Different effects of traditional Chinese medicines containing similar herbal constituents on prednisolone pharmacokinetics

Saibokuto as a Possible Therapy for Type B Insulin Resistance Syndrome: The Disappearance of Anti-insulin Receptor Antibody and a Marked Amelioration of Glycemic Control by Saibokuto Treatment

Type B insulin resistance syndrome is a rare autoimmune disease and no effective therapy has yet been established. On the other hand, it is known that Saibokuto, one type of Japanese Kampo medicine, may have beneficial effects on various symptoms associated with this disease and it is therefore occasionally prescribed for various immune disorders. We herein describe a case of type B insulin resistance syndrome in which anti-insulin receptor antibody disappeared and the patient's glycemic control markedly improved after the administration of Saibokuto. At first, we administered various anti-oral diabetic drugs and insulin therapy, but the patient's glycemic control became further aggravated. In addition, Helicobacter pylori eradication therapy was not effective, although its benefit has been reported. Interestingly, after the patient started taking Saibokuto, her glycemic control markedly improved. In addition, the patient's plasma insulin levels markedly decreased and anti-insulin receptor antibody became negative after taking Saibokuto. Taken together, there is a possibility that Saibokuto may one of the options for type B insulin resistance syndrome therapy.

Therapeutic Risk and Benefits of Concomitantly Using Herbal Medicines and Conventional Medicines: From the Perspectives of Evidence Based on Randomized Controlled Trials and Clinical Risk Management

Despite increased awareness of the potential of herb-drug interactions (HDIs), the lack of rigorous clinical evidence regarding the significance provides a challenge for clinicians and consumers to make rational decisions about the safe combination of herbal and conventional medicines. This review addressed HDIs based on evidence from randomized controlled trials (RCTs). Literature was identified by performing a PubMed search till January 2017. Risk description and clinical risk management were described. Among 74 finally included RCTs, 17 RCTs (22.97%) simply addressed pharmacodynamic HDIs. Fifty-seven RCTs (77.03%) investigated pharmacokinetic HDIs and twenty-eight of them showed potential or actual clinical relevance. The extent of an HDI may be associated with the factors such as pharmacogenomics, dose of active ingredients in herbs, time course of interaction, characteristics of the object drugs (e.g., administration routes and pharmacokinetic profiles), modification of herbal prescription compositions, and coexistence of inducers and inhibitors. Clinical professionals should enhance risk management on HDIs such as increasing awareness of potential changes in therapeutic risk and benefits, inquiring patients about all currently used conventional medicines and herbal medicines and supplements, automatically detecting highly substantial significant HDI by computerized reminder system, selecting the alternatives, adjusting dose, reviewing the appropriateness of physician orders, educating patients to monitor for drug-interaction symptoms, and paying attention to follow-up visit and consultation.

Natural Health Product Interactions with Medication

Natural health products (or dietary supplements) refer to those products found in oral dosage forms, containing 1 or more active ingredients considered to be a nutrient, an herbal product, or any other nonnutrient/nonherbal substance. Their use continues to increase in the general population and in patients seen by nutrition support clinicians. Aside from an appraisal of product safety and effectiveness, attention should be paid to the potential for these product ingredients to interact with medication. Estimates are that at least 15 million adults in the United States are at risk for supplement-drug interactions. These can occur through both pharmacokinetic and pharmacodynamic mechanisms. This review describes the influence of dietary supplements on both the disposition and the effect of medication and provides numerous examples. Patients at greatest risk for interactions are those with chronic disease, who use multiple medications-particularly those with a narrow therapeutic range-have genetic variants in drug metabolism, impaired organ function, and are at either end of the age spectrum. Knowledge of the specific effects on drug absorption, metabolism, and effect is still incomplete. Relative to the large number of possible interactions between supplements and medication, only a small number of combinations have been examined or reported. The greatest limiting factor remains the quality or reliability of the existing evidence, as many widely accepted interactions are only theoretical based either on in vitro data or known pharmacology. A distinction needs to be clearly drawn between "documented" interactions and "potential" interactions. Although drug-drug interactions have been widely recognized, supplement-drug interactions may be as important to recognize, report, and manage.

Interactions between herbs and conventional drugs: overview of the clinical data

This article provides an overview of the clinical evidence of interactions between herbal and conventional medicines. Herbs involved in drug interactions--or that have been evaluated in pharmacokinetic trials--are discussed in this review. While many of the interactions reported are of limited clinical significance and many herbal products (e.g. black cohosh, saw palmetto, echinacea, hawthorn and valerian) seem to expose patients to minor risk under conventional pharmacotherapy, a few herbs, notably St. John's wort, may provoke adverse events sufficiently serious to endanger the patients' health. Healthcare professionals should remain vigilant for potential interactions between herbal medicines and prescribed drugs, especially when drugs with a narrow therapeutic index are used.

Concurrent use of corticosteroids with licorice-containing TCM preparations in Taiwan: a National Health Insurance Database study

OBJECTIVES

This study used a nationwide population-based dataset from the 1997-2003 National Health Insurance claims to explore the prevalence, frequency, and relative risk of concurrent use of systemic corticosteroids with licorice-containing Traditional Chinese Medicine (TCM) preparations that might possibly result in drug-herb interactions.

DESIGN

This study was based on the complete datasets of Western medicine and TCM outpatient reimbursement claims from 1997 to 2003 contained in the National Health Insurance Research Database of Taiwan. According to the date and duration of prescriptions, the patients who concurrently used systemic corticosteroids with licorice-containing TCM preparations were derived for statistical analysis.

SETTING

This study was set in Taiwan.

OUTCOME MEASURES

Descriptive statistics were used to analyze the demographics of patients who used corticosteroids with licorice-containing TCM preparations concurrently, including age, gender, and the frequency and percentage of major diseases in International Classification of Diseases, 9th version, Clinical Modification (ICD-9-CM) categories. The relative risk of potential corticosteroid-herb interaction was also analyzed with respect to different characteristics of the patients (age, sexuality etc.).

