Prevalence of Polypharmacy and Factors Associated with it Among Saudi Older Adults - Results from the Saudi National Survey for Elderly Health (SNSEH).

Background and Objectives: The percentage of Saudi older adults (SOA) is increasing over time. With advanced age, the prevalence of chronic diseases and multiple disabilities are increasing. This leads to increase utilization of multiple medications. The objectives of this study were to describe medication utilization, determine the prevalence of polypharmacy (PP) and factors associated with it among SOA. Methods: This cross-sectional study was conducted among community-dwelling SOA aged ≥ 60 years old using the Saudi National Survey for Elderly Health (SNSEH). The survey was conducted between 2006 and 2007 by the Ministry of Health on a nationally representative sample of SOA. The data included demographics, socioeconomic and health information such as diseases and medications. Polypharmacy was defined as the concurrent use of medications from ≥ 5 therapeutic classes. A modified Poisson multivariable regression was used to study factors associated with PP controlling for confounders. All analyses were done using STATA 14. Results: The study included 2,946 SOA; 50.4% were males, 60.9% were 60-70 years old, and 69.6% were illiterate. The most common medications used among SOA were: Paracetamol (67%), joint pain medications and NSAIDs (50% each), anti-diabetic and multivitamins and minerals (47% each). PP was identified in (51.5%) of participants. The most medication associated with PP were: Paracetamol (79.9%), multivitamins and minerals (71.6%), steroid and DMARDs (70.1%), NSAIDs (66.4%), anti-diabetic and anti-hypertensive (61.3%). Higher risk of PP was associated with diabetes (RR: 1.863; 95% CI: 1.686-2.059), hypertension (RR: 1.829; 95% CI: 1.624-2.060), having pain (RR: 2.282; 95% CI: 1.918-2.713), urinary incontinence (RR: 1.389; 95% CI: 1.238-1.560; ref: no urinary incontinence) or suggestive depression (RR: 1.379; 95% CI: 1.259-1.512). Similarly, compared to low income (<2500 SAR), higher incomes were more likely to have PP. On the other hand, compared to the central region, southern and northern regions were less likely to have PP (RR = 0.741; 95% CI: 0.652-0.843 and RR: 0.736; 95% CI: 0.596-0.908, respectively). Severe cognitive impairment was associated with a lower risk of PP (RR: 0.708; 95% CI: 0.501-1.000). Conclusion: The prevalence of PP among a nationally representative SOA was very high, i.e., 51.5%. Higher risk of PP was associated with many factors such as region, income, diabetes, hypertension, musculoskeletal pain, urinary incontinence, and depression. PP leads to many negative implications such as drug interactions, combined side effects, hospitalization, and death. Therefore, raising the knowledge of health care providers on the consequences of PP and providing medication therapy management services may help decrease the negative consequences of PP and improve therapy outcomes.

Estimation of Tacrolimus Clearance in Saudi Adult Kidney Transplant Recipients.

Tacrolimus is commonly used in adult kidney transplant patients. Only few studies have so far described the pharmacokinetics of tacrolimus in the Saudi population. Thus, the goal of this study is to determine the population pharmacokinetics of tacrolimus in Saudi adult kidney transplant recipients and to identify the factors that explain variability. We performed a retrospective chart review of adult patients who received oral tacrolimus at two centers. We developed the population pharmacokinetic models using Monolix 4.4. The factors screened for influence on these parameters were weight, age, gender, liver function tests, and creatinine clearance. The analysis included a total of 149 tacrolimus plasma concentrations from 139 patients. A one-compartment open model with linear absorption and elimination adequately described the data. The average parameter estimates for apparent clearance (CL/F) and apparent volume of distribution (V/F) were 9.1 L/h and 912 L, respectively. The interindividual variabilities (coefficients of variation) in CL/F and V/F were 20% and 18%, respectively. Aspartate aminotransferase was identified to be the main covariate that influences tacrolimus CL/F. In conclusion, the population pharmacokinetic model of tacrolimus was established and a significant covariate of the model was identified. These findings offer a rationale for the personalization of tacrolimus dosing regimens. Further studies are required to understand the factors that may influence the pharmacokinetics of tacrolimus and assist in drug dosage decisions.

An update on the potential role of intestinal first-pass metabolism for the prediction of drug-drug interactions: the role of PBPK modeling.

INTRODUCTION: The intestinal absorption process is a combination of several events that are governed by various factors. Several transport mechanisms are involved in drug absorption through enterocytes via active and/or passive processes. The transported molecules then undergo intestinal metabolism, which together with intestinal transport may affect the systemic availability of drugs. Many studies have provided clear evidence on the significant role of intestinal first-pass metabolism on drug bioavailability and degree of drug-drug interactions (DDIs). Areas covered: This review provides an update on the role of intestinal first-pass metabolism in the oral bioavailability of drugs and prediction of DDIs. It also provides a comprehensive overview and summary of the latest update in the role of physiologically based pharmacokinetic models modeling in prediction of intestinal metabolism and DDIs in humans. Expert opinion: The contribution of intestinal first-pass metabolism in the oral bioavailability of drugs and prediction of DDIs has become more evident over the last few years. Several in vitro, in situ, and in vivo models have been developed to evaluate the role of first-pass metabolism and to predict DDIs. Currently, physiologically based pharmacokinetic modeling is considered the most valuable tool for the prediction of intestinal first-pass metabolism and DDIs.

Patients' understanding of prescription drug label instructions in developing nations: The case of Saudi Arabia.

BACKGROUND: Processing health-related data is challenging for patients. It is believed that low education level and low socioeconomic status are associated with prescription label misunderstanding, which may lead to poor clinical outcomes, increased adverse drug reactions, and increased health costs. OBJECTIVES: The aim of this study was to gain a better insight into the current understanding of prescription drug labels, and to determine the main factors affecting patients' understanding of prescription labels. METHOD: A total of 511 adult participants in 4 major hospitals in Riyadh were interviewed. The primary outcome was patient understanding of prescription labels for 5 commonly prescribed medications. Prescription label understanding was assessed using a prespecified structured interview protocol. Participants with less than a 6th-grade education level and monthly income less than 10,000 Saudi Riyal were considered to have a low education level and low monthly income, respectively. Logistic regression analysis was used to examine the cross-sectional association of socioeconomic factors with the participants' understanding of the medication label. RESULTS: The prevalence of poor understanding of the medication labels was 38.6% among the participants. Out of those participants with poor understanding, 27.9% incorrectly understood at least 4 of the 5 labels. The degree of misunderstanding significantly worsened for older participants (P-value = 0.004), male (P-value < 0.001), with low education level (P-value = 0.002), and low monthly income (P-value = 0.012). The most common features misunderstood were duration of treatment (38.9%) and storage instructions (29.5%). CONCLUSIONS: Prescription label misunderstanding is common among participants. More efforts should be made to improve patients' understanding by reducing the ambiguity of the prescription labels.