Drug Interactions with St John???s Wort

Patterns and prevalence of antidepressant drug use in the German state of Baden-Wuerttemberg: a prescription-based analysis

PURPOSE

Population-based data about patterns and prevalence of antidepressant drug use is limited in Europe and presently unavailable for Germany. Therefore, we have identified patterns and prevalence of antidepressant use among outpatients on a population-based scale in the German state of Baden-Wuerttemberg.

METHODS

We conducted a historical cohort study using a computerised prescription database referring to all members of the major German public health insurance company AOK. We assessed the prevalence of antidepressant drug use over a 3-year period, calculated the number of prescription items purchased per patient and compared first-line and second-line treatments.

RESULTS

The 1-year prevalence of antidepressant drug use among more than 4,000,000 health insurance members was 7.4% (male: 4.3%; female: 10.2%). Importantly, almost 40% of the patients received only a single prescription item from 2000 to 2002. Though the use of serotonin-reuptake inhibitors (SSRIs) markedly increased by about 65% within the study period, these are primarily used as second-line drugs and still much less frequently than St. John's wort or tricyclic antidepressants such as amitryptiline or doxepin.

CONCLUSIONS

The prevalence of antidepressant drug use is higher than previously reported for other European countries. The preferred use of St. John's wort and tricyclics over SSRIs and other modern-type antidepressants in Germany is quite unique in Europe and different from the US. The identified drug use pattern leaves a major room for improvement in view of the numerous single prescription items purchased.

Drug Treatment in Juvenile Depression - Is St. John's Wort a Safe and Effective Alternative?

Analyses of juvenile depression studies with long established anti-depressants (tricyclic anti-depressants) have revealed discouragingly little benefit, while side effects have been profound. Modern anti-depressants like selective serotonin reuptake inhibitors seemed to solve part of this problem until they were found to be associated with an increased risk of suicidal attempts and ideation, hostile behaviour and self-harm, while meta-analyses have revealed only marginal therapeutic effects for the majority. Actually, no drug is unequivocally accepted as the gold-standard for young depressive patients. St. John's Wort (SJW) has been traditionally used in Europe to treat symptoms associated with juvenile depression. Close to 50 clinical studies performed over the last two decades have been presented as evidence that standardized SJW preparations are equally effective as synthetic anti-depressants in the treatment of mild to moderate depression in adults. Tolerability is excellent, but some relevant drug interactions have to be considered. Today, SJW is by far the most frequently prescribed medication for child and adolescent depression in Germany. Some pilot and observational studies from Germany, Canada and the US have delivered promising results. However, randomised controlled trials amongst this age group have yet to be carried out and are long overdue.

Herbal hepatotoxicity

There is appropriate concern about the potential risk for hepatotoxicity from herbal products because they are unregulated and therefore not standardized with regard to their contents. This is particularly the case for the crude herbals that are commonly formulated as a mixture, so that their ingredients may be ambiguous and even contain harmful contaminants. Presented here is an overview of the more commonly recognized herbal products that have been reported to be associated with liver injury. Although many of them are clearly implicated, there are some, particularly those identified solely through an occasional case report, for which the relationship is uncertain.

A Review of Drug Interactions With Psychiatric Medicines for the Pharmacy Practitioner

With thousands of potential drug interactions, it is next to impossible to remember them all, especially with many people on multiple prescriptions and over-the-counter medications. With the increasing use of psychiatric medicines in the general population, drug interactions may occur without recognition or warning. Pharmacy computer software programs provide help with identifying the majority of potential drug interactions, but these systems are only as good as the user who develops them. Some drug interactions are negligible, whereas others are quite significant. It is most important to remember drug interactions that may have a significant clinical effect. Approximately half of all medications prescribed today are affected by cytochrome P450 enzymes, but other interactions that involve various mechanisms can also be problematic. This review identifies drug interactions that may occur with the most frequently prescribed psychiatric medications and provides a review of selected interactions that may be clinically relevant for the pharmacist to review.

Drug-herb interaction: effect of St John's wort on bioavailability and metabolism of procainamide in mice

CONTEXT

St John's wort induces the activity of the cytochrome P450 enzyme system causing treatment failure because of increased metabolism of many drugs. Procainamide is metabolized by a different pathway to N-acetyl procainamide.

OBJECTIVE

To study St John's wort-procainamide interaction using a mouse (Swiss Webster) model.

DESIGN

One group of mice (group A, 4 mice in each group) was fed St John's wort each day for 2 weeks (last dose 1 day before administration of procainamide); another group (group B) received the same dose of St John's wort for 1 week. The third group (group C) received only a single dose 1 hour before administration of procainamide, and the control group (group D) received no St John's wort. All groups later received a single oral dose of procainamide. Blood was drawn 1, 4, and 24 hours after administration of procainamide and concentrations in serum of procainamide as well as N-acetyl procainamide were measured using immunoassays.

RESULTS

The procainamide concentrations 1 hour after administration was highest in group C (mean, 11.59 microg/mL) followed by group A (9.92 microg/mL), whereas group B (7.44 microg/mL) and control group D (7.36 microg/mL) showed comparable values. The concentration in group C was significantly greater than the control group D (P = .03, 2-tailed independent t test). N-Acetyl procainamide concentrations and estimated half-life of procainamide among groups were comparable. In a separate experiment when mice were fed purified hypericin, the active component of St John's wort, a significant increase in bioavailability (53%) of procainamide was observed compared with the control group.