RESULTS

The prevalence of concurrent use of systemic corticosteroids with licorice-containing TCM preparations through prescriptions from different Chinese medicine and Western medicine physicians was 1.495%. Among the major disease categories, ICD-9-CM codes 280-289 had the highest prevalence rate of 3.803%.

CONCLUSIONS

Potential risk of corticosteroid-licorice interactions may happen, even through formal medical services. In the future, such educational propagations should be reinforced. Furthermore, an alert device that includes well-recognized drug-herb interactions should be built into every hospital's computer system to remind physicians to be cautious on drug safety.

The in-vivo effects of sho-saiko-to, a traditional Chinese herbal medicine, on two cytochrome P450 enzymes (1A2 and 3A) and xanthine oxidase in man

The Chinese herbal medicine sho-saiko-to is a mixture of seven herbal components (Bupleurum root, Pinellia tuber, Scutellaria root, Jujube fruit, Ginseng root, Glycyrrhiza root and Ginger rhizome) that is widely administered to patients with chronic hepatitis in Japan. We assessed the effects of sho-saiko-to on the activity of cytochrome P450 (CYP) 1A2, CYP3A and xanthine oxidase (XO) in man. Twenty-six healthy subjects were studied to evaluate their baseline activity of CYP1A2 and XO by the respective urinary metabolic ratios of an 8-h urine sample after an oral 150-mg dose of caffeine and of CYP3A by a urinary excretion ratio of 6β-hydroxycortisol (6β-HC) to free cortisol (FC). Thereafter, the subjects received a twice-daily 2.5-g dose of sho-saiko-to for five days, and underwent the caffeine test on day 1 and day 5. The mean activity of CYP1A2 decreased by 16% on both day 1 and day 5 compared with the baseline (P = 0.001). The mean activity of XO also significantly decreased by 25% on day 1 and 20% on day 5 (P < 0.0001) compared with the baseline value. The activity of CYP3A tended to be lower on day 5 than the baseline (P = 0.146). It is concluded that sho-saiko-to reduces CYP1A2 and XO activity in man.

Comparing two botulinum toxin type A formulations using manufacturers? product summaries

BACKGROUND AND OBJECTIVE

Because of the unique pharmacology and clinical versatility of botulinum toxin (BoNT), particularly BoNT serotype A (BoNTA), a need exists for discussion of the current data on similarities and differences between two BoNTA products, BOTOX and Dysport.

METHODS

We compared the physiochemical and pharmacological properties of BOTOX and Dysport using information from the Summary of Product Characteristics (SmPC) documents from a number of countries around the world.

RESULTS AND DISCUSSION

Our analysis based on the SmPC documents demonstrated distinct differences in physical characteristics, breadth of approved indications, dosing and administration, and the incidence and severity of adverse events.

CONCLUSION

BOTOX and Dysport are not bioequivalent. Many of the differences between BOTOX and Dysport discussed within are probably related to the differences in their physical characteristics.

The effect of Shoseiryuto, a traditional Japanese medicine, on cytochrome P450s, N-acetyltransferase 2 and xanthine oxidase, in extensive or intermediate metabolizers of CYP2D6

OBJECTIVE

Shoseiryuto (TJ-19) contains eight herbal components, including Ephedra sinica, and has been used for treating asthma and allergic rhinitis in Asian countries for several centuries. In this study, we investigated the potential herb-drug interaction of TJ-19 in healthy volunteers and attempted to ascertain whether or not the interaction might be affected by the cytochrome P450 (CYP) 2D6 genotype.

METHODS

We assessed the effect of TJ-19 on the activities of CYP1A2, CYP2D6, CYP3A, xanthine oxidase (XO), and N-acetyltransferase 2 (NAT2) in 37 healthy subjects. The subject pool consisted of 19 extensive metabolizers (EMs) with CYP2D6*Wild/*Wild, and 18 intermediate metabolizers (IMs) with CYP2D6*10/*10. The baseline activities of five enzymes were ascertained by their respective urinary metabolic ratios from an 8-h urine sample, after an oral 150-mg and 30-mg dose of caffeine and dextromethorphan were administrated, respectively. Thereafter, the subjects received 4.5 g of TJ-19 twice daily for 7 days, and underwent the same phenotyping test on postdose day 7.

RESULTS

The activities of all enzymes examined did not differ before or after the 7-day administration of TJ-19. Consequently, the influence of the CYP2D6 genotype on the herb-drug interaction remained unsolved.

CONCLUSION

Our results indicate that TJ-19 at the generally recommended dosage is unlikely to cause pharmacokinetic interaction with co-administered medications primarily dependent on the CYP1A2, CYP2D6, CYP3A, XO, and NAT2 pathways for elimination.

Natural health product-drug interactions: a systematic review of clinical trials

Interactions between natural health products (NHP) and prescription medications are of increasing concern. This paper aims to identify all clinical trials of NHP-drug interactions. To determine the prevalence and outcomes of clinical investigations of NHP-drug pharmacokinetic interactions, electronic databases were searched from inception through March 2004, as well as reference lists from published reports and experts in the field for unpublished studies. Eligible studies were clinical investigations of the interaction between a NHP and the metabolism of a regulated medication in humans. Studies were excluded that only investigated the metabolism of an NHP or examined food-drug or NHP-NHP interactions. Two reviewers selected studies for inclusion and independently extracted data. Forty-seven trials were identified, studying an average of 14 participants/study (95% confidence interval [CI] 11-18), examined drug interactions with 19 different herbal preparations. All trials were pharmacokinetic studies, 41 of healthy volunteers and 6 of patients. Ten different herbal medicines as well as 5 different traditional herbal concoctions were studied. Potentially clinically significant drug interactions were observed with St. John wort (16/24 studies), garlic (2/5 studies), and American ginseng (1 study). Research on NHP-drug interactions is limited in number and scope. With the exception of St. John wort, clinicians and the public do not have information that permits strong inferences about interactions between NHPs and conventional medications.

