Imidazopyridazine is a heterocyclic compound containing fused imidazole and pyridazine rings. The fusion of these two heterocyclic rings can yield three different isomers, namely imidazo[4,5-c]pyridazine and imidazo[4,5-d]pyridazine, both of which contain two nitrogen atoms in each ring. A third possible structure is imidazo[1,2-b]pyridazine, in which one nitrogen atom is shared between the imidazole and pyridazine rings (and hence contains one less nitrogen atom and therefore is non-isomeric). Ponatinib, a medication used to treat chronic myeloid leukemia, contains an imidazo[1,2-b]pyridazine substructure. Examples of experimental drugs containing this ring system include darigabat (an imidazo[4,5-c]pyridazine), as well as GBLD-345 and SRI-42127 (both imidazo[1,2-b]pyridazines).
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