The following discussion focuses on

The following discussion focuses on several dietary supplements known or suspected of interacting with conventional medications and their purported mecha- nism(s). Each example illustrates some aspect of the complex nature of botanical supplement/drug interactions and the variables, known and unknown, that must be considered when evaluating the likelihood of such interactions.


ST. JOHN’S WORT (HYPERICUM PERFORATUM)

Extracts of H. perforatum have been touted for their antidepressant activity, although the efficacy of many St. John’s Wort products remains questionable.17 Nevertheless, some small clinical trials have demonstrated efficacy comparable to tricyclic antidepressants and the selective serotonin reuptake inhibitors (SSRIs), but with a more favorable short-term safety profile than conventional antidepressive agents.18–20 When used as a single agent, a favorable risk/benefit ratio has made St. John’s Wort one of the most readily consumed dietary supplements in the world.18 In turn, the popularity of St. John’s Wort has also contributed to its distinction as being one of the most problematic dietary supplements with regard to herb–drug interactions.
The preponderance of evidence from case reports and prospective studies clearly indicates that St. John’s Wort reduces the efficacy of conventional medications that are CYP3A4 and/or P-gp substrates (e.g., cyclosporine, digoxin, indinavir, simvas- tatin, oral contraceptives).21–24 Phenotype assessment studies employing the CYP3A4 probe, midazolam, and the 14C-erythromycin breath test confirm that St. John’s Wort extracts induce both intestinal and hepatic CYP3A4 activity.25–28 Further ver- ification comes from Western blot analysis of human duodenal biopsy samples that reveal increased CYP3A4 expression following sustained supplementation with St. John’s Wort.26 Phenotypic trait assessments using digoxin and fexofenadine also indicate that prolonged Hypericum administration induces P-gp and possibly OATP function.26–29 Western blot analysis of human intestinal biopsies26 and flow cytome- try/reverse transcriptase polymerase chain reaction studies on human peripheral blood lymphocytes30 verify that P-gp expression increases severalfold in subjects treated with St. John’s Wort.

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Pembahasan berikut berfokus pada beberapa suplemen diet dikenal atau diduga berinteraksi dengan obat-obatan konvensional dan mereka diakui mecha - nism(s). Setiap contoh menggambarkan beberapa aspek dari sifat kompleks interaksi suplemen/obat botani dan variabel, dikenal dan diketahui, yang harus dipertimbangkan ketika mengevaluasi kemungkinan interaksi tersebut.ST JOHN'S WORT (HYPERICUM PERFORATUM)Ekstrak H. perforatum telah disebut-sebut untuk aktivitas antidepresi mereka, meskipun kemanjuran banyak St John's Wort produk tetap questionable.17 Namun demikian, beberapa uji klinis yang kecil telah menunjukkan kemanjuran dibandingkan dengan antidepresan trisiklik dan inhibitor reuptake serotonin selektif (SSRI), tetapi dengan lebih menguntungkan jangka pendek keselamatan profil daripada konvensional agents.18–20 antidepressive bila digunakan sebagai agen tunggal, rasio risiko/manfaat menguntungkan telah St John's Wort salah satu suplemen makanan paling mudah dikonsumsi di World.18 pada gilirannya, popularitas St John's Wort berkontribusi keunikan sebagai salah satu suplemen diet yang paling bermasalah berkaitan dengan interaksi ramuan-obat.Dominan bukti dari kasus laporan dan calon studi dengan jelas menunjukkan bahwa St John's Wort mengurangi efektivitas obat konvensional yang menghambat CYP3A4 dan/atau P-gp substrat (misalnya, siklosporin, digoksin, indinavir, simvas-tatin, kontrasepsi oral).21-24 fenotipe studi mempekerjakan probe menghambat CYP3A4, midazolam, dan 14C-Eritromisin napas tes mengkonfirmasi bahwa St John's Wort ekstrak menginduksi baik usus dan menghambat CYP3A4 hepatik activity.25–28 lebih lanjut ver-tentang ification yang berasal dari Barat blot analisis manusia duodenum biopsi sampel yang mengungkapkan peningkatan menghambat CYP3A4 ekspresi berikut berkelanjutan suplementasi dengan St John's Wort.26 fenotipik sifat penilaian menggunakan digoxin dan fexofenadine juga menunjukkan yang berkepanjangan Hypericum administrasi menginduksi P-gp dan mungkin OATP function.26–29 Barat blot analisis manusia usus biopsies26 dan aliran cytome-coba/transkriptase reaksi berantai polimerase studi tentang darah perifer manusia lymphocytes30 memverifikasi bahwa meningkatkan ekspresi P-gp severalfold dalam mata pelajaran yang diperlakukan dengan St John's Wort.