Baclofen (Intrathecal)

Uses

Baclofen (Intrathecal) is used for:

• Spasm.
• Spinal cord diseases.
• Cerebrovascular accidents or neoplastic or degenerative brain disease.
• Muscle spasm of cerebral origin especially infantile cerebral palsy.
• The alleviation of spasticity resulting from multiple sclerosis

Baclofen (Intrathecal) is also used to associated treatment for these conditions: Joint Pain, Soreness, Muscle, Flexor spasm, Reversible Spasticity, Severe cerebral origin Spasticity, Severe spinal cord origin Spasticity

How Baclofen (Intrathecal) works

The exact mechanism of action of baclofen is not fully understood at this time , . Many studies indicate that baclofen is a GABA-B receptor agonist , , , , . Despite this, there is no conclusive evidence that the effects of baclofen on GABA systems are involved in the production of its clinical effects .

Baclofen (Intrathecal) is an effective and widely used antispastic agent with a spinal site of action. Its mechanism of action and pharmacological properties are different from the effects of other antispastic agents. In addition, baclofen has central sites of action, shown by its adverse event profile and general CNS depressant properties . GABA-B receptors interact with signal transduction pathways and neurotransmitter systems. Baclofen (Intrathecal) exerts an antinociceptive effect. The clinical significance of this warrants further research data for clarification.

Baclofen (Intrathecal) depresses monosynaptic and polysynaptic reflex transmission, by various actions, and possibly including the stimulation of GABAβ-receptors. This stimulation results in the inhibition of excitatory neurotransmitter (glutamate and aspartate) release, which may normally contribute to pain and spasticity. Although baclofen is an analog of the inhibitory neurotransmitter gamma-amino-butyric acid (GABA), there are no conclusive data indicating GABA systems are involved in its clinical effects .

Dosage

Baclofen (Intrathecal) dosage

Adults:

Treatment should be started with low dose and increased gradually until optimum effect is achieved. The following dosage titration schedule is suggested:

5 mg 3 times daily for 3 days,

10 mg 3 times daily for 3 days,

15 mg 3 times daily for 3 days,

20 mg 3 times daily for 3 days,

25 mg 3 times daily for 3 days.

Thereafter, additional increases may be necessary. The optimum dosage generally ranges from 30 - 80 mg daily in 3 - 4 divided doses. Daily doses of 100 - 120 mg may be given to carefully supervised patients in hospitals.

Children:

Treatment should be started at a very low dose, e.g., 0.3 mg/kg per day in divided (preferably 4) doses. The dosage should be raised cautiously at 1-2 week intervals until it is sufficient for the child\'s individual needs. The usual dosage range for maintenance therapy is 0.75 to 2 mg/kg body weight per day. In children aged over 10 years a maximum daily dose of 2.5 mg/kg body weight may be given.

Renal Insufficiency:

Baclofen (Intrathecal) is excreted principally in urine as unchanged drug. So it may be necessary to reduce the dosage in patients with impaired renal function.

Side Effects

The most common side effects include drowsiness, nausea, dizziness, lassitude, lightheadedness, confusion, fatigue, muscular pain & weakness and hypotension.

Toxicity

LD50 after oral administration in rats: 145 mg/kg

Overdosage: Vomiting, muscular hypotonia, drowsiness, accommodation disorders, coma, respiratory depression, and seizures may occur with overdosage .

Pregnancy: This drug is a pregnancy category C drug. There are no adequate and well-controlled studies that have been performed with pregnant women. Baclofen (Intrathecal) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus .

Excretion in breastmilk: It is unknown whether this drug is excreted in human breast milk. Because many drugs are excreted in human milk, caution is warranted when baclofen is administered to a nursing woman .

