Herbal supplements and therapeutic drug monitoring: focus on digoxin immunoassays and interactions with St. John's wort

Interaction between Chinese medicine and digoxin: Clinical and research update

Background: Digoxin is one of the most widely and commonly used cardiac drug, which plays an irreplaceable role in treating heart failure and arrhythmia. The 2010 Edition of Pharmacopoeia of the People's Republic of China stipulates that the effective range of digoxin plasma concentration is 0.5-2.0 ng/mL and it is toxic at plasma concentration >2 ng/mL. Its effective plasma drug concentration is close to the toxic concentration, and large individual differences in the effects of the drug have been observed. It is often used in combination with other drugs, but drug interactions have a great impact on the plasma concentration of digoxin and lead to adverse reactions (ADRs), such as poisoning. Most of the reported drug interactions are with Western drugs. However, there are many combinations of traditional Chinese medicine (TCM) and Western drugs, TCM interacting with digoxin comprises monomer components, single medicines, and Chinese patent medicines. Aim of the study: We aimed i) to provide an overview of the TCM formulations affecting the pharmacology of digoxin and their mechanisms of action and ii) to provide a theoretical reference for the safe and rational use of digoxin in combination with TCM in clinical practice and to avoid ADRs. Methods: A literature search of electronic databases, including PubMed, MEDLINE, Cochrane Library, Web of Science, China National Knowledge Infrastructure, and WANFANG Data, was performed to search for articles published between 1 January 1960, and 1 August 2022. Search terms used included "digoxin," "traditional Chinese medicine," "Chinese patent medicine," and "adverse reactions" and their combinations. Results: A total of 49 articles were obtained, including clinical reports, pharmacological experiments and in vitro experiments. The mechanisms of action affecting the pharmacology of digoxin are complex. TCM formulations may affect the pharmacology of digoxin in vivo by influencing gastrointestinal motility or gastric juice pH, regulating P-glycoprotein levels, exerting cumulative pharmacological effects, and enhancing the sensitivity of the heart to digoxin. Although studies have shown that some TCM formulations interact with digoxin, they may be influenced by the complexity of the composition and the pharmacological effects of the TCM, the sensitivity of digoxin concentration determination methods, etc. The results of existing studies are controversial and further in-depth studies are required. Conclusion: Combinations of digoxin and TCM formulations are commonly used. This article serves as a reference to understand the interactions between TCM formulations and digoxin to avoid the occurrence of ADRs and improve the efficacy and safety of digoxin.

Transplacental Therapeutic Drug Monitoring in Pregnant Women with Fetal Tachyarrhythmia Using HPLC-MS/MS

Fetal arrhythmia develops in 0.1-5% of pregnancies and may cause fetal heart failure and fetal hydrops, thus increasing fetal, neonatal, and infant mortality. The timely initiation of transplacental antiarrhythmic therapy (ART) promotes the conversion of fetal tachycardia to sinus rhythm and the regression of the concomitant non-immune fetal hydrops. The optimal treatment regimen search for the fetus with tachyarrhythmia is still of high value. Polymorphisms of these genes determines the individual features of the drug pharmacokinetics. The aim of this study was to study the pharmacokinetics of transplacental anti-arrhythmic drugs in the fetal therapy of arrhythmias using HPLC-MS/MS, as well as to assess the effect of the multidrug-resistance gene ABCB1 3435C > T polymorphism on the efficacy and maternal/fetal complications of digoxin treatment. The predisposition to a decrease in the bioavailability of the digoxin in patients with a homozygous variant of the CC polymorphism showed a probable association with the development of ART side effects. A pronounced decrease in heart rate in women with the 3435TT allele of the ABCB1 gene was found. The homozygous TT variant in the fetus showed a probable association with an earlier response to ART and rhythm disruptions on the digoxin dosage reduction. high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) methods for digoxin and sotalol therapeutic drug monitoring in blood plasma, amniotic fluid, and urine were developed. The digoxin and sotalol concentrations were determined in the plasma blood, urine, and amniotic fluid of 30 pregnant women at four time points (from the beginning of the transplacental antiarrhythmic therapy to delivery) and the plasma cord blood of 30 newborns. A high degree of correlation between the level of digoxin and sotalol in maternal and cord blood was found. The ratio of digoxin and sotalol in cord blood to maternal blood was 0.35 (0.27 and 0.46) and 1.0 (0.97 and 1.07), accordingly. The digoxin concentration in the blood of the fetus at the moment of the first rhythm recovery episode, 0.58 (0.46, 0.8) ng/mL, was below the therapeutic interval. This confirms the almost complete transplacental transfer of sotalol and the significant limitation in the case of digoxin. Previously, ABCB1/P-glycoprotein had been shown to limit fetal exposure to drugs. Further studies (including multicenter ones) to clarify the genetic features of the transplacental pharmacokinetics of antiarrhythmic drugs are needed.