CONCLUSIONS

St John's wort has an acute effect to increase bioavailability of procainamide but has no effect on its metabolism.

Wheat Grass Juice May Improve Hematological Toxicity Related to Chemotherapy in Breast Cancer Patients: A Pilot Study

Myelotoxicity induced by chemotherapy may become life-threatening. Neutropenia may be prevented by granulocyte colony-stimulating factors (GCSF), and epoetin may prevent anemia, but both cause substantial side effects and increased costs. According to non-established data, wheat grass juice (WGJ) may prevent myelotoxicity when applied with chemotherapy. In this prospective matched control study, 60 patients with breast carcinoma on chemotherapy were enrolled and assigned to an intervention or control arm. Those in the intervention arm (A) were given 60 cc of WGJ orally daily during the first three cycles of chemotherapy, while those in the control arm (B) received only regular supportive therapy. Premature termination of treatment, dose reduction, and starting GCSF or epoetin were considered as "censoring events." Response rate to chemotherapy was calculated in patients with evaluable disease. Analysis of the results showed that five censoring events occurred in Arm A and 15 in Arm B (P = 0.01). Of the 15 events in Arm B, 11 were related to hematological events. No reduction in response rate was observed in patients who could be assessed for response. Side effects related to WGJ were minimal, including worsening of nausea in six patients, causing cessation of WGJ intake. In conclusion, it was found that WGJ taken during FAC chemotherapy may reduce myelotoxicity, dose reductions, and need for GCSF support, without diminishing efficacy of chemotherapy. These preliminary results need confirmation in a phase III study.

St. John's wort does not interfere with therapeutic drug monitoring of 12 commonly monitored drugs using immunoassays

St. John's wort, a popular herbal remedy for depression, is known to interact with many Western drugs because of the ability of its components to induce liver enzymes. Lower concentrations of various drugs due to increased clearance have been reported. Because immunoassays are commonly used in clinical laboratories for therapeutic drug monitoring, we studied the potential interference of St. John's wort with commonly monitored therapeutic drugs. Drug-free serum pools were supplemented with St. John's wort to achieve in vitro St. John's wort concentrations mimicking in vivo concentrations after both recommended use and overdose. Concentrations of digoxin, tricyclic antidepressants (TCAs), phenytoin, carbamazepine, theophylline, valproic acid, quinidine, phenobarbital, procainamide, and N-acetyl procainamide were measured in serum. Pooled serum specimens from patients who were taking a particular drug were also supplemented in vitro with concentrations of St. John's wort to investigate whether observed concentrations changed after supplementation with St. John's wort. The effect of St. John's wort on cyclosporine and tacrolimus (FK 506) was studied in whole blood. We found no significant interference from St. John's wort with any assay studied. Moreover, when drug-free serum was supplemented with very high concentrations of hypericin (2 microg/mL) and hyperforin (2 microg/mL) pure standard, we observed no apparent drug level with any immunoassay. The presence of both hypericin and hyperforin was also confirmed by thin layer chromatography (TLC) in both preparations of St. John's wort. We conclude that immunoassays may be used to measure levels of therapeutic drugs in patients who self-medicate with St. John's wort.

Antidepressant activity of some Hypericum reflexum L. fil. extracts in the forced swimming test in mice

We previously reported that oral administration of the methanol extract obtained from the aerial part in blossom of Hypericum reflexum L. fil. was active in the tetrabenazine and forced swimming test. In the present study, the effect of the aqueous, butanol and chloroform fractions obtained from the methanol extract of this species on the central nervous system was investigated in mice, particularly in animal models of depression. Antidepressant activity was detected in the butanol and chloroform fractions of this species using the forced swimming test since both fractions induced a significant reduction of the immobility time, producing no effects or only a slight depression on spontaneous motor activity when assessed in a photocell activity meter. Moreover, these fractions did not alter significantly the pentobarbital-induced sleeping time. On the other hand, the chloroform fraction produced a slight but significant hypothermia and was also effective in antagonizing the ptosis induced by tetrabenazine. Furthermore, the butanol fraction produced a slight potentiation of the head twitches and syndrome induced by 5-HTP. Taken together, these data indicate that the butanol and chloroform fractions from Hypericum reflexum possess antidepressant-like effects in mice, providing further support for the traditional use of these plants in the Canary Islands folk medicine against central nervous disorders.

Effect of pre-treatment with St John's Wort on nephrotoxicity of cisplatin in rats

An herbal health care supplement, St John's Wort (SJW, Hypericum perforatum) has become widely used in the treatment of depression, and is known to interact with therapeutic drugs. Here we report a preventive effect of SJW on cisplatin nephrotoxicity in rats. Rats were given SJW (400 mg/kg/day, p.o.) for 10 consecutive days, and were injected with cisplatin (5 mg/kg, i.v.) on the day after the final SJW treatment. Cisplatin treatment increased the serum creatinine level, which is an index of nephrotoxicity, to 1.51+/-0.22 mg/dl (mean+/-SE) from 0.28+/-0.05 mg/dl (control) on day 5 after the cisplatin injection. This increase fell significantly to 0.86+/-0.13 mg/dl by pre-treatment with SJW. Cisplatin-induced histological abnormality of the kidney was blocked by pre-treatment with SJW. When SJW was administered for 10 days, the amounts of renal metallothionein (MT) and hepatic multidrug resistance protein 2 (Mrp2) were increased to 164.8+/-13.0% and 220.8+/-39.3% (mean+/-SE) of controls, respectively. GSH levels in the kidney and liver were not changed. Total and free cisplatin concentration in serum was not influenced by SJW treatment. In conclusion, the results suggest that pre-treatment with SJW may diminish cisplatin nephrotoxicity.

