Case Study 2 Metastable versus Stable Form of Piroxicam

2 Case Study 2 Metastable versus Stable Form of Piroxicam 

This study examines the compound piroxicam (Fig. 2.3), a non-steroidal antiinflammatory drug. Although there are relatively few donors and acceptors (2 and 5, respectively), a rather surprising number of H-bond hypotheses can be generated. 

FIGURE 2.4 The H-bond landscape for piroxicam showing a spread of hypothetical structures (grey triangles). Optimal H-bond outcomes appear at the bottom right of the chart, whereas unlikely outcomes appear at the upper left. The thermodynamically stable form I corresponds to the dark grey square to the bottom right, metastable form II corresponds to the white circle on the left-hand side. 

FIGURE 2.5 Chart of mean hydrogen-bond propensity versus mean coordination likelihood for highly likely putative donor/acceptor pairings for axitinib. The arrangement for the metastable Forms I and VI is represented by the triangle, whilst the most likely arrangement represented by the circle corresponds to Forms XXV, IV and the thermodynamically stable Form XLI. 

---