Development of a new ultra‐high‐performance liquid chromatography–tandem mass spectrometry method for the determination of digoxin and digitoxin in plasma: Comparison with a clinical immunoassay

Cardiac glycosides digoxin and digitoxin are used in therapy for the treatment of congestive heart failure. Moreover, these compounds can be responsible for intoxication cases caused by fortuitous ingestion of leaves of Digitalis. Due to the narrow therapeutic range of these drugs, therapeutic drug monitoring is recommended in the clinical practice. In this context, immunoassays‐based methods are generally employed but digoxin‐ and digitoxin‐like compounds can interfere with the analysis. The aim of this study was to develop and validate an original UPLC–MS/MS method for the determination of digoxin and digitoxin in plasma. The method shows adequate sensitivity and selectivity with acceptable matrix effects and very good linearity, accuracy, precision, and recovery. A simple liquid–liquid extraction procedure was used for sample clean‐up. The method was applied for the analysis of n = 220 plasma samples collected in two different clinical chemistry laboratories and previously tested by the same immunoassay. The statistical comparison showed a relevant negative bias of the UPLC–MS/MS method versus the immunoassay. These results are consistent with an immunoassay overestimation of digoxin plasmatic levels due to cross‐reaction events with endogenous digoxin‐like substances.

Past, present and future perspectives of therapeutic drug monitoring in India

Therapeutic drug monitoring (TDM) is the clinical practice of performing drug assays and interpreting results to maintain constant therapeutic concentrations in patients' bloodstream. Conventional TDM was started way back in the 1960s and served to optimise pharmacotherapy by maximising therapeutic efficacy by evaluating efficacy failure and monitoring drug compliance, while minimising adverse events, in drugs with a narrow therapeutic range. Currently, the scope of TDM has been extended to additional indications which are of importance to India. Apart from the conventional indications, TDM can also help combat drug resistance amongst patients treated with antimicrobials, including anti-tubercular drugs and critically ill patients with compromised pharmacokinetics. TDM is also indicated for patients on antiretroviral drugs under specific clinical scenarios and is of high importance to India. Target concentration intervention (TCI) and apriori TDM (by merging TDM with pharmacogenomics) are emerging fields explored in developed nations. The authors sought to assess the evolution of TDM in India and evaluate the potential impact of newer indications in rationalising pharmacotherapy. In the mid-1980s, TDM was presented to India. Despite showing some initial progress, its use is limited to conventional indications. Its utility is also challenged by cost and higher reliance on conventional prescribing practices. However, the newer indications such as antimicrobial resistance, tuberculosis and HIV, with their high prevalence in developing nations, present an opportunity for the growth of TDM in these countries. Indian clinician's awareness and buoyant demands alongside expert contributions from clinical pharmacologists could widen its scope.

Targeted Strategy to Analyze Antiepileptic Drugs in Human Serum by LC-MS/MS and LC-Ion Mobility-MS

Routine small-molecule analysis is challenging owing to the need for high selectivity and/or low limits of quantification. This work reports a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantify 14 antiepileptic drugs (AEDs) in human serum. For the optimized LC-MS/MS method described herein, we applied the guidelines outlined in the Clinical and Laboratory Standards Institute (CLSI) LC-MS C62-A document and the U.S. Food and Drug Administration (FDA) Bioanalytical Method Validation Guidance for Industry to evaluate the quality of the assay. In these studies, AED linearity, analyte recovery, matrix effects, precision, and accuracy were assessed. Using liquid chromatography-drift tube ion mobility-mass spectrometry (LC-DTIM-MS), a qualitative method was also used to increase confidence in AED identification using accurate mass and collision cross section (CCS) measurements. The LC-DTIM-MS method was also used to assess the ability of drift tube CCS measurements to aid in the separation and identification of AED structural isomers and other AEDs. These data show that another dimension of information, namely CCS measurements, provides an orthogonal dimension of structural information needed for AED analysis. Multiplexed AED measurements using LC-MS/MS and LC-DTIM-MS have the potential to enable better optimization of dosing owing to the high precision capabilities available in these types of analytical studies. Taken together, these data also show the ability to increase confidence in small-molecule identification and quantification using these analytical technologies.

Marked decrease of tacrolimus blood concentration caused by compound Chinese herbal granules in a patient with refractory nephrotic syndrome

WHAT IS KNOWN AND OBJECTIVE

The blood concentration of tacrolimus can be affected by co-administrated drugs. The objective is to draw more attention to herb-drug interactions in China, where herbal medicines are commonly used.

