The heartburn drug Nexium — whose advertisements have long been ubiquitous on television — was prescribed to 1.5 million Medicare patients in 2013, for a total cost of more than $2.5 billion, the largest amount spent on any drug prescribed through the government program, according to data released by Medicare officials Thursday.

The data was the most detailed breakdown ever provided by government officials about the prescription claims of Medicare beneficiaries. It included information about 36 million patients, 1 million prescribers and $103 billion in spending on drugs under the program’s Part D in the year 2013, the most recent year available. The data did not take into account rebates that the drug manufacturers pay to the insurers that operate the Medicare beneficiaries’ drug plans.

Although the government has previously released similar data to outside entities — including ProPublica, the nonprofit news group — officials said they decided to make the information available on a public website to encourage experts to weigh in, potentially leading to new solutions for policy challenges, like how to contain costs.

“We know that there are many, many smart minds in this country,” Sean Cavanaugh, a deputy administrator at the Centers for Medicare and Medicaid Services, said in a conference call with reporters Thursday. “We are excited to unleash those minds and see what they can find in our data.”

The list of the most-prescribed drugs included less expensive generics to treat common conditions such as high blood pressure, cholesterol and diabetes. And almost all of the drugs that accounted for the most in spending — Nexium was followed by the asthma treatment Advair Diskus and Crestor, a cholesterol drug — were used in the treatment of common conditions. One exception was the cancer drug Revlimid, the 10th-costliest drug, which was prescribed to 24,600 patients but cost nearly $1.35 billion.

Some of the costliest drugs in 2013 are now available as less expensive generics, or will be available soon. Nexium, for example, lost its patent protection in 2014 and is now available as a generic; Pfizer, which bought the rights to sell Nexium from AstraZeneca, also sells an over-the-counter version.

Nexium treats a reflux condition known as gastroesophageal reflux disease, or GERD, leading Niall Brennan, Medicare’s chief data officer, to quip on Twitter: “One nation under GERD?”

In some ways, 2013 “was a year of relative calm,” David Whitrap, a spokesman for the pharmacy benefits manager Express Scripts, which handles the prescription claims of millions of Medicare beneficiaries, said in an email Thursday. His company’s analysis of a representative sample of its members showed that total drug spending in Medicare rose 2.6 percent in 2013. A year later, in 2014, spending jumped 13.8 percent, mainly owing to the arrival on the market of high-priced medications to treat hepatitis C.

Several health care experts said they were intrigued by Medicare’s analysis showing a wide geographic variation in the use of generic drugs by Medicare beneficiaries. In some areas of the country, including Texas, the South and the Northeast, use of generic drugs was relatively low, accounting for between 65 and 76 percent of prescriptions. Other regions, including the Midwest and Northwest, used generic drugs far more frequently.