The indicators and methods presented in this manual have been extensively reviewed and field tested in many developing countries. However, some unanswered questions remain regarding the implementation of the methodologies in different health environments, and the long-term usefulness of some of the indicators and recommended approaches. It is planned that the indicators in this manual will be developed further as additional field experience with their use is accumulated. It is only when the indicators are actually used by different people in different countries that they can be refined and fully validated.

The WHO Action Programme on Essential Drugs invites any reports on experiences in using these indicators, and comments on practical problems in implementation and analysis. In addition, it would be most valuable to have descriptions of second-level questions addressed after an initial drug use study has been completed, and of actions implemented to improve observed drug use problems. These experiences will be collected by the Action Programme and included in any future revision of this manual. Please send comments and reports to the Action Programme on Essential Drugs, World Health Organization, 1211 Geneva 27, Switzerland.