From the FDA Drug Label
The clearance was highly variable in infants <1 year of age. Apparent oral clearance (CL/F) decreased from approximately 190 mL/min to 20 mL/min [see Dosage and Administration (2.3) and Use in Specific Populations (8. 6)]. Coma, resolving with dialysis, has been reported in patients with chronic renal failure who were treated with gabapentin.
Gabapentin and Confusion:
- Gabapentin can cause confusion, especially in patients with impaired renal function, as evidenced by the report of coma in patients with chronic renal failure 1.
- The drug's clearance is decreased in patients with renal impairment, which can lead to increased plasma concentrations and potentially cause adverse effects such as confusion 1.
- Patients with impaired renal function should be closely monitored for signs of gabapentin toxicity, including confusion, and the dose should be adjusted accordingly.
From the Research
Gabapentin can cause confusion, particularly in patients with impaired renal function, and the risk is higher in elderly patients and those with reduced kidney function due to the drug's accumulation in the body, leading to higher blood levels and increased risk of neurological side effects, as supported by the most recent study 2.
Key Points to Consider
- The risk of confusion and other neurological side effects is increased in patients with impaired renal function due to gabapentin's primary elimination through the kidneys.
- Dosage adjustment is typically necessary for patients with creatinine clearance below 60 mL/min, with significant reductions needed for those with severe renal impairment.
- Healthcare providers should start with lower doses (such as 100-300 mg daily) and titrate slowly while monitoring for cognitive effects.
- Patients and caregivers should be advised to report any mental status changes promptly.
- The mechanism behind gabapentin-induced confusion involves its effects on GABA neurotransmission and calcium channels in the brain, which can be amplified when the drug reaches excessive levels due to impaired elimination.
Evidence-Based Recommendations
- According to the study published in 2022 3, starting a gabapentinoid at a higher versus a lower dose was associated with a slightly higher risk of a hospital visit with encephalopathy, a fall, or a fracture or hospitalization with respiratory depression.
- The study published in 2025 2 found that coprescribing gabapentinoids and other psychoactive medications was associated with an increased risk of altered mental status and falls in adults receiving dialysis.
- Therefore, it is recommended to use the lowest effective dose of gabapentin and to monitor patients closely for signs of confusion and other neurological side effects, especially in those with impaired renal function, as supported by the most recent and highest quality study 2.