gabapentin: clinical use

Prescribing considerations

• Confirm a licensed indication, agree treatment goals and periodically review benefit and continued need.
• Assess renal function and clinically important deterioration.
• Assess respiratory disease, frailty, neurological disease and concurrent CNS depressants, particularly opioids.
• Discuss dependence, addiction, tolerance and withdrawal, including eventual discontinuation.
• Review previous substance or medicine misuse and monitor for signs of misuse.
• Use caution in mixed seizure disorders with absence seizures and in myasthenia gravis.
• Avoid abrupt withdrawal, particularly when treating epilepsy.

Contraindications and cautions

• Hypersensitivity to gabapentin or any excipient in the selected product.

Monitoring

• Clinical response, adverse effects and ongoing need
• Renal function where impairment is present or likely to change
• Sedation, falls and respiratory depression in higher-risk patients
• Mood, suicidal thoughts and behavioural change
• Severe skin or systemic hypersensitivity reactions
• Dependence, misuse and withdrawal symptoms
• Infant feeding, alertness and weight gain during breastfeeding when applicable

Clinical pharmacology

Gabapentin binds the alpha-2-delta subunit of voltage-gated calcium channels. It is not appreciably protein-bound or metabolised, does not induce hepatic drug-metabolising enzymes, and is excreted unchanged by the kidneys. Absorption is non-linear; routine plasma concentration monitoring is not generally required.

Formulation and product differences

• Products include film-coated tablets, hard capsules and oral solutions; check product-specific administration instructions and excipients.
• Selected oral solutions contain propylene glycol, parabens, sodium and potassium, which may matter in young children, pregnancy or breastfeeding, renal or hepatic disease, and controlled electrolyte diets.
• The Brown & Burk oral solution is sugar-free and has product-specific instructions for compatible NG or PEG tubes; do not extrapolate these to other liquids.
• Oral solutions require an appropriate measuring device and have product-specific storage and after-opening requirements.
• Some tablets are scored and divisible, but capsules should be swallowed whole.

Capsule

Route: Oral

Strengths: 100 mg, 300 mg, 400 mg

Oral solution

Route: Oral

Strengths: 50 mg/mL

Tablet