Adverse effects profile of the herbal antidepressant St. John's wort (Hypericum perforatum L.)

Objective: This paper provides a systematic review of adverse drug reactions (ADRs) associated with the use of extracts of the herb St. John's wort (Hypericum perforatum L.) for the treatment of mild to moderate depression. Methods: Searches of four computerized literature databases were performed for records of (ADRs). Manufacturers of hypericum products, the international drug monitoring centre of the World Health Organization (WHO) and the national drug safety monitoring bodies of Germany and the United Kingdom were also contacted for information. Results: Information on (ADRs) originates from case reports, clinical trials, post-marketing surveillance and drug monitoring studies. Collectively, the data suggest that hypericum is well tolerated, with an incidence of adverse reactions similar to that of placebo. The most common adverse effects are gastrointestinal symptoms, dizziness/confusion and tiredness/sedation. A potential serious adverse effect is photosensitivity, but this appears to occur extremely rarely. Conclusions: Hypericum has an encouraging safety profile. However, as most of the current data originate from short-term investigations, more long-term studies are desirable. Received: 2 February 1998 / Accepted in revised form: 8 June 1998     

Interaction of St John's wort (Hypericum perforatum) with clozapine

St John's wort (Hypericum perforatum) is notorious for its ability to induce the enzymes of the P450 system. Especially, it induces CYP1A2 and CYP3A4, enzymes that are closely involved in the metabolism of clozapine. We present a patient with schizophrenia, who was stable on a fixed dose with stable plasma level of clozapine, and who deteriorated after she started self-medicating with St John's wort. The reduced plasma clozapine level and the psychiatric condition normalized after the withdrawal of St John's wort. It is possible that, beside the induction of P450-enzymes, the induction of P-glycoprotein by St John's wort aggravated psychiatric deterioration of the patient. Physicians should be alert to patients self-medicating with over-the-counter medicines, especially when these medicines can lower clozapine concentrations below the therapeutic range.     

Enrichment of hyperforin from St. John's wort (Hypericum perforatum) by pilot-scale supercritical carbon dioxide extraction.

St. John's Wort (Hypericum perforatum L.) was extracted with supercritical carbon dioxide using a pilot batch extraction plant. The effects of pressure, temperature, flow rate and extraction time were examined with respect to extraction yield and hyperforin content. Supercritical carbon dioxide showed a high selectivity for phloroglucinols. Extracts were analyzed using an isocratic HPLC method with a mixture of hyperforin/adhyperforin as an external standard. Within the studied range of extraction pressure (90-150 bar) and extraction time (1-5 h), extraction at 90 bar for 3 h and 120 bar for 1 h provided higher hyperforin content (up to 35%) in the resulting extracts. An increase in extraction temperature showed a negative effect, leading to increased degradation of hyperforin into orthoforin. When the total mass of carbon dioxide passing the extraction vessel was kept constant, changes in mass flow rate did not affect the extraction result.     

St John's wort (Hypericum perforatum L.): a review of its chemistry, pharmacology and clinical properties

The chemical composition of St. John's wort has been well-studied. Documented pharmacological activities, including antidepressant, antiviral, and antibacterial effects, provide supporting evidence for several of the traditional uses stated for St John's wort. Many pharmacological activities appear to be attributable to hypericin and to the flavonoid constituents; hypericin is also reported to be responsible for the photosensitive reactions that have been documented for St. John's wort. With regard to the antidepressant effects of St John's wort, hyperforin, rather than hypericin as originally thought, has emerged as one of the major constituents responsible for antidepressant activity. Further research is required to determine which other constituents contribute to the antidepressant effect. Evidence from randomised controlled trials has confirmed the efficacy of St John's wort extracts over placebo in the treatment of mild-to-moderately severe depression. Other randomised controlled studies have provided some evidence that St John's wort extracts are as effective as some standard antidepressants in mild-to-moderate depression. There is still a need for further trials to assess the efficacy of St John's wort extracts, compared with that of standard antidepressants, particularly newer antidepressant agents, such as the selective serotonin reuptake inhibitors (recent comparative studies with fluoxetine and sertraline have been conducted). Also, there is a need for further studies in well-defined groups of patients, in different types of depression, and conducted over longer periods in order to determine long-term safety. St John's wort does appear to have a more favourable short-term safety profile than do standard antidepressants, a factor that is likely to be important in patients continuing to take medication. Concerns have been raised over interactions between St John's wort and certain prescribed medicines (including warfarin, ciclosporin, theophylline, digoxin, HIV protease inhibitors, anticonvulsants, selective serotonin reuptake inhibitors, triptans, oral contraceptives); advice is that patients taking these medicines should stop taking St John's wort, generally after seeking professional advice as dose adjustment of conventional treatment may be necessary.     

