Pregnancy Risk Category C
How supplied
Tablets: 10 mg, 20 mg, 25 mg‡
Intrathecal injection: 500 mcg/ml, 2,000 mcg/ml
Action
Hyperpolarizes fibers to reduce impulse transmission. Appears to reduce transmission of impulses from the spinal cord to skeletal muscle, thus decreasing the frequency and amplitude of muscle spasms in patients with spinal cord lesions.
Indications & dosage
Spasticity in multiple sclerosis; spinal cord injury--
Adults: initially, 5 mg P.O. t.i.d. for 3 days, then 10 mg t.i.d. for 3 days, 15 mg t.i.d. for 3 days, 20 mg t.i.d. for 3 days. Dosage increase based on response, up to maximum of 80 mg daily.
Management of severe spasticity in patients who don't respond to or can't tolerate oral baclofen therapy--
Adults: screening phase--after test dose to check responsiveness, give drug by an implantable infusion pump. Administer test dose of 1 ml of 50-mcg/ml dilution into intrathecal space by barbotage over 1 minute or more. Significantly decreased severity or frequency of muscle spasm or reduced muscle tone should appear within 4 to 8 hours. If response is inadequate, give second test dose of 75 mcg/1.5 ml 24 hours after the first. If response is still inadequate, give final test dose of 100 mcg/2 ml after 24 hours. Patients unresponsive to the 100-mcg dose shouldn't be considered candidates for implantable pump.
Maintenance therapy--adjust initial dose based on screening dose that elicited an adequate response. Double this effective dose and administer over 24 hours. However, if screening dose efficacy was maintained for 12 hours or more, don't double the dose. After the first 24 hours, increase dose slowly as needed and tolerated by 10% to 30% daily. During prolonged maintenance therapy, daily dose may be increased by 10% to 40% if needed; if patient experiences adverse effects, dosage may be decreased by 10% to 20%. Maintenance doses have ranged from 12 mcg to 2,000 mcg daily; however, experience with dosages over 1,000 mcg daily is limited. Most patients need 300 to 800 mcg daily.
Adjust-a-dose: For patients with impaired renal function, oral and intrathecal dose is decreased.
Adverse reactions
CNS: drowsiness, dizziness, headache, weakness, fatigue, hypotonia, confusion, insomnia, dysarthria, seizures with intrathecal use.
CV: hypotension, hypertension.
EENT: blurred vision, nasal congestion, slurred speech.
GI: nausea, constipation, vomiting.
GU: urinary frequency.
Hepatic: increased AST and alkaline phosphatase levels.
Metabolic: hyperglycemia, weight gain.
Respiratory: dyspnea.
Skin: rash, pruritus, excessive perspiration.
Interactions
Drug-drug. CNS depressants: increased CNS depression. Avoid concomitant use.
Drug-lifestyle. Alcohol use: increased CNS depression. Avoid concomitant use.
Effects on diagnostic tests
None reported.
Contraindications
Contraindicated in patients with hypersensitivity to drug.
Nursing considerations
Patient teaching
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING