AstraZeneca Plc (AZN  ), Bristol Myers Squibb & Co (BMY  ), and Boehringer Ingelheim are willing to participate in the initial round of Medicare drug price negotiations despite having previously sued to halt the process.

Among the first ten drugs selected for price negotiations with Medicare are AstraZeneca's Type 2 diabetes drug, Farxiga, Boehringer Ingelheim's diabetes medication, Jardiance, and Bristol Myers Squibb's blood thinner, Eliquis.

These three companies are the first to signal their compliance with the negotiations, marking a significant development in the ongoing effort to curb the escalating costs of prescription medications for elderly Americans.

The manufacturers of the other seven selected drugs have until 1 October to agree to participate.

"We remain committed to ensuring patients have access to FARXIGA and plan to participate in the process outlined by CMS to communicate the value of FARXIGA to people covered by Medicare," AstraZeneca said in a statement to CNBC, referencing the Centers for Medicare and Medicaid Services.

Several pharmaceutical companies, including Bristol Myers, AstraZeneca, Boehringer Ingelheim, Johnson & Johnson (JNJ  ), and Merck & Co Inc (MRK  ), have filed multiple lawsuits challenging the constitutionality of these negotiations.

The Inflation Reduction Act, passed by Congress last year, granted Medicare the authority to negotiate drug prices for the first time in the program's history. The negotiations are set to continue until August 2024.