How fast generic prices fell for rosuvastatin, duloxetine and tadalafil

On July 20, 2016, the first week a generic 10 mg rosuvastatin tablet appeared in the federal government's drug cost survey, pharmacies were paying an average of $7.07 per tablet, according to CMS NADAC data². In the weekly file dated Aug. 24, 2016, the figure was 41 cents.

That is a 94 percent drop in five weeks. The same federal files show that generic entry does not always work that quickly. Generic duloxetine took about nine months to make a comparable fall. Generic tadalafil sat near the brand price for half a year before collapsing.

GxRadar analyzed CMS NADAC files from November 2013 through October 2026 for three widely used drugs that went generic during that window, and lined the price series up by months since the first generic NADAC rate. Set against FDA approval dates, the data show that the first generic approval was a poor guide to when the big drop would come. For two of the drugs it came within weeks or months of a batch of additional approvals. For the third it came about nine months after six applications were approved on a single day.

The first 24 months, side by side

Month 0 is the first month with a generic-classified NADAC rate for that drug and strength. Each figure is GxRadar's monthly median of the weekly per-unit rate, from the yearly datasets on data.medicaid.gov for 2014¹, 2016², 2018³ and 2019⁴. Percentages compare each month with month 0.

All three ended their second year more than 90 percent below their first generic price. The paths there were very different. Rosuvastatin fell almost all the way in a single step. Duloxetine slid slowly for half a year and then dropped hard over three months. Tadalafil barely moved for six months, then lost 93 percent of its value between May and July 2019.

Rosuvastatin's nine approvals and one collapse

FDA approved the first generic rosuvastatin on April 29, 2016, according to FDA's Drugs@FDA data⁷. On July 19, 2016, it approved eight more ANDAs covering the 10 mg tablet, all on the same day, GxRadar found in the same records. The next day's NADAC file was the first to carry a generic rate.

Week by week, the files show competitors arriving. The generic rate on July 20 covered two NDCs at $7.07, against a brand rate of $8.12 in the same 2016 file². By Aug. 24 the generic rate covered five NDCs at 41 cents, and by mid-September it covered 10. FDA approved six more ANDAs covering the 10 mg tablet on Oct. 31, 2016. Two years after entry, in July 2018, the tablet cost pharmacies 10.9 cents.

Duloxetine's slow first half-year

Generic duloxetine started with more competition on paper. FDA approved six ANDAs covering the 60 mg delayed-release capsule on Dec. 11, 2013, according to Drugs@FDA records⁷, followed by one more on Dec. 17 and two on Jan. 8, 2014. The first generic NADAC rate appeared in the file dated Feb. 19, 2014, at $5.92 per capsule, while the brand 60 mg capsule carried a rate of $7.13 in the January 2014 files¹.

In its first six months the generic price fell only 17 percent. FDA approved three more ANDAs for the strength in June 2014. The steep part of the decline began in September 2014. The monthly figure went from $4.93 in August to $3.40 in September, $2.07 in October and $1.22 in November. By February 2016, month 24, the capsule cost 49 cents. Our data show the timing. They do not show why the first six months were flat, and we do not assign a cause.

Tadalafil's one approval, then 15 more

FDA approved the first ANDA covering tadalafil 5 mg tablets on May 22, 2018, according to Drugs@FDA. A generic 5 mg NADAC rate first appeared on Dec. 19, 2018, at $8.26, against a brand rate of $10.93 that month in the 2018 files³. Through May 2019 the generic stayed between $7.86 and $8.26.

On March 26, 2019, FDA approved 15 more ANDAs covering the 5 mg tablet in one day, and another three days later, GxRadar counted in the openFDA Drugs@FDA download⁷. The NADAC fell to $4.29 in June 2019 and 52 cents in July, according to the 2019 files⁴. Part of the gap between approval in March and the price drop in June is built into the survey. CMS sends its survey on the first of each month for the previous month's invoices, so June purchases are surveyed in July and published in August, according to a 2017 CMS overview of NADAC operations⁶.

What FDA's research predicts

FDA economists have measured the same relationship across many drugs. In a December 2019 analysis⁸ of products that first went generic from 2015 to 2017, they reported median generic prices, measured with invoice-based wholesale data, relative to the brand price before generic entry.

Rosuvastatin, duloxetine and tadalafil fit that curve. Each had at least nine approved ANDAs for the strength within a year or so of first approval, and each now costs pharmacies more than 95 percent less than its brand did at entry. Our explainer on why generic prices fall as competitors enter covers the economics, and the 180-day exclusivity piece explains why a first approval is sometimes followed by months with no second one.

Approval counts come from GxRadar's analysis of FDA's Drugs@FDA data⁷ as of October 2026, counting ANDAs whose original approval included the strength shown. An approval is not proof of sales in a given month. NADAC also leaves out off-invoice discounts and rebates, according to the CMS methodology⁵, and it says nothing about what patients pay.

Full monthly series are on our pages for rosuvastatin, duloxetine and tadalafil. Tadalafil's sister drug is covered in how generic sildenafil 20 mg fell 92 percent. For a drug that went generic before our series begins, see what pharmacies paid for atorvastatin from 2013 to 2026. Our approvals tracker counts ANDA approvals by year, and the radar feed lists the newest ones as FDA posts them, which is where the next of these curves will start.