11 many developing cmintriep, so particular care is called for in selecting antibiotic for use at various levels of the health care system. Countries with high burdens of chronic disase, such as arthritis, epilepsy, diabetes, and hypertension, need to py p. cular attention to the costs of drugp used, since treatment for these conuitions is lifelong and inevitably costly.

In addition to the decision as to which essential drug is to be recommenccd as the first line drug for a given condition, there is also the decision as to whether ion-essential drugs will be used, and if so, under what conditionLs One author conduded in TIailand that while enough money was spent on drug, the actual consumption of needed drugs was in most cases below 15% of the requirement, while more expensive items, indu4ing analgeias, diuretics, tranquilizers, hormones, and antibiotics, were 'viy-and posibly wildly-overconsumed.' Between 1969 and 1976, the annual growth of consumption of psychotherapeutics and diuretics were 189% and 154% respectively. (Sepuhteda-Alvarez, 1985). In the Yemen Arab Republic between **1993** and 1987, as much as 20% of the drugs budpet was spent on drio4 human plasma and albumin injection, which are not consdered to be vital drugs. (Van Haperen, 1988) Clearly much can be done to improve decision-making about which drugs should be purchased St -n the overa scarcity of resources.

After the decision has been made as to which drugs are needed, the nr cual question cncerns the quanw:. of each drug which will be required over a gien perod, usually a year. While it may seem diMcult to amve at a **good** estimte, methods have now been developed to make use of available morbWity data and appropriate treatment scheduls in arriving **at** a workable timate. (WHO, 1988a) Such estimates can be invaluable in procurement, and can help a country to avoid such anomalies as have been reported, such as the order of 46 years' worth of consumption of a drug by a corrupt officiaL (Yudkin, 1978) However, such estimates are only as good as the morbidity data on which they are based, and the linking of the data with the provision of drugs could proVide an incentive to health staff to improve the quantity of the data they provide.

Excessive stock levels of low priority drugs tie up needed funds and run the risk of expiring unused. Surprisingly, in view of the overall scarcity which prevails, expiration of drugs is a major problem in many low-income countrieS. In Mauritania, the drug supply authorities estimated that Slm worth of expired drugs were on the shelves of the governmeut drug supply organization. On the assumption that this had accumulated over, say, 4 yeas, this mens an annual wastage of S250,000. In 1986, the government drup budget was S1m, so the value of the expired drugs represented about 25% of the totaL (WHO, 1986) In Liberia, of 318 drugs on the shelves, 44 were expired or unusabl. On the assumption that their average value was roughly equivalent, the wastage due to expiration was on the order of 15%. (Managcment Ssiences for Health, 1984) Similarly, in Ghana, a World Bank-funded quantification of drug **needs** for the public sector, based on morbidity, was recently carried out by