DLPA

The pain reliever DLPA (D,L-phenylalanine) contains two forms of the amino acid phenylalanine. The L form is a natural substance found in protein-rich foods; it's believed to bolster mood-elevating chemicals in the brain, such as dopamine and norepinephrine. The D form of phenylalanine, on the other hand, is made synthetically in a laboratory; it appears to block a nervous system enzyme that amplifies pain signals. In other words, it may prevent the breakdown of the brain's natural narcotics.