The effect of oxytetracycline and doxycycline on protein metabolism

The tetracyclines in dermatology

Tetracycline is one of the most widely used antibiotics. It may share some properties with conventional immunosuppressive drugs and act as an anti-inflammatory agent in the treatment of inflammatory disease. This article reviews cutaneous diseases that have been treated with tetracyclines and their antiinflammatory and immunosuppressive properties.

Quantitative assessment of the polysome profile of the livers of mice treated with tetracycline or doxycycline

The influence of tetracycline and doxycycline (10-100 micrograms/g i.v.) on the aggregational state of ribosomes from mouse liver was tested. Both drugs caused a disaggregation of the ribosomes as evidenced by a rise of the monosomes + disomes/polysomes ratio. Tetracycline was much more potent than doxycycline, the minimum effective doses for tetracycline being 10 micrograms/g i.v. as compared to 100 micrograms/g for doxycycline. The results show that tetracycline but not doxycycline at therapeutic dose range may interfere with the protein synthesis of the liver.

Experimental study of antibiotic-induced immunosuppression in mice. 1. Humoral and cell-mediated immune responsiveness related to in vivo antibiotic treatment

By using CBA/J mice as responders, the immunodepressive effect of seven antibacterial chemotherapeutic agents was tested, i.e. penicillin (pen), streptomycin (str), erythromycin (erm), kanamycin (kan), tetracycline (tet), colistin (col) and chloramphenicol (chl). Lymphocytotoxicity power, as well as the ability of each drug to influence secondary humoral (against sheep red blood cells or diphtheria anatoxin) or cell-mediated (against PPD and Coxsackie A9 virus) immunity were searched. Erm, col and chl markedly depressed humoral and cell-mediated immune responsiveness in vitro after in vivo treatment with non-cytotoxical amounts. The Th lymphocyte supplementation of B reactive spleen cell population recovered the immune capacity in col and chl in vivo-treated groups, but not in erm-treated group.

The effect of intravenous doxycycline hyclate on total parenteral nutrition in protein malnourished rats

To study the effects of intravenous doxycycline hyclate on protein malnourished rats, 20 male Sprague-Dawley rats, weighing 234 to 277 g, were protein depleted for 6 weeks then randomly assigned to one of two groups: group I (10 rats), total parenteral nutrition with intravenous doxycycline hyclate injections, group II (10 rats), total parenteral nutrition with normal saline injections. Both groups were then protein repleted for 7 days. Body weight; fluid intake; urine output; liver, spleen, and lung weights; nitrogen content; and serum proteins were measured. The antibiotic dosage given was 10 mg/kg body weight/day or 0.1688 +/- 0.0046 mg/kg. There was no significant difference in starting weight, weight after 6 weeks of protein depletion, weight at sacrifice, or weight gain between groups I and II. Average fluid intake/day for groups I (50 +/- 2 ml) and II (51 +/- 3 ml) were not statistically significant. There was no significant difference in average urine output/day nitrogen balance, liver weight, and liver nitrogen, spleen and lung weights, or serum albumin levels (Groups I, 2.84 +/- 0.48 g%, Group II, 2.72 +/- 0.24 g+). Intravenous doxycycline hyclate does not appear to have a protein catabolic effect on protein malnourished rats receiving total parenteral nutrition.

Effects of cloxacillin, doxycycline, fusidic acid and lincomycin on mineralization and solubility of collagen in young rats

The antibiotics doxycycline, fusidic acid and lincoymcin have recently been shown to reduce growth of bones and tensile strength of skin in young rats. Such adverse effects were not found in rats receiving cloxacillin. The present investigation deals with the influences of these four antibiotics on the mineralization of bones and on the solubility of collagen in skin. In rats receiving doxycycline the content of calcium and phosphorus in bones and the concentration of albumin in serum were reduced. None of the antibiotics had a detectable effect on the solubility of collagen.

Effects of oxytetracycline on solubility and synthesis of collagen in young rats

In a recent study we demonstrated that the antibiotic oxytetracycline reduces both growth and mechanical strength of bone and skin in young rats. The present study deals with the effects of 14 days of oxytetracycline medication on salt solubility of collagen (cross-linking) and conversion of 14C-proline to 14C-hydroxyproline in collagen (synthesis). At the end of the medication period, significantly higher solubility of collagen was found in the femurs and skin of rats receiving oxytetracycline than in controls. No effect of the antibiotic on the rate of collagen synthesis could be demonstrated. These findings may indicate that oxytetracycline in young rats causes reduced mechanical strength of bone and skin by interfering with the cross-linking of collagen.

Effects of cloxacillin, doxycycline, fusidic acid and lincomycin on the mechanical properties of bone and skin in young rats

The influence of cloxacillin, doxycycline, fuside acid and lincomycin on the mechanical properties of bone and skin in young rats was examined. The concentrations of the antibiotics in plasma corresponded to therapeutic levels in man. After 14 days of medication the weights of the rats receiving cloxacillin or doxycycline were significantly less when compared with the controls. The doxycycline, the fusidic acid and the lincomycin treated rats had reduced longitudinal growth of femur and reduced tensile strength of intact skin. No differences between any of the antibiotic groups and the control group were found in the tensile strength of incisional skin wounds or in the mechanical properties of the femur and tibia.