Çukurova Pharmaceutical

Doksinova 50

Doxycycline is a semisynthetic tetracycline derivative. It acts by inhibiting protein synthesis at the ribosomal level, predominantly by binding to the 30S ribosomal subunits of bacteria. Doxycycline is a broad-spectrum antibiotic. It exhibits a wide range of activity against gram-positive aerobic pathogens (Bacillus sp., Corynebacterium sp., Erysipelothrix rhusiopathia, Listeria monocytogenes and Streptococci.) and gram-negative bacteries (Actinobacillus sp., Bordetella sp., Francisella tularensis, Haemophilus sp., Pasteurella multocida, P. haemolytica, Yersinia sp., Campylobacter fetus, Borrelia sp. ve Leptospira sp. Moraxella bovis), anaerobic pathogens (Actinomyces sp., Fusobacterium sp.) and Mycoplasma sp., Chlamydia sp., Ehrlichia sp., Coxiella burnetti, Ehrlichia, Eperythrozoon and Anaplasma in chickens and turkeys.

The resistance rate of Mycobacterium sp., Proteus vulgaris, Pseudomonas aeroginosa, Serratia sp., Mycoplasma bovis and M. hyopneumoniae isolates against doxycycline is low.

Doxycycline acts on the subunit 30 S of the bacterial ribosome, to which is bound reversibly, blocking the union between aminoacyl-tRNA(transfer RNA) to the mRNA-ribosome complex, preventing the addition of new aminoacids into the growing peptide chain an thus interfering with protein synthesis. In general, doxycycline is quite rapidly and extensively absorbed from the gastrointestinal tract, widely distributed in the organism, not metabolised to any significant extent and excreted mostly via the faeces. Pharmacokinetics of doxycycline after single oral administration to chickens and turkeys is characterised by a quite rapid and substantial absorption from the gastrointestinal tract providing peak plasma concentrations between 0.4 and 3.3 hours in chickens and 1.5 to 7.5 hours in turkeys depending on age and the presence of food. The drug is widely distributed in the organism with Vd values close to or greater than 1, and exhibits shorter elimination half-life in chickens (4.8 to 9.4 hours) than in turkeys (7.9 to 10.8 hours). The protein binding ratio at therapeutic plasma concentrations is in the range of 70-85%. The bioavailability in chickens and turkeys may vary between 41 and 73%, and 25 and 64%, respectively also depending on the age and feeding. The presence of food in the gastrointestinal tract determines a lower bioavailability compared to that obtained in the fasted state.