A single-payer system would certainly be the simplest way to have the federal government serve the same coordinating role as it does in other areas of health care. That would still mean that provinces have jurisdictions and are responsible for the delivery of health care, including prescription drugs.
There are other options. We have a patchwork system; we can have more patches. That would probably marginally improve the situation. In Quebec, there's been mandatory insurance, which is subsidized.
There are different ways of getting there, but I think we should and probably do all agree that children should be able to get the drugs they need and not have to face cost barriers.