Methiopropamine also referred to as MPA is a thiophene ring based analog of N-methyl-1-phenylpropan-2-amine. Methiopropamine (MPA) is a thiophene ring-based structural analog of methamphetamine originally reported in 1942.. The systematic or IUPAC name for Methiopropamine is 1-(thiophen-2-yl)-2-methylaminopropane. Chemically it is not a phenethylamine or amphetamine and is not their functional analog either. It originally appeared for public sale in the UK in December 2010 as a “research chemical” or “legal high”, recently branded as Blow. It has limited popularity as a recreational stimulant.
MPA functions as a selective norepinephrine-dopamine reuptake inhibitor that is approximately 1.85 times more selective for norepinephrine than dopamine. It is approximately one third as potent as dextroamphetamine as a norepinephrine reuptake inhibitor and one fifth as much as a dopamine reuptake inhibitor. It displays negligible activity as a serotonin reuptake inhibitor.
For N-alkyl amphetamines, deamination and N-dealkylation are the major elimination pathways and renal excretion is a minor one. Methiopropamine is metabolized into active thiopropamine, 4-hydroxymethiopropamine and thiophene S-oxides. These N-demethylated metabolites are further deaminated by the cytochrome P450 enzyme CYP2C19 in the liver transforming them into inactive 1-(thiophen-2-yl)-2-propan-2-one which can be seen as a phenylacetone derivative.
Thiophene-2-carboxylic acid is the final major metabolic product. It is very hydrophilic and is excreted in urine. Methiopropamine and especially thiopropamine are also excreted renally, unchanged.
There is a four-step synthesis of MPA . It begins with (thiophen-2-yl)magnesium bromide, which is reacted with propylene oxide, yielding 1-(thiophen-2-yl)-2-hydroxypropane which is reacted with phosphorus tribromide, yielding 1-(thiophen-2-yl)-2-bromopropane which is finally reacted with methylamine, yielding 1-(thiophen-2-yl)-2-methylaminopropane.
Following the ban on ethylphenidate authorities noticed an increase in methiopropamine use by injecting users. The ACMD suggested it be banned on 18 November 2015 as it had similar effects to ethylphenidate. The government enacted a temporary drug control order a week later which came into force on 27 November 2015