Zanaflex vs Flexeril

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For patients suffering from muscle spasms or nerve-related muscle pain as a result of conditions like multiple sclerosis or certain injuries, specific medications that influence the signaling between nerves and muscles can help in reducing discomfort and managing symptoms. Zanaflex and Flexeril are two such drugs frequently prescribed for these conditions. They each impact different aspects of neuromuscular communication, but both have muscle relaxant effects in patients with muscle spasms or pain. Zanaflex is known as an alpha-2 adrenergic agonist which works by blocking nerve impulses sent to your brain thereby reducing the sensation of pain. On the other hand, Flexeril is classified primarily as a central nervous system depressant - more specifically, it functions as a serotonin receptor antagonist and reuptake inhibitor – affecting levels of neurotransmitter activity to encourage muscular relaxation.

What is Zanaflex?

Tizanidine (the generic name for Zanaflex) is a short-acting muscle relaxer, first approved by the FDA in 1996. It works by blocking nerve impulses that are sent to your brain and effectively reduces spasticity by slowing down nerve signal transmission in the spinal cord. Tizanidine is used for managing spasticity due to multiple sclerosis or spinal cord injury; it does not cure these problems but allows more normal movement as the disease/condition progresses.

On the other hand, Cyclobenzaprine (commonly known as Flexeril) has been available since 1977 and falls under a class of drugs called tricyclic antidepressants - though it's mostly used as a muscle relaxant than an antidepressant. Just like Tizanidine, Cyclobenzaprine helps with spasms, sprains and strains but works differently in that it targets pain sensations sent to your brain directly rather than targeting nerve signal transmissions like Zanaflex.

While both medications can cause side effects such as drowsiness or dry mouth, patients taking cyclobenzaprine may experience more serious ones including fast heart rate or hallucinations. Always consult with a healthcare provider when choosing between different types of medication.

What conditions is Zanaflex approved to treat?

Zanaflex is approved for the treatment of various muscle spasms and conditions, including:

  • Spasticity from conditions like multiple sclerosis or spinal cord injury
  • Muscle tightness or cramping from diseases such as cerebral palsy
  • Other situations where your doctor may recommend its use due to its muscle relaxing properties

How does Zanaflex help with these illnesses?

Zanaflex works to alleviate muscle spasticity by increasing the amount of alpha-2-adrenergic agonist available in the body. It does this by acting as an agonist at alpha-2 receptors located in the central nervous system, which reduces nerve impulse transmission and thus relaxes tense muscles. Alpha-2-adrenergic receptors are a type of receptor found on nerve cells that respond to norepinephrine, a neurotransmitter involved in regulating blood pressure, heart rate, sleep cycles and more. In cases of conditions like multiple sclerosis or spinal cord injury where muscle spasms can be severe and frequent, Zanaflex can help manage these symptoms effectively and improve patient comfort levels due to its ability to reduce excessive muscle tone.

What is Flexeril?

Flexeril, also known as cyclobenzaprine, is a muscle relaxant that works by blocking nerve impulses (or pain sensations) that are sent to your brain. It was first approved by the FDA in 1977. Unlike Zanaflex which is primarily an alpha-2 adrenergic agonist and reduces spasticity without reducing muscle tone, Flexeril acts primarily via central pathways at the brain stem level, inhibiting motor activity influencing both gamma and alpha motor systems.

Its lack of direct action on skeletal muscles means that its side-effect profile differs from those drugs directly acting on skeletal muscles like Zanaflex; it does not usually cause weakness or affect muscle tone. However, common side effects include drowsiness and dry mouth. The sedating effect may be beneficial for patients who have trouble sleeping due to their painful musculoskeletal condition. Flexeril can be particularly effective in treating acute muscular conditions caused by trauma or strain but should not be used for longer than two weeks.

What conditions is Flexeril approved to treat?

Flexeril is a muscle relaxant that is approved by the FDA for treating:

  • Muscle spasms caused by painful musculoskeletal conditions
  • Muscle stiffness and pain related to injuries

It's designed to be used along with physical therapy and rest as part of a comprehensive treatment plan. However, it should only be used short-term (up to two or three weeks), as its effectiveness beyond this time period has not been proven.

How does Flexeril help with these illnesses?

Flexeril, also known as cyclobenzaprine, is a muscle relaxant commonly used to treat muscle spasms and associated pain. Like Zanaflex, Flexeril works by acting on the central nervous system to produce its muscle relaxant effects. However, it primarily does this through antagonizing serotonin receptors and inhibiting norepinephrine reuptake in the brain's nerve signals - effectively reducing motor activity of tonic somatic origins influencing both alpha and gamma motor neurons.