Herb-drug interactions: an overview of the clinical evidence

Herbal medicines are mixtures of more than one active ingredient. The multitude of pharmacologically active compounds obviously increases the likelihood of interactions taking place. Hence, the likelihood of herb-drug interactions is theoretically higher than drug-drug interactions, if only because synthetic drugs usually contain single chemical entities. Case reports and clinical studies have highlighted the existence of a number of clinically important interactions, although cause-and-effect relationships have not always been established. Herbs and drugs may interact either pharmacokinetically or pharmacodynamically. Through induction of cytochrome P450 enzymes and/or P-glycoprotein, some herbal products (e.g. St John's wort) have been shown to lower the plasma concentration (and/or the pharmacological effect) of a number of conventional drugs, including cyclosporine, indinavir, irinotecan, nevirapine, oral contraceptives and digoxin. The majority of such interactions involves medicines that require regular monitoring of blood levels. To date there is less evidence relating to the pharmacodynamic interaction. However, for many of the interactions discussed here, the understanding of the mechanisms involved is incomplete. Taking herbal agents may represent a potential risk to patients under conventional pharmacotherapy.

Pharmacokinetics and pharmacodynamics of systemically administered glucocorticoids

Glucocorticoids have pleiotropic effects that are used to treat diverse diseases such as asthma, rheumatoid arthritis, systemic lupus erythematosus and acute kidney transplant rejection. The most commonly used systemic glucocorticoids are hydrocortisone, prednisolone, methylprednisolone and dexamethasone. These glucocorticoids have good oral bioavailability and are eliminated mainly by hepatic metabolism and renal excretion of the metabolites. Plasma concentrations follow a biexponential pattern. Two-compartment models are used after intravenous administration, but one-compartment models are sufficient after oral administration.The effects of glucocorticoids are mediated by genomic and possibly nongenomic mechanisms. Genomic mechanisms include activation of the cytosolic glucocorticoid receptor that leads to activation or repression of protein synthesis, including cytokines, chemokines, inflammatory enzymes and adhesion molecules. Thus, inflammation and immune response mechanisms may be modified. Nongenomic mechanisms might play an additional role in glucocorticoid pulse therapy. Clinical efficacy depends on glucocorticoid pharmacokinetics and pharmacodynamics. Pharmacokinetic parameters such as the elimination half-life, and pharmacodynamic parameters such as the concentration producing the half-maximal effect, determine the duration and intensity of glucocorticoid effects. The special contribution of either of these can be distinguished with pharmacokinetic/pharmacodynamic analysis. We performed simulations with a pharmacokinetic/pharmacodynamic model using T helper cell counts and endogenous cortisol as biomarkers for the effects of methylprednisolone. These simulations suggest that the clinical efficacy of low-dose glucocorticoid regimens might be increased with twice-daily glucocorticoid administration.

Herbal therapies

In summary, herbs are commonly used, and it is the physician's responsibility to have better documentation of this practice by encouraging patients to report use of herbs, and to look for any unusual side effects that can occur in terms of herb-drug or herb-herb interactions.

Up-regulating effects of glycyrrhizin on interleukin-18 gene expression by cDNA microarray

AIM: To investigate the relationship of glycyrrhizin and interleukin 18 (IL-18) gene expression and to explore the molecular biological mechanisms of glycyrrhizin in antivirus functions.

METHODS: cDNA microarray was used for the study of up-regulated gene by glycyrrhizin. Polymerase chain reaction (PCR) technique was employed to amplify the sequence of IL-18 promoter by using HepG2 cell genomic DNA as the template, named IL-18P, and the PCR product was cloned into pGEM-T vector. The IL-18P gene was cut from T-IL-18 P by KpnI and Bgl II, and then cloned into pCAT3 basic, named pCAT3- IL-18P. pCAT3-IL-18P was transfected into the HepG2 cell line and cotransfected HepG2 cells with glycyrrhizin by FuGENE 6 transfection reagents. The HepG2 cells transfected with pCAT3-basic was used as negative control. The activity of chloramphenicol acetyltransferase (CAT) in HepG2 cells transfected was detected by an enzyme-linked immunoassay (ELISA) kit after 48 h, which reflected the transactivating function of glycyrrhizin to IL-18 gene promoter.

RESULTS: The expressive vector pCAT3-IL-18P was constructed and confirmed by restriction enzyme digestion and sequencing. The expression of CAT in HepG2 cells transfected with pCAT3-IL-18P and stimulated with HepG2 was 7.7 times as higher as that of pCAT3-basic, and 1.5 times as higher as that of pCAT3-IL-18P.

CONCLUSION: HepG2 can up-regulate IL-18 gene promoter. These results provide a new evidence to explain the molecular biological mechanisms of HepG2 in immuno-regulation and antivirus.

Naturoceutical agents in the management of cardiovascular disease

During the past decade, complementary and alternative medicine (CAM) has grown in attractiveness to the Western public, and in recognition by practitioners of traditional medicine. The incorporation of effective CAM therapies into traditional practice is termed 'integrative medicine'. One form of CAM demonstrating exponential growth through mass public consumerism is the use of naturoceuticals. Naturoceutical (or nutraceutical) agents are defined as mega-dose vitamins, herbal products or other 'natural' supplements purchased and consumed with premeditated 'pharmaceutical' intention to treat or prevent an illness or disease. Dietary supplements per se, are intended to supply adequate nutrients that may be lacking from the diet, and are thus, generally health promoting. A regulatory paradox exists since naturoceuticals are classified as dietary supplements although many possess measurable pharmacologic activity. In reference to cardiovascular disorders, consumers use naturoceuticals for three distinctly recognizable purposes. These are the primary and secondary prevention of cardiovascular diseases and the treatment of diagnosed disorders such as heart failure, angina pectoris or arrhythmia. The evidence base supporting the routine use of naturoceutical products for these intentions is sparse, although the likelihood of harm from their consumption is low for an average, healthy adult. Evidence of significant harm (including fatalities) has been observed when certain herbal products are used in excess or in combination with, other herbs or prescription drugs. The safety of use at the extremes of age, or by persons with cardiac, renal or hepatic impairment is also a concern. Healthcare professionals should routinely document patient naturoceutical use, be alert for and report suspected adverse effects. Until well-designed clinical trials determine the proper indication(s), dose safety profile and risk/benefit ratio for these products, their routine use should not be advocated. Thus, the role of naturoceutical agents in the integrative management of cardiovascular disorders remains undefined.

