Comparative evaluation of the effects of tetracycline, rolitetracycline and doxycycline on some blood parameters related to liver function.

A comparative study was made on the effects of tetracycline (TC), rolitetracycline (RTC), and doxycycline (DC) at doses of 10-100 micrograms/g i.v. on serum GOT, GPT, bilirubin and urea levels of male and female mice. All tetracyclines at doses of 50-100 micrograms/g caused an increase of serum GOT and GPT activities in females after 2-8 h. This effect was less pronounced in males. The serum urea levels were markedly raised by TC and DC (50-100 micrograms/g) and RTC (10-100 micrograms/g). This effect was produced only in females. It was long-lasting (up to 8 h) after TC and RTC and more transient after DC. Likewise the tetracyclines affected the serum bilirubin only in females but not in males. All tetracyclines (25-100 micrograms/g) increased the amount of unconjugated and total bilirubin. This effect was most pronounced after TC, which also reduced the level of conjugated bilirubin.