Dissolution studies were performed with apparatus II (paddle) according to the USP specifications for ibuprofen tablets.10 The dissolution characteristics of at least 12 tablets of each batch were studied at pH 7.2 in phosphate buffer at 37°C ± 0.5°C. The dissolution tests were performed in an Erweka DT80 (Heusenstamm, Germany) at a rotating speed of 50 rpm. Samples (5 mL) were withdrawn at different sampling times (0, 5, 10, 15, 20, 30, 45 and 60 minutes) without reposition. Samples were filtered immediately after sampling with a 0.45 µm filter (hydrophilic PVDF Millex-HV, Millipore, Billerica, MA, USA). Ibuprofen was measured by UV spectrophotometry at 266 nm in a Beckman Coulter Du-6 spectrophotometer (Brea, CA, USA). The initial release rate was estimated as the ibuprofen (% of theoretical dose) released during the first 5 minutes (Q5). This parameter was used to compare differences on the release between the formulations.
Du 6 spectrophotometer
Manufactured by Beckman Coulter
Sourced in United States
The Du-6 spectrophotometer is a compact, high-performance instrument designed for accurate optical density measurements. It features a wide wavelength range, a large display, and simple operation. The Du-6 provides reliable and reproducible results for various laboratory applications.
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Lab products found in correlation
2 protocols using du 6 spectrophotometer
1
Ibuprofen Tablets Dissolution Analysis
2
Assessing Protease Activity of Albumin Fusion Proteins
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Example 43
The following assay may be used to assess protease activity of an albumin fusion protein of the invention.
Gelatin and casein zymography are performed essentially as described (Heusen et al., Anal. Biochem., 102:196-202 (1980); Wilson et al., Journal of Urology, 149:653-658 (1993)). Samples are run on 10% polyacrylamide/0.1% SDS gels containing 1% gelain orcasein, soaked in 2.5% triton at room temperature for 1 hour, and in 0.1M glycine, pH 8.3 at 37° C. 5 to 16 hours. After staining in amido black areas of proteolysis appear as clear areas against the blue-black background. Trypsin (Sigma T8642) is used as a positive control.
Protease activity is also determined by monitoring the cleavage of n-a-benzoyl-L-arginine ethyl ester (BAEE) (Sigma B-4500. Reactions are set up in (25 mMNaPO4, 1 mM EDTA, and 1 mM BAEE), pH 7.5. Samples are added and the chance in absorbance at 260 nm is monitored on the Beckman DU-6 spectrophotometer in the time-drive mode. Trypsin is used as a positive control.
Additional assays based upon the release of acid-soluble peptides from casein or hemoglobin measured as absorbance at 280 nm or colorimetrically using the Folin method are performed as described in Bergmeyer, et al., Method of Enzymatic Analysis, 5 (1984). Other assays involve the solubilization of chromogenic substrates (Ward, Applied Science, 251-317 (1983)).
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