Sho-saiko-to and Saiko-keisi-to, the traditional Chinese and Japanese herbal medicines, altered hepatic drug-metabolizing enzymes in mice and rats when administered orally for a long time

As the consumption of herbal remedies has increased, the opportunity that such herbal medicines are co-administered with other drugs has also risen gradually and we are, therefore, very much concerned about herb-drug interactions. We examined the effects of pre-administration of Kampo medicines (Sho-saiko-to, Saiko-keishi-to, Shigyaku-san and Dai-saiko-to) on the pentobarbital-induced sleeping time in mice and rats, to clarify the possibility that they could affect the drug-metabolizing enzymes. The administration of Sho-saiko-to and Saiko-keishi-to for 4 weeks significantly shortened the pentobarbital-induced sleeping time in mice and the administration of Sho-saiko-to for 2 weeks significantly reduced the sleeping time in rats. Furthermore, we tried to identify the molecular species of rat cytochrome P450s (CYPs) affected by Sho-saiko-to and Saiko-keishi-to by competitive RT-PCR. The oral administration of Sho-saiko-to for 2 weeks upregulated the mRNA expression of CYP2B, CYP3A1, CYP2E1 and CYP4A1 in rats. The treatment with Saiko-keishi-to for 2 weeks also up-regulated the mRNA expression of CYP2B, CYP3A1 and CYP4A1. Sho-saiko-to and Saiko-keishi-to may potentially influence the drug-metabolizing enzymes in man, and would thus require much attention when used in the clinical situation.

Cloning of genes differentially expressed in Jurkat cells treated with glycyrrhizin using cDNA microarray

AIM: To study the difference in gene expression profile in human lymphoma cell line Jurkat cells treated with glycyrrhizin (GL), and to further elucidate the molecular immune mechanism of glycyrrhizin against T lymphocyte.

METHODS: cDNA microarray technology was employed to detect the mRNA from Jurkat cells treated with GL and 0.9 percent sodium chloride, respectively.

RESULTS: The results indicated that among 1 152 genes which were obtained from gene expression profile analysis, there were 30 genes different from those in GenBank in which 12 genes were up-regulated and 18 genes were down-regulated in Jurkat cells treated with GL, compared to those treated with 0.9 percent sodium chloride. These genes differentially regulated by GL included human genes encoding proteins involved in immune regulation, cell signal transduction, cell proliferation and differentiation.

CONCLUSION: cDNA microarray technology is successfully used to screen the genes differentially expressed in Jurkat cells treated with GL, which brings some new clues for studying the immune regulation mechanism of GL.

Traditional oriental herbal medicine, Bakumondo-to, suppresses vagal neuro-effector transmission in guinea pig trachea

OBJECTIVE

Bakumondo-to (Maimendong tang) is a traditional oriental herbal medicine that has been used as an antitussive agent. We previously demonstrated that Bakumondo-to attenuates airway hyperresponsiveness induced by ozone. However, the mechanism(s) responsible for this effect remains unclear. In the present study, we examined the mechanism whereby Bakumondo-to inhibits ozone-induced airway hyperresponsiveness. First, we examined the effect of Bakumondo-to on prostanoids production, which are key mediators to airway hyperresponsiveness after ozone exposure. Second, we studied its effects on the vagal neuroeffector transmission, because vagal nerve is likely to play an important role in airway hyperresponsiveness after ozone.

METHODS

We measured the effects of Bakumondo-to on the concentrations of prostanoids in bronchoalveolar lavage fluid before and after ozone. We evaluated the effects of Bakumondo-to on the contraction of guinea pig tracheal smooth muscle evoked by electrical field stimulation (EFS) or the exogenous application of acetylcholine (ACh). Isometric tension of tracheal strips was measured in the presence of indomethacin (10(-6) M) and of guanethidine (10(-6) M).

RESULTS

Ozone caused significant increase in prostaglandin E2 (PGE2) and thromboxane B2 (TXB2); however, Bakumondo-to did not affect the increase in these prostanoids. Bakumondo-to (0.01 mg/mL-1 mg/mL) significantly suppressed the contraction evoked by EFS, but did not affect the ACh-evoked contraction, indicating that Bakumondo-to suppressed tracheal smooth muscle contraction pre-junctionally.

CONCLUSION

These results suggest that the mechanism by which Bakumondo-to inhibits airway hyperresponsiveness depends on inhibiting the release of acetylcholine from vagal nerve terminals.

In vitro inhibitory effects of Kampo medicines on metabolic reactions catalyzed by human liver microsomes

BACKGROUND

Although it is well known that drug-drug interactions may lead to toxicity and therapeutic failure, little is known about the incidence and consequences of herb-drug interactions in patients receiving Kampo medicines.

METHODS

We evaluated the frequency of the combined use of Kampo medicines and Western drugs at Osaka University Hospital, and investigated the effects of these formulae on the metabolic activity of different cytochrome P450 (CYP) isoforms using pooled microsomes obtained from human liver.

RESULTS

Twenty-two Kampo formulae were used together with 40 Western drugs catalyzed by the CYP isoforms CYP3A4, CYP2C9, CYP2D6 and CYP1A2. Among the Kampo medicines, HOCHUEKKI-TO, SHOSAIKO-TO, NINJINYOUEI-TO, SAIREI-TO and KAKKON-TO were most frequently used during the study period (1996-2000). These were co-administered with 11 categories of drugs, which are substrates for CYP3A4. HOCHUEKKI-TO and SAIREI-TO were competitive inhibitors of CYP3A4 with Ki values of 0.65 and 0.1 mg/mL, respectively. HOCHUEKKI-TO, SHOSAIKO-TO and SAIREI-TO inhibited the metabolic activities of CYP2C9, but had no effect on CYP2D6. HOCHUEKKI-TO and SAIREI-TO exhibited non-competitive inhibition of the metabolic activity of CYP2C9 with a similar Ki value (0.7-0.8 mg/mL). SAIRE-TO (0.25 mg/mL) was a potent inhibitor of CYP1A2 (inhibition > 68%).

