Residual marrow damage: possible explanation for idiosyncrasy to chloramphenicol.

The effect of oral administration of chloramphenicol was studied in normal mice and mice having residual marrow damage. In the concentration used the drug had no detectable effect on the marrow of normal mice but caused a progressive fall in the numbers of pluripotential stem cells and granulocytic progenitor cells in mice bearing residual marrow damage. However, cells taken from such mice were no more sensitive than normal cells to the in vitro action of chloramphenicol. The results suggest that unrecognized residual marrow damage can be an aetiological factor in marrow failure due to drug idiosyncrasy.