Baclofen is classified under centrally acting muscle relaxants. This class of drugs bring about the reduction in tone of skeletal muscles and relaxation of these muscles. This action of Baclofen proves advantageous in conditions where muscle spasticity is a prominent feature. These include acute spasms such as those seen in sprains, muscle pulls (overstretching), ligament and tendon tears; and chronic conditions, for e.g. multiple sclerosis, spinal injuries, amyotrophic lateral sclerosis and hemiplegia, paraplegia. The main action of Baclofen is on the spinal cord, which is why it is classified under ‘centrally’ acting agents.
How Baclofen Works: Baclofen is a centrally acting muscle relaxant agent. The structure is similar to the compound GABA (γ-amino butyric acid) which is an inhibitory neurotransmitter in the brain and spinal cord. Baclofen is selective for the GABAB type of receptor. The major action of Baclofen is at the spinal cord level where it depresses both polysynaptic and monosynaptic reflexes. This causes a decrease in the tone of skeletal muscles and effectively treats the spasticity seen in conditions like multiple sclerosis and spinal cord injuries. However Baclofen is less effective when used for spasticity developing after strokes, trauma and in patients of cerebral palsy.
How To Take Baclofen: Baclofen is approved for use in chronic disease with muscle spasm and spastic rigidity like multiple sclerosis, spinal cord trauma, amyotrophic lateral sclerosis, spinal cord tumours and head injuries. Though not very effective in acute conditions, Baclofen can be used in traumatic muscle spasms, ligament and tendon injuries and overstretching of muscles. Due to the presence of other muscle relaxants better suited for this purpose, Baclofen is rarely used in these conditions. Baclofen can be used as an oral formulation of tablets as well as injectable form which has to be used only via intrathecal route of administration. Oral tablets are manufactured in doses of 20 mg and 10 mg. For the above mentioned conditions, Baclofen is started at a dose of 5 mg taken thrice daily after meals. After starting the treatment, the dose is increased by 5 mg per dose in intervals of 3 days to reach a final dose of 20 mg taken three times a day. The maximum permissible dose limit of Baclofen is 80 mg/day. Generally patients do not require more than 60 mg/day and adequate response is achieved with this dosage. The least effective dose of Baclofen is recommended to be used as maintenance if required. Intrathecal administration of Baclofen is through the use of an infusion pump which is surgically implanted, and delivers the drug to the spinal cord, its main area of action. This route is to be used only in patients not responding to regular oral dosage regimens or in those who has experienced intolerable side effects of Baclofen. The direct spinal route of administration of Baclofen decreases the incidence of side effects as the drug is not circulated systemically, and much lower doses can be used. The use of Baclofen must not be discontinued abruptly as withdrawal phenomena have been reported in these circumstances.
Precautions And Side Effects Of Baclofen: Alcohol consumption is prohibited while taking Baclofen since alcohol may potentiate its effects. Operating heavy machinery and driving is also not recommended. Baclofen should be used with caution and in lower doses in patients with renal impairment, hepatic dysfunction, difficulty in micturition, diabetes mellitus, stroke and in those with history of psychiatric illness. Common side effects of Baclofen are drowsiness, nausea, confusion, light-headedness, muscle weakness, tremor, dry mouth, fatigue and tiredness. Rarer side effects of Baclofen are seizures, retention of urine, impotence, visual disturbances and occasionally psychiatric manifestations like hallucinations.