CONCLUSIONS

Frequently used Kampo medicines may interact with Western drugs, which are substrates for CYP3A4, CYP2C9 and CYP1A2. Their co-administration should be undertaken with care.

Effects of the aqueous extract from Salvia miltiorrhiza Bge on the pharmacokinetics of diazepam and on liver microsomal cytochrome P450 enzyme activity in rats

The aim of this study was to determine the effects of the aqueous extract of Salvia miltiorrhiza Bge (danshen in Chinese) on the pharmacokinetics of diazepam and on liver microsomal cytochrome P450 enzyme activity in rats. Rats (n = 5) were pretreated with danshen extract (100 mg kg(-1) per day, p.o.) for 15 consecutive days. Control rats (n = 5) received saline at the same time. Each rat was then administered a single oral dose of 15 mg kg(-1) diazepam. The pharmacokinetic parameters of diazepam were significantly different between the two groups. In the danshen pretreated group, the maximum concentration of diazepam and the area under the plasma concentration-time curve were reduced to about 72.7% and 44.4%, respectively, while the total body clearance was markedly increased by 2-fold. To help explain the results, liver microsomal suspensions were obtained from rats that were randomly divided into the control group (n = 10), and the low- (20 mg kg(-1) for 15 days, p.o., n = 10) and high-dose groups (100 mg kg(-1) for 15 days, p.o., n = 10) pretreated with danshen extract. Compared with the control rats, the microsomal protein content, cytochrome P450 enzyme level and erythromycin N-demethylase activity of pretreated rats were significantly increased. These results indicate that danshen extract can stimulate the activity of cytochrome P450 isoforms, and changes in the pharmacokinetics of diazepam resulting from danshen extract are related to an increase in metabolic activity of cytochrome P450.

Hepatotoxicity and complementary and alternative medicines

Though some herbal medicines have been shown to protect against or treat experimental liver injury in vitro, and many may possess one or a combination of antioxidant, antifibrotic, immunomodulatory, or antiviral activities, they have not been shown effective in human trials. It has been extremely difficult to construct randomized, controlled trials using complementary and alternative medicines because of an incomplete understanding of their modes of action, the lack of standardization in their manufacture, and the complexity of ingredients in any herbal extract. This may become easier once more standardized and broad-based regulatory oversight of marketing and manufacture of these products is achieved. Despite this, the use of complementary and alternative medicines is ever increasing, especially in patients having chronic liver disease. With this growing popularity, it is becoming more apparent that many of these treatments possess the potential for appreciable hepatotoxicity, in some instances resulting in significant morbidity and mortality. Until these products are more closely regulated and their advertising better scrutinized, all physicians and patients should become more familiar with the natural and alternative products that are commonly used, and recognize which can be harmful (Table 4). Better public awareness should be maintained with regard herb and prescription drug interactions.

Drug interactions: Proteins, pumps, and P-450s

The two major concerns in drug safety are adverse drug reactions and drug interactions. When multiple drug therapies are prescribed, drug interactions become an important consideration for patients and physicians. The life of a drug is reviewed with emphasis on absorption, distribution, metabolism, and excretion. Pharmacokinetic and pharmacodynamic mechanisms for drug interactions are reviewed. The contributions of P-glycoprotein, pharmacogenetic variation, and genetic polymorphisms to drug interactions are highlighted. Prediction of drug interactions is possible with knowledge of which agents are likely to cause alterations in drug metabolism. (J Am Acad Dermatol 2002;47:467-84.)

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should have an understanding of the life of a drug. This knowledge should help predict important potential drug interactions.

Immunosuppressant pharmacodynamics on peripheral-blood mononuclear cells from patients with ulcerative colitis

We investigated peripheral-blood mononuclear cell (PBMC) response to immunosuppressive drugs and its influence on glucocorticoid therapy in ulcerative colitis (UC). IC50s of immunosuppressive drugs on in vitro blastogenesis of PBMCs stimulated with concanavalin A were estimated in 76 UC and 146 healthy subjects. Individual differences in IC50s for prednisolone, methylprednisolone, cyclosporine, and tacrolimus on blastogenesis of PBMCs from UC patients were spread from 11.0 to 1000, 0.6 to 1000, 0.01 to 1000, and 0.001 to 4.6 ng/ml, respectively. Normal upper thresholds for IC50s of these drugs were estimated from the mean + 2 S.D. of the IC50s of healthy PBMCs, and the patients exhibiting IC50s over these levels were arbitrarily considered as resistant. The incidences of resistance to glucocorticoids and cyclosporine in UC were significantly higher than those in healthy subjects (p < 0.0005). In 14 UC patients, there was a significant correlation between amounts of prednisolone (p < 0.05) or period of prednisolone administration (p < 0.05) for UC treatment and prednisolone IC50. The results showed that large individual deviations in PBMC response to the drugs were observed in UC, and UC patients exhibiting low PBMC sensitivity to prednisolone required a high prednisolone amount as well as long period of prednisolone administration for treatment. Thus, the drug sensitivity tests could be informative to single out refractory patients to the immunosuppressive therapy.

Herb-drug interactions: review and assessment of report reliability

AIMS

The aim of this systematic review was to assess the published clinical evidence on interactions between herbal and conventional drugs.

METHODS

Four electronic databases were searched for case reports, case series or clinical trials of such interactions. The data were extracted and validated using a scoring system for interaction probability.

