Cost is obviously an important consideration in deciding whether to use a drug. So each evaluation should routinely include a price comparison for the new product and the existing alternatives. However, the influence on the choice of drug should come only when the clinical value (efficacy, safety and convenience) of the product has been established relative to standard therapies.

In general, new classes of drugs are far more expensive than the standard classical drugs. There are many examples of this: antihistamines (sedative versus less sedative); antidepressants (tricyclic versus SSRI), anti-allergics (inhaled steroid versus leukotriene receptor antagonist), antihypertensives (diuretics versus angiotensin receptor inhibitors). But very often, the higher cost is not accompanied by any significant advantage in terms of therapeutic value. And there is always the possibility that a new drug is harmful and less effective but only more expensive than the standard drugs.

Figure 8.1 Comparative price per month of antihypertensive drugs (in Japan)

When several new drugs from the same class (e.g. less-sedative antihistamines, statins, leukotriene receptor antagonists, angiotensin receptor inhibitors) become available (so-called ‘me-toos’), it is often the case that there is little difference between the drugs in the same chemical group.

Costs comparisons can be shown in various ways. Illustrated below are examples of the use of bar charts (Figures 8.1, 8.2 and 8.3) and a table (Table 8.1).