Posted by Cam W. on November 17, 2001, at 17:44:42
In reply to baclofen, posted by JohnX2 on November 17, 2001, at 7:07:53
John - Lioresal™ (baclophen) has also been shown to have some effect in certain types of neuropathic pain, by inhibiting monosynaptic and polysynaptic reflexes at the spinal level. These effects are probably as result of the drug's ability to hyperpolarize afferent terminals. Baclofen may also have some action at supraspinal sites, which would also contribute to it's clinical effects. I looked into the use of baclophen in neuropathic pain for a presentation that I gave to family physicians. The following is some of what I found.
You are correct in saying that baclofen's use is limited by it's side effect profile. The incidence with which people get side effects from it far outweighs it's minimal therapeutic efficacy, even when used as a muscle relaxant/antispasmotic in those with signs and symptoms of spasticity resulting from multiple sclerosis (it's original indication).
Also, baclophen must be used with caution in people with cormorbid conditions. It is tricky to find an optimal dose in those with impaired renal function (about 85% of the drug is excreted unchanged in urine). People who have had a stroke respond poorly to the drug and generally, baclophen is poorly tolerated in this population. When given to pregnant rats, the fetuses show an increased incidence in abdominal hernias and ossification defects (bones are not properly calcified during their development from cartilage). Baclofen has also been seen to cause deterioration in seizure control in those with epilepsy or those who have a history of convulsive disorders and this needs to be monitored with frequent EEGs (expensive and time consuming over the long run). Exacerbations of bladder sphincter hypertonia (possibly as a result of prostate problems) is also seen with those taking baclophen
Other populations where baclophen must be used with caution are those with peptic ulceration, hepatic problems, elevated blood sugars, respiratory problems, compliance problems and the elderly with cerebrovascular disorders.
Due to baclophen's high incidence of nausea (approx. 10%), as well as it's ability to cause abdominal pain, vomiting, and diarrhea; as well occasionally causing bloody stools (black in color), baclophen should be used with caution in those with peptic ulcers.
Baclophen can cause elevations in AST, alkaline phosphatase, and blood sugar, therefore the drug must be used with caution in those with liver disease, diabetes mellitus, and those who are predisposed to developing type-II diabetes (eg. those who are overweight or are taking olanzapine or clozapine). Baseline and frequent monitoring with appropriate laboratory tests are recommended.
Elderly patients, especially those at risk for, or already have cerebrovascular disorder must be closely monitored while taking baclophen. Palpitations, syncope, and chest pain are seen. Also, elderly patients are more susceptible to the CNS side effects of baclophen. The effects of antihypertensives are increased, resulting ina drop in blood pressure, is commonly seen; requiring a dosage adjustment of the antihypertensive.
Baclophen, especially when combined with other medications that can cause CNS effects, has profound effects sedative effects. This side effect seems to impair daily function, including driving a car or any other activity requiring alertness. TCA, MAOI and benzodiazepine activity, as well as the effects of alcohol and opiates are exacerbated by baclophen. The respiratory depression caused by these medications is also more pronounced.
Patients with psychotic disorders (psychosis, schizophrenia, confusional states, Parkinsonism, etc.) should use baclophen only under close supervision. Baclophen can exacerbate these conditions. This is probably the main reason that baclophen is not used very often in psychiatry.
Euphoria, excitement, confusion, hallucinations slurred speech, muscle incoordination and hypotonia, paresthesia, tremor, ataxia, dystonia are common side effects of baclophen.
Abrupt cessation of baclophen results in a withdrawl syndrome. This is characterized by visual and auditory hallucinations; status epilepticus (convulsions); dyskinesia; confusion; psychotic, manic, and paranoid states; anxiety with tachycardia and swaeting; insomnia; and worsening of spasticity. A slow tapering of the drug, over a 2 or 3 week period, is recommended.
Sorry for the long-winded post, John. I think that the answer to your question should be in here, somewhere ;^)
- Cam
poster:Cam W.
thread:84494
URL: http://www.dr-bob.org/babble/20011113/msgs/84535.html