Adherence with perindopril therapy: a pilot study using therapeutic drug monitoring of perindoprilat and an evaluation of the clearance estimation

Novel approach to adherence assessment based on parent drug and metabolite pharmacokinetics: pilot study with spironolactone

AIM

The aim of this study was to evaluate adherence to spironolactone in a group of unselected patients with arterial hypertension by analysis of measured serum spironolactone and canrenone concentrations according to a proposed two-step decision scheme based on pharmacokinetic considerations.

MATERIALS AND METHODS

Simulation of serum concentration-time profiles of spironolactone and canrenone based on population pharmacokinetic parameters described in literature and a body weight-normalized spironolactone dose / canrenone level nomogram derived from a group of adherent patients with conservatively treated primary hyperaldosteronism, were used to create a two-step decision scheme. 71 outpatients treated with spironolactone for resistant hypertension with spironolactone and canrenone serum concentrations measured between 2018 and 2021 were analyzed according to the proposed scheme. We compared our proposed methodology to the standard approach for adherence testing.

RESULTS

With the most sensitive traditional approach to adherence assessment through detectable serum concentrations of spironolactone and/or canrenone, 9 (12.7%) non-adherent patients were identified. With our two-step assessment of adherence, we were able to identify 18 (25.4%) non-adherent patients.

CONCLUSION

Consideration of the pharmacokinetic properties of parental drug and its metabolite led to improved sensitivity in non-adherence detection in patients with arterial hypertension. This approach enables better interpretation of measured spironolactone and canrenone serum concentrations and should be used in clinical practice.

Pharmacokinetic principles of dose adjustment of mTOR inhibitors in solid organ transplanted patients

WHAT IS KNOWN AND OBJECTIVES

mTOR inhibitors possess narrow therapeutic range and substantial pharmacokinetic variability and the consequences from suboptimal dosing are serious. The aim of this review is to summarize the current knowledge about the factors influencing mTOR inhibitors pharmacokinetics and the possibility of using these relationships in order to improve its therapy individualization in solid organ transplanted patients.

METHODS

Literature search from Pubmed and Web of Science databases were performed using Boolean search operators in order to identify relevant studies.

RESULTS AND DISCUSSION

A total of 701 reports were identified from the initial literature search. Out of which 40 studies dealt with relationships between various factors and pharmacokinetics of mTOR inhibitors and with relevance of these associations for dosage optimization.

WHAT IS NEW AND CONCLUSION

The overview of the current covariates for pharmacokinetic variability of mTOR inhibitors has been provided on the level of absorption, distribution and elimination, and consequences of these relationships for dosing optimization has been summarized.

Adherence and blood pressure control in patients with primary aldosteronism

PURPOSE

The aim of our study was to evaluate the adherence to mineralocorticoid receptor (MR) antagonists and other antihypertensive therapy and blood pressure control in conservatively treated patients with primary aldosteronism (PA).

MATERIALS AND METHODS

Conservatively treated subjects with previously confirmed PA (n-50, 64.5 ± 9 years of age, 24% women) were investigated via our outpatient hypertension clinic. All subjects underwent regular examinations in our clinic. In addition to basic laboratory and clinical parameters, 24 h ambulatory blood pressure monitoring (ABPM) (Spacelabs) was evaluated. Unplanned blood sampling for assessment of serum antihypertensive drug concentrations by the means of liquid chromatography-mass spectrometry was performed in all patients. In case of spironolactone, its active metabolite canrenone was also evaluated. Total non-compliance was then defined as the absence of all measured antihypertensive drugs. Partial non-compliance was calculated as the absence of serum levels of at least one, but not all antihypertensive drugs prescribed.

RESULTS

Good blood pressure control was detected (mean 24 h systolic/diastolic BP 130 ± 12/77 ± 9 mmHg). The average number of antihypertensive drugs was 3.9 ± 1.5. All subjects were treated by MR antagonists. 44% of patients received spironolactone (average daily dose 45 ± 20 mg) and in the remaining 56% of subjects eplerenone was administered (average daily dose 80 ± 30 mg) due to spironolactone side effects. Assessment of antihypertensive drug concentrations revealed full adherence in 80% of all subjects, partial nonadherence was noted in the remaining 20% of subjects. MR antagonist levels were detected in almost all subjects (49 out of 50).

