The Pain Medication Maze
By William L. Lippert, M.D., Colorado Springs LIVING WELL Magazine
Patients who suffer from chronic pain are often treated with a variety of medications that can effectively decrease their pain but may carry significant side effects. Patients should have at least a basic understanding of the typical side effects of the most common drugs and drug classes so they can take the medications safely. Many of the medications that are “over the counter,” anti-inflammatories (NSAIDs) and acetaminophen for example, are more familiar to patients. Controlled substances prescribed by physicians will often be selected from several very different drug classes such as narcotics, anticonvulsants, and antidepressants. We will look at some of the most common drug classes used for treating chronic pain and their unique advantages and disadvantages.
The first line of treatment of pain is often acetaminophen (Tylenol) and the anti-inflammatories (aspirin like drugs). Many of these analgesics are available without prescription depending on dose, and are familiar to patients for use with mild pain. These two entities have historically been attractive as readily available, safe, low cost pain relievers. While these two drug classes share both the qualities of mild to moderate analgesics (pain relievers) and antipyretics (fever reducers) they have some striking differences.
Acetaminophen has a small effect on inflammation and therefore would have little direct influence on inflammatory conditions. Acetaminophen is metabolized in the liver and its primary toxic effect is focused at the liver and is the primary cause of acute liver failure in the U.S. This very significant toxicity aside, acetaminophen has very few other problems and hence has a wide range of application to pain. Dosing of acetaminophen therefore should be very carefully monitored and total dose should not exceed 4 grams per day. “APAP” is the abbreviation of the chemical name for acetaminophen. APAP is often combined with narcotics to increase pain-relieving properties and allow decreased dose of narcotic.
Non-steroidal anti-inflammatories (NSAIDs) are aspirin like drugs that reduce pain and inflammation. There are many NSAIDs available, all creating potential problems for the gastrointestinal system and the kidneys. Indigestion (dyspepsia) is very common and is a dose dependent phenomenon. Gastrointestinal (GI) bleeding is also a risk, as up to 1-2% of patients may suffer a GI Bleed and one in 1,200 may die from that bleeding. What has gained significant press lately is the cardiovascular risk associated with non-aspirin NSAIDs. There is a clear connection between myocardial infarction and stroke and the use of NSAIDs. Further, the cardio protective effect of aspirin may be muted or abolished by some NSAIDs.
Opiates (narcotics) have been a mainstay of treating significant pain for literally centuries. They can produce profound pain relief and have historically been used for treating surgical pain, cancer pain, and, in the last decade, severe chronic pain. There are long and short acting narcotics of varied potencies, which are administered by a variety of routes. Common side effects include respiratory depression, nausea, constipation, dizziness, fatigue, and confusion. Tolerance (increasing doses of drugs for similar effect) is very common with narcotic treatment. Addiction (compulsive use of a substance despite its danger) is very uncommon unless there is a history of prior addiction or psychological impairment.
The anticonvulsants are a class of medications that typically are thought of as drugs used to treat seizure disorders. Introduction of two new drugs, Gabapentin (Neurontin) and later Pregabalin (Lyrica), anticonvulsants with fewer side effects, made more routine use possible. With the approval of Neurontin for the treatment of post herpetic neuralgia, the use of anticonvulsants was validated for neuropathic pain treatment. This cleared the way for adding these non-narcotic tools for fighting pain. Interestingly, the pain relieving mechanism for this class is unknown. The most common adverse symptoms with these medications are sedation, dizziness, and occasional peripheral edema. Dosing is typically three to four times per day with a new formulation available for once-per-day dosing.
As a group the antidepressant class has a common mechanism, manipulating neurotransmitters such as serotonin and norepinephrine and thereby changing the course of depression and anxiety. Interestingly, these same neurotransmitters not only affect depression but also can modulate pain. Cymbalta (duloxetine) is approved for not only treatment of depression and anxiety disorder, but also for pain of neuropathy, musculoskeletal pain and fibromyalgia. Nausea and transient dizziness are two of the most common problems with this medication. Cymbalta requires only once per day dosing which offers relative ease of treatment.
Typically, side effects from medications increase as their dose increases. By treating pain with medications from different drug classes, no individual drug dose needs to be elevated such that side effects are magnified. Each of the above medication classes also have unique pain relieving properties allowing them to be tailored to a patient’s personal pain problem. Navigation of the pain medication maze is made easier with a professional medical practitioner leading the way.
William L. Lippert, M.D. is board certified in pain management and anesthesiology. He may be reached at 719-380-7246