RESULTS

One hundred and eight cases of suspected interactions were found. 68.5% were classified as 'unable to be evaluated', 13% as 'well-documented' and 18.5% as 'possible' interactions. Warfarin was the most common drug (18 cases) and St John's wort the most common herb (54 cases) involved.

CONCLUSION

Herb-drug interactions undoubtedly do occur and may put individuals at risk. However our present knowledge is incomplete and more research is urgently needed.

Effects of sho-saiko-to (xiao chai hu tang), a Chinese traditional medicine, on the gastric function and absorption of tolbutamide in rats

This study was carried out to investigate the effects of Sho-saiko-to (Xiao Chai Hu Tang), a Chinese traditional medicine, on the gastric function including the gastric emptying rate (GER) and intragastric pH in rats. Additionally, the effects of the GER and intragastric pH on tolbutamide absorption after oral administration were examined. The GER measured at 40 min after dosing was reduced to about 70% by the pretreatment of Sho-saiko-to (500 mg/kg). The plasma tolbutamide concentration in the rats treated with a 250 mg/kg dose of Sho-saiko-to was significantly lower than that in the control group. Plasma tolbutamide concentrations increased along with the GER in the group co-administered Sho-saiko-to, and there were significant correlations between the GERs and plasma levels in both time points at 20 and 40 min after administration. In the study using pylorus-ligated rats, Sho-saiko-to significantly elevated the intragastric pH, but induced no change in the concentrations of tolbutamide dissolved in the gastric content. Additionally, Sho-saiko-to did not change the area under the plasma concentration-time curve (AUC) of tolbutamide up to 60 min after administration into the stomach loop, and gastric absorption has been considered to minimally contribute to whole absorption of tolbutamide in the gastrointestinal tract. These results indicate that Sho-saiko-to has an inhibitory effect on the function of gastric emptying in rats. The reduced gastric emptying could affect gastrointestinal absorption, resulting in the lower plasma concentration of tolbutamide after oral administration. Furthermore, it is suggested that Sho-saiko-to can raise the intragastric pH but affect neither the intragastric dissolution nor the gastric absorption of tolbutamide.

Studies on interactions between traditional herbal and Western medicines. IV: lack of pharmacokinetic interactions between Saiko-ka-ryukotsu-borei-to and carbamazepine in rats

The possibility of pharmacokinetic interactions between Saiko-ka-ryukotsu-borei-to extract powder (TJ-12), a widely used traditional Chinese herbal (Kampo) medicine, and carbamazepine (CBZ), an important anti-epileptic drug, was examined in rats. There were no significant differences in the serum protein binding of CBZ and carbamazepine- 10,11-epoxide (CBZ-E), its active metabolite, at two concentrations (1 and 10 Bg/ml) between twogroups pretreated orally with the vehicle andTJ-12 suspension (1 g/kg/d, p.o.) for 1 week. One-week repeated pretreatment with TJ- 12 (1 g/kg/d) did not influence liver weight, contents of cytochromes P450 and b5 in hepatic microsomes or the formation rate of CBZ-E from CBZ by its microsomes, while pretreatment with phenobarbital (80 mg/kg/d, i.p.) significantly increased these parameters. Neither a single nor 1-week repeated oral pretreatment with TJ-12 (1 g/kg/d) affected the plasma concentration-time profile and any pharmacokinetic parameter of CBZ or CBZ-E after oral administration of CBZ (50 mg/kg). These results indicated that oral co-administration of TJ-12 with CBZ has no effect ofthe pharmacokinetics of CBZ or CBZ-E in rats. Concomitant treatment with TJ- 12 and CBZ appears to be pharmacokinetically safe in humans.

Safety issues with herbal medicine

As herbal medicines are used by increasing numbers of people, pharmacists must be knowledgeable about their safety. This requires appreciation of the magnitude of use, as well as regulations under which the products are marketed that may affect their safety. Unexpected effects of many popular herbal products are described in the literature. Thus the pharmacist's role in ensuring protection of the consumer continues to grow.

Herb-drug interactions

Concurrent use of herbs may mimic, magnify, or oppose the effect of drugs. Plausible cases of herb-drug interactions include: bleeding when warfarin is combined with ginkgo (Ginkgo biloba), garlic (Allium sativum), dong quai (Angelica sinensis), or danshen (Salvia miltiorrhiza); mild serotonin syndrome in patients who mix St John's wort (Hypericum perforatum) with serotonin-reuptake inhibitors; decreased bioavailability of digoxin, theophylline, cyclosporin, and phenprocoumon when these drugs are combined with St John's wort; induction of mania in depressed patients who mix antidepressants and Panax ginseng; exacerbation of extrapyramidal effects with neuroleptic drugs and betel nut (Areca catechu); increased risk of hypertension when tricyclic antidepressants are combined with yohimbine (Pausinystalia yohimbe); potentiation of oral and topical corticosteroids by liquorice (Glycyrrhiza glabra); decreased blood concentrations of prednisolone when taken with the Chinese herbal product xaio chai hu tang (sho-salko-to); and decreased concentrations of phenytoin when combined with the Ayurvedic syrup shankhapushpi. Anthranoid-containing plants (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs. Many reports of herb-drug interactions are sketchy and lack laboratory analysis of suspect preparations. Health-care practitioners should caution patients against mixing herbs and pharmaceutical drugs.

A Chinese traditional medicine, sho-saiko-to (xiao-chaihu-tang), reduces the bioavailability of tolbutamide after oral administration in rats

The effects of Sho-saiko-to on the pharmacokinetics of tolbutamide were investigated in rats. After intravenous administration of tolbutamide (5 mg/kg), no significant change in the pharmacokinetics of tolbutamide was observed in both groups of single and multiple (7 days) pre-administration of Sho-saiko-to (500 mg/kg). In the study of single oral administration of tolbutamide (50 mg/kg), co-administration of Sho-saiko-to tended to accelerate the initial absorption rate of tolbutamide. The area under the plasma concentration-time curve of tolbutamide after oral administration was significantly reduced by Sho-saiko-to. Subsequently, a significant decrease was observed in the oral bioavailability of this drug when Sho-saiko-to was given concomitantly. These findings suggest that Sho-saiko-to reduces the bioavailability of tolbutamide after oral administration in rats, and that this change is not related to hepatic metabolism.

