Tablet-dissolution studies were performed in triplicate. Dissolution was achieved in a 900-mL phosphate butter (pH 7.4) using
a USP 24 Type II dissolution apparatus (Veego Scientific). The dissolution medium was stirred at 100 rpm and maintained at
37 ± 0.5 °C. Drug release was determined using an ultraviolet spectrophotometer (UV-1700, Shimadzu) at 363.5 nm. For comparison,
a commercial tablet (Metflam, Unichem Laboratories, Mumbai, India) was also studied. Data obtained from the dissolution studies
were analyzed using PCP Disso software (PCP, Pune, India).
Results and discussion
Drug-content estimation.
The granules and solid dispersion showed less variation in percentage drug content. The percentage drug content was between
96.82 ± 0.75% and 101.39 ± 1.18%. These values indicate a uniform distribution of drug in the granules and solid dispersion
obtained using myrj-52.
Figure 1: Saturation solubility of melt granulation (MG), physical mixture (PM), and solid dispersion (SD) of meloxicam with
myrj-52 in an aqueous solution at room temperature.
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Saturation solubility.
All of the test samples showed an increase in drug solubility (see Figure 1). The physical mixture, solid dispersion, and
granules prepared by melt granulation showed higher saturation solubility compared with pure meloxicam. This result might
arise from an improvement in the wetting of drug particles and localized solubilization by myrj-52.
An increase in a drug's saturation solubility can explain the improved dissolution of melt granulation, physical mixture,
and solid dispersions, according to the Noyes–Whitney equation, because the saturation solubility of a compound depends on
particle size. Thus, one can improve meloxicam's saturation solubility by reducing its particle size through various approaches.
The saturation solubility of pure meloxicam was 23 μg/mL. Melt granulation, physical mixture, and solid dispersion exhibited
improved solubility.
The saturation solubility of solid dispersion prepared with myrj-52 increased to 1.2 mg/mL. Solubility is increased almost
52.17 times with myrj-52.
Figure 2: Solubility of meloxicam in an aqueous solution of myrj-52.
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Solubilization effect of myrj-52.
The results from the current study showed that myrj-52 has a significant solubilizing effect on meloxicam. Figure 2 shows
the phase-solubility curve of meloxicam in the presence of myrj-52. Meloxicam's solubility increased when the concentration
of myrj-52 in the water increased. The solubility enhancement may result from the improved dissolution of meloxicam particles
in the water by myrj-52.
The process of the transfer of meloxicam from the pure water to the aqueous solution of myrj-52 was obtained using the values
of Gibb's free-energy change. The Gibb's free energy of transfer (Gtr) of meloxicam from the pure water to aqueous solution of myrj-52 was calculated using the following equation:
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