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Pharmacological particulars
Pharmacotherapeutic group: Anti-infectives and antiseptics for intrauterine use, antibiotics, tetracycline.
ATCvet code: QG51AA02
Pharmacodynamic properties
Tetracycline (TC) is a broad spectrum antibiotic with bacteriostatic action in vivo. The spectrum includes gram-positive and gram-negative, aerobic and anaerobic microorganisms. The primary pathogens involved in puerperal intrauterine infections, Arcanobacterium (Actinomyces) pyogenes and Escherichia coli, are susceptible to tetracycline. For systemic action against most susceptible microorganisms, in vivo serum concentrations of 0.5 – 2 µg/ml are considered efficacious, which need to be sustained over a sufficiently long period of time. Concentrations of more than 2 µg/ml of tetracycline are easily obtained in lochia following intrauterine administration of the recommended dose.
There is usually complete cross resistance amongst tetracyclines.
Pharmacokinetic properties
Absorption via mucous membranes is limited due to the amphotheric properties of the molecule. Absorption of tetracycline hydrochloride from the uterus to the peripheral blood is limited in post parturient cows. The rate of absorption of tetracycline depends on various individual factors such as the relative blood flow to the myometrium, contractions of the uterus, lochial volume, discharge from the vulva and the severity of inflammation and infection. Tetracycline undergoes enterohepatic circulation and its antimicrobially active form is eliminated primarily via urine, faeces and milk. The biological half-life following systemic administration is 8 hours in ruminants. It varies depending on the route of administration; it is prolonged in animals with renal insufficiency.