Focalin (dexmethylphenidate) is an oral medication used primarily to treat the symptoms of Attention Deficit Hyperactivity Disorder (ADHD) along with behavioral therapies and counseling.  It is part of a a class of medications called norepinephrine-dopamine reuptake inhibitors (NDRI).

It is believed that a possible cause of ADHD is a low amount of the neurotransmitters norepinephrine and dopamine, among others. In the brain, the space between where two neurons meet to communicate is called a synapse, and the synapse is where norepinephrine, dopamine, and other neurotransmitters are used to communicate between neurons. In depression, people may not have enough norepinephrine and dopamine in their brain. Normally after a chemical message is sent between neurons, the neurotransmitters are reabsorbed by the sending neuron (presynaptic neuron).

A selective norepinephrine-dopamine reuptake inhibitor will bind to the presynaptic neuron and prevent it from absorbing the norepinephrine and dopamine, and leave the neurotransmitters active in the synapse, improving mood and anxiety symptoms. Focalin also acts as a releasing agent and therefore psychostimulant, meaning that in addition to preventing reuptake, it also causes the extra release of neurotransmitters.