Preparation of the solid dispersion.
The solid dispersion was prepared by fusion. First myrj-52 was melted and the mixture of drug and StarLac was added. The
mixture was stirred for 5 min at 60 °C and cooled on aluminum foil at room temperature. Next, the solid sample was pulverized
in the mortar, sieved, and stored in the dessicator at 25 °C.
Evaluation of melt granules, physical mixture, and solid dispersion
The percentage of drug content in the granules and solid dispersion was measured by dissolving the amount of granules or
solid dispersion equivalent to 15 mg of meloxicam in 100 mL of ethanol. The drug content in the solution was measured spectrophotometrically
(UV-1700 UV–vis spectrophotometer, Shimadzu, Kyoto, Japan) at 363.5 nm.
Excess amounts of pure meloxicam were added to 30 mL of 0–10% concentrations of myrj-52 solution, sonicated, and agitated
for 24 h. The suspension was filtered (0.45-μm filter, Millipore, Billerica, MA), diluted with the same concentration of myrj-52
solution, and analyzed spectrophotometrically at 363.5 nm. The average of three experiments was taken.
Fourier transform infrared spectroscopy.
Fourier transform infrared (FTIR) spectra of samples were obtained, after appropriate background subtraction, using an FTIR
spectrometer (8400 S, Shimadzu, Kyoto, Japan) equipped with a deuterated triglycine sulfate detector, a diffuse-reflectance
accessory, and a data station. About 1–2 mg of the sample was mixed with dry potassium bromide. The sample was then scanned
at the 400- and 4000-cm–1 wavelength ranges.
Differential scanning calorimetry.
A differential scanning calorimeter (DSC 30, Mettler Toledo, Columbus, OH) was used to obtain the DSC curves representing
the rates of heat uptake. About 3 mg of sample was weighed in a standard open aluminum pan. An empty pan of the same type
was used as the reference. Samples were heated from 30 to 300 °C at a heating rate of 20 °C/min while being purged with dry
nitrogen. Calibrations of temperature and heat flow were performed with indium.
Powder X-ray diffractometry.
The solid dispersion, melt granulation, and physical mixture of meloxicam compared with the plain meloxicam were analyzed
using a powder diffractometer (PW 1830, Phillips, Eindhoven, the Netherlands). Samples were exposed to CuKα radiation to measure
the 2θ at 4–50° with a diffractometer reproducibility of ±0.001. A rate meter with a time constant of 2 × 102 pulses/s and a scanning speed of 2° (2θ)/min recorded the PXRD patterns automatically.
Scanning electron microscopy.
The samples were sputter-coated with gold to render them electrically conductive. The samples' morphology was examined using
SEM (JEOL-840 SEM, JEOL, Tokyo, Japan).
The size distribution of granules was evaluated by sieve analysis with a vibrating shaker (Labhosp, Mumbai) and #5 sieve
in the 75–1400 μm range. The fractions were collected, stored in a dessicator at 25 ± 2 °C, and used for the dissolution.
In vitro dissolution studies.
The dissolution of meloxicam alone, from the melt granulation, from the physical mixture (PM), and from the solid dispersion
(SD) were determined using a US Pharmacopeia (USP) Type II dissolution apparatus (Veego Scientific, Mumbai). The dissolution
medium consisted of phosphate buffer (pH 7.4) maintained at 37 ± 0.5 °C.