We present a comprehensive analysis of all ring systems (both heterocyclic and nonheterocyclic) in clinical trial compounds and FDA-approved drugs. We show 67% of small molecules in clinical trials comprise only ring systems found in marketed drugs, which mirrors previously published findings for newly approved drugs. We also show there are approximately 450 000 unique ring systems derived from 2.24 billion molecules currently available in synthesized chemical space, and molecules in clinical trials utilize only 0.1% of this available pool. Moreover, there are fewer ring systems in drugs compared with those in clinical trials, but this is balanced by the drug ring systems being reused more often. Furthermore, systematic changes of up to two atoms on existing drug and clinical trial ring systems give a set of 3902 future clinical trial ring systems, which are predicted to cover approximately 50% of the novel ring systems entering clinical trials.

中文翻译：

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临床试验和药物中的戒指：现在和未来

我们对临床试验化合物和 FDA 批准的药物中的所有环系统（杂环和非杂环）进行了全面分析。我们显示，临床试验中 67% 的小分子仅包含在已上市药物中发现的环状系统，这反映了先前公布的新批准药物的发现。我们还展示了大约 450 000 个独特的环系统，它们源自合成化学空间中目前可用的 22.4 亿个分子，而临床试验中的分子仅利用了这个可用池的 0.1%。此外，与临床试验中的相比，药物中的环系统更少，但这可以通过更频繁地重复使用的药物环系统来平衡。此外，现有药物和临床试验环系统上多达两个原子的系统变化给出了一组 3902 个未来临床试验环系统，