The cost of drugs will be cut in 50 countries
The new chief executive of pharmaceutical giant GlaxoSmithKline had said the company will cut prices for its drugs in the developing world.
Andrew Witty said GSK would cut the cost of drugs in the 50 poorest nations to 25% of price in the UK and US.
He also said the firm would share knowledge of patents and reinvest profits in local clinics.
Charities have long campaigned for such a policy as patents prevent cheaper generic versions of drugs.
Mr Witty told the Guardian newspaper drugs companies had a duty to help the poor.
He said: "We work like crazy to come up with the next great medicine, knowing that it's likely to get used an awful lot in developed countries, but we could do something for developing countries.
"Are we working as hard on that? I want to be able to say yes we are, and that's what this is all about - trying to make sure we are even-handed in terms of our efforts to find solutions not just for developed but for developing countries."
Formulas and processes owned by GSK under patent will be shared with researchers and 20% of the firm's profits in the developing world will be reinvested in hospitals and clinics there.
Health campaigners have said more needed to be done but they welcomed the initiative.
Oxfam said an affordable HIV treatment, for instance, could stop 6,000 people dying every day in countries affected by the HIV/Aids epidemic.
Charity World Vision's director of advocacy Mike French said: "Slashing drug prices is good. But without the necessary health infrastructure many won't be able to access those drugs. Therefore, investment by GSK, along with the knowledge pooling, make this a landmark announcement.
"This is a gutsy move in a commercial world. Witty has demonstrated a willingness to make saving lives a business goal along with making money."