Gabapentin cause weight gain
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Gabapentin and Weight Gain: A Comprehensive Review
Introduction to Gabapentin and Weight Gain
Gabapentin, an anticonvulsant and neuropathic pain medication, has been associated with weight gain in some patients. This article synthesizes findings from multiple studies to provide a clear understanding of the relationship between gabapentin and weight gain.
Incidence of Weight Gain with Gabapentin
Clinical Trials and Observations
Several studies have documented weight gain as a side effect of gabapentin. In a review of 44 patients treated with gabapentin for over 12 months, weight gain was observed in a significant number of patients. Specifically, 10 patients gained more than 10% of their baseline weight, and 15 patients gained between 5% to 10% of their baseline weight3. Another study noted that weight gain started between the second and third months of treatment and tended to stabilize after 6 to 9 months, even when the dosage remained unchanged3.
Comparative Studies
In a phase 2 trial comparing gabapentin enacarbil (GEn), a prodrug of gabapentin, with pregabalin and placebo, the incidences of weight gain were lower in the GEn groups compared to pregabalin. The study reported that 0% to 4% of patients on GEn experienced weight gain, depending on the dosage, compared to 8% of patients on pregabalin and 1% on placebo1 2. This suggests that while gabapentin can cause weight gain, it may be less pronounced compared to other similar medications.
Mechanisms Behind Weight Gain
Potential Biological Mechanisms
The exact mechanisms by which gabapentin causes weight gain are not fully understood. However, several hypotheses have been proposed. One theory suggests that gabapentin may lower blood glucose levels, stimulating appetite through effects on the hypothalamus8. Another possibility is that gabapentin enhances gamma-aminobutyric acid (GABA)-mediated neurotransmission, which could increase appetite for carbohydrates and reduce energy expenditure8.
Long-term Safety and Tolerability
A study on the long-term safety of a gastroretentive formulation of gabapentin (G-GR) in patients with postherpetic neuralgia found that the mean weight change over a 24-week period was relatively modest at +0.76 kg. Only 2.5% of patients reported weight gain as an adverse event, indicating that long-term treatment with gabapentin may be associated with minimal weight gain6.
Comparative Analysis with Other Medications
Systematic Reviews and Meta-Analyses
A systematic review and meta-analysis of various drugs associated with weight change found that gabapentin was linked to an average weight gain of 2.2 kg4. This places gabapentin among several other medications known to cause weight gain, such as amitriptyline, mirtazapine, and olanzapine4.
Weight Gain in Anticonvulsants
Gabapentin is not unique in its potential to cause weight gain among anticonvulsants. Other drugs in this category, such as valproic acid, carbamazepine, and pregabalin, are also associated with weight gain7 9. However, some anticonvulsants like lamotrigine and topiramate are either weight-neutral or associated with weight loss, providing alternative options for patients concerned about weight gain7 9.
Conclusion
Gabapentin can cause weight gain in some patients, with the extent of weight gain varying based on dosage and individual patient factors. While the mechanisms behind this side effect are not entirely clear, it is important for healthcare providers to monitor weight changes in patients on gabapentin and consider alternative medications if weight gain becomes a significant concern. Further research is needed to fully understand the biological pathways involved and to develop strategies to mitigate this side effect.
Sources and full results
Most relevant research papers on this topic
Peripheral Edema and Weight Gain in Adult Patients with Painful Diabetic Peripheral Neuropathy (DPN) Receiving Gabapentin Enacarbil (GEn) or Pregabalin Enrolled in a Randomized Phase 2 Trial (I6-1.004)
In a phase 2 study, GEn was associated with lower incidences of peripheral edema and weight gain than pregabalin, with weight gain in GEn-treated patients appearing to be dose-dependent.
RCT
Large Human Trial
Rigorous JournalPeripheral Edema and Weight Gain in Adult Patients with Painful Diabetic Peripheral Neuropathy (DPN) Receiving Gabapentin Enacarbil (GEn) or Pregabalin Enrolled in a Randomized Phase 2 Trial (I6-1.004)
In a phase 2 study, GEn was associated with lower incidences of peripheral edema and weight gain than pregabalin, with weight gain appearing dose-dependent.
RCTLarge Human TrialRigorous JournalChanges in body weight with chronic, high-dose gabapentin therapy.
Chronic, high-dose gabapentin therapy may cause weight gain in some patients, with weight stabilization after 6 to 9 months.
Observational Study
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Gabapentin may cause weight gain in some patients, especially when doses differ from those studied in initial clinical trials.
Observational StudyLong-term Safety of Gastroretentive Gabapentin in Postherpetic Neuralgia Patients
Long-term treatment with a gastroretentive formulation of gabapentin (G-GR) of 1800 mg is well tolerated and associated with little weight gain (1 kg) in postherpetic neuralgia patients.
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Topiramate and zonisamide are both antiepileptic drugs that cause strong weight loss, potentially affecting patients' health.
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