Assessing the chiral switch: approval and use of single-enantiomer drugs, 2001 to 2011
Abstract
OBJECTIVES: A "chiral switch" occurs in the pharmaceutical market when a drug made up of 2 enantiomer forms is replaced with a purified single-enantiomer version, often in the context of a patent expiration. We studied the prevalence of chiral switching in the United States over the past decade, including trends in use of, and expenditures on, these products in Medicaid.
STUDY DESIGN: Retrospective analysis.
METHODS: We used US Adopted Names prefixes (lev/levo/ar/es/dex/dextro) to identify all single-enantiomer drugs approved from 2001 to 2011. From publicly available US Food and Drug Administration (FDA) approval documents, we extracted the characteristics of the pivotal premarket trials for the single enantiomers. Specifically, we evaluated whether the single enantiomer was directly compared with the precursor racemic drug and whether there was evidence of superior efficacy. We used quarterly drug expenditure data from each state Medicaid program to chart trends in use of, and spending on, the single-enantiomer products and their racemic precursors during the study period.
RESULTS: From 2001 to 2011, the FDA approved 9 single-enantiomer products: dexlansoprazole, levoleucovorin, levocetirizine, armodafinil, arformoterol, eszopiclone, escitalopram, dexmethylphenidate, and esomeprazole. Of those 9 drugs, 3 had at least 1 pre-approval randomized trial that included the racemic precursor as a direct comparator, but there was no evidence of superiority of the single enantiomer…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
Read the paper
Related studies
- Improving sleep quality leads to better mental health: A meta-analysis of randomised controlled trials
- Tocilizumab in patients with severe COVID-19: a retrospective cohort study
- A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV: A cohort study
- Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study
- Are noise and air pollution related to the incidence of dementia? A cohort study in London, England
- Long COVID symptoms and duration in SARS-CoV-2 positive children — a nationwide cohort study
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.