Baclofen

Name: Baclofen

Which drugs or supplements interact with baclofen?

Use of baclofen with other drugs that also depress the function of nerves may lead to additional reduction in brain function.

In addition to the risk of depressing brain function, the use of baclofen and tricyclic antidepressants (for example, amitriptyline [Elavil, Endep], doxepin [Sinequan, Adapin]) together may cause muscle weakness.

Use of baclofen and monoamine oxidase inhibitors (for example, phenelzine [Nardil], tranylcypromine or [Parnate]) can result in greater depression of brain function as well as low blood pressure.

Because baclofen can increase blood sugar, doses of antidiabetic drugs may need to be adjusted when baclofen is begun.

Baclofen Dosage

Take baclofen exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The baclofen dose your doctor recommends will be based on the following:

  • the condition being treated
  • other medical conditions you have
  • other medications you are taking
  • how you respond to this medication

Oral:

Your doctor will likely start you off on a low dosage and gradually increase your dose as necessary. The recommended dosage schedule is:

  • 5 mg three times daily for 3 days
  • 10 mg three times daily for 3 days
  • 15 mg three times daily for 3 days
  • 20 mg three times daily for 3 days

The maximum daily oral (by mouth) dose is 80 mg (20 mg four times daily).

Injectable:

A doctor will surgically place the pump that will deliver the dose of the medication. The dose of intrathecal baclofen will be different for different patients and will depend on the type of muscle tightness that you have.

 

Uses For baclofen

Baclofen is used to help relax certain muscles in your body. It relieves the spasms, cramping, and tightness of muscles caused by medical problems such as multiple sclerosis or certain injuries to the spine. Baclofen does not cure these problems, but it may allow other treatment, such as physical therapy, to be more helpful in improving your condition.

Baclofen acts on the central nervous system (CNS) to produce its muscle relaxant effects. Its actions on the CNS may also cause some of the medicine's side effects. Baclofen may also be used to relieve other conditions as determined by your doctor.

baclofen is available only with your doctor's prescription.

Indications and Usage for Baclofen

Baclofen tablets USP are useful for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity.

Patients should have reversible spasticity so that Baclofen treatment will aid in restoring residual function. Baclofen tablets USP may also be of some value in patients with spinal cord injuries and other spinal cord diseases.

Baclofen tablets USP are not indicated in the treatment of skeletal muscle spasm resulting from rheumatic disorders.

The efficacy of Baclofen in stroke, cerebral palsy, and Parkinson’s disease has not been established and, therefore, it is not recommended for these conditions.

Pharmacologic Category

  • Skeletal Muscle Relaxant

Contraindications

Hypersensitivity to baclofen or any component of the formulation

Intrathecal: IV, IM, SubQ, or epidural administration

Reconstitution

Intrathecal: Screening doses are a 50 mcg/mL concentration and only the 1 mL screening ampul or screening syringe (50 mcg/mL) is used; do not further dilute. Maintenance infusions for patients who require concentrations other than 500 mcg/mL, 1,000 mcg/mL, or 2,000 mcg/mL must be diluted with preservative-free sodium chloride.

Adverse Reactions

>10%:

Central nervous system: Hypotonia (2% to 35%), drowsiness (6% to 21%), confusion (1% to 11%), headache (2% to 11%)

Gastrointestinal: Nausea (1% to 12%), vomiting (2% to 11%)

1% to 10%:

Cardiovascular: Hypotension (≤9%), peripheral edema (≤3%)

Central nervous system: Seizure (≤10%), dizziness (2% to 8%), insomnia (≤7%), paresthesia (≤7%), hypertonia (≤6%), pain (≤4%), speech disturbance (≤4%), depression (2%), coma (≤2%), abnormality in thinking (≤1%), agitation (≤1%), chills (≤1%)

Dermatologic: Pruritus (4%), urticaria (≤1%)

Gastrointestinal: Constipation (≤6%), sialorrhea (≤3%), xerostomia (≤3%), diarrhea (≤2%)

Genitourinary: Urinary retention (≤8%), urinary frequency (≤6%), difficulty in micturition (2%), impotence (≤2%), urinary incontinence (≤2%)

Neuromuscular & skeletal: Back pain (≤2%), weakness (≤2%), tremor (≤1%)

Ophthalmic: Ambylopia (≤2%)

Respiratory: Hypoventilation (≤4%), pneumonia (≤2%), dyspnea (≤1%)

Miscellaneous: Accidental injury (≤4%)

