In this post I am defining a drug as anything that is taken into the body, by any route (swallowed, absorbed through the skin, injected etc.) that is meant to enhance or change a bodily or mental function. This is a very broad definition that includes pharmaceuticals, herbal products, supplements and homeopathic remedies.

Drugs do their work by interacting with the body on the molecular level. Willow bark and Aspirin have the same active ingredient that inhibits a chemical created in the body when inflammation occurs. The subsequent reduction of inflammation leads to pain relief. There are many other anti-inflammatory drugs (also known as NSAIDS, non-steroidal anti-inflammatory drugs) that work similarly.

Opioids are the world’s oldest and best known painkillers. Originally they were all derived from opium (produced by the poppy) but can now be created in the laboratory. They all work by attaching to cells in the brain and spinal cord, modifying the action of these cells to produce effects.

As understanding of the neurological processes underlying pain has grown, so too has interest in drugs that change them to reduce pain. Drugs that affect neurotransmitters, the chemicals that allow nerve signal transmission from one nerve cell to another, have demonstrable efficacy in treating pain originating in the nervous system itself (e.g. neuropathic pain). Interestingly, these kinds of drug have also been used to treat depression with some degree of success.

The usefulness of dugs lies with their ability to modify chemical and cellular activity involved in the production of pain. Research that clarifies these processes facilitates the development of drugs that target them. But drugs are far from 100% effective, especially in chronic pain. Because they often act on only a single process at a time, other factors in pain production may be unaffected.

Like surgery, drugs are subject to the law of unintended consequences. Surgery can lead to complications. Drugs may have side effects, the topic of the next post.