Gabapentin Enacarbil and Butorphanol Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Gabapentin Enacarbil
Butorphanol Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of respiratory depression
Interaction Deep Dive
Concomitant use of gabapentin and other CNS depressants has resulted in serious, life-threatening, or fatal respiratory depression. If gabapentin is coadministered with another CNS depressant, especially with an opioid and in patients with underlying respiratory impairment, monitor for symptoms of respiratory depression and sedation, and consider initiating gabapentin at a low dose. Manage respiratory depression with close observation, supportive measures, and reduction or withdrawal of CNS depressants (including gabapentin)1.
Why it happens (mechanism)
Additive CNS depression
Literature reports
3 reports — tap to read
a) According to the FDA Adverse Event Reporting System (FAERS) database, between January 1, 2012 and October 26, 2017, 49 cases of respiratory depression occurred with gabapentinoids (gabapentin n=15; pregabalin n=34). A respiratory risk factor, including age-related loss of lung function or the use of a CNS depressant, was reported in 92% of cases. Twelve deaths occurred (24%) and all deaths reported at least 1 respiratory risk factor. Small, randomized trials of healthy volunteers have demonstrated that gabapentinoids alone and in combination with opioids depress respiratory function. End-tidal CO(2) increased with additive effect with exposure to pregabalin plus remifentanil, and hourly apneic episodes were more frequent during gabapentin exposure than placebo exposure. Observational studies suggest an increased risk of postoperative respiratory depression with the use of preoperative gabapentinoids compared with no preoperative gabapentinoid exposure 2.
b) Increased somnolence or sedation, dizziness, and nausea occurred per visual analog scale measurement when a single gabapentin enacarbil 600 mg dose was given 2 hours after a single 60 mg dose of morphine sulfate extended-release was administered to 18 subjects compared to the agents alone. No changes in Cmax or AUC of gabapentin, morphine, or morphine's active metabolite occurred 3.
c) In a study of 12 volunteers, a single oral dose of 60 mg controlled-release morphine was administered 2 hours prior to a single oral dose of 600 mg immediate-release gabapentin. The mean gabapentin AUC value in these patients was 44% greater compared with administration of gabapentin alone. The pharmacokinetics of morphine were not altered 45.
Common questions
Can I take Gabapentin Enacarbil and Butorphanol Injection together?
An increased risk of respiratory depression Always confirm with your pharmacist or prescriber before making any change.
How serious is the Gabapentin Enacarbil and Butorphanol Injection interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Gabapentin Enacarbil or Butorphanol Injection need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (5)
- Product Information: HORIZANT(R) oral extended-release tablets, gabapentin enacarbil oral extended-release tablets. Azurity Pharmaceuticals, Inc. (per FDA), Woburn, MA, 2025. DailyMed
- US Food and Drug Administration (FDA): Drug Safety Communications: FDA warns about serious breathing problems with seizure and nerve pain medicines gabapentin (Neurontin, Gralise, Horizant) and pregabalin (Lyrica, Lyrica CR) when used with CNS depressants or in patients with lung problems. US Food and Drug Administration (FDA). Silver Spring, MD. 2019.
- Product Information: HORIZANT(R) oral extended-release tablets, gabapentin enacarbil oral extended-release tablets. GlaxoSmithKline (per FDA), Research Triangle Park, NC, 2013. DailyMed
- Product Information: Neurontin(R) oral capsules, tablets, solution, gabapentin oral capsules, tablets, solution. Parke-Davis, New York, NY, 2010.
- Product Information: GRALISE(R) oral tablets, gabapentin oral tablets. Abbott Laboratories, North Chicago, IL, 2011.
Keep reading about Gabapentin Enacarbil
Keep reading about Butorphanol Injection
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