Gabapentin has become a widely prescribed medication in Australia over the past two decades, primarily used to manage neurological conditions such as refractory focal epilepsy and neuropathic pain. Its increasing use reflects its effectiveness, but also calls for careful consideration regarding dosing, indications, and potential risks.
Approved Uses and Indications
The Australian Therapeutic Goods Administration (TGA) officially approves gabapentin for:
- Refractory focal (partial) epilepsy: Gabapentin is used as an add-on therapy in adults and children over 3 years old who have seizures not fully controlled by other medications.
- Neuropathic pain: This includes nerve-related pain conditions like postherpetic neuralgia and diabetic neuropathy.
Despite these approved uses, gabapentin is often prescribed off-label for other conditions, including chronic nonspecific back pain, restless legs syndrome, fibromyalgia, and anxiety, although evidence supporting these uses is limited.
Dosage Guidelines
Gabapentin dosing varies depending on the condition being treated:
- Neuropathic pain: Treatment usually starts at 100 to 300 mg at night, gradually increasing every 3 to 7 days based on response. Typical effective doses range from 900 mg to 2400 mg daily, divided into three doses, with a maximum of 3600 mg per day.
- Focal seizures: Initial dosing often begins with 300 mg at bedtime on day one, increasing by 300 mg daily to reach maintenance doses between 900 mg and 1800 mg daily in three divided doses. Some patients may require up to 3600 mg daily.
- Restless legs syndrome: Effective doses for gabapentin enacarbil (a related formulation) range from 1200 to 3600 mg daily in divided doses.
Dosing should be individualized, with gradual titration to minimize side effects.
Prescribing Trends and Considerations in Australia
Gabapentin prescriptions have surged in Australia, with over 4 million prescriptions subsidized by the Pharmaceutical Benefits Scheme (PBS) between 2020 and 2021. This increase includes both approved and off-label uses.
Healthcare providers are advised to carefully assess the indication, patient characteristics, and the harm–benefit balance before prescribing gabapentin. Special caution is needed for patients with kidney disease, as gabapentin is primarily excreted by the kidneys and dose adjustments are necessary to avoid toxicity.
Risks and Safety Concerns
While gabapentin is generally well tolerated, concerns have grown regarding:
- Dependence and misuse: Chronic use can lead to dependence, and abrupt cessation may cause withdrawal symptoms such as anxiety, insomnia, nausea, pain, and sweating.
- Nonmedical use: Some effects of gabapentin, like euphoria and sedation, have led to misuse and increased accidental or deliberate poisonings.
- Monitoring: Regular patient monitoring is recommended to assess ongoing benefit and potential harms, with gradual dose tapering advised when discontinuing therapy.
The Therapeutic Goods Administration (TGA) has highlighted these risks and encourages prescribers to use the lowest effective dose for the shortest duration necessary.
Special Populations
- Paediatric use: Gabapentin is listed for use in children over 3 years with epilepsy, often under specialist guidance.
- Renal impairment: Dose adjustments are critical to prevent accumulation and adverse effects.
- Pregnancy and breastfeeding: Use during pregnancy requires careful consideration; breastfeeding is generally considered safe but should be discussed with healthcare providers.
Summary
Gabapentin plays a vital role in managing epilepsy and neuropathic pain in Australia, with established dosing protocols and clear therapeutic indications. However, increasing off-label use and concerns about misuse highlight the need for cautious prescribing and regular patient review. If you are prescribed gabapentin, it’s important to follow your healthcare provider’s instructions closely and communicate any side effects or concerns.