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.
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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.
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.
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.
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, constipation, 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
- Convulsions (seizures)
- hallucinations (seeing or hearing things that are not there)
- increase in muscle spasm, cramping, or tightness
- mood or mental changes
- unusual nervousness or restlessness
- Blurred or double vision
- muscle weakness (severe)
- irritability
- lightheadedness
- mood or mental changes
- shortness of breath or unusually slow or troubled breathingg
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.
References
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