Dr Jonathan Quick, WHO

The first model list of essential drugs, produced by WHO in 1977, has been considered a public health revolution. Right now, 160 countries have their own model list of essential drugs, most of which have been updated within the past five years. On average, there are about 400 drugs per list in low-income countries, about 600 in middleincome countries and about 1200 in high-income countries. Well over 100 countries have developed clinical guidelines that bring the essential drugs list to clinicians and link it with supply systems. Over 100 countries have developed national drug policies.

Generally, WHO updates its model essential drugs list every 2 years. In 2000-2001, WHO undertook an extensive review of the approach, and revised the definition of essential medicines. Essential medicines are defined as those that satisfy the priority health care needs of the population. They are selected with due regard to public health relevance, evidence on efficacy and safety, and comparative costeffectiveness. Essential medicines are intended to be available within the context of functioning health systems at all times in adequate amounts, in the appropriate dosage forms, with assured quality and adequate information, and at a price that the individual and the community can afford. The essential drug concept is intended to be flexible and adaptable to different situations. Hence defining which drugs are essential in a given context remains a national responsibility.

WHO has established a library on essential medicines, which brings together information from various partners. WHO has worked closely with the Cochrane Collaboration to obtain comparative data, cost data, statistics and information on adverse drug reactions. Moreover, in collaboration with the British National Formulary, WHO has developed a model formulary.

Drug regulators have a vital role to play in improving the accessibility of drugs. Consideration should be given to rational selection of essential drugs, affordable prices, sustainable financing and reliable systems.

• Rational selection - information on comparative efficacy, safety and cost-effectiveness should be considered.

• Affordable prices - high levels of generic drug use should be promoted. This requires a combination of factors such as supportive legislation and regulation, reliable quality assurance capacity, professional and public acceptance, and economic incentives.

In conclusion, much has been achieved by WHO in the past 25 years. The essential medicines concept remains a strong public health tool. Drug regulators have a vital role to play in improving drug accessibility, particularly in promoting the rational selection of essential drugs at affordable prices.