Names and pronunciation
(bak′loe-fen) Gablofen, Lioresal Intrathecal, Lyvispah
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Drug reference
(bak′loe-fen) Gablofen, Lioresal Intrathecal, Lyvispah
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Func. class.: Skeletal muscle relaxant, central acting
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Chem. class.: GABA chlorophenyl derivative
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Do not confuse: baclofen/Bactroban/bacitracin
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ACTION: Inhibits synaptic responses in CNS by stimulating GABAb receptor subtype, which decreases neurotransmit- ter function; decreases frequency, sever- ity of muscle spasms
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USES: Spasticity with spinal cord injury, multiple sclerosis
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Unlabeled uses: Neuropathic pain, tri- geminal neuralgia
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CONTRAINDICATIONS: Hyper- sensitivity, epidural, IM, IV, SUBCUT administration Precautions: Pregnancy, breastfeeding, geriatric patients, peptic ulcer disease, renal/hepatic disease, stroke, seizure dis- order, diabetes mellitus, psychosis, abrupt discontinuation (intrathecal), CNS depressants, especially opiates
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Black Box Warning: Do not discontinue IT abruptly; may be fatal Black Box Warning: Increased respira- tory depression, death—opiates; avoid concurrent use; limit quantity provided Increase: hypotension—antihypertensives Drug/Herb Increase: CNS depression—kava, vale- rian, chamomile Drug/Lab Test Increase: AST, ALT, alkaline phosphatase, blood glucose, CK
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SIDE EFFECTS CNS: Dizziness, weakness, fatigue, drowsiness, headache, disorientation, insomnia, paresthesias, tremors; seizures (IT) CV: Hypotension, bradycardia, flushing, edema EENT: Nasal congestion, blurred vision, tinnitus GI: Nausea, constipation, dry mouth, anorexia, weight gain GU: Urinary frequency, hematuria INTEG: Rash, pruritus RESP: Dyspnea MISC: Hypersensitivity, sweating, hyper- glycemia
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INTERACTIONS Increase: CNS depression—alcohol, tricyclics, opiates, barbiturates, sedatives, hypnotics, MAOIs, antihistamines; increases CNS depression; avoid concurrent use
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TREATMENT OF OVERDOSE: Induce emesis in conscious patient, dialysis, physostigmine to reduce life- threatening CNS side effects
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DOSAGE AND ROUTES Spasticity in multiple sclerosis/ spinal cord injury • Adult/child ≥12 yr: PO 5 mg tid × 3 days, then 10 mg tid × 3 days, then 15 mg tid × 3 days, then 20 mg tid × 3 days, then titrated to response, max 80 mg/ day (20 mg qid); INTRATHECAL use implantable intrathecal infusion pump; use screening trial of 3 separate bolus doses if needed 24 hr apart (50 mcg, 75 mcg, 100 mcg) • Child <8 yr: As above; max 60 mg/day • Child >2-7 yr: PO 10-15 mg/day divided q8hr; titrate q3days by 5-15 mg/ day to max 40 mg/day B • Child: INTRATHECAL initial test dose same as adult; for small children, initial dose of 25 mcg/dose may be used; 25-1200 mcg/day infusion titrated to response in screening phase Neuropathic pain including trigeminal neuralgia (unlabeled) • Adult: PO 10 mg tid, may increase by 10 mg every other day; max 80 mg/day Renal dose • Adult: PO/IT CCr 50-80 mL/min: reduce dose by 33%; CCr 30-50 mL/min: reduce dose by 50%
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Available forms: Tablets 5, 10, 20 mg; IT injection 50 mcg/mL, 500 mcg/mL, 1000 mcg/mL, 2000 mcg/mL; oral gran- ules 5-, 10-, 20-mg packets
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Administer: PO route • With meals for GI symptoms • Store in a tight container at room temperature IT route For screening, dilute to 50 mcg/mL with NaCl for injection (preservative free); give test dose over 1 min; watch for decreasing muscle tone, frequency of spasm; if inad- equate, use 2 more test doses q24hr, those with inadequate response should not receive chronic IT therapy; maintenance infusion via implantable pump of 500- 2000 mcg/mL because individual titration is required, may cause tolerance and need to taper over 2-4 wk and then restart • Do not give IT dose by injection, IV, IM, SUBCUT, epidural
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Assess: • MS: Assess for spasms, spasticity, improvement should occur • Black Box Warning: Abrupt discon- tinuation; serious adverse reactions may occur (intrathecal), may cause spasticity/ rigidity, fever, change in mental status, death • Black Box Warning: Intrathecal: Have emergency equipment nearby; assess test dose and titration; if no response, check pump, catheter for proper functioning, when switching to IT, avoid overdose by discon- tinuing other PO antispasmodic by tapering • B/P, weight, blood glucose, hepatic function periodically • Seizures (IT): for increased seizure activ- ity with seizure disorders; product decreases seizure threshold; EEG in epileptic patients • Withdrawal symptoms: agitation, tachycardia, insomnia, hyperpyrexia • Allergic reactions: rash, fever, respira- tory distress • Severe weakness, numbness in ex- tremities • CNS depression: dizziness, drowsiness
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Evaluate: • Therapeutic response: decreased pain, spasticity, ability to perform ADLs
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • Black Box Warning: IT: Not to discontinue medication quickly; hallucinations, spasticity, tachycardia will occur; product should be ta- pered off over 1-2 wk, especially intrathecal form; teach proper care of IT site • Black Box Warning: Not to take with alcohol, other CNS depressants, opioids • To avoid hazardous activities if drowsi- ness, dizziness occurs; to rise slowly to prevent orthostatic hypotension; if taken with opioids and suppressed breathing, dizziness occurs, request emergency ser- vices • To avoid using OTC medications; not to take cough preparations, antihistamines unless directed by prescriber; to take PO with food or milk • To notify prescriber if nausea, headache, tinnitus, insomnia, confusion, constipation, inadequate or painful urination continues • MS: may require 1-2 mo for full response • Pregnancy/breastfeeding: to notify prescriber if pregnancy is planned or suspected; avoid breastfeeding, pregnancy
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PHARMACOKINETICS IT: Peak 4 hr, duration 4-8 hr, half-life 2 1⁄2-4 hr, PO; 1.5-4 hr IT partially metabolized in liver, excreted in urine (unchanged), protein bind- ing 30%; CSF levels with plasma levels 100× that of the oral route
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• Adult/child ≥12 yr: PO 5 mg tid × 3 days, then 10 mg tid × 3 days, then 15 mg tid × 3 days, then 20 mg tid × 3 days, then titrated to response, max 80 mg/ day (20 mg qid); INTRATHECAL use implantable intrathecal infusion pump; use screening trial of 3 separate bolus doses if needed 24 hr apart (50 mcg, 75 mcg, 100 mcg)
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• Adult: PO 10 mg tid, may increase by 10 mg every other day; max 80 mg/day Renal dose
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• Adult: PO/IT CCr 50-80 mL/min: reduce dose by 33%; CCr 30-50 mL/min: reduce dose by 50%
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