<1% (Limited to important or life-threatening): Abdominal pain, accommodation disturbance, akathisia, albuminuria, alopecia, amnesia, ankle edema, anorexia, anxiety, apnea, ataxia, blurred vision, bradycardia, carcinoma, chest pain, contact dermatitis, decreased libido, deep vein thrombophlebitis, dehydration, dermal ulcer, diaphoresis, diplopia, dysarthria, dysautonomia, dysgeusia, dysphagia, dystonia, dysuria, epilepsy, erectile dysfunction, euphoria, excitement, facial edema, fecal incontinence, fever, gastrointestinal hemorrhage, hallucination, hematuria, hyperglycemia, hyperhidrosis, hypertension, hyperventilation, hypothermia, hysteria, inhibited ejaculation, intestinal obstruction, leukocytosis, loss of postural reflex, malaise, miosis, muscle rigidity, myalgia, mydriasis, nasal congestion, nephrolithiasis, nocturia, nystagmus, occult blood in stools, oliguria, opisthotonus, orgasm disturbance, pallor, palpitations, paranoia, personality disorder, petechial rash, priapism, pulmonary embolism, scoliosis, scoliosis progression, sedation, sexual disorder, skin rash, slurred speech, strabismus, suicidal ideation, syncope, taste disorder, tinnitus, tongue irritation, vaginitis, vasodilatation, weight gain, weight loss

ALERT U.S. Boxed Warning

Abrupt withdrawal (injection):

Abrupt discontinuation of intrathecal baclofen, regardless of the cause, has resulted in sequelae that include high fever, altered mental status, exaggerated rebound spasticity, and muscle rigidity, which in rare cases has advanced to rhabdomyolysis, multiple organ-system failure, and death.

Prevention of abrupt discontinuation of intrathecal baclofen requires careful attention to programming and monitoring of the infusion system, refill scheduling and procedures, and pump alarms. Advise patients and caregivers of the importance of keeping scheduled refill visits and educate them on the early symptoms of baclofen withdrawal. Give special attention to patients at apparent risk (eg, spinal cord injuries at T-6 or above, communication difficulties, history of withdrawal symptoms from oral or intrathecal baclofen). Consult the technical manual of the implantable infusion system for additional postimplant clinician and patient information.

Monitoring Parameters

Regular electroencephalogram (EEG) in patients with epilepsy (loss of seizure control has been reported).

Before taking this medicine

You should not use baclofen if you are allergic to it.

To make sure this medicine is safe for you, tell your doctor if you have:

  • kidney disease;

  • epilepsy or other seizure disorder;

  • a history of stroke or blood clots; or

  • if you also use a narcotic (opioid) medication.

Using baclofen during pregnancy could harm the unborn baby. In animal studies, it caused low birth weight and birth defects. However, it is not known whether these effects would occur in humans. Tell your doctor if you are pregnant or if you become pregnant while using this medicine.

It is not known whether baclofen passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using this medicine.

Using baclofen may increase your risk of developing an ovarian cyst. Talk with your doctor about your specific risk.

Baclofen is not approved for use by anyone younger than 12 years old.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What other drugs will affect baclofen?

Taking baclofen with other drugs that make you sleepy or slow your breathing can cause dangerous side effects or death. Ask your doctor before taking a sleeping pill, narcotic pain medicine, prescription cough medicine, a muscle relaxer, or medicine for anxiety, depression, or seizures.

Other drugs may interact with baclofen, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Usual Adult Dose for Spasticity

ORAL:
-Initial dose: The following gradually increasing dosage regimen is suggested, but should be adjusted to suit individual patient requirements: 5 mg orally 3 times a day for 3 days, then 10 mg orally 3 times a day for 3 days, then 15 mg orally 3 times a day for 3 days, then 20 mg orally 3 times a day for 3 days
-Maintenance dose: Should be individualized
-Maximum dose: 80 mg/day (20 mg 4 times a day)
Comment:
-The maximum dose of 80 mg/day should be administered in 4 divided doses.

Use: To alleviate symptoms of spasticity of voluntary muscle (e.g., multiple sclerosis, cerebrovascular accidents, cerebral palsy, meningitis, traumatic head injury, spastic spinal paralysis, amyotrophic lateral sclerosis, traumatic paraplegia or paraparesis, compression of the spinal cord, tumors of the spinal cord, syringomyelia, motor neuron disease, transverse myelitis, traumatic partial section of the cord)

Usual Adult Dose for Spinal Spasticity

INTRATHECAL:
SCREENING PHASE: Prior to administering this drug as a continuous intrathecal infusion, patients must show a positive response to administration of an intrathecal test dose in an initial test phase:
-FIRST TEST DOSE: 50 mcg (in a volume of 1 mL) injected into the intrathecal space by barbotage over at least 1 minute. Observe patient for 4 to 8 hours for a positive response.
-SECOND TEST DOSE (if no positive response to first test dose): 75 mcg (in a volume of 1.5 mL) may be administered 24 hours after the first test dose. Observe patient for 4 to 8 hours for a positive response.
-THIRD TEST DOSE (if no positive response to second test dose): 100 mcg (in a volume of 2 mL) may be administered 24 hours after the second test dose. Observe patient for 4 to 8 hours for a positive response. If no positive response to third test dose, the patient should not be considered for chronic intrathecal therapy.

