Effects of piroxicam-beta-cyclodextrin on the gastrointestinal tract

Piroxicam-beta-cyclodextrin (PBC), a complex of piroxicam with beta-cyclodextrin, was developed with the aim of improving the hydrosolubility and bioavailability of piroxicam. The complex is more rapidly absorbed, with a consequent reduction in the time of contact of piroxicam with the gastric and duodenal mucosa. It is hoped that the shorter contact time might reduce the local toxicity of piroxicam, but it is also possible that transiently higher local concentrations of the drug might worsen the injury to the gastro-duodenal mucosa. Four studies have been conducted in healthy volunteers in order to investigate the effects of PBC on the gastro-intestinal tract. In 3 of these trials, all of similar design, PBC (containing 20 mg of piroxicam) was compared with piroxicam 20mg and placebo given once daily with assessment of faecal blood loss using the 51Cr-labelled red-cell technique, and endoscopic appearance of gastroduodenal mucosa before and after 28 consecutive days of treatment. One study showed a significant difference in respect of faecal blood loss towards the end of the 4-week study period favouring PBC over piroxicam, while the 2 others showed comparable but non-significant trends in favour of PBC. In a fourth study, 32 non-patient volunteers received either piroxicam 20mg once daily; PBC 20mg equivalence; indomethacin 50mg twice daily; or placebo. The treatment was given double blind for 14 days. Endoscopy was performed and gastric potential differences were measured by neutral observers before and at the end of treatment. There were no significant differences in the endoscopic scores between the active treatment groups. The gastric potential difference showed greater changes with indomethacin and piroxicam than with placebo and PBC.(ABSTRACT TRUNCATED AT 250 WORDS)