St John's wort (Hypericum perforatum): drug interactions and clinical outcomes

AIMS: The aim of this work is to identify the medicines which interact with the herbal remedy St John's wort (SJW), and the mechanisms responsible. METHODS: A systematic review of all the available evidence, including worldwide published literature and spontaneous case reports provided by healthcare professionals and regulatory authorities within Europe has been undertaken. RESULTS: A number of clinically significant interactions have been identified with prescribed medicines including warfarin, phenprocoumon, cyclosporin, HIV protease inhibitors, theophylline, digoxin and oral contraceptives resulting in a decrease in concentration or effect of the medicines. These interactions are probably due to the induction of cytochrome P450 isoenzymes CYP3A4, CYP2C9, CYP1A2 and the transport protein P-glycoprotein by constituent(s) in SJW. The degree of induction is unpredictable due to factors such as the variable quality and quantity of constituent(s) in SJW preparations. In addition, possible pharmacodynamic interactions with selective serotonin re-uptake inhibitors and serotonin (5-HT(1d)) receptor-agonists such as triptans used to treat migraine were identified. These interactions are associated with an increased risk of adverse reactions. CONCLUSIONS: In Sweden and the UK the potential risks to patients were judged to be significant and therefore information about the interactions was provided to health care professionals and patients. The product information of the licensed medicines involved has been amended to reflect these newly identified interactions and SJW preparations have been voluntarily labelled with appropriate warnings.     

Topical Hypericum perforatum (St John's wort) for wound healing and scar formation

Samadi S, Khadivzadeh T, Emami A, Moosave NS, Tafaghodi M, Behnam HR. The effect of Hypericum perforatum on the wound healing and scar of cesarean. J Altern Complement Med 2010; 16: 113–17. doi: 10.1089/acm.2009.0317     

Effects of St. John's wort (Hypericum perforatum) on tacrolimus pharmacokinetics in healthy volunteers

Tacrolimus is an immunosuppressant approved for the prevention of rejection following transplantation and is a substrate for CYP3A and P-glycoprotein. A pharmacokinetic interaction between St. John's wort (antidepressant herbal product and inducer of CYP3A and P-glycoprotein) and tacrolimus was evaluated in 10 healthy volunteers. The pharmacokinetics of tacrolimus were obtained from serial blood samples collected following single oral doses (0.1 mg/kg) prior to and during an 18-day concomitant St. John's wort dosing phase (300 mg orally three times daily). Coadministration of St. John's wort significantly decreased tacrolimus AUC (306.9 microg.h/L +/- 175.8 microg.h/L vs. 198.7 microg.h/L +/- 139.6 microg.h/L; p=0.004) and increased apparent oral clearance (349.0 mL/h/kg +/- 126.0 mL/h/kg vs. 586.4 mL/h/kg +/- 274.9 mL/h/kg; p=0.01) and apparent oral volume of distribution at steady state (11.5 L/kg +/- 4.3 L/kg vs. 17.6 L/kg +/- 9.6 L/kg; p=0.04). St. John's wort appears to induce tacrolimus metabolism, most likely through induction of CYP3A and P-glycoprotein.     

