The co-payment is increasing to $500 per year from $250, but the $9.05 seniors pay for each prescription won't change.
Health Minister Madeleine Dube says the increase is needed to maintain a program that has more than doubled in cost over the last 10 years to $188 million.
The government estimates the change will save $3 million per year and will affect less than half the 48,000 seniors who take part in the prescription drug payment program.
Only those receiving more than 28 prescriptions per year and reaching their current $250 maximum will be affected.
Dube is encouraging seniors to examine all of their options in reducing their drug costs, including purchasing a 90-day supply of some drugs instead of a 30-day supply.
But the Opposition says the Alward government is showing disrespect to the seniors in the province.
Liberal health critic Bill Fraser says many seniors on low incomes will be forced to decide between buying their prescriptions and heating their homes or putting food on the table.