The issues were thrown into sharp relief in South Africa earlier this year with a court case brought by a group of international drugs companies wanting to stop imports of cheap copies of their medicines.
The World Trade Organisation is due to meet at its Geneva headquarters to discuss the growing controversy over the cost of medicines in the developing world.
Drugs still covered by patents can be prohibitively expensive for patients in poor countries.
Under present rules WTO member countries - except for a few of the poorest ones - must protect the international patents on any products, including new drugs, for 20 years.
This means they have to pay whatever price the manufacturers demand.
The purpose is to allow the companies to recover the very high costs of developing new medicines.
But it means that prices are higher than they would otherwise be and patients in the poorer countries often cannot afford the medication they need.
Aids disease
This is a particular problem in relation to HIV and Aids, a disease which has hit the developing world very hard.
Many medicines for the condition are still relatively new and under patent and therefore expensive.
The issues were thrown into sharp relief in South Africa earlier this year with a court case brought by a group of international drugs companies wanting to stop imports of cheap copies of their medicines.
In the event the companies abandoned their case under pressure of bad publicity.
WTO rules do allow countries to override patent procedures in some circustances such as health emergencies.
But developing countries would like more scope to do so and more certainty about when they can.
Some discussions have already taken place within the WTO. One idea with a lot of support is different pricing arrangements in different countries - high in rich countries, low in poor nations.
The drugs companies already do this in some cases but are concerned about the possibility of the cheap drugs coming back to the rich countries.