Understanding Chronic Pain

Drugs for Pain

[From Chapter 5 of Understanding Chronic Pain]

The drugs useful for pain are vast in number and variety, but they can be conveniently divided into groupings. Some are identified by a common chemical structure and others by a common mode of biochemical action. The most widely used grouping, however, is based on clinical indications, that is, which drug for which disease. Thus there are antidepressant, anticonvulsant (anti-epileptic), antipsychotic (anti-schizophrenic), and anxiolytic (anti-anxiety) drugs. The reader will be advised that the classification of drugs according to their clinical indication is highly arbitrary. The great majority of pharmaceuticals, and this will surely be evident in the pages which follow, have multiple indications. Most are effective in the treatment of many different diseases.

The most commonly used drugs for the treatment of chronic pain are known collectively as analgesic (anti-pain) drugs. They may be subdivided, in a manner which the expert reader will recognize as somewhat simplistic, into two subgroups. One consists of agents which relieve pain by diminishing inflammation, the body's response to injury. Aspirin and Tylenol are familiar to everyone. Their mode of action is the relief of inflammation. They work at the site of injury by diminishing the release of chemicals which incite the peripheral nerves to send the message of pain to the brain. Similar drugs, and of more recent development, are known as non-steroidal anti-inflammatory drugs (NSAID). These agents imitate the action of cortisone, a drug supreme in the treatment of inflammation, but they lack that drug's steroidal chemical configuration. They also lack at least some of the disturbing side effects of cortisone, and they are the most effective drugs available for the treatment of everyday pains.

The second group, the true analgesic drugs, has little if any antiinflammatory activity. They do their work not at the site of the injury but within the brain where they alter the transmission of the painful signal. The lowest order of analgesic drugs is identified, for lack of a better word, as opiate-like. Among them are Darvon, Nubain, Stadol, and Ultram. They are not true opiates for they lack that chemical configuration, but nonetheless they stimulate opiate (endorphin) receptors and thereby diminish pain. They are all synthetically derived. Their development was the product of the quest to find the perfect drug, a non-addictive pain killer. Unfortunately, all of them carry the silent partner of agents which stimulate the endorphin system, the risk of addiction. The next order of drugs on the scale of potency are the true opiates, Codeine, Hydrocodone, Oxycodone, and Methadone (yes, the same Methadone that is used in the treatment of heroin addiction, but also an effective analgesic and probably under-used). They are usually given orally, and they are very effective in the relief of moderate to severe pain such as occurs post-operatively or with shingles or a fracture. They are often combined in a treatment form known as polypharmacy with other drugs in order to increase their effectiveness. Darvocet, Lorcet, Percocet, and most recently, Ultracet are combinations of opiate and opiate-like drugs with Tylenol. The suffix, -cet, derives from Acetaminophen, the generic name for Tylenol.

You can read the rest in Dr. Cochran's book, Understanding Chronic Pain

Last Updated: Nov 19, 08:11 AM

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