The Neurontin Lawsuit Increased Costs of Treatment for Bipolar Disorder

In the past decade, the media has reported on dozens of lawsuits regarding massive campaigns by pharmaceutical companies encouraging prescribers to use medications for unapproved (or “off-label”) indications. It is legal for doctors to prescribe medications for uses that the FDA has not approved, and such prescriptions are commonly used in the treatment of the severely mentally ill. It is illegal, however, for pharmaceutical companies to advertise their medications for any such off-label use.

The United States Department of Justice and individual states have responded to these illegal marketing campaigns with litigation. One major objective is to recoup payments by payers (eg, Medicaid) who reimbursed costs for drugs used based on fraudulent advertising.
It has become clear that lawsuits alone are not enough to discourage advertising of off-label drug uses. While the frequency of these lawsuits has increased, the penalties associated with their settlement are not enough to outweigh the revenue being earned through off-label advertising.

Incredibly, in our recent research on the impact of these lawsuits on drug prescribing, we found no previous studies that examined prescribers’ substitution of other drugs and changes in overall drug spending as a result of media attention on an illegally marketed drug. We hypothesized that the Neurontin (gabapentin) lawsuit would be an ideal case study for investigating the economic effects of such lawsuits.

In the case of Neurontin, an anticonvulsant drug that had revenues of nearly $1 billion by 2000, the illegal off-label marketing tactic seems to have worked very well. The majority of Neurontin prescribing was for off-label uses (some of which may have been effective but not approved by the FDA). The lawsuit, which was first reported in March 2002, was settled in 2004 for $430 million.

When the market share of 1 drug in a class declines, other drugs in that class—both appropriate and inappropriate—are generally prescribed as substitutes. We examined how the media coverage of the Neurontin lawsuit may have affected the use of the entire class of anticonvulsant drugs and the cost of treatment among patients with bipolar disorder. We hypothesized that the negative media coverage of Neurontin would be associated with a decline in utilization of that drug.

We found that the media coverage of the lawsuit did correspond with a decline in Neurontin market share and an increase in use of other anticonvulsants. We conservatively estimated that prescribed medication substitutions increased total US spending on anticonvulsants for bipolar disorder by over $200 million from March 2002 through December 2005. Physicians substituted a mix of on- and off-label products, some of which are expensive and lack scientific evidence for efficacy (eg, oxcarbazepine and topiramate) in the treatment of bipolar disorder.

We concluded that these lawsuits can have unintended consequences that include both the substitution of drugs that may not be scientifically substantiated and increases in overall spending. We recommend that the Department of Justice work with medical and specialty organizations (eg, the American Psychiatric Association) to educate prescribers about ongoing litigation and work toward improving the quality of care. Lawsuits that stop the illegal marketing of individual drugs are, by themselves, unlikely to prevent prescribing practices that are costly and not evidence-based, and the settlements may not achieve returns on the costs of litigation.

Financial disclosure:Ms Chace and Dr Soumerai had no relevant personal financial relationships to report.​