Physicochemical characterization of solid dispersion systems of tadalafil with poloxamer 407 Dissolution behaviour of a poorly water-soluble drug, tadalafil, from its solid dispersion systems with poloxamer 407 has been investigated. Solid dispersion systems of tadalafil were prepared with poloxamer 407 in 1:0.5, 1:1.5 and 1:2.5 ratios using the melting method. Characterization of binary systems with FTIR and XRPD studies demonstrated the presence of strong hydrogen bonding interactions, a significant decrease in crystallinity and the possibility of existence of amorphous entities of the drug. In the binary systems tested, 1:0.5 proportion of tadalafil/poloxamer 407 showed rapid dissolution of tadalafil (DE30 70.9 ± 3.6 %). In contrast, higher proportions of poloxamer 407 (1:1.5 and 1:2.5) offered no advantage towards dissolution enhancement of the drug, indicating altered rheological characteristics of the polymer at its higher concentration, which might have retarded the release rate of tadalafil.

Solid dispersion systems of a poorly water-soluble drug, etoricoxib were prepared with poloxamer 188 in 1:0.5, 1:1.5 and 1:2.5 ratios and evaluated by FTIR, powder XRD and dissolution studies. Physical studies demonstrated a strong hydrogen bonding with significant decrease in the crystallinity and formation of amorphous etoricoxib in its binary systems. All binary systems of etoricoxib showed faster dissolution than pure drug alone (P < 0.001). However, 1:2.5 proportion of etoricoxib: poloxamer 188 showed superior performance (DE45: 71.27% +/- 3.85) in enhancing solubility and dissolution rate of etoricoxib suggesting optimum ratio of the carrier.

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