Oral chemotherapeutic agents: Understanding mechanisms of action and drug interactions

PURPOSE

The mechanisms of action and drug interactions of oral chemotherapeutic agents are reviewed.

SUMMARY

The mechanisms of action, indications, and potential for drug interactions vary for oral chemotherapy. Traditional oral chemotherapy agents cause damage to cancer cells by non-specifically interfering with cellular division. Many of the newer agents have novel targets on cancer cells preferentially, resulting in a different spectrum of toxicity. Since cancer patients are at high risk for drug interactions, usually because of age-related organ dysfunction and the need for concomitant drug therapy for comorbid conditions, understanding these agents and potential for interactions is imperative for all healthcare providers.

CONCLUSION

Knowledge of the mechanisms and metabolic pathways for the oral chemotherapeutic agents allows the potential to predict possible drug interactions and response while minimizing the risk of adverse outcomes.

Role of pharmacogenetics of ATP-binding cassette transporters in the pharmacokinetics of drugs

Interindividual differences of drug response are an important cause of treatment failures and adverse drug reactions. The identification of polymorphisms explaining distinct phenotypes of drug metabolizing enzymes contributed in part to the understanding of individual variations of drug plasma levels. However, bioavailability also depends on a major extent from the expression and activity of drug transport across biomembranes. In particular efflux transporters of the ATP-binding cassette (ABC) family such as ABCB1 (P-glycoprotein, P-gp), the ABCC (multidrug resistance-related protein, MRP) family and ABCG2 (breast cancer resistance protein, BCRP) have been identified as major determinants of chemoresistance in tumor cells. They are expressed in the apical membranes of many barrier tissue such as the intestine, liver, blood-brain barrier, kidney, placenta, testis and in lymphocytes, thus contributing to plasma, liquor, but also intracellular drug disposition. Since expression and function exhibit a broad variability, it was hypothesized that hereditary variances in the genes of membrane transporters could explain at least in part interindividual differences of pharmacokinetics and clinical outcome of a variety of drugs. This review focuses on the functional significance of single nucleotide polymorphisms (SNP) of ABCB1, ABCC1, ABCC2, and ABCG2 in in vitro systems, in vivo tissues and drug disposition, as well as on the clinical outcome of major indications.

A strategy for controlling potential interactions between natural health products and chemotherapy: a review in pediatric oncology

The high prevalence of complementary and alternative medicine use including natural health products (NHPs) in the pediatric oncology population is well established. The potential for concurrent use of NHPs with conventional chemotherapy necessitates physician awareness regarding the potential risks and benefits that might come from this coadministration. Knowledge of interactions between NHPs and chemotherapy is poorly characterized; however, an understanding of potential mechanisms of interaction by researchers and clinicians is important. Concerns regarding the use of antioxidants during chemotherapy are controversial and evidence exists to support both adherents and detractors in this debate. Our review addresses issues regarding potential interactions between NHPs and chemotherapies used in pediatric oncology from a pharmacokinetic and pharmacodynamic perspective. Examples of combinations of NHP and chemotherapies are briefly presented in addition to a strategy to avoid (or induce) a possible interaction between a NHP and chemotherapy. In conclusion, more clinical research is needed to substantiate or preclude the use of NHPs in the treatment of cancer and especially in combination with chemotherapy.

Hyperforin and its analogues inhibit CYP3A4 enzyme activity

Literature indicates that herb-drug interaction of St. John's wort is largely due to increased metabolism of the co-administered drugs that are the substrates of cytochrome P450 (CYP) 3A4 enzyme, alteration of the activity and/or expression of the enzyme. The major St. John's wort constituents, acylphloroglucinols, were evaluated for their effects on CYP3A4 enzyme activity to investigate their roles in herb-drug interaction. Hyperforin and four oxidized analogues were isolated from the plant and fully characterized by mass spectral and NMR analysis. These acylphloroglucinols inhibited activity of CYP3A4 enzyme potently in the fluorometric assay using the recombinant enzyme. Furoadhyperforin (IC(50) 0.072 microM) was found to be the most potent inhibitor of CYP3A4 enzyme activity, followed by furohyperforin isomer 1 (IC(50) 0.079 microM), furohyperforin isomer 2 (IC(50) 0.23 microM), hyperforin (IC(50) 0.63 microM) and furohyperforin (IC(50) 1.3 microM). As the acylphloroglucinols are potent inhibitors of the CYP3A4 enzyme, their modulation of the enzyme activity is unlikely to be involved in increased drug metabolism by St. John's wort.

St John's wort for depression: Time for a different perspective?

OBJECTIVES

To review the development of the evidence on the herbal remedy, St John's wort (SJW) (Hypericum perforatum), in the treatment of depression.

METHODS

Searches of major biomedical and specialist databases including EMBASE, MEDLINE, PsycINFO, AMED and HerbMed were conducted. Searches aimed to identify quantitative research (systematic reviews and meta-analyses) and relevant qualitative studies. Data were extracted systematically.

