哌甲酯(英语：Methylphenidate)，商品名利他林(英语：Ritalin)，是一种中枢神经兴奋剂，被广泛应用于注意力缺陷多动障碍和嗜睡症的治疗。哌甲酯在1948年由CIBA（后被诺华公司收购）研制，它被用于治疗注意力缺陷多动障碍而在1955年获得FDA的销售许可，并在之后的几十年内成为医治该症的临床一线药物。

注意力缺陷多动障碍的病因可能与多巴胺、去甲肾上腺素和谷氨酸有关。这些物质决定了大脑的自我约束功能，并影响着人的注意力、控制力、行为、动机和执行能力。哌甲酯的作用便是抑制去甲肾上腺素和多巴胺的再摄取，使这些神经递质的浓度和强度大幅提高。哌甲酯和可卡因在结构和药理上有相似之处，但哌甲酯的效力低于后者，药效长于后者。

Methylphenidate, sold under various trade names, Ritalin being one of the most commonly known, is a central nervous system (CNS) stimulant of the phenethylamine and piperidine classes that is used in the treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy. The original patent was owned by CIBA, now Novartis Corporation. It was first licensed by the U.S. Food and Drug Administration (FDA) in 1955 for treating what was then known as hyperactivity.