Burns M
Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical Center Worcester, Massachusetts.
J Thromb Thrombolysis. 1999 Apr;7(2):137-43. doi: 10.1023/a:1008829403320.
Summary. Narrow therapeutic index (NTI) drugs are agents for which small changes in systemic concentration can lead to significant changes in pharmacodynamic response. This may result in potentially subtherapeutic or toxic effects, particularly in patients with advanced age, comorbid illness, or those receiving multiple medications. Bioequivalence among generic and innovator drug products does not always ensure therapeutic equivalence, especially with regard to NTI drugs. Warfarin is a NTI drug for which substitution is now available and may occur routinely without the knowledge of the patient or practitioner. To avoid overanticoagulation or underanticoagulation, the additional cost of patient education and monitoring may actually exceed cost savings by using the less expensive generic drug product. When brand name drug is preferred by the practitioner, "no substition" must be specified on the prescription to avoid mandated generic interchange of warfarin and other NTI drugs.
摘要。窄治疗指数（NTI）药物是指那些全身浓度的微小变化可导致药效学反应显著改变的药物。这可能会导致潜在的治疗不足或毒性作用，尤其是在老年患者、患有合并症的患者或正在接受多种药物治疗的患者中。仿制药和创新药产品之间的生物等效性并不总能确保治疗等效性，尤其是对于NTI药物而言。华法林是一种现在有替代药物且可能在患者或医生不知情的情况下常规发生替代的NTI药物。为避免抗凝过度或不足，患者教育和监测的额外成本实际上可能超过使用较便宜的仿制药产品所节省的成本。当医生更倾向于使用品牌药时，必须在处方上注明“禁止替代”，以避免华法林和其他NTI药物的强制仿制药替换。