RESULTS

Systematic reviews have been published regularly over the past 10 years. Methodology has varied resulting in differing estimates of effectiveness but overall findings have been positive when compared with placebo for mild to moderate depression. Recent reviews have focused on adverse effects and interactions. One qualitative study focusing on SJW in depression was retrieved.

CONCLUSIONS

SJW has received intensive and continued attention since initial indications of its potential effectiveness for depression. The focus appears to be moving from effectiveness to safety but the patient's perspective has received less attention and may prove a valuable avenue for future studies.

Hypericum perforatum: a 'modern' herbal antidepressant: pharmacokinetics of active ingredients

Hypericum perforatum (St John's Wort [SJW]) counts among the most favourite herbal drugs, and is the only herbal alternative to classic synthetic antidepressants in the therapy of mild to moderate depression. Several clinical studies have been conducted to verify the effectiveness of ethanolic or methanolic extracts of SJW. Alcoholic SJW extracts are a mixture of substances with widely varying physical and chemical properties and activities. Hyperforin, a phloroglucinol derivative, is the main source of pharmacological effects caused by the consumption of alcoholic extracts of SJW in the therapy of depression. However, several studies indicate that flavone derivatives, e.g. rutin, and also the naphthodianthrones hypericin and pseudohypericin, take part in the antidepressant efficacy. In contrast to the amount of documentation concerning clinical efficacy, oral bioavailability and pharmacokinetic data about the active components are rather scarce. The hyperforin plasma concentration in humans was investigated in a small number of studies. The results of these studies indicate a relevant plasma concentration, comparable with that used in in vitro tests. Furthermore, hyperforin is the only ingredient of H. perforatum that could be determined in the brain of rodents after oral administration of alcoholic extracts. The plasma concentrations of the hypericins were, compared with hyperforin, only one-tenth and, until now, the hypericins could not be found in the brain after oral administration of alcoholic H. perforatum extracts or pure hypericin. Until now, the pharmacokinetic profile of the flavonoids in humans after oral administration of an alcoholic H. perforatum extract has been investigated in only one study. More data are available for rutin and the aglycone quercetin after administration of pure substances or other flavonoid sources.

HIV/AIDS: Interactions between Natural Health Products and Antiretroviral Drugs: Pharmacokinetic and Pharmacodynamic Effects

Concurrent use of natural health products (NHPs) with antiretroviral drugs (ARVs) is widespread among human immunodeficiency virus-infected patients. This article reviews the clinical pharmacokinetic and pharmacodynamic interactions between NHPs and ARVs. Many NHPs are complex mixtures and are likely to contain organic compounds that may induce and/or inhibit drug metabolizing enzymes and drug transporters. Although the weight of evidence for the effects of certain NHPs varies and many studies of these products lack scientific rigor, it has been observed that St. John's wort clearly induces cytochrome P450 3A4 and P-glycoprotein and reduces protease inhibitor and nonnucleoside reverse-transcriptase inhibitor concentrations, thereby increasing the likelihood of therapeutic failure. Limited clinical research suggests that intake of garlic and vitamin C results in reductions in ARV concentrations. The intake of milk thistle, Echinacea species, and goldenseal inhibits cytochrome P450 enzymes in vitro and may increase ARV concentrations, but by clinically unimportant amounts. Intake of fish oil reduces ARV-induced hypertriglyceridemia without significantly affecting lopinavir concentrations. Before recommending the use of NHPs as adjuncts to ARV use, studies should first exclude significant pharmacokinetic interactions and ensure that ARV efficacy is maintained.

Hyperforin, a new lead compound against the progression of cancer and leukemia?

Extracts of the plant St John's wort, Hyperforin perforatum L., have been used for centuries in traditional medicine, notably for the treatment of depression. One of their main lipophilic components, a natural prenylated phloroglucinol termed hyperforin (HF), has been identified as the major molecule responsible for the antidepressant effects of this plant. Within the last few years, a number of studies have demonstrated that HF displays, in addition, several other biological properties of potential pharmacological interest. They include an antibacterial capacity and inhibitory effects on inflammatory mediators. It is worth noting that HF also promotes apoptosis of various cancer cells from solid tumors and hematological malignancies, including B-cell chronic lymphocytic leukemia. In addition, HF inhibits the capacity of migration and invasion of different tumor cells, as well as exhibiting antiangiogenic effects. Altogether, these properties qualify HF as a lead structure for the development of new therapeutic molecules in the treatment of various diseases, including some malignant tumors.

What patients take without telling you: holistic approach for BPH

The use of botanicals and supplements have markedly increased in men that are seeking increased protection against the potential onset and symptomatic relief of lower urinary tract symptoms that are commonly experienced with benign prostatic hyperplasia (BPH). While this implies a positive trend and considers that men are taking a more active role in health and prevention, dialog between the patient and the clinician is often deficient. This may be due to a number of factors including both the patients' inability to report about the use of certain agents and the clinicians' inability to ask. Moreover, the sense that natural agents may lack side effects coupled with ineffective communication between the doctor and patient could result in potential adverse interactions. We have performed a comprehensive search of articles published from 1990 to 2005 using the Medline databases in order examine clinical data on the most commonly researched herbs for BPH. We provide a brief update on the state of the research.

