AdrafinilvsNALT

Adrafinil is a prodrug—it is pharmacologically inactive until metabolized by hepatic cytochrome P450 enzymes (primarily CYP3A4) and possibly esterases into modafinil (the active metabolite) and modafinilic acid (inactive byproduct). The conversion involves oxidation of the sulfinyl group. Once converted, adrafinil acts identically to modafinil: inhibition of the dopamine transporter (DAT), activation of orexin/hypocretin neurons in the lateral hypothalamus, increased histamine release from tuberomammillary nuclei, and elevation of norepinephrine and serotonin in cortical regions. The hepatic first-pass conversion step explains the delayed onset (45-60 minutes vs 20-30 for modafinil) and the concern about liver enzyme elevation and oxidative stress with chronic daily use.

NALT (N-acetyl L-tyrosine) is deacetylated by aryl acylamidase in the gut and liver to release L-Tyrosine. Tyrosine is hydroxylated to L-DOPA by tyrosine hydroxylase (TH) — the rate-limiting step in catecholamine synthesis, requiring tetrahydrobiopterin as cofactor. L-DOPA is decarboxylated by aromatic L-amino acid decarboxylase (AADC) to dopamine; dopamine is converted to norepinephrine by dopamine beta-hydroxylase (DBH), and norepinephrine to epinephrine by phenylethanolamine N-methyltransferase (PNMT). Under stress or sleep deprivation, catecholamine stores in noradrenergic and dopaminergic neurons deplete rapidly. Supplemental tyrosine provides substrate to maintain synthesis when demand exceeds supply, supporting prefrontal cortex function and working memory.