Gabapentin and pregabalin (gabapentinoids) are alpha-2-delta ligands widely prescribed for neuropathic pain and seizures. They are not opioids and do not appear on standard drug panels, but they carry misuse potential, particularly among people who also use opioids, and are increasingly included in medication-monitoring programs.1
Gabapentin prescribing rose from an estimated 44 million prescriptions in 2013 to 68 million by 2017, making it one of the most prescribed medications in the US.2 The FDA has flagged gabapentinoids as a potential emerging concern,3 and misuse prevalence among people who use opioids is substantially higher than in the general population.1
Gabapentin and pregabalin are not detected by standard immunoassays and are measured by targeted LC-MS/MS. Because both are eliminated largely unchanged at high doses, urinary concentrations are very high, often exceeding 100,000 ng/mL.4 Levels confirm recent use but do not establish the dose or whether the medication was taken as prescribed.
Confirms recent gabapentinoid use. Detection indicates use within roughly 1 to 2 days for gabapentin and 1.5 to 2 days for pregabalin.
Very high levels are expected. Because these drugs are excreted largely unchanged, urinary levels commonly exceed 100,000 ng/mL and do not indicate misuse by themselves.4
Does not confirm adherence. A positive result does not establish the dose taken or that it was used as prescribed.
May indicate non-adherence. In a prescribed patient, absence can reflect missed doses, PRN use, or a regimen or interaction problem.
Not on routine panels. Standard screens do not include gabapentinoids; only targeted testing detects them.
Timing and cutoff. Absence may also reflect timing of last use or levels below the cutoff.
Gabapentinoid analytes measured on definitive testing.
| Metabolite | Clinical Significance |
|---|---|
| Gabapentin | Excreted largely unchanged; urine detection about 1 to 2 days. |
| Pregabalin | Also excreted largely unchanged; urine detection about 1.5 to 2 days. |