The binding affinity of amphetamine to 4-pyridinecarboxaldehyde and the coenzymes pyridoxal and pyridoxal-5-phosphate.

Equilibrium and rate constants have been determined for the reactions of amphetamine with pyridine-4-carboxaldehyde, pyridoxal and pyridoxal-5-phosphate to give the corresponding Schiff bases. The reactions were found to be dependent on amphetamine concentration and pH of the solution. The overall equilibrium constants are 5.97×102, 13.7×103 and 8.2×103 for amphetamine with pyridine-4-carboxaldehyde, pyridoxal and pyridoxal-5-phosphate, respectively.