Its action on these neurotransmitters may also contribute to its sedative effects - this can be beneficial for patients who have difficulty sleeping due to their muscle spasms. Because it doesn't significantly affect dopamine levels like some other drugs do (such as Zanaflex), Flexeril might be an appropriate choice for patients who are sensitive or unresponsive to medications that alter dopamine levels.

How effective are both Zanaflex and Flexeril?

Both tizanidine (Zanaflex) and cyclobenzaprine (Flexeril) are effective muscle relaxants commonly used for the treatment of muscle spasms. They were approved by the FDA only a few years apart, with Flexeril having been available slightly longer than Zanaflex. Although they work through different mechanisms of action—tizanidine acting primarily on alpha-2 receptors in the central nervous system to decrease spasticity, and cyclobenzaprine acting primarily within the brainstem to reduce tonic somatic motor activity—their effectiveness as muscle relaxants has been demonstrated in numerous clinical trials.

A 2004 study showed that both drugs had similar efficacy in reducing symptoms associated with acute musculoskeletal conditions. However, patients taking tizanidine experienced fewer side effects such as dry mouth and drowsiness compared to those taking cyclobenzaprine.

With regards to safety profiles, it is worth noting that while both medications have potential side effects including dizziness and sedation, some studies have suggested that tizanidine may be better tolerated overall. It's also important to note that cyclobenzaprine is generally considered a first-line treatment option due its long history of use and extensive research supporting its safety and efficacy. Tizanidine tends not to be prescribed until other options like NSAIDs or physical therapy have failed or aren’t suitable.

Despite this distinction between their uses in practice, there remains significant overlap regarding when each drug might be chosen over another depending on individual patient factors - i.e., specific contraindications (medical reasons why a particular drug should not be used), patient preference towards certain route of administration (both are oral but zanaflex can also come as capsule), presence of liver disease etc.

abstract image of a researcher studying a bottle of drug.

At what dose is Zanaflex typically prescribed?

Oral dosages of Zanaflex range from 4–36 mg/day, but studies have indicated that starting with a dose of 4 mg/day is suitable for most people to manage muscle spasticity. The dosage may be increased gradually over a few weeks if there is no response, up to a maximum daily dosage of 36 mg. In comparison, Flexeril can be taken in doses from 5-10mg three times per day but should not exceed a total of 30mg per day. Always remember that these medications must be used as prescribed by your healthcare provider and any changes in the dosage or frequency should only be made under their guidance due to potential side effects and interactions.

At what dose is Flexeril typically prescribed?

Flexeril therapy typically begins with a dosage of 5 mg three times per day. The dose can then be increased to up to 10 mg three times a day, depending on tolerance and efficacy. These doses should be spaced evenly throughout the day, ideally eight hours apart. A maximum daily dose is 30 mg divided into three doses of 10 mg each and spaced approximately eight hours apart, which may be tried if there's no satisfactory response to lower dosages after several weeks. As always, changes in dosage must only occur under medical supervision based on individual therapeutic response.

What are the most common side effects for Zanaflex?

Common side effects of Zanaflex can include:

  • Drowsiness/sleepiness
  • Dry mouth
  • Asthenia (general weakness and fatigue)
  • Dizziness, nervousness
  • Urinary tract infection
  • Vomiting, constipation or diarrhea
  • Speech disorder
  • Hypotension (low blood pressure)
  • Bradycardia (slower than normal heart rate)

On the other hand, Flexeril may cause:

-Dry mouth -Somnolence (sleepiness/drowsiness) -Dizziness -Fatigue -Nausea, constipation or upset stomach. -Increased heart rate

These are not exhaustive lists. If you experience any other symptoms that concern you while taking either medication, seek medical advice promptly.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Zanaflex?

Although Zanaflex is typically well-tolerated, in rare cases it can cause serious side effects, including:

  • Hallucinations or changes in thought processes
  • Allergic reactions: hives; difficulty breathing; swelling of your face, lips, tongue, or throat
  • Vision changes: blurred vision or loss of sight
  • Cardiovascular symptoms: slow heart rate, low blood pressure leading to dizziness and fainting
  • Liver problems - nausea, upper stomach pain, itching, tired feeling, loss of appetite
  • Signs of a nervous system reaction such as high fever sweating confusion fast or uneven heartbeats tremors feeling like you might pass out.

If any symptoms seem severe or persist over time consult with your healthcare provider immediately.

What are the most common side effects for Flexeril?