Use of herbs and herbal products by Hispanics in south Florida

OBJECTIVES

To provide insight into the use of herbs by Hispanic Americans, identify specific herbal products that health care professionals should inquire about in this population, and assess information sources and expenditures.

DESIGN

Cross-sectional survey.

SETTING

South Florida.

PARTICIPANTS

Convenience sample of 200 Hispanic adults.

INTERVENTIONS

Participants completed a descriptive, self-administered survey.

MAIN OUTCOME MEASURES

Specific herbs and herbal remedies use, monthly expenditures, sources of information, and attitudes and beliefs regarding herbs.

RESULTS

Of the 200 surveys that were distributed, 142 were completed for a response rate of 71%. Of the respondents, 75% reported using at least one herb in the last 12 months. Women between 25 and 34 years of age were most likely to be herb users (P = .001), while men in that age group were the least likely (P = .013). Chamomile (58.5%) and aloe vera (45.3%) were used most frequently. Two frequently used herbs--linden (35.8%) and star anise (33.0%)--are ones that are generally not well known to health care professionals. Family tradition (36%) and safety (17%) were the major reasons for use of herb/herbal remedies. Participants most commonly reported spending 25 dollars or less per month for herbs and herbal products.

CONCLUSION

Hispanics in south Florida reported using herbs and herbal products at a higher rate than that those reported previously for the general population of the United States. While money spent on herbs and herbal products was generally minimal, study participants had a disconcerting level of confidence in the safety and efficacy of herbal products.

Herbal remedies: effects on clinical laboratory tests

CONTEXT

Complementary and alternative medicine (herbal medicines) can affect laboratory test results by several mechanisms.

OBJECTIVE

In this review, published reports on effects of herbal remedies on abnormal laboratory test results are summarized and commented on.

DATA SOURCES

All published reports between 1980 and 2005 with the key words herbal remedies or alternative medicine and clinical laboratory test, clinical chemistry test, or drug-herb interaction were searched through Medline. The authors' own publications were also included. Important results were then synthesized.

DATA SYNTHESIS

Falsely elevated or falsely lowered digoxin levels may be encountered in a patient taking digoxin and the Chinese medicine Chan Su or Dan Shen, owing to direct interference of a component of Chinese medicine with the antibody used in an immunoassay. St John's wort, a popular herbal antidepressant, increases clearance of many drugs, and abnormally low cyclosporine, digoxin, theophylline, or protease inhibitor concentrations may be observed in a patient taking any of these drugs in combination with St John's wort. Abnormal laboratory results may also be encountered owing to altered pathophysiology. Kava-kava, chaparral, and germander cause liver toxicity, and elevated alanine aminotransferase, aspartate aminotransferase, and bilirubin concentrations may be observed in a healthy individual taking such herbal products. An herbal product may be contaminated with a Western drug, and an unexpected drug level (such as phenytoin in a patient who never took phenytoin but took a Chinese herb) may confuse the laboratory staff and the clinician.

CONCLUSIONS

Use of alternative medicines may significantly alter laboratory results, and communication among pathologists, clinical laboratory scientists, and physicians providing care to the patient is important in interpreting these results.

Analysis of frankincense from various Boswellia species with inhibitory activity on human drug metabolising cytochrome P450 enzymes using liquid chromatography mass spectrometry after automated on-line extraction

In our search for herbal remedies with inhibitory activity on cytochrome P450 (CYP) enzymes, we identified extracts of the gum-resin of Boswellia carteri, Boswellia frereana, Boswellia sacra and Boswellia serrata as equally potent, non-selective inhibitors of the major drug metabolising CYP enzymes 1A2/2C8/2C9/2C19/2D6 and 3A4. LC/LC/ESI-MS fingerprint analyses of the boswellic acids 11-keto-beta-boswellic acid, alpha-boswellic acid, beta-boswellic acid and their 3-O-acylated derivatives were used for the authentication of the commercially obtained frankincense samples. Although the boswellic acids could be identified as moderate to potent inhibitors of the applied CYP enzymes, they are not the major CYP inhibitory principle of frankincense.

Drug transporters in pharmacokinetics

This review deals with the drug transporters allowing drugs to enter and leave cells by carrier-mediated pathways. Emphasis is put on liver transporters but systems in gut, kidney, and blood-brain barrier are mentioned as well. Drug-drug interactions on carriers may provoke significant modification in pharmacokinetics as do carrier gene polymorphisms yielding functional carrier protein mutations. An integrated phase concept should reflect the interplay between drug metabolism and drug transport.

Evidence-based drug–herbal interactions

Due to the growing use of herbals and other dietary supplements healthcare providers and consumers need to know whether problems might arise from using these preparations in combination with conventional drugs. However, the evidence of interactions between natural products and drugs is based on known or suspected pharmacologic activity, data derived from in vitro or animal studies, or isolated case reports that frequently lack pertinent information. The usefulness of such information is questionable. More recently an increasing number of documented case reports, in vivo studies, and clinical trials have evaluated herbal-drug interactions. Results have sometimes been contradictory and more research is needed. Since there is a lack of rigorous studies that can establish the clinical significance of herb-drug interactions, an evidence-based evaluation of the current literature concerning commonly used herbal-drug interactions, as well as other dietary supplements, was conducted.

