Baclofen chemical structure
Find information on thousands of medical conditions and prescription drugs.

Baclofen

Baclofen (brand names Kemstro® and Lioresal®) is a derivative of gamma-aminobutyric acid, and is an agonist specific to mammalian but not fruit fly (Drosophila) GABAB receptors. It is used for the treatment of spastic movement, especially in instances of spinal cord injury and in multiple sclerosis. Its beneficial effects result from actions at spinal and supraspinal sites. Baclofen can also be used to treat hiccups. more...

Home
Diseases
Medicines
A
B
Baciim
Bacitracin
Baclofen
Bactrim
Bactroban
Barbexaclone
Barbital
Baros
Basiliximab
Baycol
Beclamide
Beclometasone
Beclovent
Beconase
Beldin
Benadryl
Benazepril
Bendroflumethiazide
Benserazide
Bentiromide
Benylin
Benzaclin
Benzalkonium chloride
Benzocaine
Benzonatate
Betacarotene
Betadine
Betahistine
Betamethasone
Betaxolol
Bextra
Biaxin
Bibrocathol
Bicalutamide
Bicillin
Biclotymol
Biotin
Bisoprolol
Bleomycin
Blocadren
Boldenone
Boniva
Bontril
Bosentan
Bravelle
Brethaire
Brevibloc
Brevicon
Bricanyl
Bromazepam
Bromelain
Bromhexine
Bromocriptine
Brompheniramine
Bronkodyl
Bronopol
BSS
Bucet
Budesonide
Bumetanide
Bupivacaine
Buprenex
Buprenorphine
Buserelin
Buspar
Buspirone
Busulfan
Butalbital
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z

Description of compound

Baclofen is a white to off-white, odorless or practically odorless crystalline powder, with a molecular weight of 213.66. It is slightly soluble in water, very slightly soluble in methanol, and insoluble in chloroform.

Routes of administration

Baclofen can be administered either orally or intrathecally (directly into the spinal fluid). Intrathecal administration is often indicated in spasticity patients, as very little of the oral dose actually reaches the spinal fluid.

Intrathecal administration is particularly used in patients with multiple sclerosis who have severe painful spasms which are not controllable by oral baclofen. A test dose is given to assess the effect, and if successful a chronic intrathecal catheter in inserted and connected to a computer-controlled implanted pump. The reservoir in the pump can be replenished by percutaneous injuection. These pump systems are quite sophisticated and expensive so careful patient selection is required.

History

Historically Baclofen was designed to be a drug for epilepsy in the 1920’s, and was derived from diazepam (Valium©). The effect on epilepsy was disappointing but it was found that in certain patients spasticity decreased. Baclofen was and is still given orally with variable effects. In the severely affected children, the oral dose is so high that side effects appear and the treatment loses its benefit. How and when Baclofen came to be used in the spinal sack is not really clear but this is now an established method for the treatment of spasticity in many conditions.

How Baclofen works

Baclofen has its effect in the spinal cord, which is the main connection between the brain and then rest of the body. The spinal cord is a reflex system, a feedback loop. The most obvious reflex is the withdrawal to heat. This movement is brisk and not very well controlled. This is what happens in Cerebral Palsy. Without adequate control from the brain, every movement is like a reflex, being rough and uncontrolled. The reflex can spread through the body causing spasms or “arching”. These spasms can be painful and interrupt sleep.

Baclofen works on this reflex circuit. The reflex circuit in the spinal cord contains the Renshaw cells. These cells are very sensitive to a natural chemical produced by the nervous system: GABA, gamma-amino-butyric-acid. GABA slows the reflex circuit down and Baclofen acts like GABA. The dose of intrathecal Baclofen necessary to slow down the reflex circuit is variable but is generally one thousand times smaller than the oral dose.

Pharmacokinetics

The drug is rapidly absorbed after oral administration and is widely distributed throughout the body. Biotransformation is low and the drug is predominantly excreted in the unchanged form by the kidneys.

Read more at Wikipedia.org


[List your site here Free!]


Baclofen and Esophageal Reflux in Healthy Persons
From American Family Physician, 5/15/00 by Richard Sadovsky

The principal cause of esophageal reflux in healthy persons and in patients with reflux disease is transient relaxation of the lower esophageal sphincter (LES). Factors that control the rate of LES relaxations and the occurrence of reflux during transient LES are not well understood. Gastric distention is one known stimulus and appears to be the main reason that episodes of reflux increase after meals. The medullary brain-stem centers are thought to be involved in triggering LES relaxations, and inhibiting this triggering mechanism may reduce the frequency of reflux episodes. g-Aminobutyric acid (GABA) is an important inhibitory neurotransmitter that plays a role in swallowing control, esophageal motility and respiration. Because there is a close relationship between respiration and swallowing, GABA agonists might inhibit the triggering mechanism of transient LES relaxations. Baclofen, a GABA-receptor agonist, has been shown to inhibit transient LES relaxations and gastrointestinal reflux in dogs and ferrets, but there are no data about its effectiveness in humans. Lidums and associates evaluated the effects of baclofen on LES function and gastrointestinal reflux in healthy subjects.

Twenty healthy persons with no gastrointestinal symptoms or conditions that would influence esophageal motor function underwent initial manometric measurement of LES pressure and esophageal pH. Subjects were randomized to receive oral baclofen (40 mg) or a placebo on separate days at least one week apart. Sixty minutes after drug administration, a similar meal was given to each person and, after the meal, esophageal manometry and pH were measured for three hours. In addition, sensations of fullness, nausea, hunger and other perceptions were measured at baseline and again at 60-minute intervals. Baseline blood samples were obtained for plasma levels of baclofen and growth hormone.

Baclofen significantly reduced the rate of transient LES relaxations from a median of 5.7 per hour to 2.2 per hour. The reduction was sustained for each of the three postprandial hours. However, baclofen had no effect on the likelihood of acid reflux occurring during a transient LES relaxation. Baclofen also significantly reduced the rate of reflux episodes from a median of 1.0 per hour to 0.3 per hour, but this effect was significant only in the first postprandial hour. Persons taking baclofen had an increased growth hormone level, which peaked 90 minutes after dosing. Symptom scores did not differ significantly among subjects. Baclofen had no effect on blood pressure or heart rate.

The authors conclude that controlling reflux by controlling the rate of transient LES relaxations may be a useful way to manage reflux disease. Baclofen appeared to reduce LES relaxation rate, increase basal LES pressure and reduce the number of reflux episodes in healthy persons. Further study of the effectiveness of GABA agonists in patients with reflux disease is now needed.

RICHARD SADOVSKY, M.D.

Lidums I, et al. Control of transient lower esophageal sphincter relaxations and reflux by the GABAB agonist baclofen in normal subjects. Gastroenterology January 2000;118:7-13.

COPYRIGHT 2000 American Academy of Family Physicians
COPYRIGHT 2000 Gale Group

Return to Baclofen
Home Contact Resources Exchange Links ebay