Medical cannabis laws had minimal effect on pharmaceutical marketing to physicians

Medical cannabis law enactment was associated with weak evidence of small, delayed reductions in pharmaceutical detailing for substitute prescription drugs and opioids. Effects were slightly more pronounced among smaller pharmaceutical firms. However, the magnitudes were economically small, likely because only a small percentage of doctors actively recommend cannabis for medical treatment.

Exploited geographic and temporal variation in medical cannabis laws across US states. Used office detailing records from 2014-2018 aggregated to the county level. Examined changes in direct-to-physician marketing by pharmaceutical firms following MCL enactment.

If medical cannabis truly substitutes for prescription drugs, pharmaceutical companies should reduce marketing in response. The finding of minimal marketing response suggests either that cannabis substitution is limited in practice or that pharma companies do not perceive cannabis as a serious market threat.

The muted pharmaceutical marketing response to cannabis laws contrasts with survey data showing patients self-reporting large-scale prescription substitution. This disconnect suggests that at the population level, medical cannabis may not yet be shifting prescription drug markets as dramatically as individual surveys suggest.

Observational with county-level aggregation. Cannot directly measure prescription substitution. Detailing records may not capture all marketing channels. 2014-2018 period captures early MCL effects only.