Pimonidazole hydrochloride is widely used in biomedical research as a hypoxia marker. It binds selectively to hypoxic cells, which are regions in tissues with low oxygen levels, making it valuable for studying conditions like cancer. In tumors, hypoxic areas are often resistant to radiation and chemotherapy, so identifying these regions helps in developing targeted therapies. Researchers use it to visualize and quantify hypoxia in animal models, aiding in the understanding of tumor biology and treatment efficacy. It is also employed in studying ischemic conditions, such as stroke or heart disease, where oxygen deprivation plays a critical role. Its application extends to evaluating the effectiveness of drugs designed to improve oxygen delivery to tissues.