Toxicity of Hypericum perforatum (St. John's wort) administered during pregnancy and lactation in rats

The popularity of St. John's wort (Hypericum perforatum) for the treatment of depression is increasing and, in recent years, concerns about its use during pregnancy and breastfeeding have emerged. The purpose of this study was to investigate, in Wistar rats, the effects of a treatment with hypericum administered prenatally and during breastfeeding (from 2 weeks before mating to 21 days after delivery). Two doses of the extract were chosen, 100 mg/kg per day, which, based on surface area, is comparable to the dose administered to humans, and 1000 mg/kg per day. A microscopical analysis of livers, kidneys, hearts, lungs, brains, and small bowels was performed. A severe damage was observed in the livers and kidneys of animals euthanized postnatally on days 0 and 21. The lesions were more severe with the higher dose and in animals that were breastfed for 21 days; however, an important renal and hepatic damage was evident also with the dose of 100 mg/kg per day. In addition, similar serious hepatic and renal lesions were evident also in animals that were exposed to hypericum only during breastfeeding. In particular, a focal hepatic damage, with vacuolization, lobular fibrosis, and disorganization of hepatic arrays was evident; in the kidney, a reduction in glomerular size, disappearance of Bowman's space, and hyaline tubular degeneration were found. The results obtained in this study indicate that further, appropriate histological studies should be performed in other animal species to better evaluate the safety of hypericum extracts taken during pregnancy and breastfeeding.     

Hypericum perforatum L (St John's wort) preferentially increases extracellular dopamine levels in the rat prefrontal cortex

The effects of hydro-alcoholic extracts of Hypericum perforatum L on extracellular serotonin (5-HT), noradrenaline (NA) and dopamine (DA) levels and the acidic metabolites (3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA)) were examined by in vivo microdialysis in the prefrontal cortex of awake rats. Thus, a single dose (60 mg kg(-1) i.p. or 300 mg kg(-1) p.o.) of H. perforatum increased DA concentrations to 165 and 140% of control values, respectively, and increased locomotor activity in nonhabituated rats. DOPAC and HVA levels were markedly reduced. 5-HT concentrations were elevated only moderately, while the NA levels were not affected by any treatment. The whole-tissue analysis revealed that hypericum increased, whereas the monoamine oxidase (MAO) A/B inhibitor phenelzine decreased DA and 5-HT turnover. The present data indicate that the mechanism of action of hypericum extract in vivo is more complex than the inhibition of monoamine reuptake or metabolism observed in vitro. The finding of preferential enhancement of DA transmission is in agreement with human studies measuring DA-mediated neuroendocrine responses.     

Aqueous ethanolic extract of St. John's wort (Hypericum perforatum L.) induces growth inhibition and apoptosis in human malignant cells in vitro

