Frequently discordant results from therapeutic drug monitoring for digoxin: clinical confusion for the prescriber

Safety profile of intravenous digoxin in Chinese patients with acute heart failure with reduced ejection fraction: a small-scale prospective cohort study

Background: Adverse effects of intravenous digoxin vary from patients and disease status, which should be closely monitored. Aims: To explore the safety profile of intravenous digoxin in acute heart failure with reduced ejection fraction (HFrEF) among Chinese patients. Methods: A clinical prospective, single-center, single-arm, open-label exploratory clinical trial was performed in patients with acute HFrEF at Wuhan Asia Heart Hospital. A fixed dose of 0.5 mg digoxin was used intravenously once per day for 3 days. The normalized dosage of digoxin (NDD), toxic serum digoxin concentration (SDC), and adverse reactions of intravenous digoxin were recorded. Results: A total of 40 patients were recruited in the study. The SDC increased from 1.03 ± 0.34 ng/mL to 1.95 ± 0.52 ng/mL during treatment. 50% (20/40) patients reached a toxic SDC of 2.0 ng/mL, and toxic effects were seen in 30% (12/40) patients. Estimated glomerular filtration rate (eGFR) < 60 mL/min [HR: 5.269; 95% CI: 1.905-14.575, p = 0.001], NDD ≥7 μg/kg [HR: 3.028; 95% CI: 1.119-8.194, p = 0.029], and ischemic cardiomyopathy [HR: 2.658; 95% CI: 1.025-6.894, p = 0.044] were independent risk factors for toxic SDC. Toxic SDC was effectively identified [area under the receiver operating characteristic (ROC) curve = 0.85, p < 0.001] using this model, and patients would have a higher risk of toxicity with more risk factors. Conclusion: Intravenous digoxin of 0.5 mg was safe and effective for initial dose but not suitable for maintenance treatment in Chinese patients with acute HFrEF. Patients who had lower eGFR, received higher NDD, and had ischemic cardiomyopathy should be closely monitored to avoid digoxin toxicity.

Therapeutic Drug Monitoring and Pharmacogenetic Testing in Northern China

Background: Therapeutic drug monitoring (TDM) and pharmacogenetic (PGx) testing are widely used as approaches to improve individualized (personalized) pharmacotherapy. Little is known about TDM and PGx testing services in China. This study is aimed to describe the TDM and PGx testing services in northern China, and to lay the foundation for improving these services.

Methods: We developed an electronic survey using online software and disseminated it to 32 public hospitals in northern China from May to July 2019. The data were analyzed using the Statistical Package for Social Sciences (SPSS) program (Ver.27.0).

Results: We collected 29 of the 32 questionnaires (90.6% response rate) from public hospitals in seven provinces of northern China. Twenty-two public hospitals (76%) utilized TDM; immune suppressants, antiepileptic drugs and anti-infective drugs were the main drugs monitored. The hospitals that did not provide TDM service were traditional Chinese medicine hospitals and hospitals with a smaller number of hospital beds. Seventeen public hospitals (58.6%) had PGx testing programs. The hospitals that did not offer PGx testing service had a smaller number of hospital beds and had fewer daily outpatients.

Conclusion: TDM is available in the vast majority of public hospitals in northern China, although mainly in tertiary hospitals. PGx testing, a newer approach, is less widely available. We recommend that more hospitals be encouraged to provide TDM and PGx testing services and more efforts be directed toward quality control, delivery of results and counseling of patients based on those results.

A review of the pharmacology and clinical uses of pimobendan

OBJECTIVE

To review the pharmacology, research developments, and clinical uses of pimobendan

DATA SOURCES

Original research articles and clinical studies from 1984 to August 2011.

VETERINARY DATA SYNTHESIS

Pimobendan is approved for use in dogs for the treatment of congestive heart failure (CHF) secondary to chronic valvular heart disease (CVHD) and dilated cardiomyopathy (DCM). Expert-based veterinary guidelines recommend the use of pimobendan in the management of acute, hospital-based therapy for patients with CHF attributable to CVHD.

CONCLUSIONS

The use of pimobendan, an inodilator with phosphodiesterase 3 (PDE3) inhibitory and calcium-sensitizing properties, is regarded as a component of the standard of care in the management of dogs with CHF secondary to both DCM and CVHD. Further studies are warranted to confirm the safety and efficacy of pimobendan for the off-label use of this drug in asymptomatic CVHD, pulmonary arterial hypertension, asymptomatic myocardial diseases, CHF from all other causes and in cats with CHF.

