{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T01:50:19Z","timestamp":1789091419927,"version":"build-2803163510"},"reference-count":57,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T00:00:00Z","timestamp":1742342400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004569","name":"Ministerstwo Edukacji i Nauki","doi-asserted-by":"publisher","award":["NdS-II\/SN\/0270\/2023\/01"],"award-info":[{"award-number":["NdS-II\/SN\/0270\/2023\/01"]}],"id":[{"id":"10.13039\/501100004569","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Chem."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>The term post-cycle therapy (PCT) often appears in bodybuilding forums in the context of anabolic-androgenic steroids (AAS) cessation. To reduce the negative impact of AAS on the hormonal system, unapproved PCT is used, which consist of medications that help restore hormonal balance. The most used medicinal products are selective estrogen receptor modulators (SERMs), aromatase inhibitors (AIs), and preparations containing human chorionic gonadotropin (hCG). These substances are prohibited in sports by the World Anti-Doping Agency.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Between January 2020 and the end of August 2024, 601 samples seized by the police and prosecutor\u2019s office from the illegal market, intended for use as performance-enhancing drugs (PEDs), were tested at the Polish Official Medicines Control Laboratory. Samples were analyzed using accredited methods, including liquid chromatography coupled with high-resolution hybrid mass spectrometry and X-ray powder diffraction, to estimate PCT drug prevalence among other PED samples. In total, 411 (68.4%) samples declaring to contain AAS, 63 (10.5%) declaring to contain substances used in PCT, and 127 (21.1%) other PEDs were tested.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Among the PCT drug samples, 33.3%, 25.4%, and 41.3% indicated the presence of SERMs (tamoxifen and clomiphene), AIs (anastrozole, letrozole, and exemestane), and other substances (hCG, cabergoline, and mesterolone), respectively according to the label. However, not all samples were consistent with the declarations. In 65.1% of the samples, the declared active pharmaceutical ingredients (APIs) were present, whereas in 34.9%, they were not. Furthermore, among the samples in which the declared API was found, 58.7% contained only the declared API, while 6.4% included an additional undeclared API. Conversely, among the samples without the declared API, 20.6% contained neither a declared API nor any API, while 14.3% had other undeclared APIs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>We have shown that illicit drugs used in PCT may be substituted, adulterated, or contain no active ingredients. Our results indicate that in view of the high prevalence of illicit AAS use, the self-administration of unapproved PCT using illegal and falsified medicines is dangerous and can be considered a potential threat to consumer health.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fchem.2025.1536858","type":"journal-article","created":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T12:02:56Z","timestamp":1742385776000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":8,"title":["Illegal and falsified medicines self-administrated in not approved post-cycle therapy after the cessation of anabolic-androgenic steroids \u2013 qualitative analysis"],"prefix":"10.3389","volume":"13","author":[{"given":"Agata","family":"Blazewicz","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Magdalena","family":"Poplawska","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Beata","family":"Daniszewska","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karolina","family":"Piorunska","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michal","family":"Karynski","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,3,19]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"375","DOI":"10.1016\/j.ejmech.2015.08.010","article-title":"Recent developments in steroidal and nonsteroidal aromatase inhibitors for the chemoprevention of estrogen-dependent breast cancer","volume":"102","author":"Ahmad","year":"2015","journal-title":"Eur. 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