baclofen: clinical use

Prescribing considerations

• Define functional goals and consider whether reducing tone could impair posture, transfers, walking or self-care.
• Increase vigilance in older people and cerebral-origin spasticity, where adverse effects may be more prominent.
• Review psychiatric illness, suicide risk, substance misuse, epilepsy, Parkinson's disease, respiratory disease, cerebrovascular disease and urinary retention.
• Renal impairment substantially increases accumulation and encephalopathy risk.
• Intrathecal therapy requires specialist screening, implantation, programming, aseptic refilling and an emergency plan for interruption.

Contraindications and cautions

• Hypersensitivity to baclofen or product excipients.
• Selected oral products: peptic ulceration.
• Intrathecal products: pharmacoresistant epilepsy and administration by any route other than intrathecal.
• Product-specific excipients may preclude use, including wheat allergy with Lioresal tablets and hereditary fructose intolerance with some sorbitol-containing liquids.

Monitoring

• Clinical benefit, function, muscle tone, sedation, balance and falls risk.
• Renal function and toxicity signs such as somnolence, confusion, myoclonus or reduced consciousness.
• Mood, behaviour, misuse, dependence and suicidal thinking where risk factors are present.
• Seizure control and paradoxical worsening of spasticity.
• Liver tests or blood glucose where relevant.
• For intrathecal treatment: respiratory and cardiovascular status, infection, catheter and pump function, reservoir schedule, withdrawal signs and scoliosis.

Clinical pharmacology

Baclofen is a GABA derivative and GABA-B receptor agonist that suppresses excitatory spinal reflex transmission. Oral baclofen is rapidly absorbed, undergoes little metabolism and is eliminated mainly unchanged by the kidneys; intrathecal delivery produces a spinal effect with lower systemic exposure.

Formulation and product differences

• Oral tablets and liquids are considered bioequivalent; liquids can help people unable to swallow tablets and allow finer measurement.
• Oral liquids differ in concentration, excipients, measuring devices, storage and in-use shelf life; prescriptions should specify the intended product clearly.
• Lioresal tablets contain wheat starch with very low gluten content and are unsuitable for people with wheat allergy.
• Intrathecal products are specialist-only, preservative-free preparations for screening or pump administration and must never be given by another route.

Solution for infusion

Route: Intravenous

Strengths: 0.5 mg/mL, 2 mg/mL

Oral solution

Route: Oral

Strengths: 5 mg/5 mL, 10 mg/5 mL