Extracts of Hypericum perforatum (St. John's wort) are widely and effectively used in the treatment of mild to moderate depression. In addition, hypericin, a component of Hypericum p. extracts, exhibits light-dependent phototoxic properties and can be used in phototherapy. We therefore investigated the cytotoxic activity of two total Hypericum p. extracts, namely from fresh and dried plants in the dark and after exposure to 7.5 J/cm2 white light illumination and compared it with the effect of hypericin on K562, U937, LN229 glioblastoma cell lines and normal human astrocytes. The chemical toxicity of non-illuminated Hypericum p. extracts in the cells tested is low as expressed by a LC50 between 1.9-4.1 mg/ml, which corresponds to 10.3-17.3 microM hypericin and 114.4-190.7 microM hyperforin after 48 h treatment. Hypericum p. extracts induced dose-dependent growth arrest of human malignant cells in the absence of illumination with GI50 values between 0.43-1.77 mg/ml (2.3-9.7 microM hypericin, 26.1-106.7 microM hyperforin) for the fresh plant extract and 0.59-3.03 mg/ml (2.5-12.8 microM hypericin, 24.2-124.7 microM hyperforin) for the dried extract. The growth inhibitory effect of fresh Hypericum p. extract was more pronounced in leukemia cell lines K562 and U937, the GI50 concentrations being about 7-fold lower than the corresponding LC50 for the cell lines K562 and U937, but almost the same as the LC50 for LN229 and NHA cells. GI50 (microgram/ml) for tumor cell lines K562 and U937 (432 and 799) established after 48 h differed significantly (p < 0.05) from those of LN229 and normal human astrocytes (1767 and 2900). The light-exposed extracts were more toxic, their LC50 and GI50 values were reduced to values corresponding to LC50 concentration of 3.7-7.4 microM and a GI50 of 1.3-3.5 microM for phototoxic hypericin. After exposure to light, there was a significant difference (p = 0.006) between the GI50 of glioblastoma LN229 cells (582 micrograms/ml) and normal human astrocytes (1050 micrograms/ml). Morphological examination by light microscopy and phosphaditylserine exposure on the outer plasma membrane investigated by Annexin V-binding with flow cytometry after 24 h confirmed that Hypericum p. extracts caused apoptosis of treated cells without exposure to light. Hypericum p. extracts derived from fresh herbs and from dried herbs which differ in their levels of phloroglucinols (hyperforin and adhyperforin) were compared. The hyperforin content of fresh St. John's wort extract exceeded that of dried plant extract by 47% and the GI50 values of fresh plant extract were 73%, 77% and 58% of those established for dried extract in the three malignant cell lines K562, U937 and LN229 in the dark (p < 0.05). Under white light (7.5 J/cm2), both extracts exerted comparable growth inhibitory and apoptosis inducing effects due to the phototoxicity of hypericin, the corresponding concentrations of which were in the range of 1.3-3.5 microM. The data reported in this study suggest that illumination is not essential for the growth inhibitory and apoptotic effects of Hypericum p. extracts, but light activation potentiates them. Furthermore, the constituent hyperforin is at least partly responsible for these effects in the dark.     

St John's wort (Hypericum perforatum) diminishes cognitive impairment caused by the chronic restraint stress in rats.

In this study we tested the hypothesis that St John's wort (Hypericum perforatum) may counteract stress-induced memory impairment. Object recognition test and Morris water maze were used to determine whether administration of H. perforatum (350 mg kg(-1) for 21 days), standardized to 0.3% hypericin content, protects against non-spatial and/or spatial memory impairments due to chronic restraint stress (2h daily for 21 days). A group of rats administered the exogenous corticosterone at the dose of 5 mg kg(-1) daily for 21 days, yielding its similar plasma levels as these observed in stress was run in parallel. In the first experiment all rats were tested for recognition memory in the object recognition test. On the following day, the animals were tested in open field and elevated "plus" maze to control for the contribution of respectively, motor and emotional effects of our treatments to the memory tests. In the second experiment, new group of stressed animals was tested for spatial memory in the water maze. We observed that H. perforatum prevented the deleterious effects of both chronic restraint stress and long-term corticosterone on learning and memory as measured in both, the object recognition and the water maze tests. The herb not only prevented stress- and corticosterone-induced memory impairments, but it significantly improved recognition memory (p<0.01) in comparison to control. These results suggest that H. perforatum has a potential to prevent stress memory disorders.     

Catalytic inhibition of human DNA topoisomerase IIalpha by hypericin, a naphthodianthrone from St. John's wort (Hypericum perforatum)

