The principles of the Canada Health Act, particularly as they relate to accessibility, actually forbid there being extra billing or user charges of any kind for what are called “insured services under the act”. The insured services, if you were to add pharmaceuticals, would have to be defined in relation to some sort of national formulary, which would be the minimum package of drugs available to Canadians.
The terms of the act would preclude you from having a copayment on those drugs, and in many cases you probably would want what's again referred to as a value-based copayment that says if the drug is preventative and best value for money in our health system, it's free for patients. If it's more discretionary and perhaps a second- or third-tier drug, value-based formularies internationally might see a patient pay $50 or even $100 for a prescription if it's not a first-line therapy.
The Canada Health Act would preclude you from doing that unless you had specific carve-outs in the act. I don't mean to dissuade you from going down that path in terms of making a recommendation; it's just that you could have a parallel act that had much the same intent, purpose, and outcome as the Canada Health Act, but didn't hold pharmacare to the exact standards of the CHA.