G Schindler

Systemic Availability and Pharmacokinetics of Thymol in Humans

Essential oil compounds such as found in thyme extract are established for the therapy of chronic and acute bronchitis. Various pharmacodynamic activities for thyme extract and the essential thyme oil, respectively, have been demonstrated in vitro, but availability of these compounds in the respective target organs has not been proven. Thus, investigation of absorption, distribution, metabolism, and excretion are necessary to provide the link between in vitro effects and in vivo studies. To determine the systemic availability and the pharmacokinetics of thymol after oral application to humans, a clinical trial was carried out in 12 healthy volunteers. Each subject received a single dose of a Bronchipret® TP tablet, which is equivalent to 1.08 mg thymol. No thymol could be detected in plasma or urine. However, the metabolites thymol sulfate and thymol glucuronide were found in urine and identified by LC‐MS/MS. Plasma and urine samples were analyzed after enzymatic hydrolysis of the metabolites by headspace solid‐phase microextraction prior to GC analysis and flame ionization detection. Thymol sulfate, but not thymol glucuronide, was detectable in plasma. Peak plasma concentrations were 93.1 ± 24.5 ng ml−1 and were reached after 2.0 ± 0.8 hours. The mean terminal elimination half‐life was 10.2 hours. Thymol sulfate was detectable up to 41 hours after administration. Urinary excretion could be followed over 24 hours. The amount of both thymol sulfate and glucuronide excreted in 24‐hour urine was 16.2% ± 4.5% of the dose.

Urinary Excretion and Metabolism of Arbutin after Oral Administration of Arctostaphylos uvae ursi Extract as Film‐Coated Tablets and Aqueous Solution in Healthy Humans

Bearberry leaves and preparations made from them are traditionally used for urinary tract infections. The urinary excretion of arbutin metabolites was examined in a randomized crossover design in 16 healthy volunteers after the application of a single oral dose of bearberry leaves dry extract (BLDE). There were two groups of application using either film‐coated tablets (FCT) or aqueous solution (AS). The urine sample analysis was performed by a validated HPLC cool‐array method (hydroquinone) and a validated capillary electrophoresis method (hydroquinone‐glucuronide, hydroquinone‐sulfate). The total amounts of hydroquinone equivalents excreted in the urine from BLDE were similar in both groups. With FCT, 64.8% of the arbutin dose administered was excreted; with AS, 66.7% was excreted (p = 0.61). The maximum mean urinary concentration of hydroquinone equivalents was a little higher and peaked earlier in the AS group versus the FCT group, although this did not reach statistical significance (Cur max = 1.6893 μmol/ml vs. 1.1250 μmol/ml, p = 0.13; tmax (t midpoint) = 360 h vs. 440 h P = 038). The relative bioavailability of FCT compared to AS was 103.3% for total hydroquinone equivalents. There was substantial intersubject variability. No significant differences between the two groups were found in the metabolite patterns detected (hydroquinone, hydroquinone‐glucuronide, and hydroquinone‐sulfate).

Herbal medicine with curcuma and fumitory in the treatment of irritable bowel syndrome: A randomized, placebo-controlled, double-blind clinical trial

Objective. Irritable bowel syndrome (IBS) is a common functional disorder for which there is no reliable medical treatment. The aim of this study was to determine the efficacy of two herbal remedies used in the treatment of IBS. Material and methods. In a randomized, double-blind, placebo-controlled trial, IBS patients were randomly assigned to one of three treatment groups: 1) Curcuma xanthorriza 60 mg daily (curcuma group) (n=24), 2) Fumaria officinalis 1500 mg daily (fumitory group) (n=24) and 3) placebo (n=58). The study treatment was applied three times a day for 18 weeks. The main outcome parameters were changes in global patient ratings of IBS-related pain and distension on a visual analogue scale (0–50 mm) between baseline and at the end of treatment. Additional outcome parameters included global assessments of changes in IBS symptoms and psychosocial stress caused by IBS. Results. A total of 106 patients (mean age 48±12 years, 63% F) were included in the intention-to-treat group. IBS-related pain decreased by −0.9±11.5 (mm±SD) in the fumitory group, −0.3±9.9 in the placebo group and increased by 2.0±9.5 in the curcuma group (p=0.81). IBS-related distension decreased by −1.4±12.5 in the curcuma group, −2.1±9.2 in the placebo group and increased by 0.3±9.3 in the fumitory group (p=0.48). Additionally, the global assessment of changes in IBS symptoms and psychological stress due to IBS did not differ significantly among the three treatment groups. Conclusions. Neither fumitory nor curcuma showed any therapeutic benefit over placebo in patients with IBS. Therefore, the use of these herbs for the treatment of IBS cannot be recommended.