The high prices of drugs in the US make them unavailable to large sections of the population. Generic drugs are an important means of reducing healthcare costs and consequently improving patient access.

The drug supply chain is complex and includes manufacturers, payers, wholesalers, retailers, patients and other groups. However, it has so far been unclear which of these parties’ drive generics manufacturer choice, which could inform economic models of generics markets and improve understanding of how populations use generic drugs. Understanding what drives manufacturer choice could also be important in designing strategies to increase access to drugs through increased competition.

To address this knowledge gap, a recent study [1] evaluated associations between manufacturer and a range of variables including pharmacy chain, county and Medicare* Part D plan provider. The study looked at US Medicare claims for two common anticoagulants (warfarin and enoxaparin) for 2014.

Regression analysis showed that the manufacturers of these drugs received by Medicare Part D beneficiaries was strongly associated with the dispensing pharmacy chain. For prescriptions filled at large chains, more than 75% of variance in generics manufacturer could be explained by the dispensing pharmacy chain.

Pharmacy chain alone predicted over 75% of the variability in warfarin manufacturer and 83% of the variability in enoxaparin manufacturer. This trend was maintained over extended timeframes (up to five years) and was also observed for other commonly prescribed drugs including CNS stimulants.

This study indicates that the pharmacy chain has a significant influence on the manufacturer of a generic drug received by Medicare Part D beneficiaries, bigger than that of payers or geographic location.

The authors suggest that this knowledge could be used to inform economic models of generics competition and epidemiological studies investigating how different populations use generic drugs.

*Medicare is a government health insurance programme which provides treatments for older patients (age 65 and over) and patients with certain conditions such as ALS.

Conflict of interest
This manuscript reflects the views of the authors and should not be construed to represent FDA’s or CMS’ views or policies.

Editor’s comment
This article for GaBI Online is a summary of the full manuscript published in GaBI Journal.

If you would like to receive a copy of the GaBI Journal manuscript, please send us an email.

Readers interested to learn more about the US generic drug market are invited to visit www.gabi-journal.net to view the following manuscripts published in GaBI Journal:

US generic prescription drug markets 2004‒2016

Barriers to generics policy reform: a US case study

A comparison of European and US generic drug markets

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Reference
1. Kozlowski S, Tworkoski E, Dekmezian C, et al. Pharmacy chain drives choice among manufacturers of generic drugs in the US Medicare population. Generics and Biosimilars Initiative Journal (GaBI Journal). 2019;8(3). Epub ahead of print

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