Analgesic drugs and techniques diminish the perception of painful stimuli while causing minimal loss of sensibility to other stimuli. Analgesic drugs include aspirin, acetaminophen, ibuprofen, morphine and other narcotics, general anesthetics in low doses, and local anesthetics. Analgesic techniques include acupuncture, biofeedback, hypnosis, electrical stimulation, and surgical separation of nerve fibers.
Treatment of acute pain is necessary after surgery, dental procedures, muscular strains and sprains, or trauma. Chronic pain requiring therapy may arise following infection, with malignancies, or with nerve irritation or compressionÑfor example, a pinched nerve. Pain may be a symptom of an underlying problem that needs further treatment.
Some of the nonprescription drugs most often used as analgesics are acetylsalicylic acid (aspirin), the drug most commonly taken for the relief of mild pain; acetaminophen (Tylenol), comparable to aspirin in reducing pain and fever but much less effective in alleviating inflammation; ibuprofen (Advil), less irritating to the stomach than aspirin and also acts to reduce inflammation; and naproxen sodium (Aleve), which provides a longer duration of pain relief per dose. All of the above drugs achieve their analgesic effect through inhibition of the synthesis of prostaglandins in the body. Propoxyphene (Darvon), which is effective in relieving mild pain, has been used in the treatment of narcotic addiction. Prescription drugs are used for stronger pain relief. Narcotic analgesics are used only for the treatment of severe pain. Opium, derived from the juice of the poppyseed capsule, has been in use for centuries; codeine, heroin, and morphine are derivatives.
Small amounts of general anesthetics can be used for pain relief without producing unconsciousness. Topical local anesthetics, such as benzocaine (ethylaminobenzoate), are widely used for blocking the transmission of pain signals to the brain from the affected area. A local anesthetic can be injected near nerve fibers to block pain sensation in an entire area of the body.
This procedure is useful for analgesia in treatment of chronic pain and during localized surgery.
Electrical stimulation of large fibers by the placement of electrodes on the skin, in specific nerves, or within the spinal cord has produced analgesia. Hypnosis is a proven method for achieving pain relief in both acute and chronic disorders in some susceptible patients, but the effectiveness of this technique cannot be predicted. Acupuncture, a technique derived from Chinese medicine and involving the insertion of needles into the skin at certain points on the body, is also sometimes successful in producing adequate analgesia for some surgical procedures and for the relief of chronic pain. Biofeedback control has been useful in relieving some forms of chronic pain; the patient learns to modify his or her response to stress through concentration and relaxation.
The placebo effectÑby which patients given a sugar pill experience the same lessening in pain as when given an analgesicÑmust be considered whenever analgesics are compared. Studies show that up to 30 percent of a group of patients will experience some relief of pain when given a dummy pill.
In the early 1970s it was discovered that opiates bind to specific receptors in the brain. Subsequently, naturally occurring compounds called encephalins and endorphins, which bind to the opiate receptors, were isolated from animal brain tissue. As more is learned about these compounds, artificial regulation of their levels may produce effective analgesia.