Effect of the Chinese herbal medicine, Bakumondo-to, on airway hyperresponsiveness induced by ozone exposure in guinea-pigs

OBJECTIVE

Bakumondo-to (Maimendong tang) is a Chinese herbal medicine that has been used as an anti-tussive agent. However, the effects of Bakumondo-to on airway hyperresponsiveness are unknown. We examine whether Bakumondo-to can inhibit airway hyperresponsiveness induced by ozone.

METHODOLOGY

Measurements of airway responsiveness and plasma extravasation and bronchoalveolar lavage (BAL) were performed before and after ozone exposure (3 p.p.m., 2 h). Guinea-pigs were anaesthetized with pentobarbital sodium and mechanically ventilated. Airway responsiveness was determined by an inhalation of doubling concentration of histamine, and the concentration of histamine required to produce a 200% increase in R(L) (PC200) was calculated by log-linear interpolation. Plasma extravasation was evaluated by measuring the extravasation of Evans blue dye in the airway.

RESULTS

Ozone produced significant airway hyperresponsiveness and plasma extravasation, with an influx of neutrophils in BAL fluid. Bakumondo-to (400 mg/kg p.o.) significantly inhibited airway hyperresponsiveness, but had no effect on neutrophil influx or plasma extravasation.

CONCLUSIONS

We demonstrated that Bakumondo-to can attenuate airway hyperresponsiveness induced by ozone without affecting airway inflammation, which suggests that Bakumondo-to may act on the subsequent mechanisms after the induction of inflammation, such as mediator release.

Effects of naloxone, glycyrrhizic acid, dexamethasone and deoxycorticosterone in repetitive stress

1. The present study examined the effect of naloxone (NAL), glycyrrhizic acid (GCA), deoxycorticosterone (DOC) and dexamethasone (DEX) on daily repeated 2 h chronic restrained stress (RS) on the locomotor activity (LA) of rats tested in the open field arena to elucidate the possible roles of opioids, glucocorticoids and mineralocorticoids in response to stress. 2. Intact and adrenalectomized (ADX) rats were either injected with 0.1 mL of NAL (0.32 microgram/100 g BW), 2.4 mg/kg DOC or 120 micrograms/kg DEX or had 1.0 mg/mL GCA dissolved in their drinking water or normal saline (for the ADX group) dissolved in their drinking water. 3. In intact groups, treatment with NAL completely blocked the stress response and treatment with GCA, DOC and DEX partially prevented the stress response. Adaptation occurred on either days 4, 5, 6 or 7 for intact rats treated with DEX, DOC, GCA or control rats, respectively. All ADX control rats died following the first 2 h RS. Adrenalectomized rats treated with DEX or DOC adapted later compared with intact rats, while rats given either GCA or NAL were unable to block or adapt to chronic RS. 4. These findings demonstrate that the stress response is primarily mediated by endogenous opioids, in that it is blocked by NAL. Both mineralocorticoids and glucocorticoids, which can act centrally to inhibit endorphins, partially blocked the stress response. The effect of GCA in intact rats was similar to that of both DEX and DOC in intact rats. Adrenalectomized rats treated with GCA (despite their lack of endogenous corticosterone) showed a stress response that was significantly different from the other ADX groups, implying that GCA had effects independent of endogenous corticosterone.

Short- and long-term effects of glycyrrhizic acid in repetitive stress

1. This study was carried out to determine the effect of short-term and long-term ingestion of glycyrrhizic acid on the response to 2 h of restraint stress by measuring locomotor activity and plasma corticosterone levels. 2. Male Sprague-Dawley rats were randomly assigned into four groups, each group having eight rats. Group 1 (control) was given ordinary tap water, while groups 2 (short term), 3 and 4 (both long term) were given tap water containing 1 mg/mL glycyrrhizic acid to drink for 10 days, 4 weeks and 9 weeks, respectively. All the rats were subjected to 2 h of restraint stress and the locomotor activity assessed using an activity test in an open field arena followed by blood sampling to determine the plasma corticosterone level. These procedures were repeated daily for 14 days. 3. The basal locomotor activity scores for rats given glycyrrhizic acid for 10 days or 4 weeks were similar to those of controls; however, that of the rats treated long term with glycyrrhizic acid was significantly lower (21.0 +/- 3.0 squares crossed; P < 0.0005). Following the first period of restraint stress there was a highly significant decrease in locomotor activity, which remained significantly lower until the seventh and subsequent periods, indicating an adaptation to the repeated stress had occurred. Although the decrease in locomotor activity was partially blocked and adaptation to repetitive stress was enhanced in the rats given glycyrrhizic acid for 10 days, this was not seen in rats treated with glycyrrhizic acid for 4 or 9 weeks. The corticosterone levels in control rats were significantly elevated for 4-5 days following the exposure to repetitive stress but decreased gradually from day 7 onwards. However, both short- and long-term glycyrrhizic acid-treated rats had higher plasma corticosterone levels than the controls (P < 0.05). 4. In conclusion, repetitive restraint stress caused decreased locomotor activity associated with increased plasma corticosterone levels, both of which, in normal rats, decreased with adaptation to stress. The stress response was partially blocked and adaptation enhanced in rats given glycyrrhizic acid for 10 days, but not in rats given glycyrrhizic acid for 4 and 9 weeks. Glycyrrhizic acid ingestion caused high plasma corticosterone.

