Comparative effects of tetracycline and doxycycline on liver function of young adult and old mice.

The effects of tetracycline and doxycycline (25 and 100 micrograms/g i.v.) on serum GOT, GPT, urea, bilirubin, cholesterol and triglycerides and on the hepatic cholesterol and triglyceride levels have been investigated comparatively in female mice of two age groups: young adult and old. Both tetracyclines caused increases in the serum transaminases and bilirubin and in the triglyceride and cholesterol contents of the liver that were less pronounced in old than in young adult mice. The reason for the age difference may be that doxycycline and tetracycline accumulated to a greater extent in the livers of the younger age group. Only the rise of the serum urea levels after tetracycline and doxycycline was greater in old mice than in the young adults.