Pregabalin

Pregabalin, approved in the U.S. in 2004, is the more potent and faster-absorbed of the two main gabapentinoids (the other being gabapentin). It is FDA-approved for nerve pain from diabetes and shingles, spinal-cord-injury pain, fibromyalgia, and as add-on therapy for partial-onset seizures, and is used off-label for generalized anxiety. Unlike gabapentin, it was classified as a federally controlled substance from its release, reflecting recognized abuse potential.

Pregabalin is structurally similar to the neurotransmitter GABA but does not act on GABA receptors. Like gabapentin, it binds the alpha-2-delta subunit of voltage-gated calcium channels in the central nervous system, reducing the release of excitatory neurotransmitters and thereby calming overactive nerve signaling. It is absorbed more efficiently and predictably than gabapentin, which contributes to both its faster onset and its somewhat higher misuse potential.

At therapeutic doses pregabalin causes dizziness, drowsiness, and fluid retention, and is more likely than gabapentin to cause weight gain. When misused at high doses, users report sedation, euphoria, and relaxation. Tolerance develops with sustained heavy use, and misuse frequently occurs alongside opioids to intensify their effects — a pattern documented in people with opioid use disorder taking very large daily doses.

As with gabapentin, the FDA's December 2019 warning flags serious, life-threatening, and fatal respiratory depression, especially when pregabalin is combined with opioids or other CNS depressants or used by people with compromised breathing. Physical dependence can develop, and abrupt discontinuation after regular use produces a withdrawal syndrome that can be severe — anxiety, insomnia, sweating, and body aches — so it must be tapered rather than stopped suddenly. Misuse and dependence risk is greatest in people with existing substance use disorders, particularly opioid use disorder, where high-dose pregabalin dependence and difficult withdrawals are well documented. The label also carries warnings about suicidal thoughts and behavior.