The gabantin 300 is an anti-convulsant drug that helps people with epilepsy control their seizures. Restless legs syndrome (RLS) and some kinds of nerve pain may both be treated with gabantin. The gabantin 100 appears to work by influencing the activity of chemicals called neurotransmitters, which send messages between nerve cells, and altering electrical activity in the brain. Horizant, Gralise, and Neurontin are all brand names for gabapentin. Capsules, tablets, and liquid versions of the medication are available.