Agmatine is an intermediate in the biosynthesis of the polyamines putrescine and spermine. Agmatine binds with high affinity to �±2-adrenergic receptors and imidazoline binding sites and produces blockade of the NMDA-receptor associated cation channels. Agmatine is a competitive inhibitor of nitric oxide synthase activity owing to mimicry of the natural NOS substrate arginine.
