Phenylbutazone and chromosomal damage.

Investigation of 44 paired test and control patients, all suffering from rheumatoid arthritis, following exposure to phenylbutazone (PBZ) and/or oxyphenbutazone (OPB), suggests that there is no significant increase in the level of chromosomal damage in lymphocytes. The control subjects comprised two series, one previously exposed to PBZ and/or OPB, but not for at least 1-5 years, and the other never exposed to PBZ or OPB. No significant difference in the level of chromosome damage was found between patients never exposed, previously exposed, or now receiving PBZ and/or OPB.