Types of Reactors Used in the Pharmaceutical Industry Pharmaceutical reactors are engineered vessels in which active pharmaceutical ingredients (APIs) and formulations are synthesized or processed under tight GMP, contamination-control, and cleanability requirements. The dominant types are batch stainless-steel reactors, continuous-flow reactors, single-use systems, jacketed agitated vessels, fixed-bed catalytic reactors, and bioreactors. The correct choice depends on the