Mexico's precursor chemical controls: emergence of less potent types of methamphetamine in the United States.

Abstract

This study examines whether Mexico's controls on ephedrine and pseudoephedrine, the two precursor chemicals that yield the most potent form of methamphetamine, d-methamphetamine, impacted the prevalence/availability of less potent types of methamphetamine in the United States-types associated with the alternative precursor chemical P2P. Using ARIMA-intervention time series analysis of monthly drug exhibits (a prevalence/availability indicator) from the System to Retrieve Information from Drug Evidence (STRIDE), we tested whether Mexico's controls, which began in 2005, were associated with growth/decline in d-methamphetamine and growth/decline in P2P-associated, less potent l-methamphetamine, racemic methamphetamine (a 50:50 ratio of d- and l-isomers), and mixed isomer methamphetamine (an unequal ratio of d- and l-isomers). Heroin, cocaine and marijuana exhibits were used for quasi-control (01/2000-04/2011). Mixed-isomer exhibits constituted about 4% of the methamphetamine exhibits before Mexico's controls, then rose sharply in association with them and remained elevated, constituting about 37% of methamphetamine exhibits in 2010. d-Methamphetamine exhibits dropped sharply; l-methamphetamine and racemic methamphetamine exhibits had small rises. d-Methamphetamine exhibits partially recovered in the US West, but little recovery occurred in the US Central/South. Quasi-control series were generally unaffected. The US methamphetamine market changed. Widespread emergence of less potent methamphetamine occurred in conjunction with Mexico's controls. And prevalence/availability of the most potent type of the drug, d-methamphetamine, declined, a partial recovery in the West notwithstanding. Granting that lower potency drugs typically engender less dependence and attendant problems, these findings suggest that, following Mexico's controls, the potential harm of a sizeable amount of the US methamphetamine supply decreased.