1.1. Adults
Gabapentin (Neurontin®, Gralise®) is FDA-approved for use in adults with postherpetic neuralgia pain and as adjunctive therapy for managing partial seizures with or without secondary generalization in epileptic patients.1-6 Gabapentin enacarbil (Horizant®) has been FDA-approved for management of moderate-to-severe restless legs syndrome (RLS) in adults, and is also approved for pain reduction in postherpetic neuralgia (PHN).1-4, 7 Gralise® and Horizant® are not interchangeable with Neurontin® and available generics due to differing chemical forms and pharmacokinetic properties. Maximum recommended adult dosages are summarized in Table 11-7. The maximum time interval between gabapentin immediate-release doses should not exceed 12 hours. Patient profiles containing doses that exceed the maximum recommended dose will be reviewed1-15.
While not FDA-approved, gabapentin has also been evaluated in adult clinical trials for use in neuropathic pain, fibromyalgia, and vasomotor symptoms with favorable results1-3.
Table 1: Maximum Recommended Adult Gabapentin Dosages
Treatment Indication | Drug Name | Dosage Form/Strength | Maximum Recommended Dosage |
---|---|---|---|
Partial seizures with/without secondary generalized tonic-clonic seizures | gabapentin (Neurontin®, generics) | 100 mg, 300 mg, 400 mg immediate-release (IR) capsules 600 mg, 800 mg IR tablet 250 mg/5 mL, 300 mg/ 6 mL oral solution | 2400 mg/day (in three divided doses*) |
Postherpetic neuralgia-associated neuropathic pain | gabapentin (Neurontin®, generics) | 100 mg, 300 mg, 400 mg IR capsules 600 mg, 800 mg IR tablet 250 mg/5 mL, 300 mg/ 6 mL oral solution | 3600 mg daily in divided doses+ |
Postherpetic neuralgia-associated neuropathic pain | gabapentin (Gralise®) | 300 mg, 600 mg extended-release (ER) tablets | 1800 mg once daily |
Postherpetic neuralgia-associated neuropathic pain | gabapentin enacarbil (Horizant®) | 300 mg, 600 mg ER tablet | 1200 mg daily in two divided doses |
Restless legs syndrome | gabapentin enacarbil (Horizant®) | 300 mg, 600 mg ER tablet | 600 mg daily at 5 pm^ |
Legend:
- *Doses of 3600 mg/day have also been well tolerated in small numbers of patients for abbreviated treatment durations.
- +Doses up to 3600 mg/day have been administered with therapeutic effect; however, additional benefit with doses greater than 1800 mg/day may not be observed.
- ^Gabapentin enacarbil doses up to 1200 mg daily have been used in clinical trials with no additional benefit and increased adverse reactions.