Hypericum extract reverses S-ketamine-induced changes in auditory evoked potentials in humans - possible implications for the treatment of schizophrenia

BACKGROUND

Auditory evoked potentials (AEP) provide a correlate of cognitive dysfunction in schizophrenia. Both cognitive dysfunction and AEP-characteristics might be related to reduced glutamatergic neurotransmission as induced by glutamate-antagonist like ketamine. Hypericum extract LI160 has demonstrated a ketamine-antagonising effect. We examined whether LI160 reverses changes of a low dose ketamine on AEP in healthy subjects.

METHODS

We performed a double-blind randomized treatment with either 2 x 750 mg LI 160 or placebo given one week, using a crossover design, in 16 health subjects. A test-battery including AEPs, the oculodynamic test (ODT) and a cognitive test were performed before and after an infusion with 4 mg of S-ketamine over a period of 1 hour.

RESULTS

S-ketamine lead to a significant decrease in the N100-P200 peak to peak (ptp) amplitude after the placebo treatment, whereas ptp was significantly increased by S-ketamine infusion in the LI160 treated subjects. The ODT and the cognitive testing revealed no significant effect of ketamine-infusion and therefore no interaction between treatment groups.

CONCLUSIONS

AEP measures are sensitive means to assess the effect of low dose ketamine. Provided that ketamine mimics cognitive deficits in schizophrenia, LI160 might be effective to treat these symptoms.

Hyperforin in St. John's wort drug interactions

Recently, interactions of herbal medicines with synthetic drugs came into focus of particular interest. In the past 3 years, more than 50 papers were published regarding interactions between St. John's wort (Hypericum perforatum L.; SJW) and prescription drugs. Co-medication with SJW resulted in decreased plasma concentrations of a number of drugs including amitriptyline, cyclosporine, digoxin, indinavir, irinotecan, warfarin, phenprocoumon, alprazolam, dextrometorphane, simvastatin, and oral contraceptives. Sufficient evidence from interaction studies and case reports indicate that SJW is a potent inducer of cytochrome P450 enzymes (particularly CYP3A4) and/or P-glycoprotein. Recent studies could show that the degree of enzyme induction by SJW correlates strongly with the amount of hyperforin found in the product. Products that do not contain substantial amounts of hyperforin (<1%) have not been shown to produce clinically relevant enzyme induction. On the other hand, some evidence suggests that hyperforin may also contribute to the antidepressant activity of SJW. However, clinical studies using SJW preparations with a low hyperforin amount (<1%) clearly demonstrated the superiority of this plant extract over placebo and its equivalence to imipramine and fluoxetine in the treatment of mild to moderate forms of depression. In the present paper clinical significant SJW interactions are critically evaluated against the background of hyperforin.

Safety of St. John's Wort extract compared to synthetic antidepressants

The clinical efficacy of some standardized St. John's Wort extracts (SWEs) such as WS((R)) 5570, WS((R)) 5572 or LI 160 in the treatment of mild, moderate and severe major depression has been demonstrated in 38 controlled clinical trials and two recent meta-analyses. Sixteen post-marketing surveillance studies with such preparations, based on a total of 34,804 patients, recorded an incidence of adverse events (AEs) among patients between 0% and 6%. Of these studies, the four large-scale surveillance studies with a total of 14,245 patients recorded a rate of AEs ranging from 0.1% to 2.4% and a drop-out rate due to AEs of 0.1-0.9%. This is at least ten-fold lower than that recorded with synthetic antidepressants. AEs associated with SWE treatment were mild and transient in nearly all cases. As with synthetic antidepressants, pharmacokinetic interactions may occur occasionally as a result of activity changes of drug-metabolising and drug-transporting proteins, especially CYP 3A4 and P-gp. Risks to the patient are not caused by SWE but by drugs with a narrow therapeutic range. Consequently, SWE preparations should not be taken concurrently with other antidepressants, with coumarin-type anticoagulants, the immunosuppressants cyclosporine and tacrolimus, protease and reverse transcriptase inhibitors used in anti-HIV treatment or with certain antineoplastic agents. However, such cases are extremely rare and, with medical supervision, easily avoided. In conclusion, the safety of SWE must be considered more favourable than that of synthetic antidepressants.

From traditional Ayurvedic medicine to modern medicine: identification of therapeutic targets for suppression of inflammation and cancer

Cancer is a hyperproliferative disorder that involves transformation, dysregulation of apoptosis, proliferation, invasion, angiogenesis and metastasis. Extensive research during the last 30 years has revealed much about the biology of cancer. Drugs used to treat most cancers are those that can block cell signalling, including growth factor signalling (e.g., epidermal growth factor); prostaglandin production (e.g., COX-2); inflammation (e.g., inflammatory cytokines: NF-kappaB, TNF, IL-1, IL-6, chemokines); drug resistance gene products (e.g., multi-drug resistance); cell cycle proteins (e.g., cyclin D1 and cyclin E); angiogenesis (e.g., vascular endothelial growth factor); invasion (e.g., matrix metalloproteinases); antiapoptosis (e.g., bcl-2, bcl-X(L), XIAP, survivin, FLIP); and cellular proliferation (e.g., c-myc, AP-1, growth factors). Numerous reports have suggested that Ayurvedic plants and their components mediate their effects by modulating several of these recently identified therapeutic targets. However, Ayurvedic medicine requires rediscovery in light of our current knowledge of allopathic (modern) medicine. The focus of this review is to elucidate the Ayurvedic concept of cancer, including its classification, causes, pathogenesis and prevention; surgical removal of tumours; herbal remedies; dietary modifications; and spiritual treatments.

