calcium;(6aR,10S,10aR,11S,11aR,12R)-8-carbamoyl-10-(dimethylamino)-4,6a,7,11-tetrahydroxy-12-methyl-6,9-dioxo-10a,11,11a,12-tetrahydro-10H-tetracen-5-olate
Doxycycline Calcium is the calcium salt form of doxycycline exhibiting antimicrobial activity.  Doxycycline blocks binding of aminoacyl-tRNA to the mRNA-ribosome complex, thereby inhibiting protein synthesis.  In addition, this agent has exhibited inhibition of collagenase activity. (NCI)