Complex sentence: Gabapentin (Neurontin) is an eponymously named synthetic amino acid that behaves anticonvulsant and analgesic drug; originally developed to treat epilepsy, it is currently also used to relieve neuropathic pain.
Split into simpler sentences: Gabapentin (Neurontin) is an anticonvulsant and analgesic drug. It was originally developed to treat epilepsy, and is currently also used to relieve neuropathic pain.