Precaution

Patients suffering from psychotic disorders, schizophrenia, depressive or manic disorders, confusional states or Parkinson\'s disease, should be treated cautiously with Baclofen (Intrathecal). Baclofen (Intrathecal) stimulates gastric acid secretion and should be used with caution in patients with a history of peptic ulcer and avoided in those with active peptic ulcer disease . Liver function should be monitored in patients with liver disease; patients with renal impairment need a reduced dose. Baclofen (Intrathecal) should be used with caution in patients with respiratory impairment. Observations of increased blood sugar concentrations suggest caution in patients with diabetes mellitus. Care is also required in the elderly, in whom adverse effects may be more common, and in patients with cerebrovascular disease (who tolerate Baclofen (Intrathecal) poorly). Baclofen (Intrathecal) may cause drowsiness; patients affected should not drive or operate machinery. Abrupt withdrawal of Baclofen (Intrathecal) may result in a withdrawal syndrome and exacerbation of spasticity; dosage should be reduced gradually over at least 1 to 2 weeks, or longer if symptoms occur.

Interaction

Alcohol and other CNS depressants may exacerbate the CNS effects of Baclofen (Intrathecal) and should be avoided. There may be increased weakness if Baclofen (Intrathecal) is given to patients taking a tricyclic antidepressant and an increased hypotensive effect if it is given to patients receiving antihypertensive therapy.

Food Interaction

• Avoid alcohol.
• Take with food. Take with food or milk to reduce gastric irritation.

[Moderate] GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents.

Use in combination may result in additive central nervous system depression and
MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol.

Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

Baclofen (Intrathecal) Drug Interaction

Major: acetaminophen / hydrocodone, acetaminophen / hydrocodoneModerate: duloxetine, duloxetine, pregabalin, pregabalin, alprazolam, alprazolam, cetirizine, cetirizineUnknown: polyethylene glycol 3350, polyethylene glycol 3350, acetaminophen, acetaminophen, cyanocobalamin, cyanocobalamin, ascorbic acid, ascorbic acid, cholecalciferol, cholecalciferol

Baclofen (Intrathecal) Disease Interaction

Major: renal dysfunctionModerate: autonomic dysreflexia, psychoses, seizure disorders

Volume of Distribution

Apparent volume of distribution: 59 liters .

Baclofen (Intrathecal) does not readily cross the blood-brain barrier .

Elimination Route

Rapidly and almost completely absorbed from the gastrointestinal tract. Absorption may be dose-dependent, being reduced with increased doses .

Baclofen (Intrathecal), when introduced directly into the intrathecal space, allows for effective CSF concentrations to be achieved with resulting plasma concentrations 100 times less than concentrations occurring with oral administration , .

Half Life

Elimination half-life: Approximately 5.5 hours .

Clearance

Total systemic clearance: 180 mL/min Renal clearance: 103 mL/min

Baclofen (Intrathecal) is primarily excreted unchanged by the kidneys. It should be administered cautiously, and it may be necessary to reduce the dosage in patients with reduced renal function .

Elimination Route

Baclofen (Intrathecal) is rapidly and extensively eliminated from the body. There is significant intersubject variation in elimination rates. Baclofen (Intrathecal) is excreted mainly by the kidney as unchanged drug. Seventy to eighty (70 - 80%) of a dose is measured in the urine as unchanged drug. The remainder of the dose is excreted as unchanged drug in the feces or as metabolites in the urine and feces. Excretion is complete within 72 hours after administration .

Pregnancy & Breastfeeding use

There are no adequate and well controlled studies of Baclofen (Intrathecal) in pregnant women. So it should be used during pregnancy only if the potential benefit outweighs the potential risk to the fetus.

Baclofen (Intrathecal) is excreted in breast milk. However, evidence suggests that the quantities are so small that no undesirable effect on the infant would be expected.

Contraindication

Baclofen (Intrathecal) is contraindicated in patients with hypersensitivity to any component of this product.

Special Warning

Renal Insufficiency: Baclofen (Intrathecal) is excreted principally in urine as unchanged drug. So it may be necessary to reduce the dosage in patients with impaired renal function.

Acute Overdose

Prominent features are signs of central nervous system depression. No specific antidote of Baclofen (Intrathecal) is known. Elimination of the agent from GI tract, artificial respiration, administration of fluid with a diuretic and dialysis should be considered.

Interaction with other Medicine

Alcohol and other CNS depressants may exacerbate the CNS effects of Baclofen (Intrathecal) and should be avoided. There may be increased weakness if Baclofen (Intrathecal) is given to patients taking a tricyclic antidepressant and an increased hypotensive effect if it is given to patients receiving antihypertensive therapy.

Storage Condition

Store in cool & dry place, away from children.

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