What is the maximum dose of gabapentin (Neurontin) for a patient with impaired renal function, specifically a creatinine clearance (CrCl) of 59 mL/min and an estimated glomerular filtration rate (eGFR) of 42 mL/min/1.73m², for the treatment of neuropathy?

From the FDA Drug Label

TABLE 1 Gabapentin Tablets Dosage Based on Renal Function Renal Function Creatinine Clearance (mL/min) Total Daily Dose Range (mg/day) Dose Regimen (mg) ...

30-59 400-1400 200 BID 300 BID 400 BID 500 BID 700 BID

The maximum dose of gabapentin for a patient with a CrCl of 59 and eGFR of 42 for neuropathy is 1400 mg/day. The dose regimen can be 200-700 mg twice a day 1.

From the Research

For a patient with a CrCl of 59 mL/min and eGFR of 42 mL/min/1.73m², the maximum recommended gabapentin dose for neuropathy is 1800 mg per day, divided into three doses (600 mg three times daily). This dose adjustment is necessary because gabapentin is primarily eliminated unchanged through the kidneys, and with this level of renal impairment (mild to moderate), the drug's half-life is extended, increasing the risk of side effects like dizziness, somnolence, and peripheral edema if standard doses are used 2.

Key Considerations

• Start with a lower dose of 300 mg once daily and gradually titrate up over 1-2 weeks to improve tolerability.
• Take doses with food to reduce gastrointestinal side effects.
• Monitor for excessive sedation, dizziness, and edema, especially during dose increases.
• If the patient's renal function worsens, further dose reductions would be necessary.

Rationale

The dosing of gabapentin in patients with renal impairment is critical to avoid adverse effects while maintaining therapeutic efficacy. Studies have shown that the use of estimated glomerular filtration rate (eGFR) and creatinine clearance (CrCl) can help guide dose adjustments in patients with declining renal function 3, 2. However, the choice of equation for estimating renal function can impact the accuracy of dose adjustments, and the Cockcroft-Gault equation may be more suitable for drug dosing adjustments in elderly patients with renal insufficiency 2.

Clinical Context

In the context of diabetic peripheral neuropathic pain management, gabapentin has been compared to other treatments such as duloxetine and pregabalin, showing comparable efficacy and tolerability 4, 5. However, the primary concern in this scenario is the patient's renal function and the need for dose adjustment to prevent adverse effects. By prioritizing the patient's renal function and adjusting the gabapentin dose accordingly, clinicians can minimize the risk of adverse effects while maintaining therapeutic efficacy.