Human immunodeficiency virus and depression in primary care: a clinical review

BACKGROUND

Human immunodeficiency virus (HIV)-infected individuals are at increased risk of developing depression. Depressive syndromes in these patients pose a challenge both diagnostically and therapeutically. These syndromes reflect both the presence of preexisting mood disorders and the development of depressive syndromes subsequent to HIV infection.

DATA SOURCES

A search of the literature to 2005 was performed using the PubMed and Ovid search engines. English- and Portuguese-language articles were identified using the following keywords: HIV or AIDS and depression, mental illness, suicide, fatigue, psychiatry, and drug interactions. Additional references were identified through bibliography reviews of relevant articles.

DATA SYNTHESIS

The clinical presentation and differential diagnosis of depressive symptoms in HIV illness and the role of HIV in the development of these conditions are reviewed. Management issues including suicide assessment and treatment options are then discussed, and potentially important pharmacokinetic interactions are reviewed.

CONCLUSIONS

Individuals with HIV show higher rates of depression. This phenomenon may be due to a preexisting psychiatric disorder or to the HIV infection. Untreated depression symptoms may lead to non-compliance with drug regimens or increased high-risk behaviors. Given the adverse sequelae of untreated depressions in HIV illness, identification and management of depression are integral components of comprehensive HIV care.

St John's wort modulation and developmental expression of multidrug transporters in the rat

Extracts of St John's wort (SJW) (Hypericum perforatum) are a potent inducer of enzymes of the cytochrome P450 system and of the transport protein P-glycoprotein, and interactions with a range of commonly prescribed medications have been described. In addition, recent experimental data suggest that, this otherwise safe treatment, could have some side effects when consumed during pregnancy and lactation. The aim of this study was to investigate, in Wistar rats, the effect of a treatment with high doses of SJW extract (100 and 1000 mg/kg/day) administered prenatally and during breastfeeding, on the level of transcripts of mdr1a, mdr1b, mrp1, mrp2 and cyp3A2 genes. All transcripts were detected in the liver, and their level of expression increased from fetuses to adults. SJW administration, at both dosages, caused a significant decrease of the levels of mdr1a, mdr1b, mrp1 and mrp2 in the livers of fetuses, and an increase in the levels of mdr1a, mdr1b, mrp2 and cyp3A2 in the mothers. In the other organs examined, a physiological regulation during ontogenesis was also evident, but SJW administration did not modify the expression level of the considered transcripts. These data suggest that the administration of the extract together with drugs that are substrates of transport proteins could be particularly hazardous during pregnancy.

Aging and HIV infection

With the advent of highly active antiretroviral therapy (HAART) in mid-1995, the prognosis for HIV-infected individuals has brightened dramatically. However, the conjunction of potent antiviral therapy and longer life expectancy may engender a variety of health risks that, heretofore, HIV specialists have not had to confront. The long-term effects of HIV infection itself and exposure to antiretroviral agents is unknown. Several aspects of aging, including psychiatric disease, neurocognitive impairment, and metabolic and hormonal disorders, may be influenced by chronic exposure to HIV and/or HIV therapeutics. In this paper, we discuss the health issues confronting HIV-infected older adults and areas for future research.

Role of efflux pumps and metabolising enzymes in drug delivery

The impact of efflux pumps and metabolic enzymes on the therapeutic activity of various drugs has been well established. The presence of efflux pumps on various tissues and tumours has been shown to regulate the intracellular concentration needed to achieve therapeutic activity. The notable members of efflux proteins include P-glycoprotein, multi-drug resistance protein and breast cancer resistance protein. These efflux pumps play a pivotal role not only in extruding xenobiotics but also in maintaining the body's homeostasis by their ubiquitous presence and ability to coordinate among themselves. In this review, the role of efflux pumps in drug delivery and the importance of their tissue distribution is discussed in detail. To improve pharmacokinetic parameters of substrates, various strategies that modulate the activity of efflux proteins are also described. Drug metabolising enzymes mainly include the cytochrome P450 family of enzymes. Extensive drug metabolism due to the this family of enzymes is the leading cause of therapeutic inactivity. Therefore, the role of metabolising enzymes in drug delivery and disposition is extensively discussed in this review. The synergistic relationship between metabolising enzymes and efflux proteins is also described in detail. In summary, this review emphasises the urgent need to make changes in drug discovery and drug delivery as efflux pumps and metabolising enzymes play an important role in drug delivery and disposition.

The extent of induction of CYP3A by St. John’s wort varies among products and is linked to hyperforin dose

OBJECTIVE

Induction of CYP3A by St. John's wort (SJW) extracts with high hyperforin (HYF) content is well described. Since SJW products vary in the amount of HYF and other main constituents, the aim of the study was to evaluate the effect on CYP3A function of SJW preparations with a range from very low to high HYF content.

METHODS

Forty-two male, healthy volunteers were randomized into six parallel SJW medication groups with varying composition especially with regard to HYF content. Midazolam plasma concentration profiles were characterized after a single oral dose of 7.5 mg midazolam on the day before and on the 14th day of SJW medication.

