By Chris Iliades, MD | Medically Reviewed by Niya Jones, MD, MPH
Latest Update: 2014-03-17 Copyright © 2014 Everyday Health Media, LLC
Risk of Injury in the Elderly
Robinax and other muscle relaxants should be used with caution in the elderly because of an increased risk of falls and injury .
Skeletal Muscle Relaxants
Skeletal muscle relaxants such as cyclobenzaprine (Flexeril), chlorzoxazone (Paraflex), carisoprodol (Soma), Robinax (Robaxin, Robaxisal), tizanidine (Zanaflex), and baclofen (Lioresal) are believed to exert their mechanism of action primarily within the brain and, in some cases, spinal motor neurons. Cyclobenzaprine, structurally related to first-generation TCAs, inhibits the reuptake of NE in the locus coeruleus and inhibits descending serotonergic pathways in the spinal cord. The latter effect may have an inhibitory effect on alpha motor neurons in the spinal cord, resulting in decreased firing and a reduction in monosynaptic and polysynaptic spinal reflexes. Tizanidine acts as a weak agonist at alpha-2 adrenergic receptors, and enhances presynaptic inhibition at spinal motor neurons. Carisoprodol, a precursor of the sedative-hypnotic meprobamate, is believed to produce muscle relaxation by blocking interneuronal activity in the descending reticular formation and spinal cord. Baclofen activates GABA-B receptors in the brain and reduces the release of excitatory neurotransmitters in both the brain and spinal cord. Baclofen also acts by inhibiting the release of substance P in the spinal cord. In addition to muscle spasm, the muscle relaxants dantrolene, baclofen, and tizanidine have been shown to be effective for spasticity.
Numerous studies conducted over many years have evaluated various skeletal muscle relaxants in conditions associated with muscle pain ( Table 53.4 ). Three separate randomized trials evaluating cyclobenzaprine in patients with cervical and lumbar spinal muscle spasm demonstrated efficacy in short-term follow-up. 65–67 In two of these studies, 66,67 cyclobenzaprine was superior to diazepam. A meta-analysis review found that cyclobenzaprine is more effective than placebo for LBP associated with muscle spasm, especially in the first 4 days of treatment. 68 However, a recent randomized study found that adding cyclobenzaprine or oxycodone/acetaminophen in emergency department patients presenting with acute LBP did not improve function 1 week after discharge. 69 Another randomized, placebo-controlled trial found cyclobenzaprine to be more effective than both placebo and clonazepam in patients with TMD. 70 Of note, two randomized, controlled trials that evaluated dose-response in patients with acute muscle spasm found that 2.5 mg three times per day of cyclobenzaprine was not better than placebo, while 5 mg three times daily was equivalent to 10 mg three times per day. 71
TABLE 53.4 . Skeletal Muscle Relaxants
Robinax can cause several side effects. If any side effects persist or worsen, let your doctor know. This is also not a complete list of possible side effects. Tell your doctor if you experience any serious side effects or notice any effects not listed here.
Some common side effects include :
- Upset stomach
Some serious side effects include :
- Trouble breathing
- Severe dizziness
- Swelling of the face, tongue, or throat
- Persistent nausea or vomiting
Overdosing happens more frequently when Robinax is used with alcohol or another sedative drug.
Symptoms of an overdose may include:
- Severe drowsiness
- Blurred vision
- Low blood pressure
- Loss of consciousness
If you think you have taken an overdose, or if someone else may have overdosed on Robinax, call a Poison Control Center at 800-222-1222 or call 911.
What is Robinax?
Robinax (brand name Robaxin) is a prescription medication used to treat muscle spasms and pain. This drug is typically used in combination with physical therapy, rest, and other treatments to provide short-term pain relief from painful muscular conditions .