Baclofen is an effective muscle relaxant and antispastic agent with a spinal site of action. Baclofen is structurally similar to the inhibitory neurotransmitter gamma-amino-butyric acid, though its actions are different. It binds stereospecifically to GABA-B receptors. It is thought that activation of the GABA-B receptors on presynaptic terminal reduces evoked transmitter release, perhaps through reduced presynaptic Ca2+ influx. Baclofen can inhibit the function of inward calcium currents in some cells. The drug is rapidly absorbed after oral administration and is widely distributed throughout the body.
Adult: The determination of optimal dosage requires individual titration. 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
Thereafter additional increases may be necessary but the total daily dose should not exceed a maximum of 80 mg daily (20 mg q.i.d.). The lowest dose compatible with an optimal response is recommended.
Children: Treatment should be started at a very low dose, e.g., 0.3 mg/kg per day in divided (preferably 4) doses. The dosage should be raised cautiously at 1-2 week intervals until it is sufficient for the child’s individual needs. The usual dosage range for maintenance therapy is 0.75 to 2 mg/kg body weight per day. In children aged over 10 years a maximum daily dose of 2.5 mg/kg body weight may be given.