Gabapentin 300 mg (Neurontin, Gralise, Horizant) is a medicine used to treat partial seizures, nerve pain from shingles and restless leg syndrome. It works on the chemical messengers in your brain and nerves. Gabapentin 300 mg is from a group of medicines called anticonvulsants. Different brands of gabapentin 300 mg are not interchangeable and they are FDA a...