Comparison of occult blood loss caused by pirazolac and diclofenac sodium: a double-blind crossover study.

A study was carried out in 10 healthy subjects to compare the faecal blood loss caused by pirazolac, a new non-steroidal anti-inflammatory drug, and diclofenac sodium, using chromium51-labelled red blood cells. After 1 week on placebo, subjects received at random either 200 mg pirazolac 3-times daily or 50 mg diclofenac sodium 3-times daily for 7 days. They were then crossed over to the alternative medication for a further 7 days, preceded and followed by 1 week on placebo. Stool samples were collected and bulked for each day and total blood loss over 14 days (7 days on treatment and 7 days immediately after) was calculated for each period. The results showed that both drugs caused a greater blood loss than that measured in the placebo run-in period, and diclofenac sodium caused significantly greater blood loss than did pirazolac. Three subjects reported gastro-intestinal side-effects during diclofenac sodium treatment but there were no reports of any side-effects whilst subjects were receiving pirazolac.