A RATIONAL BASIS FOR SELECTION AMONG DRUGS OF THE SAME CLASS
- Correspondence to:
Professor Morris Brown, Clinical Pharmacology Unit, Level 6, ACCI, Addenbrookes Hospital, Box 110, Cambridge CB2 2QQ, UK;
Much of medicine is concerned with choosing the right treatment, and cardiologists have done well in recent years to ensure the choice is supported by good evidence. However, the greatest choice often starts where the evidence finishes—namely between drugs of the same class. This article seeks therefore to offer the principles which govern when and how it is appropriate to differentiate drugs within a class, and discuss topical examples among the drugs commonly used in cardiology.
The parameters which can reasonably be compared between drugs are shown in table 1. If this were all, it might be possible to devise semi-automatic algorithms to calculate which drug(s) have the highest score for any given indication. However, the relatively factual answers that could be filled in each cell of the table for a given drug are only part of the decision making process, and more judgemental are: (1) the strength of evidence for each of the answers; and (2) the second order issues of how to compare, for example, one drug of apparently superior efficacy with another which is better tolerated. Compliance is sometimes cited as a reason for choosing one drug rather than another; compliance is not itself a property of the drug, but a composite phenomenon reflecting the interplay between efficacy, tolerability, frequency or route of administration, and cost. Particularly contentious are questions of cost effectiveness. For example, the quality of the evidence for effectiveness may vary between drugs; or the cost of two drugs may be differentially influenced by factors like laboratory tests or number of visits, where savings can seem more virtual than real.
In this article I shall address some of the controversies regarding choice of drugs from commonly used classes in cardiology: angiotensin converting enzyme (ACE) inhibitors, statins, and β …