As MCOs explore opportunities for delivering more cost-effective medical care, prioritization based on drug utilization reviews alone may not adequately highlight those disease states that consume a disproportionate share of overall resource cost; the daily cost of pharmacotherapy may not reflect the overall economic effect. As the elderly proportion of the population grows, the treatment of congestive heart failure may represent for MCOs an increasingly important opportunity to achieve acceptable or even improved outcomes while controlling the costs of hospitalization and other resources. The introduction of new pharmaceuticals presents an ongoing challenge for managed care to determine whether they offer a pharmacoeconomic advantage over current treatment regimens. This paper reports on an economic assessment made between a new and an existing loop diuretic in the treatment of congestive heart failure.