by Jeffrey Ventimiglia and Amir H. Kalali, MD
Mr. Ventimiglia is Analyst, Strategy and Solutions, Global Customer Management, Quintiles, Inc., Durham, North Carolina; Dr. Kalali is Vice President, Global Therapeutic Group Leader CNS, Quintiles, Inc., and Professor of Psychiatry, University of California, San Diego, California.

Psychiatry (Edgemont) 2010;7(6):9–11

Funding: There was no funding for the development and writing of this article.

Financial Disclosures:
Dr. Kalali and Mr. Ventimiglia report no conflicts of interest relevant to the content of this paper.

Key words: antidepressant, generic, trade, brand, generic penetration, Zoloft, Celexa, prescription, psychiatrists


In this article, we explore the accelerated penetration of generic antidepressants in the United States market following the availability of generic citalopram and sertraline. Analysis suggests that overall, generic penetration into the antidepressant market has grown from approximately 41 percent in January 2004 to over 73 percent in January 2010. Similar trends are uncovered when branded and generic prescriptions are analyzed by specialty.


It has been just over three and a half years since generic sertraline entered the antidepressant market, and over five years since generic citalopram became available. In this Trend Watch, we investigated the use of branded versus generic agents in the retail antidepressant market to understand generic penetration in the market overall and by physician specialty.


We analyzed monthly retail pharmacy prescription data from SDI Health, which captures over two billion prescriptions per year. This data set includes prescriptions from a variety of retail sources (e.g., national retail chains, mass merchandisers) from a near-census of pharmacies in the United States. The database captures information from all payer types, including cash.


Prescription data suggests that between January 2004 and January 2010, monthly retail antidepressant prescriptions grew by 11.4 percent. Figure 1 shows that at the beginning of this timeframe, only 41 percent of prescriptions in the retail antidepressant market were for generic products. Between October 2004 and April 2005, generic penetration grew from 43.5 to 51.1 percent—a direct result of the availability of generic citalopram beginning in October 2004. However, Pfizer’s Zoloft® continued to maintain strong sales, and, after conversion to generic, citalopram caused a quick increase in the generic share of the antidepressant market. Subsequently, the retail market stabilized and branded agents represented approximately 50 percent of prescriptions for the following 14 months. In June 2006, however, generic sertraline was introduced to the market, and by September 2006, the generic share of antidepressant prescriptions increased from 49.2 to 61.3 percent. Generic penetration continued to grow over the next three years, fueled by a growing number of generic alternatives available in the United States antidepressant market. As of January 2010, generic products represented 73.1 percent of all antidepressant prescriptions.

We compared prescriptions for branded versus generic antidepressants by specialty and found that, like the overall market, there was an increase in generic penetration between October 2004 and April 2005, and, again, starting in June of 2006, within psychiatrists, primary care physicians (PCPs), and a grouping of all other specialties writing antidepressant prescriptions (Figure 2). As seen in Figure 2, generic penetration trends are similar within the major specialties. While the overall trend of increased generic penetration within each specialty group mirrored the overall market, it is interesting to note that from January 2004 to January 2010 psychiatrists have maintained a slightly lower mix of generic prescriptions than other specialists.