Medicinal chemistry is a scientific discipline of chemistry and pharmacology. Isoxazole is an azole with an oxygen atom next to the nitrogen. It is also the class of compounds containing this ring. Isoxazolyl is the univalent radical derived from isoxazole. Isoxazole rings are found in some natural products, such as ibotenic acid and muscimol. Isoxazoles also form the basis for a number of drugs, including the COX-2 inhibitor valdecoxib and a neurotransmitter agonist AMPA. An isoxazolyl group is found in many beta-lactamase-resistant antibiotics, such as cloxacillin, dicloxacillin and flucloxacillin. Leflunomide is an isoxazole-derivative.The work on new isoxasole derivatives are establish how a substance operates in the body and its suitability for use as a drugs.