POST-IMPLANT DOSE TITRATION PERIOD:
-The test dose that received a positive response should be doubled and given over 24 hours, unless the efficacy of the bolus dose was maintained for more than 8 hours, in which case the starting daily dose should be the screening dose delivered over 24 hours.
-No dose increases should be given in the first 24 hours.

-ADULT PATIENTS WITH SPASTICITY OF SPINAL CORD ORIGIN: After the first 24 hours, the daily dosage should be increased slowly by 10% to 30% increments and only once every 24 hours, until the desired effect is achieved.
-ADULT PATIENTS WITH SPASTICITY OF CEREBRAL ORIGIN: After the first 24 hours, the daily dose should be increased slowly by 5% to 15% only once every 24 hours, until the desired effect is achieved.

MAINTENANCE DOSING FOR SPASTICITY OF SPINAL CORD ORIGIN PATIENTS:
-During periodic refills of the pump, the daily dose may be increased by 10% to 40%, but no more than 40%, to maintain adequate symptom control.
-The daily dose may be reduced by 10% to 20% if patients experience side effects.
-Maintenance dosage for long term continuous infusion: 12 to 2003 mcg/day, with most patients adequately maintained on 300 to 800 mcg/day; there is limited experience with daily doses greater than 1000 mcg/day.

MAINTENANCE DOSING FOR SPASTICITY OF CEREBRAL ORIGIN PATIENTS:
-During periodic refills of the pump, the daily dose may be increased by 5% to 20%, but no more than 20%, to maintain adequate symptom control.
-The daily dose may be reduced by 10% to 20% if patients experience side effects.
-Maintenance dosage for long term continuous infusion: 22 to 1400 mcg/day, with most patients adequately maintained on 90 to 703 mcg/day; there is limited experience with daily doses greater than 1000 mcg/day.

POTENTIAL NEED FOR DOSE ADJUSTMENTS IN CHRONIC USE:
-During long term treatment, approximately 5% of patients become refractory to increasing doses. There is not sufficient experience to make recommendations for tolerance treatment; however, this tolerance has been treated on occasion, in hospital, by a "drug holiday" consisting of the gradual reduction of intrathecal dosing over a 2 to 4 week period and switching to alternative methods of spasticity management.
-After the "drug holiday," intrathecal dosing may be restarted at the initial continuous infusion dose.

Comments:
-Determination of the optimal dose requires individual titration. The lowest dose with an optimal response should be used.
-For patients with spasticity due to head injury, it is recommended not to proceed to long-term until the symptoms of spasticity are stable (i.e., at least one year after the injury).
-A positive response consists of a significant decrease in muscle tone and/or frequency and/or severity of spasms.
-Many patients require gradual increases in dose over time to maintain optimal response during chronic therapy.
-A sudden large requirement for dose escalation suggests a catheter complication (i.e., catheter kink or dislodgement).
-Careful dose titration is needed when spasticity is necessary to sustain upright posture and balance in locomotion or whenever spasticity is used to obtain optimal function. Allowing occasional spasms may help support circulatory function, possibly prevent the formation of deep vein thrombosis, and optimize activities of daily living.
-Except in overdose related emergencies, dosing should be reduced slowly if the drug is discontinued for any reason.
-An attempt should be made to discontinue concomitant oral antispasticity medication to avoid possible overdose or adverse drug interactions, either prior to screening or following implant and initiation of chronic infusion.
If there is not a substantive clinical response to increases in the daily dose, check for proper pump function and catheter patency. Patients must be monitored closely in a fully equipped and staffed environment during the screening phase and dose-titration period immediately following implant. Resuscitative equipment should be immediately available for use in case of life-threatening or intolerable side effects.

Use: For the management of severe spasticity. Patients should first respond to a screening dose prior to consideration for long term infusion via an implantable pump. For spasticity of spinal cord origin, chronic infusion via an implantable pump should be reserved for patients unresponsive to oral therapy, or those who experience intolerable CNS side effects at effective doses. Patients with spasticity due to traumatic brain injury should wait at least one year after the injury before consideration of long term intrathecal therapy.

Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Drowsiness, dizziness, or sedation, which may affect your ability to drive or operate machinery or perform other hazardous tasks. The sedative effect of baclofen may be enhanced by alcohol or by other medications that also cause sedation (such as benzodiazepines, opiates).
  • Weakness, fatigue, insomnia, nausea, constipation, low blood pressure, headache, and confusion have also been reported.
  • Sudden discontinuation of baclofen has been associated with hallucinations and seizures. Baclofen should be withdrawn slowly unless it is an emergency.
  • May not be suitable for some people, including those with a history of stroke or who rely on spasticity to maintain an upright position, balance, or for increased function. The dosage of baclofen should be reduced in those with kidney disease.
  • People with a history of seizures or epilepsy should be monitored regularly for changes in seizure control or EEG recordings.
  • May cause an increase in the risk of ovarian cysts.

Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.

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