Comvac 4® is a uniform suspension of Diphtheria toxoid, Tetanus toxoid, B pertussis whole cell inactivated and Hepatitis B Surface Antigen adsorbed on a mineral carrier aluminium phosphate gel in isotonic saline solution (in-situ gel formulation).The Diphtheria and Tetanus components are toxoids prepared by formalin inactivation using established technology. The Pertussis component is a whole cell culture, inactivated by using standard methods. The Hepatitis B Surface Antigen of the Hepatitis B virus is manufactured by recombinant DNA technology.