Generic name
Baclofen
Brand Names
Pacifen
Drug Class
- Anti-epileptic
- GABA Agonist
Indications
- Alleviation of signs and symptoms of spasticity and concomitant pain, clonus, and muscular rigidity resulting from multiple sclerosis, spinal cord injuries and other spinal cord diseases
- Hiccups
Pharmacology
- Mechanism of action is not known
- Kidney is the primary elimination site (85%)
Preparations
- Tablet: 10 mg
- Intrathecal injection 0.05 mg/ml
Dosing
- The following dosage titration schedule is suggested:
- 5 mg t.i.d. for 3 days
- 10 mg t.i.d. for 3 days
- 15 mg t.i.d. for 3 days
- 20 mg t.i.d. for 3 days
Adverse effects
- Respiratory (panic disorders):
- respiratory depression
- apnea
- dyspnea
- hyperventilation
- acute bronchospasm
- Psychiatric
- paranoia,
- mania
- euphoria,
- depression,
- anxiety,
- psychosis,
- hallucinations,
- paresthesias,
- hysteria, and
- personality disorder
- slurred speech
- nightmares
- confusion
- headache
- memory impairment
- insomnia
- excitement
- Nervous system: Nervous system side effects have been commonly reported following intrathecal injection of baclofen.
- Dizziness, weakness, and fatigue have been reported commonly.
- Akathisia
- ataxia,
- opisthotonos
- nystagmus
- somnolence,
- dystonia
- decreased reflexe
- coma and
- Gastrointestinal:
- Nausea
- Vomiting
- Constipation
- abdominal pain
- diarrhea
- dysphagia
- fecal incontinence
- gastrointestinal hemorrhage, and
- tongue disorder have been reported
- Cardiovascular:
- Hypertension
- Bradycardia
- Orthostatic hypotension
- Genitourinary:
- Urinary frequency have been reported in 2% to 6% of treated patients.
- Enuresis,
- urinary retention,
- dysuria,
- abnormal ejaculation,
- kidney calculus,
- oliguria,
- vaginitis
- impotenc
- inability to ejaculate
- Dermatologic:
- Rash
- Sweating
- Alopecia
- contact dermatitis
- skin ulcer
Drug interactions
Interaction with TCAs may potentiate the effect of baclofen and result in muscle hypotonia
Please update this section.
Contraindications
Hypersensitivity to baclofen
Metabolism
Is cleared from body 85% by kidneys
Pregnancy
Use in pregnancy if you feels that it is absolutely necessary and that the potential benefits justify the unknown risks to patient
Special percussions
- When given intrathecal, toxicity and withdrawals have been reported.
- May potentiate the sedating effects of alcohol and benzodiazepines when given intrathecal
- Monitor individuals with seizure disorders
- Drowsiness, dizziness and fatigue may be reported at the beginning of treatment
- Withdrawal symptoms of discontinuation may present if used for more than a couple of months (auditory hallucinations, visual hallucinations, tactile hallucinations, delusions, confusion, agitation, delirium, disorientation, fluctuation of consciousness, insomnia, dizziness, nausea, feeling faint, inattention, memory impairments, perceptual disturbances, pruritus/itching, anxiety, depersonalization, hypertonia, hyperthermia, formal thought disorder, psychosis, mania, mood disturbances, restlessness, and behavioral disturbances, tachycardia, seizures, tremors, autonomic dysfunction, hyperpyrexia, extreme muscle rigidity resembling neuroleptic malignant syndrome and rebound spasticity)
Note
This document was prepared by the “Mental Health for All” team and was edited by Dr. Siavash Jafari (MDm MHSc, FRCPC, ABAM). This document is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Essentials of Medicine. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.
Note:
This document is prepared by Dr Siavash Jafari, MD, MHSc, FRCPC. This document is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Essentials of Medicine. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.
References:
- Martindale The Extra Pharmacopoeia, 31st ed.,Reynolds, J. E. F., ed., Royal PharmaceuticalSociety (London, UK: 1996), pp. 1515-1516.
- Vacher, C. M., and Bettler, B., GABAB receptors as potential therapeutic targets. Curr. Drug Target
- CNS Neurol. Disord., 2(4), 248-259 (2003).
- Wang, D., et al., Pre- and postsynaptic GABAB receptors modulate rapid neurotransmission from suprachiasmatic nucleus to parvocellular hypothalamic paraventricular nucleus neurons. Neuroscience, 118(1), 49-58 (2003).
- Ferguson, S. C., and McFarlane, S., GABA and development of the Xenopus optic projection.J. Neurobiol., 51(4), 272-284 (2002).
- Takigawa, T., and Alzheimer, C., Interplay between activation of GIRK current and deactivation of Ih modifies temporal integration of excitatory input in CA1 pyramidal cells. J. Neurophysiol., 89(4), 2238-2244 (2003).
- Zhu, Z., and Neirinck, L., Chiral separation and determination of R-(-)- and S-(+)-baclofen in human plasma by high-performance liquid chromatography. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci., 785(2), 277-283.
- Leo, R. J.; Baer, D. (Nov-Dec 2005). “Delirium Associated With Baclofen Withdrawal: A Review of Common Presentations and Management Strategies”. Psychosomatics 46 (6): 503–507.
- Grenier, B.; Mesli, A.; Cales, J.; Castel, J. P.; Maurette, P. (1996). “[Severe hyperthermia caused by sudden withdrawal of continuous intrathecal administration of baclofen]”. Ann Fr Anesth Reanim 15 (5): 659–662.