Newer analgesics: with special reference to pentazocine.

The problem of pain relief is one that faces every doctor. Indeed as Sir Hugh Cairns (1949) told medical students in an inaugural address at King's College some twenty years ago, 'Tour patients need from you more than diagnostic and therapeutic efficiency. They do not come to you to be cured; they come to be relieved of their pains and other symptoms, and to be comforted." There can be no doubt that Sir Hugh deliberately specified pain because this symptom more than any other drives the patient to seek his doctor's help. But the difficulties involved in providing such help should not be underestimated. The oldest and the best known analgesic is opium; for centuries the crushed seeds of the poppy have provided pain relief unsurpassed by any other drug and there are many today who still regard opium, or its purified version morphine, as the best analgesic available. Certainly it is the reference point in the assessment of any new analgesic drug and drugs with an analgesic action like opium are known as "opioids". Morphine relieves pain partly by its influence on mood and this is the cause of the only major drawback to its use, the tendency for patients treated with morphine to develop both a physical and psychic dependence on i t In an attempt to overcome this disadvantage chemists prepared the related compound heroin, and it was some years before it was discovered that this drug had an even greater abuse liability than morphine itself. Many years later the story was repeated when the introduction of pethidine (Demerol) in 1939 led to a marked increase in the number of known drug addicts in many countries.