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Baclofen, Uses, Dosage, Side Effects, Interactions ,Pregnancy

Baclofen is a synthetic chlorophenyl-butanoic acid derivative used to treat spasms due to spinal cord damage and multiple sclerosis, muscle-relaxing Baclofen acts as a gamma-aminobutyric acid (GABA) agonist specific for GABA-B receptors. It acts at spinal and supraspinal sites, reducing excitatory transmission.

Baclofen is a GAMMA-AMINOBUTYRIC ACID derivative that is a specific agonist of GABA-B RECEPTORS. It is used in the treatment of MUSCLE SPASTICITY, especially that due to SPINAL CORD INJURIES. Its therapeutic effects result from actions at spinal and supraspinal sites, generally the reduction of excitatory transmission.

Baclofen is a centrally acting muscle relaxant commonly prescribed for spasticity in patients with multiple sclerosis. Baclofen has not been linked to rare instances of mild, self-limited, clinically apparent liver injury.

It is a muscle relaxant and antispastic. Oral skeletal muscle relaxant; derivative of the inhibitory neurotransmitter GABA; used to treat spasticity in patients with MS and other spinal cord lesions; also improves bowel and bladder function in some of these patients. Its chemical name is 4-amino-3-(4-chlorophenyl) butanoic acid. Baclofen USP is a white to off-white, odorless or practically odorless crystalline powder. It is slightly soluble in water, very slightly soluble in methanol and insoluble in chloroform.

Mechanism of Action of Baclofen

Baclofen’s mechanism of action is not fully understood, but it is believed that the drug works mainly at the level of the spinal cord to block polysynaptic afferent pathways and, to a lesser extent, monosynaptic afferent pathways. Baclofen may inhibit the transmission of impulses through these pathways by acting as an inhibitory neurotransmitter itself or by hyperpolarizing the primary afferent nerve terminals, which inhibits the release of excitatory neurotransmitters such as glutamate and aspartic acids. Because of large doses of baclofen cause CNS depression, it is postulated that the drug works at supraspinal sites as well. Baclofen has been described as a gamma-aminobutyric acid (GABA) agonist; the drug stimulates the GABA-B receptor. This leads to a decreased release of the neurotransmitters aspartate and glutamate and decreased excitatory input into alpha-motor neurons.

Baclofen is a direct agonist at GABAB receptors. The precise mechanism of action of Baclofen is not fully known. It is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect.

Baclofen is a muscle relaxant and antispastic. Baclofen is 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. Although Baclofen is an analog of the putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA), there is no conclusive evidence that actions on GABA systems are involved in the production of its clinical effects. In studies with animals, Baclofen has been shown to have general CNS depressant properties as indicated by the production of sedation with tolerance, somnolence, ataxia, and respiratory and cardiovascular depression. Baclofen is rapidly and extensively absorbed and eliminated. Absorption may be dose-dependent, being reduced with increasing doses. Baclofen is excreted primarily by the kidney in unchanged form and there is relatively large intersubject variation in absorption and/or elimination.

Baclofen is a synthetic chlorophenyl-butanoic acid derivative used to treat spasms due to spinal cord damage and multiple sclerosis, muscle-relaxing Baclofen acts as a gamma-aminobutyric acid (GABA) agonist specific for GABA-B receptors. It acts at spinal and supraspinal sites, reducing excitatory transmission.

Indications of Baclofen

These medicines work by acting on the central nervous system and may be used for the relief of muscle spasms, cramping or tightness caused by diseases such as

Cerebral palsy
Diseases of the spinal cord
PLID
Lumbago
Sciatica
Low back pain or Lumbergo
Complete or incomplete spinal cord injury
Meningitis
Motor neuron disease
Multiple sclerosis
Cerebrovascular accidents
Other injuries or diseases which affect the brain and nervous system.
Treatment of dystonia
Treatment of spasticity associated with cerebral palsy
Treatment of intractable spasticity associated with spinal cord injury or multiple sclerosis
Trigeminal neuralgia
Spastic cerebral pulsy
Postoperative paresthesia,
Scoliosis
Hiccup
Muscle spasm, spasticity due to scoliosis
Parkinson’s disease
Paresthesia, muscle pain, coordination disorder, tremor, rigidity, dystonia, ataxia, nystagmus, strabismus, dysarthria, epileptic seizure
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.

Contra Indications of Baclofen

Severely Decreased Platelets
Having Thoughts of Suicide
Persens. to drug class compon.
Avoid abrupt withdrawal
Caution in elderly pts
Renal impairment
CHF class III, IV NYHA
Angioedema hx
Angioedema risk
Depression
CNS depressant use
Alcohol use
The decrease in the Sharpness of Vision
Atrioventricular Heart Block
Chronic Heart Failure
Suddenly serious symptoms of heart failure
rhabdomyolysis
Drowsiness

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Dosage of Baclofen

Strengths : 10 mg; 20 mg; 0.05 mg/mL; 0.5 mg/mL;

Spasticity

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 orally 4 times a day)

Cerebral Spasticity

First Screening Dose: 50 mcg (in a volume of 1 mL) administered into the intrathecal space by barbotage over at least 1 minute; observe patient for 4 to 8 hours for a positive response
Second Screening Dose: (if no positive response to first screening dose): 75 mcg (in a volume of 1.5 mL) bolus dose administered 24 hours after the first screening dose; observe the patient for 4 to 8 hours for a positive response
Third Screening Dose: (if no positive response to second screening dose): 100 mcg (in a volume of 2 mL) bolus dose administered 24 hours after the second screening dose; observe patient for 4 to 8 hours for a positive response; if no positive response to third screening dose, the patient should not be considered for chronic intrathecal therapy.
No dose increases should be given in the first 24 hours (i.e., until a steady state is achieved).
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.
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.

