Which substance produced in the laboratory is used as a post exposure preventative measure against rabies?

I think the answer is synthetic immunoglobulins: Immunoglobulins are also called antibodies, they are glycoproteins molecules produced by plasma cells (white blood cells). They act as the critical part of the immune response by specifically recognizing and binding to particular antigens, such as bacteria and viruses, and enhancing their destruction. Synthetic immunoglobulins may differ in structure to that of an antibody and can be generated either from nucleic acids, as in the case of aptamers, or from non-immunoglobulin protein scaffolds/peptide aptamers, into which hypervariable loops are inserted to form the antigen binding site.

Idid the calculation and i get 875,000,000 which can be written as 8.75 x 10^6?

Must be negative.substance increases