Rufast 50 ml Oral Solution is an antihistamine medication produced by Opsonin Pharma Ltd. in Bangladesh. It contains Rupatadine Fumarate, a second-generation, long-acting, non-sedating antihistamine that also antagonizes platelet-activating factor (PAF). This dual action helps alleviate allergic symptoms such as sneezing, nasal congestion, itching, and hives.