Role of patient compliance in clinical pharmacokinetics. A review of recent research

An updated review of mesoporous carbon as a novel drug delivery system

The nanotechnology approach has been recently adopted to provide more reliable, effective, controlled, and safe drug delivery systems. Nanostructured materials have gained great interest, including siliceous and carbonaceous nanoparticles. The effectiveness of mesoporous carbon nanoparticles (MCNs) in tumor imaging, targeting, and treatment is urging for more future studies. MCNs possess superior properties such as their biocompatibility, large surface area, large pore volume, tunability, and more responsive behavior to internal and external release triggers. These outstanding features make MCNs more applicable for stimuli-responsive drug delivery than the conventional forms of mesoporous silica nanoparticles (MSNs) and other carbon nanoparticles. In this review, we outlined the latest updates regarding the safety, benefits, and potential applications of MCNs.

Assessment of medication self-administration using artificial intelligence

Errors in medication self-administration (MSA) lead to poor treatment adherence, increased hospitalizations and higher healthcare costs. These errors are particularly common when medication delivery involves devices such as inhalers or insulin pens. We present a contactless and unobtrusive artificial intelligence (AI) framework that can detect and monitor MSA errors by analyzing the wireless signals in the patient's home, without the need for physical contact. The system was developed by observing self-administration conducted by volunteers and evaluated by comparing its prediction with human annotations. Findings from this study demonstrate that our approach can automatically detect when patients use their inhalers (area under the curve (AUC) = 0.992) or insulin pens (AUC = 0.967), and assess whether patients follow the appropriate steps for using these devices (AUC = 0.952). The work shows the potential of leveraging AI-based solutions to improve medication safety with minimal overhead for patients and health professionals.

A data-driven typology of asthma medication adherence using cluster analysis

Asthma preventer medication non-adherence is strongly associated with poor asthma control. One-dimensional measures of adherence may ignore clinically important patterns of medication-taking behavior. We sought to construct a data-driven multi-dimensional typology of medication non-adherence in children with asthma. We analyzed data from an intervention study of electronic inhaler monitoring devices, comprising 211 patients yielding 35,161 person-days of data. Five adherence measures were extracted: the percentage of doses taken, the percentage of days on which zero doses were taken, the percentage of days on which both doses were taken, the number of treatment intermissions per 100 study days, and the duration of treatment intermissions per 100 study days. We applied principal component analysis on the measures and subsequently applied k-means to determine cluster membership. Decision trees identified the measure that could predict cluster assignment with the highest accuracy, increasing interpretability and increasing clinical utility. We demonstrate the use of adherence measures towards a three-group categorization of medication non-adherence, which succinctly describes the diversity of patient medication taking patterns in asthma. The percentage of prescribed doses taken during the study contributed to the prediction of cluster assignment most accurately (84% in out-of-sample data).

A systematic review of factors influencing treatment adherence in chronic inflammatory skin disease - strategies for optimizing treatment outcome

Adherence describes how a patient follows a medical regime recommended by a healthcare provider. Poor treatment adherence represents a complex and challenging problem of international healthcare systems, as it has a substantial impact on clinical outcomes and patient safety and constitutes an important financial burden. Since it is one of the most common causes of treatment failure, it is extremely important for physicians to reliably distinguish between non-adherence and non-response. This systematic review aims to summarize the current literature on treatment adherence in dermatology, focusing on chronic inflammatory skin diseases such as psoriasis, atopic dermatitis and acne. A systematic literature search was performed using the PubMed Database, including articles from 2008 to 2018. Low treatment adherence is a multidimensional phenomenon defined by the interplay of numerous factors and should under no circumstances be considered as the patient's fault alone. Factors influencing treatment adherence in dermatology include patient characteristics and beliefs, treatment efficacy and duration, administration routes, disease chronicity and the disease itself. Moreover, the quality of the physician-patient relationship including physician-time available for the patient plays an important role. Understanding patients' adherence patterns and the main drivers of non-adherence creates opportunities to improve adherence in the future. Strategies to increase treatment adherence range from reminder programs to simplifying prescriptions or educational interventions. Absolute adherence to treatment may not be realistically achievable, but efforts need to be made to raise awareness in order to maximize adherence as far as possible.

"Wounds Home Alone"-Why and How Venous Leg Ulcer Patients Self-Treat Their Ulcer: A Qualitative Content Study

BACKGROUND

Venous leg ulcers (VLUs), the most common type of leg ulcerations, have long healing times and high recurrence rates; reimbursement rules and a general shortage of nursing staff have put self-treatment into focus. The study aimed to investigate why and how patients with VLUs self-treat their ulcers.

METHODS

Patients with VLUs (N = 32) were selected by criterion sampling for a multicentric qualitative study using semi-structured interviews. The interviews were analyzed via inductive qualitative content analysis.

RESULTS

More than two-thirds of participants sometimes self-treated VLU and one quarter changed their prescribed treatment. Experiences were expressed through four themes as follows: (a) current local VLU therapy; (b) VLU self-treatment; (c) patient education; and (d) psychosocial issues. The main reasons for self-treatment were a lack of healthcare resources, reimbursement restrictions, and dissatisfaction with conventional treatment together with insufficient knowledge about the wound-healing process and possible side effects. No educational materials were provided for patients or caregivers. Many patients adopted homemade remedies.

CONCLUSION

Patients with VLUs practice self-care due to limited healthcare availability, a low awareness of the causes of their condition, and the effects of therapy on VLU healing. Future educational intervention is needed to enhance self-treatment.

