How does this medication work? What will it do for me?

Orphenadrine belongs to the group of medications called skeletal muscle relaxants. It is used to treat acute muscle spasms.

Muscle tightening or spasms result largely from signals in the nervous system telling the muscles to tighten or contract. Orphenadrine helps to relieve muscle tightening and stiffness by reducing the strength of those signals in the nervous system.

Muscle relaxants such as orphenadrine are used to help relieve the stiffness, pain, and discomfort caused by sprains and strains of the muscles in the neck, back, or other areas of the body. Your doctor may prescribe additional treatments such as appropriate rest, exercise, or physical therapy to help your stiff muscles.

Your doctor may have suggested this medication for conditions other than the ones listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

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What form(s) does this medication come in?

Norflex is no longer being manufactured for sale in Canada. For brands that may still be available, search under orphenadrine. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The recommended adult dose of orphenadrine to be taken by mouth, is 100 mg twice daily, in the morning and evening. It may be taken with or without food. The recommended injectable dose is 60 mg injected into a vein or a muscle.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature. Protect it from heat and moisture. Protect the injectable from from light. Keep all forms of this medication out of the reach of children.

This medication is available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

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Who should NOT take this medication?

Do not take orphenadrine if you:

  • are allergic to orphenadrine or any ingredients of the medication
  • are experiencing cardiospasm
  • have an enlarged prostate
  • have bladder neck obstruction
  • have glaucoma
  • have myasthenia gravis
  • have pyloric or duodenal obstruction (blockage in the upper digestive system)
  • have stenosing peptic ulcers
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What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • confusion
  • constipation
  • dizziness or lightheadedness
  • drowsiness
  • dry mouth
  • excitement, irritability, or nervousness
  • false sense of well-being
  • headache
  • muscle weakness
  • nausea
  • trembling
  • urination difficulties (retention of urine)
  • vision problems
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • blurred vision
  • dilated pupils
  • fast or pounding heartbeat
  • palpitation
  • unusual tiredness or weakness

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • eye pain
  • fainting
  • hallucinations
  • signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Contact lenses: Orphenadrine may make the eyes dry, resulting in discomfort or blurred vision if you wear contact lenses.

Dependence: Physical dependence, psychological dependence, and abuse have occurred with the use of orphenadrine. People with a history of past or current substance use problems may be at greater risk of developing abuse or addiction while taking this medication.

If you have a history of drug or alcohol use problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Orphenadrine may cause temporary dizziness and lightheadedness. Do not drive, operate machinery, or engage in any potentially hazardous activities until you determine how this medication affects you

Heart disease: Orphenadrine may make the symptoms of certain heart problems worse. If you have coronary insufficiency, irregular heartbeat (arrhythmias), or fast heart rate, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: The kidneys help to remove orphenadrine from the body. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: The liver helps to remove orphenadrine from the body. If you have reduced liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if orphenadrine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: Orphenadrine is generally not recommended for people who are over the age of 65 due to the increased risk of side effects such as drowsiness and dizziness.

What other drugs could interact with this medication?

There may be an interaction between orphenadrine and any of the following:

  • alcohol
  • anticholinergic medications (e.g., atropine, scopolomine)
  • antihistamines (e.g., chlorpheniramine, diphenhydramine, hydroxyzine)
  • antipsychotics (e.g., haloperidol, quetiapine, risperidol)
  • baclofen
  • barbiturates (e.g., butalbital, phenobarbital)
  • benzodiazepines (e.g., clonazepam, diazepam, lorazepam)
  • benztropine
  • brimonidine
  • buprenorphine
  • buspirone
  • carbamazepine
  • dimenhydrinate
  • droperidol
  • gabapentin
  • ipratropium
  • lamotrigine
  • levetiracetam
  • MAO inhibitors (e.g., maprotiline, phenelzine, moclobemide)
  • methocarbamol
  • narcotic pain relievers (e.g,. codeine, fentanyl, morphine)
  • phenytoin
  • pimozide
  • potassium chloride
  • propoxyphene
  • St. John's wort
  • tramadol
  • tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, nortriptyline)
  • valerian
  • zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.