Cladribine (Latin Cladribinum) is a synthetic drug that is an analogue of purine bases in its chemical structure. Cladribine is used both intravenously and subcutaneously, and orally. Cladribine was first synthesized in the USA in the 1980s, and in clinical trials it showed effectiveness in hairy cell leukemia. Cladribine was first approved by the FDA in 1993 as