A systematic review led by Doctor Igho J. Onakpoya from Oxford University's Nuffield Department of Primary Health Care Sciences looked at 462 drugs withdrawn between 1953 and 2013. It showed that drugs banned on safety grounds in some countries are still legally available in others. Inconsistent regulation of drugs across the world means that people in developing nations are far less likely to see unsafe medications withdrawn.

Universal guidelines are needed to improve global drug regulation and transparency in adverse drug reactions. Dr Igho J. Onakpoya, Nuffield Department of Primary Health Care Sciences

Harmful drugs stayed on the market for longer in Africa than in any other continent. Of 462 drugs that were withdrawn over a period of 60 years, only 63 drugs were withdrawn in Africa, less than half the number withdrawn in Asia and North America, and a fifth of the number withdrawn in Europe.

Dr Onakpoya said: 'The inconsistencies across countries reflect the lack of a universal framework for dealing with adverse drug reactions and drug withdrawal procedures.

'There is better co-ordination among drug regulators in Asia, Europe, and North and South America than in Africa, but universal guidelines are needed to improve global drug regulation and transparency in adverse drug reactions.'

According to the World Health Organization (WHO), only 4% of African nations have moderately developed drug surveillance systems and 39% lack adequate regulatory capacity. The WHO proposes to establish an African Medicines Agency by 2018 to improve the situation.

The most common reasons for withdrawal of the 462 drugs were liver damage and immune-related reactions, accounting for 30% of withdrawals. Deaths occurred in 25% of cases, and heart or brain related issues were also common.

Only 43 of the drugs were withdrawn worldwide, while 179 were withdrawn in one country only. Most drugs were withdrawn from two or more countries.

Dr Onakpoya said: ‘There were significant delays in withdrawals. It took an average of five years for a drug to be withdrawn after the first reported adverse reaction. This has stayed the same throughout the last 50 years.

He added: ‘It is important to note that withdrawals make up only a small proportion, around 3%, of new drug approvals. However, greater coordination between regulators could improve medicine safety.’