Description

Baclofen inhibits both monosynaptic and polysynaptic reflexes at the spinal level by stimulating the GABAB receptors, which inhibits the release of glutamate and aspartate. It may also act at intraspinal sites producing CNS depression. Baclofen also exerts an antinociceptive effect.

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

The most common adverse reactions associated with Baclofen are transient drowsiness, daytime sedation, dizziness, weakness and fatigue. Central Nervous System: Headache (<10%), insomnia (<10%), and rarely, euphoria, excitement, depression, confusion, hallucinations, paraesthesia, nightmares, muscle pain, tinnitus, slurred speech, co-ordination disorder, tremor, rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic seizures, respiratory depression. Cardiovascular: Hypotension (<10%), rare instances of dyspnoea, palpitation, chest pain, syncope. Gastrointestinal: Nausea (approximately 10%), constipation (<10%) and rarely, dry mouth, anorexia, taste disorder, abdominal pain, vomiting, diarrhoea and positive test for occult blood in stool. Genitourinary: Urinary frequency (<10%) and rarely, enuresis, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, haematuria. Other: Instances of rash, pruritus, ankle oedema, excessive perspiration, weight gain, nasal congestion, visual disturbances, hepatic function disorders and paradoxical increase in spasticity. Muscular hypotonia of a degree sufficient to make walking or movement difficult may occur but is usually relieved by readjusting the dosage. For this purpose, the daytime dosage may be reduced and the evening dosage increased.

Pregnancy category B3. Safe use of Baclofen during pregnancy has not been established. Baclofen crosses the placental barrier. Baclofen should only be administered to pregnant women when in the judgement of the physician concludes that the potential benefits outweigh the possible hazards. Baclofen is excreted in breast milk however evidence to date suggests that the quantities are so small that no undesirable effects on the infant would be expected.

Lower doses (approximately 5 mg per day) should be used for patients with impaired renal function or those undergoing chronic haemodialysis. Patients suffering not only from spasticity but also from psychotic disorders, schizophrenia, depressive or manic disorders or confusional states should be treated cautiously and closely monitored as exacerbations of these disorders may occur. In patients with epilepsy and muscle spasticity, Baclofen may be used under appropriate supervision and provided that adequate anticonvulsive therapy is continued. Lowering of the convulsion threshold may occur and seizures have been reported after the cessation of Baclofen therapy or with overdose. Baclofen should be used with caution in patients with or with a history of peptic ulcers, cerebrovascular diseases, or hepatic, renal or respiratory failure. Careful monitoring of respiratory and cardiovascular function is essential especially in patients with cardiopulmonary disease and respiratory muscle weakness. During treatment with Baclofen, neurogenic disturbances affecting emptying of the bladder may improve. However in patients with preexisting sphincter hypertonia, acute retention of urine may occur. Baclofen should be used with caution in these circumstances. Baclofen has not significantly benefited patients with stroke. These patients have also shown poor tolerance to the medicine. Appropriate laboratory tests should be performed periodically in patients with hepatic diseases or diabetes mellitus to ensure that no medicine induced changes in these underlying diseases have occurred.

Gastric lavage is important in case of severe overdose.

Centrally acting Skeletal Muscle Relaxants