When taking Flexeril, you may experience some of the following side effects:

  • Dry mouth or throat discomfort
  • Blurred vision or dizziness
  • Nausea, stomach discomfort, loss of appetite and constipation
  • Sleep disturbances including insomnia
  • Excessive sweating and feelings of nervousness
  • Rapid heart rate
  • Confusion or agitation
  • Skin rash could develop in rare cases
  • Weight fluctuations might occur
    -Increased frequency of urination can happen with prolonged use. It is also common to experience headaches and muscle or joint pain as they are symptoms often related to the conditions for which Flexeril is usually prescribed.

Are there any potential serious side effects for Flexeril?

When taking Flexeril, there are certain serious side effects to be aware of. These include:

  • Signs of allergic or severe skin reactions: hives, itching, fever, swollen glands, difficulty breathing and swelling in your face or throat
  • Sudden chest pain or discomfort
  • Fast or irregular heartbeats
  • Seizures (convulsions)
  • Unusual changes in mood or behavior such as confusion and hallucinations
  • Vision problems like blurred vision or seeing halos around lights

If you experience any of these symptoms after taking Flexeril, seek immediate medical attention. Although rare, these signs can indicate a potentially life-threatening condition requiring urgent care.

Contraindications for Zanaflex and Flexeril?

Both Zanaflex and Flexeril, like other muscle relaxants, can potentially worsen symptoms in some people. If you observe an increase in dizziness, confusion or abnormal behavior after taking these medications, it's important to seek immediate medical attention.

Zanaflex should not be taken if you're currently using fluvoxamine or ciprofloxacin due to the increased risk of severe side effects. Similarly, Flexeril is contraindicated with MAOIs as it may lead to life-threatening interactions; a washout period of about 14 days is required if switching from an MAOI to Flexeril.

It's crucial that you always inform your healthcare provider about all medications you are taking. Both Zanaflex and Flexeril have potential drug-drug interactions that could result in serious complications. A thorough understanding of your medication history allows for safer prescription practices.

How much do Zanaflex and Flexeril cost?

For the brand name versions of these drugs:

  • The price for 30 tablets of Zanaflex (4 mg) averages around $200, which works out to about $6.70/day.
  • The price for 30 capsules of Flexeril (10 mg), also known as Cyclobenzaprine, is approximately $80 or roughly $2.67/day.

If you are in the higher dosage range for Zanaflex (i.e., taking up to three doses a day at max strength), then Flexeril may be less expensive on a per-day treatment basis if you are using it once daily. However, cost should not be your primary consideration when deciding between these two muscle relaxants.

For the generic versions:

  • Tizanidine HCL (generic Zanaflex) comes in packs ranging from 30 to 120 tablets with an approximate cost starting at just under $1 per pill for smaller quantities and decreasing significantly when purchased in larger amounts.
  • Cyclobenzaprine HCL (generic Flexeril) is available in similar packs with costs averaging around half that of its counterpart, making it generally more affordable but still offering comparable relief from muscle spasticity.

Popularity of Zanaflex and Flexeril

Tizanidine, also known by its brand name Zanaflex, is a short-acting muscle relaxant that was prescribed to approximately 3.5 million people in the US in 2020. It's used primarily for managing spasticity caused by conditions like multiple sclerosis or spinal cord injury. Tizanidine accounts for around 15% of all muscle relaxant prescriptions and has seen steady use over the past decade.

Cyclobenzaprine, marketed under the brand name Flexeril among others, is another commonly prescribed muscle relaxant with roughly 16.7 million prescriptions filled in the USA during the same year. This makes it one of the most widely-used drugs within this class, accounting for nearly half of all muscle relaxant prescriptions nationwide. Despite being on the market for longer than tizanidine, cyclobenzaprine's usage rate has remained fairly consistent over recent years.


Both Zanaflex (tizanidine) and Flexeril (cyclobenzaprine) have demonstrated efficacy in treating muscle spasms associated with conditions like multiple sclerosis, fibromyalgia, or certain injuries. They are supported by a broad range of clinical studies indicating that they provide more relief than placebo treatments. Both drugs work through different mechanisms of action; Zanaflex is an alpha-2 adrenergic agonist that inhibits nerve signals causing muscles to tighten, while Flexeril acts primarily on the central nervous system to produce its muscle relaxant effects.

Zanaflex can be considered as a first-line treatment option due to its quick onset of action and short duration, which makes it suitable for patients who need fast relief from acute muscle spasms. On the other hand, Flexeril has a longer half-life and is usually prescribed for those requiring continuous control over their symptoms.

Both medications are available in generic forms, making them affordable options for most patients. However, both may require an adjustment period since their full effect might not be noticeable immediately.

The side effect profile is similar between these two drugs; however, drowsiness tends to be more pronounced with Flexeril compared with Zanaflex. It's important for patients starting either medication to monitor their response closely and seek medical help if they experience severe side effects such as hallucinations or irregular heartbeat.