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PubMedDate not supplied

Determination of aflatoxins in medicinal herbs by HPLC. An efficient method for routine analysis.

A fast and easy to perform method for the routine determination of aflatoxins in medicinal herbs was developed. The described method involves a single-step extraction with a non-chlorinated solvent, an immunoaffinity clean-up and HPLC with fluorescence detection. Whilst assays with naturally contaminated and with spiked samples of several herbs showed that the recoveries were somewhat low and dependent on the kind of sample and the degree of grinding, the intra-batch reproducibility was good, allowing a reliable quantitation by the standard-addition method. Good linearity, repeatability and accuracy were demonstrated in assays involving several medicinal herbs. The limit of quantitation was of the order of 0.05-0.1 ng/g, being dependent of the species analysed, and the method required no tedious concentration or back-extraction steps.

Aflatoxins↗
PubMed2004

Risks of herbal medicinal products.

PURPOSE: Herbal medicinal products (HMPs) are again highly popular. Their current popularity renders the assessment of their safety an urgent necessity. METHOD: Narrative review using examples only. RESULTS: Constituents of HMPs can be toxic and numerous examples of liver, kidney or other organ damage are on record. All HMPs contain a range of pharmacologically active constituents, and users of HMPs often combine HMPs with prescribed drugs. Thus herb-drug interactions are a real possibility. In most countries, HMPs are not submitted to stringent regulation and control. Thus unreliable quality can be a problem. In particular, this poses a risk when HMPs are contaminated (e.g. with heavy metals) or adulterated (e.g. with prescription drugs). The medical literature holds numerous examples for all of these scenarios and some are used in this article to illustrate the above points. As this area is grossly under-researched, it is rarely possible to define the size of the problem. CONCLUSIONS: It is concluded that the widespread notion of HMPs being inherently safe is naive at best and dangerous at worst. More research is required to minimise the risk HMPs may pose to consumers' health.

Child↗
PubMed2001

A comparison of methods for adaptive sample size adjustment.

In fixed sample size designs, precise knowledge about the magnitude of the outcome variable's variance in the planning phase of a clinical trial is mandatory for an adequate sample size determination. Wittes and Brittain introduced the internal pilot study design that allows recalculation of the sample size during an ongoing trial using the estimated variance obtained from an interim analysis. However, this procedure requires the unblinding of the treatment code. Since unblinding of an ongoing trial should be avoided whenever possible, there should be some benefit of this design compared with blinded sample size recalculation procedures to justify the unveiling of the treatment code. In this paper, we compare several sample size recalculation procedures with and without unblinding. The simulation results indicate that the procedures behave similarly. In particular, breaking of the blind is not required for an efficient sample size adjustment. We also compare these pure sample size adaptation procedures with study designs which additionally allow for early stopping. Evaluation of the cumulative distribution function of the resulting sample sizes shows that the option for early stopping may lead to lower expectation but generally to a higher variability. The procedures are illustrated by an example of a trial in the treatment of depression.

Computer Simulation↗
PubMedDate not supplied

Comparing phytopharmaceuticals: the example of St. John's Wort.

At present, dosage in phytotherapy often falls victim to an undifferentiated point of view. In the case of St. John's Wort, for example, 900 mg of extract has become the standard dosage; however, no studies have investigated the dose-effect ratio, even though there are numerous indications that smaller amounts, particularly of ethanolic extracts, are sufficient to achieve the desired effect. Moreover, listing extract dosages is of no use unless other identifying characteristics are also specified. If phytopharmaceuticals are to be compared with one another, the scope of consideration cannot be limited to single components. The comparison must be carried out comprehensively.

Chromatography, High Pressure Liquid↗
PubMed2001

[St. John's wort: interaction with cyclosporine increases risk of rejection for the kidney transplant and raises daily cost of medication].

ANAMNESIS: A 55-year-old female kidney transplant patient has suffered from diabetes mellitus since being a child. A kidney transplantation was carried out in 1985, requiring a standard immunosuppressive regime of cyclosporine. Cyclosporine blood levels (trough levels) remained stable over the years. DRUG INTERACTION: In 1995 the female patient started self-medication with St John's wort because of medium reactive depression. The standardized St John's wort extract (sold under the brand name Neuroplant) was taken at a dose of 300 mg three times daily. Laboratory investigations between 1995 and April 2000 showed decreased cyclosporine blood concentrations. The mean cyclosporine blood concentration before the comedication with St John's wort was 210.0 ng/ml (95% confidence interval: 171.8-248.2 ng/ml), during the comedication 81.1 ng/ml (95% confidence interval: 60.8-101.4 ng/ml) and was without the herbal remedy 149.8 ng/ml (95% confidence interval: 61.2-238.5 ng/ml). Cyclosporine dosage during the comedication with St John's wort was increased to a mean dosage of 8.2 mg/kg body weight daily (95% confidence interval: 7.0-9.4 mg/kg). In April 2000 the interaction of St John's wort with cyclosporine was suspected and the patient's self-medication was stopped. After stopping treatment with St John's wort, cyclosporine blood levels remained within the therapeutic range. CONCLUSION: Apart from an increased risk of graft rejection, the interaction also had cost implications because the dosage of this expensive drug had to be increased. In the period from 1995 to April 2000 an amount of approximately 15,300.- [symbol: see text] (30,000.- DM) of cyclosporine medication was necessary to avoid transplant rejection. The trend of the graphs strongly suggests that the treatment with St John's wort was the cause of the drop in plasma cyclosporine. It is of particular interest since this long-term observation uniquely reveals the raise of costs.

Antidepressive Agents↗
PubMed1997

[Reversible increase in photosensitivity to UV-B caused by St. John's wort extract].

A 61-year-old woman with depression developed recurring elevated itching erythematous lesions in light-exposed areas after taking St. John's Wort-extract for three years. Routine patchtesting did not reveal any relevant reactions and photopatch testing was negative. Using a systemic oral photoprovocation test with St. John's Wort, we were able to demonstrate a decrease of the MED-UVB which was reversible after withdrawal of the medication.

Antidepressive Agents↗