title: Mexico's precursor chemical controls: emergence of less potent types of methamphetamine in the United States.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Family and Community Medicine, The University of Arizona, 1450 N Cherry Avenue, Tucson, AZ 85719, USA. jkcunnin@email.arizona.edu
authors.forename: James K
authors.initials: JK
authors.lastname: Cunningham
authors.forename: Jane Carlisle
authors.initials: JC
authors.lastname: Maxwell
authors.forename: Octavio
authors.initials: O
authors.lastname: Campollo
authors.forename: Lon-Mu
authors.initials: LM
authors.lastname: Liu
authors.forename: William J
authors.initials: WJ
authors.lastname: Lattyak
authors.forename: Russell C
authors.initials: RC
authors.lastname: Callaghan
mesh_terms: D000465:Algorithms; D002188:Cannabis / Q000737:chemistry; D000697:Central Nervous System Stimulants / Q000032:analysis* / Q000737:chemistry; D003042:Cocaine / Q000032:analysis; D004335:Drug and Narcotic Control / Q000331:legislation & jurisprudence* / Q000639:trends; D004809:Ephedrine / Q000737:chemistry; D005843:Geography; D003932:Heroin / Q000032:analysis; D006801:Humans; D008694:Methamphetamine / Q000032:analysis* / Q000737:chemistry; D008800:Mexico; D015233:Models, Statistical; D009294:Narcotics / Q000032:analysis; D054199:Pseudoephedrine / Q000737:chemistry; D013237:Stereoisomerism; D014481:United States
chemical_list: D000697:Central Nervous System Stimulants; D009294:Narcotics; D008694:Methamphetamine; D003932:Heroin; D054199:Pseudoephedrine; D004809:Ephedrine; D003042:Cocaine