From the FDA Drug Label
Gabapentin elimination half-life is 5 to 7 hours and is unaltered by dose or following multiple dosing. The half-life of gabapentin is 5 to 7 hours 1.
- The half-life is not affected by the dose or multiple dosing.
- It may be altered in patients with impaired renal function or in elderly patients.
From the Research
The half-life of gabapentin is approximately 5 to 9 hours in patients with normal renal function. This means it takes about 5-9 hours for the concentration of gabapentin in the bloodstream to decrease by half after it has been administered. The drug is primarily eliminated unchanged through the kidneys, which explains why the half-life can be significantly prolonged in patients with renal impairment, as noted in a study published in 2022 2. For those with reduced kidney function, the half-life may extend to 20 hours or longer, requiring dosage adjustments. This relatively short half-life in patients with normal renal function is why gabapentin is typically prescribed to be taken multiple times per day (usually three times daily) to maintain therapeutic blood levels.
Some key points to consider about gabapentin's pharmacokinetics include:
- The elimination half-life is directly related to renal function, with impaired renal function leading to longer half-lives 3, 2.
- Gabapentin is not metabolized and is excreted unchanged in the urine, which simplifies dosage adjustments based on renal function 4.
- In patients with severe renal impairment, such as those on dialysis, the half-life can be significantly prolonged, up to 132 hours, emphasizing the need for careful dose adjustment in these patients 2, 5.
- The drug's pharmacokinetic properties, including its half-life, support the recommendation to taper the dose gradually when discontinuing gabapentin to minimize withdrawal symptoms.
Given the most recent and highest quality evidence, the half-life range of 5 to 9 hours for gabapentin in patients with normal renal function is the most accurate and clinically relevant information for guiding treatment decisions, as supported by the study published in 2022 2.