Doxycycline is a tetracycline antibiotic with bacteriostatic activity against gram-positive and gram-negative bacteria, including Mycoplasma spp, Rickettsia spp. and Chlamydia spp
It is completely absorbed from the G.I.T and slowly excreted from the body via the bile and urine.
Action of doxycycline is based on inhibition of bacterial protein synthesis by binding to ribosomes in the bacteria and inhibiting protein synthesis so the bacteria cannot reproduce.