Clinical evaluation of mild analgesics.

1 Mild analgesics pose particular problems in evaluation because of difficulty in getting suitable patients, the frequent use of oral administration and their long-term use. 2 Despite their limitations it is possible to quantify both pain severity and pain relief using either 'pain scores' or 'visual analogues'. 3 A trained observer can add information in addition to the patient's interpretation of pain. 4 There are particular problems using crossover studies with analgesics and the sequential method of evaluating results is not as useful with mild analgesics as with more potent drugs. 5 Opinions differ as to the importance of dummy medication in the study of analgesic drugs; difficulties may arise from ethical as well as practical reasons. 6 In the overall evaluation of mild analgesics it is important to consider their long term side effects. 7 Access to a large number of patients with a constant pain of 6-8 h duration and a smaller number with long-term pain is the most important prerequisite in the evaluation of mild analgesic drugs.