CONCLUSIONS

Good blood pressure control and adherence to therapy were detected in conservatively treated patients with PA. Eplerenone had to be used quite often as male subjects did not tolerate dose escalation due to spironolactone side effects.

Recent advances in the personalized treatment of estrogen receptor-positive breast cancer with tamoxifen: a focus on pharmacogenomics

Introduction: Tamoxifen is still an important drug in hormone-dependent breast cancer therapy. Personalization of its clinical use beyond hormone receptor positivity could improve the substantial variability of the treatment response.Areas covered: The overview of the current evidence for the treatment personalization using therapeutic drug monitoring, or using genetic biomarkers including CYP2D6 is provided. Although many studies focused on the PK aspects or the impact of CYP2D6 variability the translation into clinical routine is not clearly defined due to the inconsistent clinical outcome data.Expert opinion: We believe that at least the main candidate factors, i.e. CYP2D6 polymorphism, CYP2D6 inhibition, endoxifen serum levels may become important predictors of clinical relevance for tamoxifen treatment personalization in the future. To achieve this aim, however, further research should take into consideration more precise characterization of the disease, epigenetic factors and also utilize an appropriately powered multifactorial approach instead of a single gene evaluating studies.

The Assessment of Serum Drug Levels to Diagnose Non-Adherence in Stable Chronic Heart Failure Patients

Background: The aim of our study was to evaluate the prevalence of drug non-adherence in stable chronic heart failure (CHF) patients using serum drug levels (SDL) assessment. Methods: CHF patients were prospectively enrolled during scheduled outpatient visit. Except standard procedures an unanticipated blood sampling for the SDL assessment was obtained. Analysis was focused on the prescribed heart failure and antihypertensive medication and was performed by liquid chromatography coupled with mass spectrometry. The patient was labelled as non-adherent if at least one of drugs assessed was not found in the serum. In the first half of patients multiple SDL have been evaluated during the follow-up. Results: Eighty one patients were enrolled. The non-adherence was proven in twenty of them (25%). In the subgroup of thirty eight patients with multiple SDL evaluation the non-adherence raised significantly with increasing number of visits assessed together (21% for single visit, 29% for two of three visits assessed together and 34% for all three visits evaluated together, all p < 0.001). Conclusion: The non-adherence was proven in significant part of stable CHF patients using SDL assessment. This method seems to be reliable and effective and should be a part of clinical assessment in selected patients with CHF.

Prediction of the Renal Elimination of Drugs With Cystatin C vs Creatinine: A Systematic Review

Serum cystatin C has been proposed as a kidney biomarker to inform drug dosing. We conducted a systematic review to synthesize available data for the association between serum cystatin C and drug pharmacokinetics, dosing, and clinical outcomes in adults (≥18 years). PubMed, Ovid MEDLINE, Ovid EMBASE, EBSCO CINAHL, and Scopus were systematically searched from 1946 to September 2017 to identify candidate studies. Studies of cystatin C as a predictor for acute kidney injury or for management of contrast-associated acute kidney injury were excluded. Also, studies were excluded if drug concentrations were unavailable and if a reference standard for drug dosing (eg, serum creatinine) was not concurrently reported. The outcomes of interest included drug clearance (L/h), concentrations (mg/L), target level achievement (%), therapeutic failure (%), and drug toxicity (%). We included 28 articles that evaluated 16 different medications in 3455 participants. Vancomycin was the most well-studied drug. Overall, cystatin C-based estimated glomerular filtration rate (eGFR_{Cystatin C}) was more predictive of drug levels and drug clearance than eGFR_Creatinine. In only one study were target attainment and outcomes compared between 2 drug-dosing regimens, one based on eGFR_{Creatinine-Cystatin C} and one dosed with the Cockcroft-Gault creatinine clearance equation. Compared with eGFR_Creatinine, use of eGFR_{Cystatin C} to predict elimination of medications via the kidney was as accurate, if not superior, in most studies, but infrequently were data on target attainment or clinical outcomes reported. Drug-specific dosing protocols that use cystatin C to estimate kidney function should be tested for clinical application.