The sharp drop-off in FDA warning letters for lies and misleading statements in ads in recent years, comes amid a 62 percent increase in direct-to-consumer ad spending by pharmaceutical companies, according to the New York Daily News, which first reported the record low.
Drugmakers now spend more than $6 billion annually on such ads.
In 2013, the FDA issued 24 warning letters to drugmakers, the Daily News reported. That fell to nine in 2014, with that same number again in 2015.
Last year, the drug regulatory agency sent out 11 letters.
But until mid-November of this year, the FDA had sent out just two warning letters.
The FDA warned Orexigen that the ad was misleading because it "fails to include important risk information associated with the drug," such as listing multiple conditions for which Contrave is contraindicated.
The second warning letter was sent in August to Cipher Pharmaceuticals for an ad for its extended-release opioid ConZip. The FDA said the ad had left out "important risk information associated with the use of ConZip and omits other material facts."
On Nov. 14, the FDA sent Amherst Pharmaceuticals a warning related to a webpage promoting the insomnia-treating medication Zolpimist.
"Both the webpage and the exhibit panels ... fail to communicate any risk information," the FDA said in its letter.
The agency went on to say the omission could "create a misleading impression about the drug's safety," which is "especially problematic from a public health perspective given the serious and potentially life-threatening risks associated with the drug."
In its story about the record low number of warning letters, the Daily News quoted a former FDA official who said the agency's Office of Prescription Drug Promotion — which monitors drug ads — is "a very, very small unit" that has "historically been underfunded."
CNBC asked the FDA about the report, and whether agency officials have been told to pull back on issuing warning letters this year.
FDA spokeswoman Stephanie Caccomo, in an emailed statement, said "Staff have not been instructed to avoid or reduce the number of enforcement letters issued to companies."
Caccomo added, "Issuing warning letters is just one component of the FDA's multi-faceted program" for overseeing promotion of medical products.
She said the agency uses "a risk-based approach to carefully allocate its resources among these activities to have the greatest beneficial public health impact."
"Therefore, one cannot get a complete picture of the FDA's program area by looking at a snapshot of time for warning letters," Caccomo said. "Reviewing the number of warning letters that the FDA issues on a particular topic within a year timeframe does not take into account the work that the FDA does on the other priorities to assist companies with compliance, such as policy and guidance development and core launch reviews, to fulfill its public health mission."