Why generic prices fall as competitors enter

In August 2016, retail pharmacies paid an average of $6.99 for a single generic 10 mg rosuvastatin tablet, according to the federal government's monthly survey of pharmacy invoices. The next month the survey put the figure at 41 cents. By October 2026 it was under 4 cents.

The timing lines up with FDA's approval records. Drugs@FDA data⁸ show one rosuvastatin generic application approved on April 29, 2016, eight more on July 19, 2016, and six more on Oct. 31, 2016. A single competitor barely moved the price. A crowd of them collapsed it.

That pattern, a modest first drop followed by a steep slide as more makers arrive, is the central fact of generic drug pricing. FDA measured it across 181 products in a December 2019 study¹, and the numbers explain both why generics save so much money and why some generic markets become fragile. GxRadar tracks the result for 47 drugs on our price pages.

FDA's study of 181 products

FDA economists looked at products that saw their first generic entry between January 2015 and December 2017, covering 711 generic drug codes and 3,688 product-months. They compared each generic price with the brand price before generics arrived, using two measures. One was the average manufacturer price (AMP), which manufacturers report to CMS for the Medicaid rebate program and which reflects what they receive for drugs sold to retail pharmacies. The other was invoice prices from a commercial national sales dataset, which reflect what wholesalers bill pharmacies and so include wholesaler markups.

The table shows the median generic price as a share of the pre-entry brand price, and the reduction that implies (one minus the ratio), as reported in FDA's study¹:

Across all observations, the median generic price was 40 percent of the brand price on the AMP measure and 49 percent on the invoice measure. Most observations, 61 percent, came from markets with only one or two generic makers, which is why the overall median sits well above the figures for six or more.

Why the first generic barely dents the price

A lone generic maker has one rival, the brand. It can price somewhat below the brand and still win a large share of prescriptions, because pharmacies and plans generally prefer a generic once one exists. There is little pressure to cut deeper.

Federal law can also give the first generic a head start. Under 21 U.S.C. 355(j)⁶, the first company to file a qualifying patent challenge can earn 180 days of exclusivity before other generics are approved, a mechanism explained in our piece on 180-day exclusivity. During that window a market often has just the brand and one generic, which fits the 30 to 39 percent reduction in the first row of the table.

What happens when the second, third and fourth makers arrive

FDA rates approved generics as therapeutically equivalent to the brand, so one maker's version can stand in for another's. Wholesalers and large pharmacy buyers can switch suppliers on price alone. With several suppliers, each competes for the same big contracts, and losing one can mean losing most of the volume. Bids drift toward the cost of making the drug.

In FDA's data, moving from one maker to two takes the AMP-based reduction from 39 percent to 54 percent. By four makers it reaches 79 percent. Past six, prices settle at a few percent of the old brand price.

GxRadar's NADAC files show the same curve in real time for two drugs whose generics launched within our data window; our piece on rosuvastatin, duloxetine and tadalafil follows each launch month by month.

Figures are GxRadar's monthly values from CMS NADAC files⁷, generic rows only, for rosuvastatin and tadalafil. For tadalafil, Drugs@FDA⁸ records seven tadalafil generic approvals on Feb. 5, 2019, and a larger batch on March 26, 2019, across strengths. Approval dates are not launch dates, since patents and settlements can hold a product off the market, and NADAC lags purchases by about two months.

Why the two FDA measures differ

Reductions are larger on the AMP measure than on invoice prices at almost every step. FDA traced most of the gap to wholesaler markups, which are proportionally larger on cheap generics. The study cites published estimates of average wholesale markups of 19 percent on generics and 1 percent on brands. After adjusting for them, the invoice-based median ratio of 41.6 percent came close to the AMP-based median of 40 percent, FDA found¹. How those layers stack up is covered in how pharmacies get paid.

The same pattern in other federal data

A 2016 Government Accountability Office report⁴ on Medicare Part D found that prices for a basket of newly billed generic drugs fell about 54 percent from the first quarter of 2010 to the first quarter of 2011, compared with a decline of less than 10 percent for established drugs over the same period.

FDA now publishes yearly estimates of what new approvals save, listed on its generic competition and drug prices page². For the 773 generic applications fully approved in 2023, it estimated net savings of $18.6 billion in the 12 months after approval. First generics accounted for $2.4 billion of that, or 13 percent, and later entrants for the remaining $16.2 billion, the 2023 savings report said³.

Congress has also targeted markets where competition is thin. The FDA Reauthorization Act of 2017 created the Competitive Generic Therapy pathway for drugs with "inadequate generic competition," defined as not more than one approved drug in the active section of the Orange Book. The first approved applicant can earn 180 days of exclusivity if it starts marketing within 75 days of approval, according to FDA's 2022 guidance⁵. Our explainer on competitive generic therapy has the details.

Limits of the data

FDA's study is a price study, and it says so. It covers only drugs sold through retail pharmacies, since AMP data cover only those. It does not capture rebates paid to health plans or pharmacy benefit managers, and it does not look at what patients pay at the counter. It also notes that very low prices may be linked to shortages, a topic FDA analyzed separately in its 2019 shortage report⁹ and that our explainer on why drug shortages happen covers.

That last point runs the other way, too. When the number of makers shrinks, the curve can reverse, as it did in the generic price spikes of 2013 to 2015.