report.[14 35 ] The goat cornea was mounted between donor and receiver compartments of Franz diffusion cell keeping epithelial surface toward donor side. 100 μL of marketed eyedrops (0.09%) or an equivalent amount of NPs suspended in 100 μL STF was poured into the donor compartment while receiver compartment was filled with STF (5 mL). All of the study was conducted at 32 ± 0.5^°C; samples were withdrawn periodically (1 mL) up to 3 h and quantitatively analyzed at absorption maxima (λ_max) 270 nm by using UV-VIS spectrophotometer (double beam, Shimadzu, Japan).