Doxycycline is a long-acting tetracycline derived from oxytetracycline. Like minocycline, it is lipophilic and can diffuse through the lipid bilayer of bacteria. Doxycycline reversibly binds to the bacterial 30S ribosomal subunit and to a lesser extent the 50S subunit, blocking the binding of aminoacyl tRNA to the A site on the ribosome-RNA complex. Binding inhibits bacterial protein synthesis and hence cell growth.
Doxycycline may be used to treat treat non-gonococcal urethritis and cervicitis, adult periodontitis, rosacea, inflammatory acne vulgaris and syphilis in patients allergic to penicillin. It may also be used as prophylaxis against chloroquine-resistant and/or mefloquine-resistant P. falciparum, one of the species of malaria-causing parasites.
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