St. John's wort (Hypericum perforatum) is the most widely used herbal medicine for the treatment of depression. However, concerns have arisen about the potential of its interaction with other drugs due to the induction of cytochrome P450 isozymes 1A2 and 3A4 by the components hypericin and hyperforin, respectively. Structurally similar natural products are often employed as antitumor agents due to their action as inhibitors of DNA topoisomerases, nuclear enzymes that modify DNA during cellular proliferation. Preliminary findings that hypericin inhibited the DNA relaxation activity of topoisomerase IIalpha (topo II; EC 5.99.1.3) led us to investigate the mechanism of enzyme inhibition. Rather than stabilizing the enzyme in covalent complexes with DNA (cleavage complexes), hypericin inhibited the enzyme prior to DNA cleavage. In vitro assays indicate that hypericin is a potent antagonist of cleavage complex stabilization by the chemotherapeutics etoposide and amsacrine. This antagonism appears to be due to the ability of hypericin to intercalate or distort DNA structure, thereby precluding topo II binding and/or DNA cleavage. Supporting its non-DNA damaging, catalytic inhibition of topo II, hypericin was shown to be equitoxic to both wild-type and amsacrine-resistant HL-60 leukemia cell lines. Moreover, hypericin was incapable of stimulating DNA damage-responsive gene promoters that are activated by etoposide. As with the in vitro topo II assay, antagonism of DNA damage stimulated by 30 microM etoposide was evident in leukemia cells pretreated with 5 microM hypericin. Since many cancer patients experience clinical depression and concomitantly self-medicate with herbal remedies, extracts of St. John's wort should be investigated further for their potential to antagonize topo II-directed chemotherapy regimens.     

St. John's wort (Hypericum perforatum): a review of the current pharmacological, toxicological, and clinical literature

RATIONALE: St. John's wort (Hypericum perforatum) has recently gained popularity as an alternative treatment for mild to moderate depression. Given the current widespread use of this herbal remedy, it is important for medical professionals to understand the potential pharmacological pathways through which Hypericum may exert an antidepressant effect. OBJECTIVES: (1) To review the current pharmacological, toxicological, and clinical literature available on Hypericum, and (2) to provide a synthesis of this information into a form that may be easily used by health care providers. METHOD: A comprehensive review of the recent scientific literature (January 1990-March 2000) was performed using the following electronic databases and reference publications: MEDLINE, The Cochrane Library, HealthSTAR, Current Contents (all editions), European Scientific Cooperative on Phytotherapy monographs, German Commission E monographs, and the Physicians' Desk Reference for Herbal Medicines, 1st edition. RESULTS: One hundred and seven (107) publications in the English language and three publications in German were included in the review. Collectively, the data suggest that therapeutic preparations of Hypericum extract appear to exert potentially significant pharmacological activity within several neurochemical systems believed to be implicated in the pathophysiology of depression. However, little information exists regarding the safety of Hypericum, including potential herb-drug interactions. CONCLUSIONS: Additional research on the pharmacological and biochemical activity of Hypericum and its several bioactive constituents is necessary to further elucidate the mode(s) of antidepressant action. Given what is currently known and unknown about the biological properties of Hypericum, those who choose to use this herb should be closely monitored by a physician.     

St John's wort (Hypericum perforatum) modulates evoked potentials in guinea pig hippocampal slices via AMPA and GABA receptors.

The effects of an ethanolic extract of the plant Hypericum perforatum L. (St John's wort) (HYP) and its hydrosoluble fraction (HYPWS) on electrically evoked population spikes and fEPSP were investigated in this study. Concentration dependent (10(-6) to 10(-4) g/l) excitatory effects were found. Above concentrations of 10(-3) g/l, HYP reduced the evoked responses, whereas HYPWS further increased them. Paired pulse facilitation was unaffected with HYPWS (10(-4) to 10(-2) g/l). The excitatory effects of HYPWS were amplified by the GABA(A) and GABA(B) receptor antagonists bicuculline and phaclofen, respectively. These excitations were antagonised by the AMPA receptor antagonist CNQX. Excitations caused by hypericum were not antagonised by the NMDA receptor antagonists D-APV and MK801, the metabotropic glutamate receptor (type I and II) antagonist MCPG, or the L-type calcium channel blocker verapamil. Hypericin and hyperforin, two components of H. perforatum, were found not to be responsible for the excitatory effects of the extract.