A drug used to treat many types of bacterial infections. It stops the growth of bacteria by keeping them from making proteins. It is a type of antibiotic. Also called doxycycline hyclate. OR A synthetic, broad-spectrum tetracycline with antimicrobial activity. Doxycycline binds reversibly to the 30S ribosomal subunit and possibly to the 50S ribosomal subunit, blocking the binding of aminoacyl-tRNA to the mRNA-ribosome complex, which results in an inhibition of bacterial protein synthesis. In addition, this agent may inhibit collagenase activity.