Pronunciation:

DAN-troe-leen

Brand Names:

• Dantrium

Dosage Forms:

• Capsule

Warnings:

Dantrolene may cause hepatotoxicity, and symptomatic hepatitis (fatal and nonfatal) has been reported at various dose levels. Risk of hepatic injury appears to be greater in patients taking a higher dosage, in females, in patients older than 35 years, and in patients taking additional medication(s). Monitor hepatic function, including frequent determination of SGOT or SGPT, during therapy. Discontinue therapy after 45 days if there is no observable benefit .

Classifications:

Therapeutic—

Skeletal Muscle Relaxant, Direct Acting

Uses of This Medicine:

Dantrolene is used to help relax certain muscles in your body. It relieves the spasms, cramping, and tightness of muscles caused by certain medical problems such as multiple sclerosis (MS), cerebral palsy, stroke, or injury to the spine. Dantrolene does not cure these problems, but it may allow other treatment, such as physical therapy, to be more helpful in improving your condition. Dantrolene acts directly on the muscles to produce its relaxant effects.

Dantrolene is also used to prevent or treat a medical problem called malignant hyperthermia that may occur in some patients during or following surgery or anesthesia. Malignant hyperthermia consists of a group of symptoms including very high fever, fast and irregular heartbeat, and breathing problems. It is believed that the tendency to develop malignant hyperthermia is inherited.

This medicine is available only with your doctor's prescription.

Before Using This Medicine:

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies—

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children—

Appropriate studies have not been performed on the relationship of age to the effects of dantrolene in children below 5 years of age. Safety and efficacy have not been established.

Older adults—

No information is available on the relationship of age to the effects of dantrolene in geriatric patients.

Breast-feeding—

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Other medicines—

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Alprazolam
• Amlodipine
• Amobarbital
• Aprobarbital
• Buprenorphine
• Butabarbital
• Butalbital
• Calcium Oxybate
• Carisoprodol
• Chloral Hydrate
• Chlordiazepoxide
• Chlorzoxazone
• Cinnarizine
• Clevidipine
• Clobazam
• Clonazepam
• Clorazepate
• Diazepam
• Diltiazem
• Estazolam
• Ethchlorvynol
• Felodipine
• Flunitrazepam
• Flurazepam
• Halazepam
• Isradipine
• Ketazolam
• Levoketoconazole
• Lorazepam
• Lormetazepam
• Magnesium Oxybate
• Medazepam
• Mephenesin
• Mephobarbital
• Meprobamate
• Metaxalone
• Methadone
• Methocarbamol
• Methohexital
• Methotrexate
• Midazolam
• Nicardipine
• Nifedipine
• Nimodipine
• Nisoldipine
• Nitrazepam
• Oxazepam
• Oxycodone
• Pentobarbital
• Pexidartinib
• Phenobarbital
• Potassium Oxybate
• Prazepam
• Primidone
• Quazepam
• Secobarbital
• Sodium Oxybate
• Tapentadol
• Temazepam
• Thiopental
• Triazolam
• Verapamil

Other interactions—

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems—

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

• Heart disease or
• Liver disease, history of or
• Lung disease (e.g., emphysema, asthma, bronchitis)—The chance of serious side effects may be increased.

• Liver disease, active (e.g., hepatitis, cirrhosis) or
• Muscle spasms caused by rheumatic disorders—Should not be used in patients with these conditions.

Proper Use of This Medicine:

Dantrolene may be taken with or without food or on a full or empty stomach. However, if your doctor tells you to take the medicine a certain way, take it exactly as directed.

Take this medicine only as directed by your doctor. Do not take more of it and do not take it more often than your doctor ordered.

Dosing—

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage form (capsules):
  • For prevention or treatment of malignant hyperthermia:
    • Adults—Dose is based on body weight and must be determined by your doctor. The usual dose is 4 to 8 milligrams (mg) per kilogram (kg) of body weight each day, and is divided in 3 or 4 doses. Your doctor will tell you exactly when and how often to take your medicine.
    • Children—Use and dose must be determined by your doctor.
  • To relieve muscle spasms:
    • Adults—At first, 25 milligrams (mg) once a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 100 mg four times a day.
    • Children—Dose is based on body weight and must be determined by your doctor. At first, 0.5 milligram (mg) per kilogram (kg) of body weight twice a day. Your doctor may adjust the dose as needed. However, the dose is usually not more than 3 mg per kg four times a day or 100 mg four times a day.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Precautions While Using This Medicine:

If you will be taking dantrolene for a long time (e.g., several months at a time), your doctor should check your progress at regular visits. Blood tests will be needed to check for unwanted effects.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; other muscle relaxants; or anesthetics, including some dental anesthetics. Therefore, do not drink alcoholic beverages, and check with your doctor before taking any of the medicines listed above, while you are using this medicine.

This medicine may cause drowsiness, dizziness or lightheadedness, vision problems, or muscle weakness in some people. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert, well-coordinated, and able to see well.

This medicine may make your skin more sensitive to sunlight. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Serious side effects are very rare when dantrolene is taken for a short time, for example, when it is used for a few days before, during, or after surgery or anesthesia to prevent or treat malignant hyperthermia. However, serious side effects may occur, especially when the medicine is taken for a long time.

Check with your doctor immediately if any of the following side effects occur:

Less common

Bloody or black, tarry stools

bloody or dark urine

bluish color changes in skin color

changes in speech

chest pain

confusion

constipation

convulsions (seizures)

decrease in frequency of urination

decrease in urine volume

difficult urination

difficulty in moving

difficulty in passing urine (dribbling)

difficulty in swallowing

fast, pounding, or irregular heartbeat or pulse

increased frequency of urination

increased urge to urinate during the night

joint pain

light-colored stools

lightheadedness

loss of bladder control

mental depression

muscle aching or cramping

muscle pains or stiffness

muscle spasm or jerking of all extremities

nausea and vomiting

pain in lower back

pain or burning while urinating

pain, tenderness, or changes in skin color

painful urination

severe stomach pain

shortness of breath

skin rash, hives, or itching

slow or troubled breathing

sudden decrease in amount of urine

sudden loss of consciousness

swelling of foot or leg

swollen joints

unusual tiredness or weakness

upper right abdominal pain

vomiting of blood or material that looks like coffee grounds

waking to urinate at night

yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Diarrhea

dizziness

drowsiness

general feeling of discomfort or illness

muscle weakness

Less common

Abdominal or stomach cramps or discomfort

abnormal hair growth

acne-like rash

blurred or double vision or any change in vision

change in taste

chills and fever

disturbed color perception

excessive tearing

halos around lights

headache

itching skin

loss of appetite

night blindness

overbright appearance of lights

redness of skin

seeing double

skin rash, encrusted, scaly and oozing

sleeplessness

slurring of speech or other speech problems

sudden decrease in amount of urine

sweating

trouble in sleeping

tunnel vision

unable to sleep

unusual nervousness

weight loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.