Muscle Relaxants
Tight, stiff muscles are common in fibromyalgia. They can feel so tense that you may notice you have hard nodules in them that feel like rocks. Your muscles hurt to touch and radiate pain. This is especially true for those in your shoulders, neck and back because they seldom get a break (except when you are sleeping). Naturally, you would like to take a medication that could loosen up your muscles and lessen your pain.
Medications that might help relax your muscles fall into a variety of drug classes. While tizanidine, baclofen, and metaxalone are classified as muscle relaxants, there are other types of drugs that can help relax your sore muscles. Examples include cyclobenzaprine, a tricyclic antidepressant, along with a couple benzodiazepines (clonazepam and alprazolam).
Despite your desire to find a medication that can ease muscle pain and stiffness, fibromyalgia patients are often disappointed by muscle relaxants. This is because the more potent types of muscle relaxants are equally sedating, e.g., tizanidine, baclofen, and cyclobenzaprine. You don’t want to go through the day feeling hung over, so what can you do?
Three fibromyalgia specialists answer this question: Robert Katz, M.D., a rheumatologist, and researcher, affiliated with Rush University Medical Center in Chicago, IL, Richard Podell, M.D., an internist who was affiliated with UMDNJ-Robert Wood Johnson Medical School, NJ (now retired), and David McLain, M.D., a rheumatologist in Shelby, AL, who has researched the use of tizanidine in fibromyalgia.
Katz: Muscle relaxants do help reduce tenderness and may relax patients or ease their anxiety. I tend to prescribe tizanidine and low dose cyclobenzaprine, and I use them quite often in the treatment of fibromyalgia. I don’t want my patients sedated, but want their muscles relaxed.
I start with very low doses, sometimes half a tablet of the lowest dose, and see how they respond. I like to try to give these medications during the daytime when patients have their greatest amount of pain and muscle tenderness. Muscle relaxants have a transient effect. This means that patients cannot take them at bedtime to reduce morning stiffness eight hours later. They must be on board when the patient has the most amount of pain.
I suspect that this class of medications somehow relaxes the central nervous system a bit and they also have a relaxing effect on the peripheral system (i.e., the muscles). It is somewhat like getting a massage. However, I have never been able to document how much these agents reduce muscle tenderness.
Podell: Some patients find benzodiazepines, cyclobenzaprine or metaxalone useful for reducing muscle pain, stiffness, twitching, and spasms. Two muscle relaxants used in multiple sclerosis to treat muscle spasms, tizanidine and baclofen, are sometimes helpful in fibromyalgia too. The major drawback for daytime use of these medications is sedation, except for metaxalone because it does not affect the central nervous system (it is a peripheral-acting agent but may be less effective for fibromyalgia).
With regards to dosing, I typically begin with 25-50 percent of the usual standard starting dose. Fibromyalgia patients as a group are very sensitive to medication side effects, necessitating that one start low and build up slowly. Otherwise, the initial drug effects are likely to bowl a patient over.
As to why these medications work, we know so little about drug mechanisms that I’ve learned to be quite humble. Some treatments should help in theory but they don’t, and vice versa. More impressively, various drugs act one way in one person and the opposite in others, and it is not just people with fibromyalgia. It is well-known that benzodiazepine/valium-type relaxants cause sedation and relieve anxiety in most people, but produce activation and increased anxiety in a small yet significant subset.
McLain: I use tizanidine to improve the sleep in people with fibromyalgia. Taken at bedtime, it’s sedating and decreases muscle tightness and stiffness. It lasts for about eight hours, so its hypnotic effect should be worn off by morning.
One study in fibromyalgia patients showed tizanidine reduced central nervous system levels of substance P, a transmitter that signals pain. In addition, the drug helps calm the sympathetic nervous system’s hyperactivity known to disrupt fibromyalgia sleep (may also reduce racing thoughts).
I did a study using 2 to 12 mg of tizanidine in a group of fibromyalgia patients and the drug significantly reduced pain, daytime fatigue, and overall function. Common side effects include sedation (desired at night), reduced blood pressure, dizziness, and dry mouth/eyes.
Like most treatments for fibromyalgia, tizanidine is usually used in combination with other medications prescribed in low doses, as this tends to work better.
Side Effects
Putting aside sedation issues, muscle relaxants may have other side effects that you should be aware of:
Cyclobenzaprine causes dry cotton-ball mouth and dry eyes, urinary retention (edema and bloating), vivid dreams (or nightmares), irregular heartbeat, and weight gain. The undesirable side effects usually occur right away, but the benefits of the drug may take up to two weeks (if at all). Starting at the lowest possible dose helps minimize side effects while your body acclimates to this drug, and you may need to wait 1-2 weeks before increasing the dose.
Tizanidine’s effect on blood pressure needs to be emphasized because a subgroup of fibromyalgia patients already has low blood pressure and easily get lightheaded. If you have this symptom, this side effect of tizanidine could be a showstopper for you.
Baclofen may cause dizziness, nausea, and headache. This medication does not stay active in the body for long (only 4 hours), so the need to take frequent doses can be a drawback. One bonus of baclofen (if you can tolerate it), is that it appears to have pain-relieving and anti-seizure qualities in addition to relaxing the muscles.
Clonazepam and alprazolam: Both are benzodiazepines and regulated by the Drug Enforcement Agency (DEA) as schedule IV medications. They can be habit-forming, potentially addictive, and they may also impair cognition. Clonazepam only needs to be taken once a day (typically at bedtime) because it stays active in the body for 24 hours. Alprazolam lasts for 12 hours, so it may need to be taken twice a day.
Metaxalone should not be taken with a long list of drugs (check with your doctor). It also may cause dizziness and stomach/GI upset. On the upside, it is not so sedating to restrict daytime use.