Although it currently is not a controlled substance, gabapentin increasingly is being misused in ways similar to opioid abuse. First . Food and Drug Administration (FDA) approved to be taken in combination with other drugs for treating epileptic seizures, it also has an indication to treat postherpetic neuralgia (PHN), the nerve pain that persists after having shingles. Gabapentin misuse appears to be most common among individuals already misusing alcohol or other drugs. Some use it to enhance effects from methadone, opioids or heroin; others claim that high doses provide feelings of excitement, sociability and/or tranquility. Both gabapentin and its follow-on, Lyrica® (pregabalin - Pfizer), are analogs of gamma-aminobutyric acid (GABA). An inhibitory neurotransmitter that slows down nerve impulses, GABA generally has relaxing effects. Lyrica, already classed as a C-V controlled substance, has FDA approvals for treating seizures, fibromyalgia and PHN. Both drugs are used off-label for a number of other conditions, including some anxiety disorders. In the ., pregabalin is sold only as the brand; but gabapentin has been available generically since 2004. It also is marketed as the brands Neurontin® (Pfizer), Gralise® (Depomed) and Horizant® (gabapentin enacarbil - Arbor Pharmaceuticals). Recently, authorities in the United Kingdom began action to reclassify gabapentin-type drugs as controlled, and some . states have begun tracking gabapentin and pregabalin prescriptions for signs of misuse.