A major pillar of congressional efforts to rein in opioid abuse is giving out an overdose antidote to first responders, but two senators are raising concerns about price and access.

Sens. Susan Collins, R-Maine, and Claire McCaskill, D-Mo., wrote to five manufacturers of naloxone on Friday to ask what the drug companies are doing to preserve access to the generic product. Collins and McCaskill head the Senate Special Committee on Aging, which has been investigating high generic drug prices.