Attention deficit hyperactivity disorder management
There are two major medications derived from methylphenidate's isomers: a racemic mixture of half d-threo-methylphenidate and half l-threo-methylphenidate called methylphenidate (Ritalin, Concerta), and an enantiopure formulation containing just d-threo-methylphenidate called dexmethylphenidate (Focalin).
Moclobemide
Moclobemide is a benzamide, derivative of morpholine, which acts pharmacologically as a selective, reversible inhibitor of monoamine oxidase A (RIMA), a type of monoamine oxidase inhibitor (MAOI), and increases levels of norepinephrine (noradrenaline), dopamine, and especially serotonin. in neuronal cells as well as in synaptic vesicles; extracellular levels also increase which results in increased monoamine receptor stimulation and suppression of REM sleep, down regulation of 3-adrenoceptors. A single 300 mg dose of moclobemide inhibits 80% of monoamine oxidase A (MAO-A) and 30% of monoamine oxidase B (MAO-B), blocking the decomposition of norepinephrine, serotonin and, to a lesser extent, dopamine. There is also some evidence pointing towards moclobemide possessing neuroprotective properties. There is no cumulative effect of moclobemide centrally when taken long-term. With long-term use of moclobemide, there is a significant down-regulation of B-adrenoceptors. Single or repeated dosing with 100–300 mg of moclobemide leads to a reduction in deaminated metabolites of amines such as 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethylglycol as well as 5-HIAA. Excretion of homovanillic acid and vanillylmandelic acid via urine is also reduced. There is also a temporary increase in prolactin during initial intake of 100–300 mg of moclobemide. L-dihydroxyphenylalanine is also reduced. However, suppression of the serotonin metabolite is less pronounced than the inhibition of the metabolite of noradrenaline which suggest there are other major metabolic pathways for serotonin other than MAO-A.