Tizanidine hydrochloride is a commonly prescribed muscle relaxant in the United States. In 2022, it was prescribed nearly 7 million times, according to the US Government Agency for Healthcare Research and Quality's 2023 report.
That makes this medication one of the top 100 prescriptions given in this country. So, what about this particular muscle relaxer makes it such a popular prescription, and what exactly is it used for?
This article examines the clinical uses, mechanisms of action, benefits, side effects, and key considerations of tizanidine hydrochloride.
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What is Tizanidine Hydrochloride?
Tizanidine exerts its muscle relaxant effects primarily by acting as an alpha-2 adrenergic receptor agonist, which reduces excitatory neurotransmitter release in the central nervous system.
Tizanidine primarily affects spinal nerves and is used to manage spasticity. Some research suggests it may also have mild pain-relieving effects.
In addition, because tizanidine hydrochloride works on spinal nerves, it can reduce spasticity and have some pain-relieving (antinociceptive) properties.
Tizanidine agonizes alpha-2 adrenergic receptors, G-protein-coupled receptors that play a critical role in neurotransmitter release and control.
By activating these receptors, tizanidine inhibits the release of excitatory neurotransmitters, thus reducing the hyperactivity in motor neurons.
More specifically, tizanidine hydrochloride binds to alpha-2 adrenergic receptors located in the spinal cord and interrupts the transmission of nerve signals that cause muscle contraction.
Medical Uses of Tizanidine Hydrochloride
Marketed under the brand name Zanaflex, tizanidine was approved by the FDA in 1996 for managing muscle spasticity associated with conditions such as multiple sclerosis and spinal cord injury.
Some research has explored its use for other types of pain, but these applications are not FDA-approved.
Recent research has shown some success in using tizanidine for muscle spasticity resulting from traumatic brain injury (TBI) and stroke.
Some healthcare providers may prescribe tizanidine off-label for conditions such as migraine headaches, insomnia, and as part of anticonvulsant therapy. However, these uses have not been evaluated or approved by the FDA.
Some reports suggest that tizanidine may be used in certain cases of analgesic rebound headaches or during opioid tapering, but these uses are not FDA-approved and should be discussed with a healthcare provider.
Dosage and Administration
With the wide range of conditions for which it is prescribed, tizanidine can have a variety of dosages.
Patients must follow their healthcare provider's instructions precisely, as deviations could result in adverse effects. Tizanidine is available in pill and capsule forms.
Standard adult guidelines for tizanidine are 2 mg every 6-8 hours as needed. A physician can increase the dosage up to:
- Maximum daily dosage: 36 mg
- Maximum single dose: 16 mg
Children should only take this medication under the close watch of a physician.
Patients should take tizanidine only as prescribed and consult their healthcare provider before making any changes to their dosage.
Special population dosage suggestions include:
- Hepatic (liver) impaired: No dosage change has been suggested for those with liver deficiencies. However, tizanidine has the potential to damage the liver, and these patients should be closely monitored. Liver enzymes (AST, ALT) can increase three times normal levels when taking this drug.
- Renal (kidney) impaired: Reduce by more than 50% in elderly patients with renal insufficiency, defined as patients with a creatinine clearance < 25 mL/min. Tizanidine may have longer-lasting effects in this population and should be used with caution.
- Women taking oral contraceptives: Tizanidine effectiveness can drop up to 50% when interacting with oral contraceptives.
How to Take Tizanidine
Here are the guidelines for taking tizanidine:
- With or without food, but patients should be consistent in how they take this medication.
- Taking with food increases the absorption by 20% but slows the time for onset.
- Pills should be taken whole, not crushed.
- Capsules can be opened and sprinkled over food or taken whole.
- Because tizanidine has a relatively rapid onset, patients should follow their prescribed regimen closely to optimize symptom relief.
Side Effects and Safety
As with any medication, tizanidine may have side effects ranging from the most common mild effects to severe and potentially dangerous effects.
Common Side Effects
Common side effects of tizanidine include:
- Dizziness
- Drowsiness
- Muscle weakness
- Nervousness
- Depression
- Vomiting
- Tingling in the arms, legs, hands, and feet
- Dry mouth
- Constipation
- Diarrhea
- Stomach pain
- Heartburn
- Increased muscle spasms
- Back pain
- Rash
- Sweating
Severe Side Effects
Serious side effects of tizanidine include:
- Unusual bleeding or bruising
- Lack of energy
- Loss of appetite
- Pain in the upper right part of the stomach
- Jaundice (yellowing of the skin or eyes)
Seek immediate medical attention for:
- Extreme tiredness
- Confusion
- Slow heartbeat
- Fainting
- Slow or shallow breathing
- Loss of consciousness
- Visual hallucinations
- Audio hallucinations
Higher doses of tizanidine have been associated with an increased risk of falls, particularly in older adults or individuals with balance concerns. Special care should be taken when going from a sitting or lying down position to standing.
Drug Interactions
Tizanidine, like other medications, may cause side effects, ranging from mild to severe. Patients should consult a healthcare provider if they experience concerning symptoms.
Do not combine with:
- Opioid pain medications
- Caffeine
- Alcohol
- Grapefruit juice
- Parsley
- Tobacco products
Patients and their doctors should closely investigate any medication interactions that may exist.
While not classified as addictive, caution is advised for patients with a history of substance use disorders.
Tizanidine Hydrochloride vs. Other Muscle Relaxers
There are several muscle relaxers, and patients may find one works better for their needs.
According to the American Academy of Family Physicians, the most comprehensively understood and most used muscle relaxers are:
- Cyclobenzaprine is suitable for a wide variety of general musculoskeletal issues.
- Tizanidine is helpful for insomnia as well as muscle relaxation.
- Methocarbamol is less effective but does not cause excessive sleepiness.
- Metaxalone offers less effective muscle relaxation but without dizziness.
- Baclofen is often preferred for multiple sclerosis and spinal cord injuries, though it carries a higher risk of withdrawal-related seizures.
Cost Comparison
The cost of tizanidine varies by insurance programs, however:
- Tizanidine is available as a generic medication.
- Most insurance plans cover it.
- Medicare and Medicaid cover it.
- Copays may vary by insurance.
- Some manufacturers and pharmacies offer discount programs or copay assistance for eligible patients.
- The VA lists this as a Tier 2 medication with an $8 copay for a 30-day supply.
- Without insurance, 150-2 mg tablets cost $138.
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Key Takeaways
- Tizanidine hydrochloride is frequently prescribed. It blocks neural signals in the spine.
- It is used for multiple sclerosis muscle spasticity, general muscle spasticity and pain, and insomnia.
- It is generally not addictive, comes in a generic form, and is covered by most insurance companies, Medicare, Medicaid, and the VA.
- Tizanidine may cause a range of side effects, the majority of which are mild and self-limiting, though severe reactions require immediate medical attention.
- Anyone taking tizanidine should seek medical help if they have extreme tiredness, confusion, slow heartbeat, fainting, or other alarming symptoms.
- Patients should consult their healthcare provider regarding potential interactions between tizanidine and substances such as caffeine, alcohol, grapefruit juice, parsley, or tobacco.
- Patients should work closely with their physician and medical team, as with any prescription medication, to ensure proper compliance, use, and safety.
- Patients need to remember that a muscle relaxer does just that: it relaxes the muscles, meaning they are at a higher risk for falling, dropping items, and tripping.
- When used as prescribed, tizanidine may help manage muscle spasticity in certain conditions. Patients should discuss risks and benefits with their healthcare provider.
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