Cladribine, also known as Leustatin, is a synthetic anti-cancer drug used to treat hairy cell leukemia and multiple sclerosis, functioning as a purine analog that inhibits adenosine deaminase. It is distinguished by its minimal side effects, targeting mainly blood cells while preserving normal cell integrity. For optimal efficacy, cladribine must be stored at -20°C and is subject to specific return policies regarding damaged or incorrectly ordered goods.