CASE DESCRIPTION

The blood concentration of tacrolimus in a girl with refractory nephrotic syndrome decreased nearly a half despite no change in dose. Nebulizer therapy, cyclophosphamide and a compound Chinese herbal medicine were the only additional treatments than usual.

WHAT IS NEW AND CONCLUSION

The most possible cause of the decrease in tacrolimus concentration was the administration of Radix Astragali among compound Chinese herbal medicine granules.

Professional ethics in complementary and alternative medicines in management of Parkinson's disease

The practice of complementary and alternative medicine (CAM) is not, at present, considered an integral part of conventional medicine. As the popularity of CAM grows and access to information about CAM increases through the media and internet where CAMs are often promoted, patients are at risk of exposure unvalidated information. Therefore, there is a need for physicians to examine objectively the efficacy and safety of CAM, compare it with current medications, and become actively involved in the CAM treatment with patients. In accordance with these needs, this manuscript reviews the utility, scientific evidence, safety and cost-effectiveness of CAM in the treatment of Parkinson's disease (PD). We also address the ethical issues of CAM practices.

Therapeutic Drug Monitoring of Mycophenolic Acid

Mycophenolic acid (MPA) is an immunosuppressant requiring therapeutic drug monitoring. Although immunoassays are commercially available, there is significant positive bias using this approach when compared to high-performance liquid chromatography or LC combined with mass spectrometry (LC/MS) or tandem mass spectrometry (LC/MS/MS). Positive bias is due to variable cross-reactivity of MPA acyl glucuronide with antibodies traditionally used in immunoassay formats. As can be expected, the magnitude of bias varies considerably. MPA strongly binds albumin and, as a result, disproportionate increases in free MPA occur in patients with uremia, hypoalbuminemia, and hepatic dysfunction. As such, monitoring free MPA poses additional challenges. Because MPA inhibits inosine monophosphate dehydrogenase, monitoring this enzyme may provide an alternative approach.

Commonly Used Dietary Supplements on Coagulation Function during Surgery

BACKGROUND

Patients who undergo surgery appear to use dietary supplements significantly more frequently than the general population. Because they contain pharmacologically active compounds, dietary supplements may affect coagulation and platelet function during the perioperative period through direct effects, pharmacodynamic interactions, and pharmacokinetic interactions. However, in this regard, limited studies have been conducted that address the pharmacological interactions of dietary supplements. To avoid possible bleeding risks during surgery, information of potential complications of dietary supplements during perioperative management is important for physicians.

METHODS

Through a systematic database search of all available years, articles were identified in this review if they included dietary supplements and coagulation/platelet function, while special attention was paid to studies published after 1990.

RESULTS

Safety concerns are reported in commercially available dietary supplements. Effects of the most commonly used natural products on blood coagulation and platelet function are systematically reviewed, including 11 herbal medicines (echinacea, ephedra, garlic, ginger, ginkgo, ginseng, green tea, kava, saw palmetto, St John's wort, and valerian) and 4 other dietary supplements (coenzyme Q₁₀, glucosamine and chondroitin sulfate, fish oil, and vitamins). Bleeding risks of garlic, ginkgo, ginseng, green tea, saw palmetto, St John's wort, and fish oil are reported. Cardiovascular instability was observed with ephedra, ginseng, and kava. Pharmacodynamic and pharmacokinetic interactions between dietary supplements and drugs used in the perioperative period are discussed.

CONCLUSIONS

To prevent potential problems associated with the use of dietary supplements, physicians should be familiar with the perioperative effects of commonly used dietary supplements. Since the effects of dietary supplements on coagulation and platelet function are difficult to predict, it is prudent to advise their discontinuation before surgery.

Concurrent herb-prescription medication use and health care provider disclosure among university students

OBJECTIVES

To determine the extent to which college students are intermixing mood-altering herbs with prescription medications and whether they are disclosing this information to their health care providers.

DESIGN AND SETTING

A nonrandom sample was drawn from the student body of a Northwestern state university (n=305).

METHODS

In November 2008 participants completed an online survey detailing herb use, disclosure to health care providers and herb/medicinal intermixing.

RESULTS

There were no demographic differences between herb users and non-users. Most herb usage was self-prescribed (60%) and undisclosed to healthcare providers (only 25% of herb users disclosed to a healthcare provider). 34% of herb users used them to treat a mood disorder. Of herb users, 13% had simultaneously used herbs and prescription medication in the last year. In addition, herb users who intermixed herbs with prescription medications had higher depression and anxiety scores than those who did not intermix.

CONCLUSIONS

College student herb use is primarily self prescribed and undisclosed to healthcare professionals, who may prescribe pharmaceuticals that interact negatively with herbals. Physician awareness and query is invaluable for the prevention of adverse herb and drug interactions.