Impact of renal aging on drug therapy

The MGPIDP-L project: Potentially inappropriate drug prescribing and its associated factors

OBJECTIVE

The aim of this study was to identify the prevalence of potentially inappropriate drug prescribing¹ (PIDP) using a combination of explicit and implicit criteria in a sample of Lebanese older adults taking 5 or more chronic medications per day in ambulatory care settings and to identify which factors were associated with PIDP. The explicit criteria included five different lists: Beers, Laroche, European Union (EU(7)-PIM list), STOPP/ START, STOPP Frail, and Alert and Mastering of Iatrogenesis issued by the French High Authority of Health. We also performed a sensitivity analysis to compare the potentially inappropriate medications according to each criterion.

METHODS

Data were collected from each patient via a face-to-face interview. Logistic regressions were conducted to evaluate both objectives.

RESULTS

Many factors were positively associated with PIDP. The risk of PIDP was positively associated with age (OR =4.692, 95% CI [1.889-11.655]). Treatment for insomnia doubled the odds of PIDP (P<0.05). Participants who picked their medications from the pharmacy and had excess stock of drugs were at higher risk of having PIDP by 2.042 (95% CI [1.199-3.478]) and 2.965(95% CI [1.133-7.762]) respectively. However, patients with a perception of being heavily medicated and patients with a missed dose in the last two weeks had lower odds of PIDP.

CONCLUSION

Our study showed a high prevalence of PIDP in Lebanon, which is associated with various correlates. Selecting the appropriate tools to assess PIDP and providing patient education regarding the risks associated with potentially inappropriate medications are issues to be addressed among older adults.

Clinical characteristics and cost of hospital stay of octogenarians and nonagenarians in intensive care nephrology unit

PURPOSE

As the population gets older, the elderly and very elderly patients are increasingly been treated in nephrology intensive care units (ICU). In this study we evaluated the characteristics and outcomes of the octogenarians (80-89 years old), nonagenarians (≥ 90 years old) and compared them with elderly (65-79 years old) patients treated in nephrology ICU.

METHODS

Eighteen nonagenarians, 70 octogenarians and 88 elderly patients were included in the study. Indication for hospitalization, presence of comorbid diseases, and requirement for acute dialysis treatment were investigated. Need for mechanical ventilation, vasopressors, central venous catheterization, urinary catheterization, anticoagulation, and transfusion of blood products were evaluated. Mortality rate and hospital cost were calculated. Data about survival at 1 month after discharge was collected.

RESULTS

Causes of hospitalization, need for dialysis treatment, mechanical ventilation, vasopressors, central venous catheterization, urinary catheterization, anticoagulation, and transfusion of blood products were not different between age groups. Diabetes mellitus and malignancy were more frequent in elderly, whereas dementia/Alzheimer's disease was more common in nonagenarians. Although, mortality in ICU was increased as the age increased, it was statistically insignificant. However, 1 month mortality rate after discharge from hospital was increased especially in nonagenarians. In nonagenarians infection, whereas in octogenarians need for dialysis treatment, were related with mortality. Length of intensive care stay and hospital cost did not differ between age groups.

CONCLUSION

Length of nephrology intensive care stay, mortality rate and hospital cost did not differ for very elderly age groups, but mortality risk was higher for nonagenarians after discharge from hospital.

Risk of Kidney Dysfunction from Polypharmacy among Older Patients: A Nested Case-Control Study of the South Korean Senior Cohort

Polypharmacy, the concurrent use of multiple medicines, could increase the risk of kidney dysfunction among older adults because it likely burdens the aging kidneys to excrete multiple pharmaceutical ingredients and their metabolites. This study aimed to examine the relation between polypharmacy and kidney dysfunction among older patients. A nested case-control study was conducted using the National Health Insurance Service - Senior Cohort (NHIS-SC, 2009-2013), representative of the Korean senior population. It consisted of all health insurance claims linked to records of mandatory health examination. Kidney dysfunction was defined as having an eGFR lower than 60, with a decline rate of 10% or more compared to the baseline eGFR. Polypharmacy was defined based on daily counts of pharmaceutical ingredients during one year prior to the case's event date. It was classified into polypharmacy (five to 10 ingredients) and excessive polypharmacy (10 or more ingredients). After matching case and control groups based on a range of potential confounders, conditional logistic regression was performed incorporating adjustments on disease-specific, medication-specific, and lifestyle-related risk factors. The matching resulted in 14,577 pairs of cases and controls. Exposure to polypharmacy was significantly associated with increase in the risk of kidney dysfunction; i.e., crude model (polypharmacy: OR = 1.572, 95% CI = 1.492-1.656; excessive polypharmacy: OR = 2.069, 95% CI = 1.876-2.283) and risk adjustment model (polypharmacy: OR = 1.213, 95% CI = 1.139-1.292; excessive polypharmacy: OR = 1.461, 95% CI = 1.303-1.639). The significant associations were robust across different definitions of kidney dysfunction. These findings inform healthcare providers and policy makers of the importance of polypharmacy prevention to protect older adults from kidney dysfunction.

