baclofen, B Gablofen, Lioresal

 Indications

PO: Treatment of reversible spasticity due to multiple

sclerosis or spinal cord lesions. IT: Treatment of severe

spasticity of cerebral or spinal origin (should be reserved

for patients who do not respond or are intolerant

to oral baclofen) (should wait at least one year in

patients with traumatic brain injury before considering

therapy). Unlabeled Use: Management of pain in

trigeminal neuralgia.

Action

Inhibits reflexes at the spinal level. Therapeutic Effects:

Decreased muscle spasticity; bowel and bladder

function may also be improved.

Pharmacokinetics

Absorption: Well absorbed after oral administration.

Distribution: Widely distributed; crosses the placenta.

Protein Binding: 30%.

Metabolism and Excretion: 70–80% eliminated

unchanged by the kidneys.

Half-life: 2.5–4 hr.

TIME/ACTION PROFILE (effects on spasticity)

ROUTE ONSET PEAK DURATION

PO hr–wk unknown unknown

IT 0.5–1 hr 4 hr 4–8 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity.

Use Cautiously in: Patients in whom spasticity

maintains posture and balance; Patients with epilepsy

(maypseizure threshold); Renal impairment (pdose

may be required); OB, Lactation: Safety not established;

Pedi: Children 4 yr (intrathecal) (safety not established);

Geri:qrisk of CNS side effects.

Adverse Reactions/Side Effects

CNS: SEIZURES (IT), dizziness, drowsiness, fatigue,

weakness, confusion, depression, headache, insomnia.

EENT: nasal congestion, tinnitus. CV: edema, hypotension.

GI: nausea, constipation. GU: frequency.

Derm: pruritus, rash.Metab: hyperglycemia, weight

gain. Neuro: ataxia. Misc: hypersensitivity reactions,

sweating.

Interactions

Drug-Drug:qCNS depression with other CNS depressants

including alcohol, antihistamines,

opioid analgesics, and sedative/hypnotics. Use

with MAO inhibitors may lead toqCNS depression or

hypotension.

Drug-Natural Products: Concomitant use of

kava-kava, valerian, or chamomile canqCNS depression.

Route/Dosage

PO (Adults): 5 mg 3 times daily. May increase q 3 days

by 5 mg/dose up to 80 mg/day (some patients may have

a better response to 4 divided doses).

PO (Children 8 yr): 30–40 mg daily divided q 8 hr;

titrate to a maximum of 120 mg/day.

PO (Children 2–7 yr): 20–30 mg daily divided q 8

hr; titrate to a maximum of 60 mg/day.

PO (Children 2 yr): 10–20 mg daily divided q 8 hr;

titrate to a maximum of 40 mg/day.

IT (Adults): 100–800 mcg/day infusion; dose is determined

by response during screening phase.

IT (Children 4 yr): 25–1200 mcg/day infusion (average

275 mcg/day); dose is determined by response

during screening phase.

Availability (generic available)

Tablets: 10 mg, 20 mg. Cost: Generic—10 mg

$10.83/100, 20 mg $11.04/100. Intrathecal injection:

50 mcg/mL, 500 mcg/mL, 1000 mcg/mL, 2000

mcg/mL.