Pharmaceutical Advertising in Dynamic Equilibrium

Direct-to-consumer advertising (DTCA) of prescription drugs may expand treatment access but also risks promoting overuse and business stealing without generating welfare gains. Among developed nations, only the United States and New Zealand permit DTCA, whereas detailing - promotion aimed at prescribers - is widely practiced. This paper analyzes the impact of DTCA on profits by modeling a counterfactual environment in which DTCA is banned. This is implemented through a dynamic equilibrium framework that adapts the Experience-Based Equilibrium (Fershtman and Pakes, 2012) for empirical analysis. EBE incorporates constraints on the cognitive abilities of decision-makers and mitigates researchers' computational concerns. Using data from four therapeutic markets, we first validate the EBE's ability to replicate observed advertising patterns, then simulate counterfactual DTCA bans. Both the data and our empirical work indicate that DTCA and detailing are strong complements, and our results illuminate the need to account for this when evaluating the ban. The ban leads firms to reduce detailing and has a negative effect on profits in all markets, but the magnitude of the effect varies from under 5% in the market for Ulcer to 27.5% for Asthma medications.