Pentamidine is a medication primarily used to treat certain infections caused by parasites, particularly Pneumocystis jirovecii, which can lead to pneumonia in individuals with weakened immune systems, such as those with HIV/AIDS. It can also be used for other conditions, including leishmaniasis, a disease caused by parasites transmitted through sandfly bites. The drug is administered through injection or inhalation, depending on the condition being treated. While effective, pentamidine can have side effects, including low blood pressure and kidney issues, so it is important for patients to be monitored by healthcare professionals during treatment.