Intrathecal mainteinance dosing

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; most patients require gradual increases in dose to maintain optimal response during chronic therapy
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.

Intrathecal mainteinance dosing for spasticity of cerebral origin

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; most patients require gradual increases in dose to maintain optimal response during chronic therapy.
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 dosage adjustment 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, 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.

Spinal Spasticity

Intrathecal screening phase

Prior to pump implantation for chronic infusion, patients must show a positive response to an intrathecal bolus dose in a screening trial.
First Screening Dose: 50 mcg (in a volume of 1 mL) administered into the intrathecal space by barbotage over at least 1 minute; observe patient for 4 to 8 hours for a positive response.
Second Screening Dose: (if no positive response to first screening dose): 75 mcg (in a volume of 1.5 mL) bolus dose administered 24 hours after the first screening dose; observe patient for 4 to 8 hours for a positive response
Third Screening Dose: (if no positive response to second screening dose): 100 mcg (in a volume of 2 mL) bolus dose administered 24 hours after the second screening dose; observe patient for 4 to 8 hours for a positive response; if no positive response to third screening dose, the patient should not be considered for chronic intrathecal therapy

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Intrathecal Post implant dose titration period

The screening dose that received a positive response should be doubled and administered 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 (i.e., until steady state is achieved).
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.
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.

Intrathecal maintenance dosing for spasticity of spinal cord

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; most patients require gradual increases in dose to maintain optimal response during chronic therapy
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

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; most patients require gradual increases in dose to maintain optimal response during chronic therapy.
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 adjustment 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, 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.

Spasticity

12 years and older

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 orally 4 times a day)

For Hiccup

If the hiccup are reached the severe condition the beclofen 5 mg tab twich daily for 7 day. It must be come in control gradually

Pediatric Cerebral Spasticity

4 years and older ; The starting screening dose for pediatric patients is the same as in adult patients, (50 mcg); however, for very small patients, a screening dose of 25 mcg may be tried first

Intra thecal screening

Prior to pump implantation for chronic infusion, patients must show a positive response to an intrathecal bolus dose in a screening trial.
First Screening Dose: 25 to 50 mcg (in a volume of 1 mL) administered into the intrathecal space by barbotage over at least 1 minute; observe patient for 4 to 8 hours for a positive response
Second Screening Dose: (if no positive response to first screening dose): 75 mcg (in a volume of 1.5 mL) bolus dose administered 24 hours after the first screening dose; observe patient for 4 to 8 hours for a positive response
Third Screening Dose: (if no positive response to second screening dose): 100 mcg (in a volume of 2 mL) bolus dose administered 24 hours after the second screening dose; observe patient for 4 to 8 hours for a positive response; if no positive response to third screening dose, the patient should not be considered for chronic intrathecal therapy.

Maintenance dose
The same dosing recommendations for adults with spasticity of cerebral origin are used in pediatric patients 4 years and older

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.

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Maintenance dosage for long term continious infusion

Pediatric patients 4 to under 12 years may require a lower daily dose: 274 mcg/day, with a range of 24 to 1199 mcg/day
Age 12 years and older: 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

Side effects of Baclofen

More common

Constipation
Frequently passing urine
Loss of muscle coordination
sleepiness or unusual drowsiness
clumsiness or unsteadiness
dizziness
drowsiness
dry mouth
false sense of well-being
increased watering of mouth
lightheadedness
constipation;
vision changes;
breast swelling (in men or women); or
decreased sex drive, impotence, or difficulty having an orgasm.
blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
restless muscle movements in your eyes, tongue, jaw, or neck;
a light-headed feeling, like you might pass out;

Common

Drowsiness and lightheadedness the day after taking the medicine.
Confusion.
Numbed emotions.
Visual disturbances such as blurred vision or double vision.
Shaky movements and unsteady walk (ataxia).
Loss of memory (amnesia).
Muscle weakness.
Dizziness.
Headache.
Skin rashes.
Disturbances of the gut such as diarrhoea, c onstipation, nausea, vomiting or abdominal pain.
Difficulty in passing urine (urinary retention).
Changes in sex drive.
Low blood pressure (hypotension).
Blood disorders.
Unexpected aggression, restlessness or irritability (tell your doctor if you experience this).
Nightmares or hallucinations (tell your doctor if you experience this).

Rare

Drug Interactions of Baclofen

Baclofen may interact with following drugs, supplyments, & may change the efficacy of drugs

antihistamines (e.g., cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
aripiprazole
antidiabetes medications
barbiturates (e.g., butalbital, pentobarbital, phenobarbital)
benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
carbamazepine
gabapentin
levodopa – carbidopa
magnesium sulfate
mirtazapine
monoamine oxidase inhibitors (MAOIs; e.g. rasagiline, selegiline, phenelzine, rasagiline, selegiline, )
other muscle relaxants
phenytoin
selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, duloxetine, fluoxetine, paroxetine, sertraline)
tapentadol
topiramate
tramadol
tricyclic antidepressants (e.g., desipramine, nortriptyline)

Pregnancy & Lactation of

FDA Pregnancy Category C

Pregnancy

It is not known if baclofen is safe and effective for use in pregnant women. Tell your doctor if you’re pregnant or plan to become pregnant. Baclofen should be used during pregnancy only if the potential benefit justifies the potential risk.Call your doctor right away if you become pregnant while taking this drug.

Lactation

It isn’t known if baclofen passes into breast milk. If it does, it may cause side effects in a child who is breastfed. Talk to your doctor if you breastfeed your child. You may need to decide whether to stop breastfeeding or stop taking this medication.