RESULTS

All SJW preparations tested resulted in a decrease in midazolam AUC, although the extent of the effect differed. The extract LI 160 (HYF 41 mg/day) decreased midazolam AUC0-12h by 79.4% (95% CI -88.6; -70.1), which was significantly greater than the effect by any other medication (p<0.05). SJW powder tablets 2.7 g/day (HYF 12 mg/day) resulted in a midazolam AUC0-12h decrease of 47.9% (95% CI -59.7;-36.2), while 2.7 g/day SJW powder tablets that were almost devoid of HYF (0.13 mg/day) reduced midazolam AUC0-12h by only 21.1% (95% CI -33.9; -8.3). Considering all six SJW medications tested, the extent of midazolam AUC decrease correlated significantly with increasing HYF dose (r=-0.765, p<0.001), but not with hypericin dose (r=-0.067; p=0.673).

CONCLUSION

The extent of induction of CYP3A varies among St. John's wort products and depends on hyperforin dose.

Toxicity and drug interactions associated with herbal products: ephedra and St. John's Wort

Health care providers are being increasingly confronted with the use of herbal medications by their patients. It is imperative that patients be questioned regarding herbal preparation use and that health care providers become familiar with these agents. Research into the active components and mechanisms of action of various herbals is ongoing [350]. Long-range studies need to be performed to follow patients for efficacy or toxicity in chronic use [351,352]. Adverse reactions to herbal remedies should be reported to the FDA MedWatch at http://www.fda.gov/medwatch. As withany therapeutic agent, risk of use must always be weighed against potential benefits.

Highly active antiretroviral therapy and the kidney: an update on antiretroviral medications for nephrologists

Highly active antiretroviral therapy has dramatically altered the treatment and life expectancy of individuals who are infected with HIV. More than 20 antiretroviral drugs and drug combinations now are available in the United States. Nephrologists need to have an understanding of the pharmacokinetics of antiretroviral medications and the proper dosing of these medications in patients with impaired kidney function. It is also important for nephrologists to be aware of drug-drug interactions that can occur between antiretroviral medications and other medications that they may prescribe, including immunosuppressive medications that are used for renal transplantation, as this becomes more common in HIV-infected patients. Adverse reactions that affect the kidneys and cause fluid-electrolyte complications occur with certain antiretroviral agents, although most are relatively free of nephrotoxicity. This article reviews the clinical pharmacology and dosing modifications of the newer antiretroviral medications in patients with reduced kidney function; important drug-drug interactions involving these medications, particularly with other medications that are likely to be prescribed by nephrologists; and renal toxicities of antiretroviral agents.

Effects of oral androstenedione on steroid metabolism in liver of pregnant and non-pregnant female rats

It is unknown whether androstenedione, a steroidal dietary supplement taken to enhance athletic performance, can affect physiological hormone levels by altering liver enzyme activities that metabolize steroid hormones. Altered hormone levels could be especially devastating during pregnancy. Mature female rats were gavaged with 0, 5, 30 or 60 mg/kg/day androstenedione beginning two weeks prior to mating and continuing through gestation day 19. Non-pregnant female rats were gavaged over the same time frame with 0 or 60 mg/kg/day androstenedione. Livers were removed from dams on gestation day 20 and from non-pregnant rats after five weeks' treatment. Liver microsomes were incubated with 200 microM testosterone, and the reaction products were isolated and analyzed by HPLC. In pregnant rats, formation of 6alpha-, 15beta-, 7alpha-, 16beta-, and 2beta-hydroxytestosterone was increased significantly vs. control at the highest dose level only. Formation of 6beta-hydroxytestosterone increased significantly at both the 30 and 60 mg/kg/day dose levels. In non-pregnant rats, 60 mg/kg/day androstenedione significantly increased formation of 15beta-, 6beta-, 16beta-, and 2beta-hydroxytestosterone. The data suggest that high oral doses of androstenedione can induce some female rat liver cytochromes P450 that metabolize steroid hormones and that the response to androstenedione does not differ between pregnant and non-pregnant female rats.

Hypericin?an inhibitor of proteasome function

Hypericin is the presumed active moiety within Saint John's wort. Extracts of Saint John's wort are widely used as an effective treatment for depression. Available as "over-the-counter" drugs, they are frequently part of the self-medication of patients undergoing radiation therapy for malignant diseases. In addition to antidepressive properties, hypericin has been shown to be able to induce apoptosis and radiosensitize tumor cells, and to have antiinflammatory and phototoxic skin effects. However, the underlying mechanisms are not clear. In this study, we investigated possible inhibitory effects of hypericin on proteasome function and related pathways. Extracts from U373 human glioma cells were incubated with different concentrations of hypericin. Three proteasome activities were monitored using a fluorogenic peptide assay. Activity of the transcription factor NF-kappaB and protein levels of p65, p50, IkappaBalpha and caspase-3 were investigated by EMSA and Western blotting, respectively. Hypericin caused a dose-dependent and photoactivation-independent inhibition of proteasome function. Hypericin treatment (6.25-50 microM) inhibited NF-kappaB, caused accumulation of phosphorylated IkappaBalpha, decreased p50 protein levels and induced cleavage of p65 protein in U373 cells. These effects were observed in MCF-7 cells only at higher concentrations of hypericin (12.5-50 microM). Additionally, inhibition of NF-kappaB activity in U373 cells by hypericin was prevented by caspase inhibition. Although hypericin clearly inhibits proteasome function, its effect NF-kappaB DNA-binding activity was not exclusively proteasome-dependent. The underlying mechanism might also involve caspase activation, a consequence of proteasome inhibition.