Reconstituant

Reconstituant is a term that refers to a substance used to reconstitute a dried, powdered, or lyophilized material back to its usable form. While more common in French, English usage appears in pharmaceutical labeling and laboratory protocols as a label for the solvent or diluent added to a product prior to administration or use. In many contexts the preferred English terms are reconstituting solvent or diluent; "reconstituant" may be used to describe that component in official documentation.

In pharmaceuticals, many injectable drugs are provided as lyophilized powder and require reconstitution before use. The reconstituant is selected to be chemically compatible with the drug and to provide a safe, isotonic solution. Typical reconstituting solvents include sterile water for injection, normal saline, or bacteriostatic water. Instructions specify the exact volume to add and any handling limits; once reconstituted, some products have a defined stability window and must be used promptly or stored under specified conditions.

Wider usage includes nutrition and laboratory science, where powders or dried reagents are dissolved in a solvent to form a solution. In biochemistry and molecular biology, reconstitution can also refer to restoring a biomolecule to its native state, with the reconstituting solution containing ions, cofactors, or buffers. The terminology varies by field, and in many English texts the reconstituting solvent is described directly rather than using the noun "reconstituant."