Herbal interventions in asthma and allergy

This paper reviews the role of herbal-based medicines in the treatment of asthma and allergic rhinitis. A comprehensive literature search was performed of relevant English-language papers and abstracts were identified through a MEDLINE search and from bibliographies of the identified papers. Papers and studies pertaining to the use of medicinal plants in the treatment of asthma and allergic rhinitis were identified. They were then analyzed according to design, inclusion and exclusion criteria, population studied, variables tested, method of treatment (i.e., specific medicinal plants or herbal combinations), and results. The data have been reviewed and divided on the basis of culture and the effects of medicinal plants in asthma and allergy. A number of studies were found that support the use of some herbal medicines in asthma and allergy. Various derivatives from specific medicinal plants were identified as the antiasthma components and some mechanisms of action were explored. The results show positive effects of these herbs on bronchodilation, pulmonary function tests, and antagonism of asthma mediators such as histamine and platelet activating factor, corticosteroid levels, and clearance of mucus. Improved symptoms were also seen in patients with allergic rhinitis specifically on histamine-induced reactions, e.g., rhinorrhea, sneezing, and itching. From the review, there has been a role for some herbal medicines in the treatment of asthma and allergic rhinitis. Usage of herbal medicines has increased in recent years. Many of these medicinal plants provided relief of symptoms equal to allopathic medicines used. Specific chemical derivatives have been isolated from many of these plant products which act on the mechanisms and mediators that cause asthma and allergies. The amount of research on these products, especially in the United States, is limited. There is a lack of control of quantity and quality of the components in these remedies. Yet, many have fewer side effects than current therapy. Throughout the history of medicine, drugs have been developed from traditional medicine. By continuing to investigate how some of these herbal interventions work, we may be able to find additional effective medicines to treat asthma and allergies.

Why there is a need for pharmacovigilance

Not everything is known about a medicine when it receives its licence for marketing. The merits of a new drug, balancing its beneficial and its untoward effects, become only established after sufficient experience has been gained from its use in real practice. Part of the reason for this is that our extensive phase III clinical trials fail to detect some side-effects. Why is this so? Three groups of reasons may be envisaged, namely (1) our trials lack the power to detect rare side-effects; (2) some side-effects do not occur in the context of clinical trials; (3) some side-effects, though common enough, fully or partly escape detection due to lack of suitable detection techniques. The following presents a closer look at these three mechanisms.

Harmless herbs? A review of the recent literature

Herbal medicines have become a popular form of therapy. They are often perceived as being natural and therefore harmless. This article reviews the recent literature on the adverse effects of herbal remedies. Examples of allergic reactions, toxic reactions, adverse effects related to an herb's desired pharmacological actions, possible mutagenic effects, drug interactions, drug contamination, and mistaken plant identities are provided. Because of underreporting, our present knowledge may well be just the "tip of the iceberg." Little is known about the relative safety of herbal remedies compared to synthetic drug treatments, although for some herbal remedies, the risks may be less than for conventional drugs.

Effects of Sho-saiko-to on the pharmacokinetics and pharmacodynamics of tolbutamide in rats

Although Sho-saiko-to (Xiao Chai Hu Tang), a major Chinese traditional medicine, is frequently prescribed with other synthetic or biotechnological drugs for the treatment of various chronic diseases, there is a dearth of information about interactions between sho-saiko-to and co-administered drugs. This paper reports the effects of Sho-saiko-to on the pharmacokinetics and glucose responses of a sulphonylurea hypoglycaemic agent, tolbutamide, after their oral administration in rats. After oral administration of tolbutamide (50 mg kg(-1)) with or without Sho-saiko-to extract powder (300 mg kg(-1)) to male Sprague-Dawley rats cannulated in the jugular vein, plasma tolbutamide and glucose levels were periodically measured. Co-administration of Sho-saiko-to tended to elevate the plasma tolbutamide concentration in the absorption phase. A two-compartment lag-time model was found to describe the plasma tolbutamide concentration-time data. The maximum concentration of tolbutamide was significantly increased and time to reach the maximum concentration was reduced to about 70% by co-administration with Sho-saiko-to. There was no significant change in area under the curve or in the elimination half-life of tolbutamide. The extent of the lowering effect of tolbutamide on plasma glucose levels was increased up to 0.75 h and decreased after 5 h after co-administration of Sho-saiko-to. In conclusion, these studies suggest that sho-saiko-to slightly hastens the gastrointestinal absorption of tolbutamide. Furthermore, it is considered that elevation of the gastrointestinal absorption rate by Sho-saiko-to might potentiate the hypoglycaemic effect of this sulphonylurea in the early period after oral administration.

Systematic analysis of post-administrative saiboku-to urine by liquid chromatography to determine pharmacokinetics of traditional Chinese medicine

To disclose the mystery of a traditional Chinese medicine and to identify biologically active components, we analysed post-administrative urine for Saiboku-To, an anti-asthmatic Chinese herbal remedy. Systematic analysis of the components appearing in the urine was carried out by high-performance liquid chromatography (HPLC) with normal- and reversed-phase modes in combination. beta-D-glucuronidase-treated urine was subjected to rapid-flow fractionation (RFF) to achieve fractional extraction of lipophilic components with exhaustive recovery rates. The extracts were analysed by HPLC equipped with a multi-channel UV-detector. In the first stage of HPLC, we conducted a normal-phase mode run to find magnolol derived from Magnolia officinalis, as the most hydrophobic component showing minimum retention time among the urinary products of Saiboku-To. In the next stage, mobile phase solvent composition for reversed-phase HPLC was optimized so as to retain magnolol up to 60 min. Under these conditions, other Saiboku-To urinary products, which were more polar than magnolol, appeared within 60 min. Our HPLC method used marker compounds like magnolol and could indicate the terminal peak position on the reversed-phase chromatography. We found a total of eight components in the post-administrative Saiboku-To urine. Structure identification of the isolated pure materials was achieved using nuclear magnetic resonance (NMR)-, mass (MS)- and UV-spectra, and HPLC retention profiles. They were magnolol and 8,9-dihydroxydihydromagnolol stemming from M. officinalis, medicarpin and liquiritigenin from Glycyrrhiza glabra, baicalein, wogonin, and oroxylin A from Scutellaria baicalensis, and davidigenin of an unknown origin. The pharmacological mystery of Saiboku-To should be disclosed by resolving the pharmacokinetics and pharmacodynamics of these urinary products independently and synergistically.