Doxycycline hyclate was origninally used as a broad spectrum antibiotic. However, for the treatment of periodontal disease, doxycycline is administered at subantimicrobial doses with absolutely no antibiotic action. The drug is meant to enhance and maintain the benefits of scaling and root planing treatments for periodontal disease as well as to prevent the disease from spreading. When doxycyclin hyclate is administered at these subantimicrobial doses, the drug acts as to suppress the activity of the enzyme collagenase. Collagenase belongs to a class of enzymes known as proteases.
Proteases are enzymes which degrade or break down other proteins and enzymes.
Collagenase is the protease which degrades collagen, one of the body's primary connective tissues. In patients with periodontal disease, the collagen which forms the structural basis of the periodontium is broken down by collagenase. Elevation in the levels of metalloproteases is believed to account for the majority of the connective tissue destruction which occurs in periodontitis. Studies have shown that both host cells and invading bacteria produce and secrete collagenase into the periodontal pocket. These cells are believed to be activated by bacterial substances and by proinflammatory cytokines present in the disease.