this is true for severe depression or for longer than 12 weeks. supplement strength varies by manufacturer and possibly by batch. with antidepressants, one "may have to try a few before finding what works best," notes the united states national library of medicine. in china, st. john's wort combined with eleutherococcus senticosus is sold as an antidepressant under the name shugan jieyu jiaonang (chinese: 舒肝解郁胶囊; pinyin: shūgān jiěyù jiāonáng; lit. 'liver soothing depression relief capsules'), according to the pharmacopoeia of the people's republic of china. the pharmacopoeia states in chinese that it is used "for mild and moderate unipolar depression". phytochemicals and dietary supplement st john's wort, similarly to other herbs, contains different phytochemical constituents. although st. john's wort is sold as a dietary supplement, there are no standardized manufacturing procedures, and some marketed products may be contaminated with metals, fillers or other impurities.comparison of selected chemical constituents of hypericum perforatum compoundconc.log ppsapkaformulamwcyp1a2cyp2c9cyp2d6cyp3a4pgpt1/2 (h)tmax (h)cmax (mm)css (mm)notes/biological activity phloroglucinols (2–5%) adhyperforin0.2–1.910–1371.48.51c36h54o4550.81 ? ? ? ? ? ? ? ? ? ? hyperforin2–4.59.7–1371.48.51c35h52o4536.78++/-–++3.5–162.5–4.415-23553.7– naphthodianthrones (0.03-3%) hypericin0.003-37.5–101566.9±0.2c30h16o8504.440– (3.4 μm)– (8.5 μm)– (8.7 μm) ?2.5–6.56–480.66-46 ? ? pseudohypericin0.2–0.236.7±1.81767.16c30h16o9520.44 ? ? ? ? ?24.8–25.431.4–160.6–10.8– flavonoids (2–12%) amentoflavone0.01–0.053.1–5.11742.39c30h18o10538.46 ?– (35 nm)– (24.3 μm)– (4.8 μm) ? ? ? ? ? ? apigenin0.1–0.52.1±0.56876.63c15h10o5270.24 ? ? ? ? ? ? ? ? ? ? catechin2–41.8±0.851108.92c15h14o6290.27 ? ? ? ? ? ? ? ? ? ? epigallocatechin ?−0.5–1.51318.67c15h14o6290.27 ? ? ? ? ?1.7±0.4a1.3–1.6a ? ? ? hyperoside0.5-21.5±1.71746.17c21h20o12464.38 ? ? ? ? ? ? ? ? ? kaempferol ?2.1±0.61076.44c15h10o6286.24 ? ? ?+/- ? ? ? ? ? ? luteolin ?2.4±0.651076.3c15h10o6286.24– ? ? ? ? ? ? ? ? ? quercetin2–42.2±1.51276.44c15h10o7302.24– (7.5 μm)b– (47 μm)b– (24 μm)b– (22 μm)b–20–72c8c ? ? ? rutin0.3–1.61.2±2.12666.43c27h30o16610.52 ? ? ? ? ? ? ? ? ? ? phenolic acids (~0.1%) caffeic acid0.11.4±0.477.83.64c9h8o4180.16 ? ? ?– ? ? ? ? ? ? chlorogenic acid<0.1%-0.36±0.431653.33c16h18o9354.310000 ? ? ? ? ? ? acronyms and symbols acronym/symbolmeaning mwmolecular weight in g•mol−1. pgpp-glycoprotein t1/2elimination half-life in hours tmaxtime to peak plasma concentration in hours cmaxpeak plasma concentration in mm csssteady state plasma concentration in mm log ⁡ p partition coefficient. psapolar surface area of the molecule in question in square angstroms (å2). obtained from pubchem conc.these values pertain to the approximation concentration (in %) of the constituents in the fresh plant material –indicates inhibition of the enzyme in question. +indicates an inductive effect on the enzyme in question. 0no effect on the enzyme in question. 5-ht5-hydroxytryptamine – synonym for serotonin. dadopamine nenorepinephrine gabaγ-aminobutyric acid gluglutamate glyglycine chcholine a ? b ? c ? notes: in brackets is the ic50/ec50 value depending on whether it is an inhibitory or inductive action being exhibited, respectively. as with last note values given in brackets are ic50/ec50 depending on whether it's an inhibitory or inductive action the compound displays towards the biologic target in question. if it pertains to bacterial growth inhibition the value is mic50 interactions besides its allergenic effects, st john's wort can interfere (in potentially life-endangering ways) with the effects of many prescription drugs, including the anti-psychotics risperidone and 9-hydroxyrisperidone (i.e. paliperidone, xeplion or invega), cyclosporine, digoxin, hiv drugs, cancer medications including irinotecan, and warfarin. combining both st john's wort and antidepressants could lead to increased serotonin levels causing serotonin syndrome. it should not be taken with the heart medication ranolazine. combining estrogen-containing oral contraceptives with st john's wort can lead to decreased efficacy of the contraceptive and, potentially, unplanned pregnancies. consumption of st john's wort is discouraged for those with bipolar disorder, schizophrenia or dementia, and for people using dietary supplements, headache medicine, anticoagulants, and birth control pills. pharmacodynamics st john's wort has been shown to cause multiple drug interactions through induction of the cytochrome p450 enzymes cyp3a4 and cyp1a2. this drug-metabolizing enzyme induction results in the increased metabolism of certain drugs, leading to decreased plasma concentration and potential clinical effect. the principal constituents thought to be responsible are hyperforin and amentoflavone. there is strong evidence that the mechanism of action of these interactions is activation of the pregnane x receptor. st john's wort has also been shown to cause drug interactions through the induction of the p-glycoprotein efflux transporter. increased p-glycoprotein expression results in decreased absorption and increased clearance of certain drugs, leading to lower plasma concentrations and impaired clinical efficacy. examples of drugs whose effectiveness may be reduced by st. john's wort class drugs antiretrovirals non-nucleoside reverse transcriptase inhibitors, protease inhibitors benzodiazepines alprazolam, midazolam hormonal contraception combined oral contraceptives immunosuppressants calcineurin inhibitors, cyclosporine, tacrolimus antiarrhythmics amiodarone, flecainide, mexiletine beta-blockers metoprolol, carvedilol calcium channel blockers verapamil, diltiazem, amlodipine, pregabalin statins (cholesterol-reducing medications) lovastatin, simvastatin, atorvastatin others digoxin, methadone, omeprazole, phenobarbital, theophylline, warfarin, levodopa, buprenorphine, irinotecan, risperidone, paliperidone reference: rossi, 2005; micromedex