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A Dynamic Oligopoly Structural Model for the Prescription Drug Market After Patent Expiration


  • Andrew Ching


Motivated by the slow diffusion of generic drugs and the increase in prices of brand-name drugs after generic entry, I incorporate consumer learning and consumer heterogeneity into an empirical dynamic oligopoly model. In the model, firms choose prices to maximize their expected total discounted profits. Moreover, generic firms make their entry decisions before patent expiration. The entry time of generics depends on the FDA random approval process. I apply this model to the market of clonidine. The demand side parameters are estimated in a previous paper (Ching (2003)). The supply side parameters are estimated and calibrated here. The model replicates the stylized facts fairly well. I confirm that consumer heterogeneity in price sensitivity plays an important role in explaining the brand-name pricing pattern. I also apply the model to examine the impact of a policy experiment, which shortens the expected approval time for generics. Although this experiment brings generics to the market sooner, it also reduces the number of generic entrants as the likelihood of entering a crowded market in the early periods increases. Given the change in the magnitude of the policy parameter, the experiment improves the rate of learning, and lowers the equilibrium generic prices throughout the period. However, it hardly raises the overall welfare

Suggested Citation

  • Andrew Ching, 2004. "A Dynamic Oligopoly Structural Model for the Prescription Drug Market After Patent Expiration," Econometric Society 2004 Far Eastern Meetings 735, Econometric Society.
  • Handle: RePEc:ecm:feam04:735

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    Dynamic Oligopoly; Consumer Learning; Pharmaceutical Industry;

    JEL classification:

    • C61 - Mathematical and Quantitative Methods - - Mathematical Methods; Programming Models; Mathematical and Simulation Modeling - - - Optimization Techniques; Programming Models; Dynamic Analysis
    • L13 - Industrial Organization - - Market Structure, Firm Strategy, and Market Performance - - - Oligopoly and Other Imperfect Markets
    • L65 - Industrial Organization - - Industry Studies: Manufacturing - - - Chemicals; Rubber; Drugs; Biotechnology; Plastics

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