Health Minister Ted Flemming says premiums will be based on income. (CBC)

New Brunswick's Health minister says premiums for the province's new drug plan will decrease over time.

Ted Flemming was responding to concerns that some people may not be able to afford the premiums once the program becomes mandatory for all New Brunswickers without drug coverage in 2015.

"Premiums go down when the critical mass of participants expands. We have every reason to expect our premiums to go down in the second phase," Flemming told CBC's Information Morning in Saint John.

Premiums will be based on income with no deductible, he said.

The plan is designed to cover prescription drugs for people who don’t have insurance through their employers.

Phase 1 of the plan, which begins on May 1, will be voluntary.

The provincial government is still working out details about how business owners will contribute to the plan, said Flemming.

"Business people have been excluded for the time being until we meet with business leaders and reps to find out and work with them as to the best way they can join," he said.

Flemming estimates it will be at least a year before the plan is in place for businesses.

About 70 per cent of employers in New Brunswick currently offer a drug plan, according to the provincial government.

About 60,000 people are already part of a provincially-subsidized drug program, officials have said.

The province estimates 70,000 families have no drug coverage and are not eligible for existing provincial coverage for people on social assistance.

The plan will cover any prescription drugs that are on the provincial formulary, a list of covered drugs. That list includes some so-called catastrophic drugs like Remicade, but does not include others.