L-amphetamine is less potent than D-amphetamine in increasing certain neurochemicals and is primarily responsible for peripheral effects like increased blood pressure and heart rate.

“L amphetamine tends to be the amphetamine that increases blood pressure and heart rate what we call peripheral effects because it happens in the periphery outside the central nervous system peripheral effects like increased heart rate increased blood pressure sweating Etc are mostly activated by L amphetamine whereas D amphetamine tends to work mainly on receptors in the brain and therefore have effects mainly restricted to the brain”