Drug-making giant Johnson & Johnson will officially start marketing four of its medications on the Trump administration's TrumpRx website on Friday, CBS News exclusively learned. 

The pharmaceutical company announced in January that it had entered into a voluntary agreement with the Trump administration to lower costs for Americans by providing Medicaid access to affordable prescriptions and marketing its drugs on TrumpRx in exchange for exemption from the president's tariff agenda. 

One of the drugs offered on White House's discounted pharmaceutical site is metformin, a popular prescription to treat Type 2 diabetes. 

Johnson & Johnson previously agreed to invest $55 billion in research and production sites in Pennsylvania and North Carolina. 

The addition of Johnson & Johnson pharmaceuticals to the TrumpRx site means the administration has more than doubled the number of drugs featured on the low-cost site. 

The prescription drug prices on the site, however, are only available to patients who are uninsured, or whose insurance doesn't cover it, and who must pay the full list price out of pocket. Those with insurance coverage generally pay lower prices already.

This is a developing story and will be updated.