Renal Transporter-Mediated Drug-Drug Interactions: Are They Clinically Relevant?

The kidney, through the distinct processes of passive glomerular filtration and active tubular secretion, plays an important role in the elimination of numerous endobiotics (eg, hormones, metabolites), toxins, nutrients, and drugs. Renal transport pathways mediating active tubular secretion and reabsorption in the proximal tubule are complex, involving apical and basolateral transporters acting in concert. Detailed studies of the molecular mechanisms of net active tubular secretion have established the involvement of multiple transporters with overlapping substrate specificity mediating competing secretion and reabsorption pathways. Although drug interactions arising from inhibition of renal transporters are rare relative to other mechanisms, they can involve commonly administered drugs (eg, cimetidine, metformin), may be underappreciated due to muted effects on plasma pharmacokinetics relative to tissue levels, can affect narrow-therapeutic-index medications (eg, antiarrhythmic, oncology medications), and may disproportionately affect sensitive populations where polypharmacy is common (eg, the elderly, diabetics). In particular, there is the potential for larger-magnitude interactions in subjects with reduced glomerular filtration rates due to the increased relative contribution of tubular secretion. The assessment of additional endpoints in drug-drug interaction studies including pharmacodynamics, positron emission tomography imaging, and metabolomics promises to expand our understanding of the clinical relevance of renal drug interactions.

Inflammation and pharmacokinetics: potential implications for HIV-infection

INTRODUCTION

The physiological changes accompanying inflammation may alter the pharmacokinetics (PK) of certain medications. Individuals infected with HIV have chronically elevated inflammatory markers despite viral suppression following effective antiretroviral therapy (ART), as well as age-related inflammation. Understanding the potential clinical implications of inflammation on the PK of medications is important for understanding dose-response relationships and necessitates future research. Areas covered: An extensive literature search was carried out using PubMed and associated bibliographies to summarize the current state of knowledge regarding altered PK in response to inflammation and its application to the field of HIV. Expert opinion: Preclinical and clinical studies show that inflammation leads to a downregulation of certain drug metabolizing enzymes and both up and down regulation of transporters depending on the transporter and cell type. Decreased gastric acidity, fluid shifts, and plasma protein alterations also occur with inflammation, leading to potential absorption, distribution, and clearance changes. More research is needed including controlled PK studies to address the clinical relevance of these observations, especially in the aging HIV-infected population. Results from future studies will enable us to better predict drug concentrations in individuals with inflammation, in line with efforts to provide personalized pharmacotherapy in our healthcare system.

Glomerular filtration rate equations: a comprehensive review

Since evaluation of glomerular filtration rate (GFR) is very important in daily medical care, and reliable methods for measuring GFR are too complicated, there has been along decades an enormous effort for developing accurate GFR equations. In the present review article, we performed a comprehensive analysis of the mainly described GFR equations, and we concluded that although MDRD, CKD-EPI, DRA and Gregori-Macías equations are valid to monitor renal function as well as to stage and follow up renal patients, the clinical nephrological evaluation still remains the best alternative for diagnosing renal health and disease.

A New Method for Individualized Digoxin Dosing in Elderly Patients

BACKGROUND

Digoxin is a frequently prescribed drug in the elderly population. Estimated glomerular filtration rate is widely used to adjust dosages. The HUGE value is a tool for differentiating the presence or absence of chronic kidney disease in elderly patients. We aimed to investigate the usefulness of the HUGE value to predict the initial dose of digoxin in patients aged older than 70 years.

METHODS

We reviewed retrospectively the medical records of patients aged older than 70 years with serum digoxin concentrations (SDCs) monitored over a 6-month period (63 patients). A linear regression relating the patient's SDC, maintenance dose of digoxin and the HUGE value was estimated to generate a dosage equation. This equation was validated retrospectively (33 patients) and prospectively (35 patients) in comparison with two existing methods based on creatinine clearance.

RESULTS

An equation (HUGE_DIG) was generated to calculate the initial digoxin dose to reach a specific target SDC. Thus, to achieve a SDC of 0.8 ng/mL: Digoxin (mg/day) = 0.091 - 0.006 x HUGE. After retrospective validation, the calculated digoxin doses with this equation were administered in the prospective phase and we did not observe statistical differences between measured and desired SDCs. Moreover, the predictive performance of our equation was better than that obtained with the compared methods.

CONCLUSIONS

We offer a new validated digoxin dosing equation for elderly patients. Our results support the need to perform digoxin dosing in elderly people, bearing in mind the changes in renal physiology secondary to ageing and not merely the estimated glomerular filtration rate.