Digoxin and ouabain induce the efflux of cholesterol via liver X receptor signalling and the synthesis of ATP in cardiomyocytes

Cardioactive glycosides exert positive inotropic effects on cardiomyocytes through the inhibition of Na(+)/K(+)-ATPase. We showed previously that in human hepatoma cells, digoxin and ouabain increase the rate of the mevalonate cascade and therefore have Na(+)/K(+)-ATPase-independent effects. In the present study we found that they increase the expression and activity of 3-hydroxy-3 methylglutaryl-CoA reductase and the synthesis of cholesterol in cardiomyocytes, their main target cells. Surprisingly this did not promote intracellular cholesterol accumulation. The glycosides activated the liver X receptor transcription factor and increased the expression of ABCA1 (ATP-binding cassette protein A1) transporter, which mediates the efflux of cholesterol and its delivery to apolipoprotein A-I. By increasing the synthesis of ubiquinone, another derivative of the mevalonate cascade, digoxin and ouabain simultaneously enhanced the rate of electron transport in the mitochondrial respiratory chain and the synthesis of ATP. Mice treated with digoxin showed lower cholesterol and higher ubiquinone content in their hearts, and a small increase in their serum HDL (high-density lipoprotein) cholesterol. The results of the present study suggest that cardioactive glycosides may have a role in the reverse transport of cholesterol and in the energy metabolism of cardiomyocytes.

A survey of therapeutic drug monitoring services in Malaysia

In Malaysia, therapeutic drug monitoring (TDM) service was started in the 1980s. Since then, the number of hospitals that offer the service has increased. In this paper, we report the findings of a nationwide survey describing the practice of TDM in these hospitals. Questionnaires were mailed to 128 government hospitals. Data were collected for general characteristics of the hospitals, administrative, and laboratory activities related to TDM service. One hundred and twenty-one hospitals responded to the survey. Thirty-four hospitals (28.1%) provided the service with their own TDM laboratories, 44 hospitals (36.4%) provided the service using other hospitals' laboratories and 43 hospitals (35.5%) did not provide the service at all. TDM services were more likely to be offered in larger hospitals with various medical specialties. Since it is managed entirely by hospital pharmacists, these pharmacists assume an important role in ensuring optimum use of the TDM service.

Current status of therapeutic drug monitoring in Australia and New Zealand: a need for improved assay evaluation, best practice guidelines, and professional development

The measurement of drug concentrations, for clinical purposes, occurs in many diagnostic laboratories throughout Australia and New Zealand. However, the provision of a comprehensive therapeutic drug monitoring (TDM) service requires the additional elements of pre- and postanalytical advice to ensure that concentrations reported are meaningful, interpretable, and clinically applicable to the individual patient. The aim of this project was to assess the status of TDM services in Australia and New Zealand. A range of professions involved in key aspects of TDM was surveyed by questionnaire in late 2007. Information gathered included: the list of drugs assayed; analytical methods used; interpretation services offered; interpretative methods used; and further monitoring advice provided. Fifty-seven responses were received, of which 42% were from hospitals (public and/or private); 11% a hospital (public and/or private) and pathology provider; and 47% a pathology provider only (public and/or private). Results showed that TDM is applied to a large number of different drugs. Poorly performing assay methods were used in some cases, even when published guidelines recommended alternative practices. Although there was a wide array of assays available, the evidence suggested a need for better selection of assay methods. In addition, only limited advice and/or interpretation of results was offered. Of concern, less than 50% of those providing advice on aminoglycoside dosing in adults used pharmacokinetic tools with six of 37 (16.2%) respondents using Bayesian pharmacokinetic tools, the method recommended in the Australian Therapeutic Guidelines: Antibiotic. In conclusion, the survey highlighted deficiencies in the provision of TDM services, in particular assay method selection and both quality and quantity of postanalytical advice. A range of recommendations, some of which may have international implications, are discussed. There is a need to include measures of impact on clinical decision-making when assessing assay methodologies. Best practice guidelines and professional standards of practice in TDM are needed, supported by an active program of professional development to ensure the benefits of TDM are realized. This will require significant partnerships between the various professions involved.