Changing over-the-counter ephedrine and pseudoephedrine products to prescription only: Impacts on methamphetamine clandestine laboratory seizures

Background: Clandestine laboratory operators commonly extract ephedrine and pseudoephedrine-precursor chemicals used to synthesize methamphetamine-from over-the-counter cold/allergy/sinus products. To prevent this activity, two states, Oregon in 07/2006 and Mississippi in 07/2010, implemented regulations classifying ephedrine and pseudoephedrine as Schedule III substances, making products containing them available by prescription only. Using simple pre-regulation versus post-regulation comparisons, reports claim that the regulations have substantially reduced clandestine laboratory seizures (an indicator of laboratory prevalence) in both states, motivating efforts to implement similar regulation nationally. This study uses ARIMA-intervention time-series analysis to more rigorously evaluate the regulations' impacts on laboratory seizures. Methods: Monthly counts of methamphetamine clandestine laboratory seizures were extracted from the Clandestine Laboratory Seizure System (2000-early 2011) for Oregon, Mississippi and selected nearby states (for quasi-control). Findings: Seizures in Oregon and nearby western states largely bottomed out months before Oregon's regulation, and changed little thereafter. No significant impact for Oregon's regulation was found. Mississippi and nearby states generally had elevated seizures before Mississippi's regulation. Mississippi experienced a regulation-associated drop of 28.9 seizures (50.2%) in the series level (p<. 0.01), while nearby states exhibited no comparable decline. Conclusions: Oregon's regulation encountered a floor effect, making any sizable impact infeasible. Mississippi, however, realized a substantial impact, suggesting that laboratories, if sufficiently extant, can be meaningfully impacted by prescription precursor regulation. It follows that national prescription precursor regulation would have little impact in western states with low indicated laboratory prevalence, but may be of significant use in regions facing higher indicated prevalence.