Adalimumab; The costs for certain widely used medicines continue to rise in the United States; but even amid competition from similar products, according to a new study. The results run contrary to normal expectations about market forces on prices. “That was one of the more disheartening findings” of the study, said lead author Nathan E. Wineinger, PhD, from Scripps Research in La Jolla, California.

In an article published today in JAMA Network Open, Wineinger and his coauthors said they found; “highly synchronized” relative cost changes for blockbuster drugs in well-established categories; insulin for diabetes and tumor necrosis factor inhibitors for rheumatoid arthritis.

The median monthly cost of the rheumatoid arthritis drug adalimumab (Humira, AbbVie) rose 124%; from $1940 in January 2012 to $4338 in December 2017; while the cost of a similar drug etanercept (Enbrel, Pfizer), increased 133%, from $1862 to $4334 in the same period.

Fast-acting forms of insulin

Meanwhile, the monthly cost of two fast-acting forms of insulin also more than doubled between 2012 and 2017. The median total monthly cost for Humalog from Eli Lilly rose from $126 to $274; while that of NovoLog from Novo Nordisk rose from $244 to $532. “Such seeming coordination coinciding with high price increases is particularly worrisome,” Wineinger and colleagues write.

These price increases continued well after the drugs reached the market. Two of the initial Food and Drug Administration (FDA) approvals for these drugs date to the 20th century; Humalog in 1996 and Enbrel in 1998. The FDA then approved NovoLog in 2000 and Humira in 2002, according to the agency’s website.

The pattern of persistently rising costs for well-established products was seen with other products in the study, the researchers said. Of the 36 drugs studied that have been available since 2012, 28 (78%) showed an increase in insurer and out-of-pocket costs of more than 50%. Sixteen (44%) of these medicines have more than doubled in price.

Top-selling branded drugs: Adalimumab

“We did not find evidence that products that entered the market 3 to 6 years ago have different trends compared with other drugs in the first years of availability. This finding, along with the consistent, once- or twice-a-year price increases of most drugs we examined, implies that this cycle will persist throughout the lifetime of a drug in the current, private pharmaceutical insurance market,” the authors write.

Wineinger and his coauthors focused on 49 top-selling branded drugs, restricting their analysis to drugs that exceeded $500 million in US sales or $1 billion in worldwide sales. They used Blue Cross Blue Shield pharmacy claims data from January 1, 2012, through December 31, 2017.

They note that a limitation of their analysis is the lack of information on how rebates affect net pharmaceutical prices. About 16% of spending by private insurers on branded drugs was returned as rebates in 2016, according to previous data. Yet there is variation in how these discounts are applied, depending on the drug and insurer. Moreover, the rebates cannot be linked to individual claims, Wineinger and colleagues write.