The hyclate salt form of doxycycline, a synthetic, broad-spectrum tetracycline antibiotic exhibiting antimicrobial activity. Doxycycline hyclate binds reversibly to the 30S ribosomal subunit, possibly to the 50S ribosomal subunit as well, thereby blocking the binding of aminoacyl-tRNA to the mRNA-ribosome complex. This leads to an inhibition of protein synthesis. In addition, this agent has exhibited inhibition of collagenase activity. Check foractive clinical trials using this agent.