The present invention relates to pyrimidine derivatives of Formula (Ia) and(Ib)(including tautomers, isomers, prodrugs, and pharmaceutically acceptable saltsthereof).Said compounds are useful in the treatment of pain (such as neuropathic pain),inflammation, and epilepsy (by acting as anticonvulsants). Methods of medicaltreatment making use of said compounds, as well as additional compounds ofFormula(IIa) and (IIb), are also disclosed.(see formula IIa and IIb)