Psychotropic drugs

The interaction between the cognitive component (the perception of nociceptive, or painful stimuli) and the affective component of pain is reflected in the overlap between the actions of anti-nociceptive agents (analgesics) and mood-altering drugs (psychotropics) when treating pain patients. Anxiety, depression, fear and sleeplessness may all respond to psychotropic drugs, and this may result in a reduction in pain or a greater ability to cope with it. This may enable a patient's pain to be controlled with a smaller dose of analgesic. In this sense psychotropic drugs have an 'analgesic' effect but it is a misleading use of the word, and has been the source of much misunderstanding. In the day-to-day management of pain problems the two groups of drugs do have well-defined indications. Acute pain is invariably associated with nociception, and responds to analgesics or other antinociceptive treatments. Chronic pain (except that due to cancer or arthritis) is rarely associated with an identifiable nociceptive stimulus and frequently does not respond to simple antinociceptive measures. Psychotropic drugs (Table 1) play an important part in the management of chronic pain. Cancer pain is a special case. Loeser (1980) and others have proposed that chronic cancer pain should be characterized as long-standing acute pain because it is associated with a continuous nociceptive input and responds better to antinociceptive measures. Psychotropic drugs have a lesser part to ptay in cancer pain than in other types of chronic pain (Hanks, 1984).