Relationship Between Adherence Rate Threshold and Drug 'Forgiveness'

The medication adherence rate (A) is the proportion of prescribed drug doses consumed within a given time period. It is often assumed that there is an adherence rate threshold (A _th) at or above which the therapeutic effect of the medication is maintained. Drug forgiveness (F) is the number of consecutive doses that can be missed while still maintaining a therapeutic effect. At a given value for A, the therapeutic effect of the drug will be continuously maintained if there is no possibility of >F missed doses. Hence, for a once-daily drug prescribed for N days, A _th and F are related by the formula, A _th = (N - F)/N. At adherence rates below A _th the probability of maintaining the therapeutic effect is equal to the probability of there being no instances of >F consecutive missed doses. Since F is a function of the duration of the drug effect (D) and D varies depending on the specific drug's pharmacokinetic/pharmacodynamic properties, there is no universal A _th applicable to all drugs.

Self-reported adherence and biomarker levels of CoQ10 and alpha-tocopherol

PURPOSE

Women with breast cancer were randomized to receive coenzyme Q10 (CoQ10) plus Vitamin E or placebo in a clinical trial. The objective of this evaluation is to examine the association between participant self-reported adherence to the study supplements and changes in plasma biomarker levels.

PATIENTS AND METHODS

Correlation coefficients quantified the association between changes in alpha-tocopherol and CoQ10 levels and the association between self-reported adherence and changes in biomarkers. Participants were categorized by self-reported adherence; Kruskal- Wallis tests compared changes in alpha-tocopherol and CoQ10 levels between self-reported adherence groups.

RESULTS

Women (N=155) provided baseline and post-treatment biomarkers; 147 completed at least one diary. While changes in alpha-tocopherol and CoQ10 levels were moderately correlated, correlations ranged from 0.40 to 0.48, association between self-reported adherence and plasma alpha-tocopherol or CoQ10 levels was weak; correlations ranged from 0.10 to 0.29 at weeks 8, 16, and 24. Some participants with high self-reported adherence actually had decreases in their biomarker levels.

CONCLUSION

These findings support that self-reported adherence is likely to be overestimated. Biological and other measures of adherence that can better identify true adherence to study pills provided in clinical trials are greatly needed as they may assist in improving the interpretation of findings of future clinical trials.

Triple-combination therapy in the treatment of hypertension: a review of the evidence

Hypertension is a serious public health concern with inadequate control of blood pressure (BP) worldwide. Contributing factors include low efficacy of drugs, underuse of combination therapies, irrational combinations, physicians' therapeutic inertia and poor adherence to treatment. Current guidelines recommend the use of initial (dual) combination therapy in high-risk patients for immediate BP response, better short- and long-term BP control, and continued/improved patient adherence. This article aims to review the existing evidence of triple-combination therapies with respect to efficacy, safety and adherence to treatment. It is estimated that three drugs are required to achieve BP control in approximately one-fourth to one-third of patients. Randomised controlled trials (RCTs) have shown that triple combinations of amlodipine/valsartan/hydrochlorothiazide, amlodipine/olmesartan/hydrochlorothiazide and amlodipine/telmisartan/hydrochlorothiazide produce greater BP reductions, with greater proportions of patients achieving BP control compared with dual therapies. Further evidence also demonstrates that triple-combination therapy is efficacious for moderate to severe hypertension, with substantial additional BP reduction over dual regimens. Both RCTs and post-marketing observational studies have shown consistent and comparable efficacy in both the general population and high-risk hypertensive subgroups. Triple therapies are generally well tolerated with adverse event profiles similar to dual regimens. In addition, fixed-dose combinations used as single pill improve patient adherence leading to better long-term BP control. Depending on regional circumstances, they may also be cost effective. Thus, single-pill triple combinations of different classes of drugs with complementary mechanisms of action help to treat patients to goal with improved efficacy and better adherence to treatment.

The role of the affective temperament in the treatment adherence in psychiatry

Introduction

Adherence to psychotropic medications is affected by factors related to the treatment, to the physician, to the environment and to the patient himself. The purpose of the present study was to investigate the influence of affective temperaments on treatment adherence.

Methods

Thirty six stabilized outpatients were recruited from the aftercare consultation of Psychiatry to perform Temperament Evaluation of Memphis, Pisa, Paris and San Diego Auto questionnaire version (TEMPS-A) for affective temperaments and the Medication Adherence Rating Scale (MARS) for treatment adherence.

Results

The total MARS score was negatively correlated with the irritable temperament score. The MARS’s score relative to the attitude of patients to psychotropic medications and their negative side effects was negatively correlated with the cyclothymic, the irritable and anxious temperaments. Patients having a diagnosis of psychotic disorder had a significantly greater medication adherence and behaviour toward medication score compared to those having a diagnosis of affective disorder. A greater MARS’s score for the negative side effects and attitudes to psychotropic medication was associated with medication by neuroleptics with prolonged action.

Conclusion

The results of the present study suggest that patients with irritable temperament may have more difficult to follow psychotropic medications, and that patients with cyclothymic, irritable and anxious temperaments may be more attentive and sensitive toward psychotropic medications and their negative side effects.

Adherence to fingolimod in multiple sclerosis: an investigator-initiated, prospective, observational, single-center cohort study

OBJECTIVES

Adherence to multiple sclerosis (MS) treatment is essential to optimize the likelihood of full treatment effect. This prospective, observational, single-center cohort study investigated adherence to fingolimod over the 2 years following treatment initiation. Two facets of adherence - implementation and persistence - were examined and compared between new and experienced users of disease-modifying treatments (DMTs).

MATERIALS AND METHODS

Implementation rates were based on the proportion of days covered and calculated as percentages per half-yearly visits and over 2 years, captured through refill data, pill count, and self-report. Nonadherence was defined as taking less than 85.8% of prescribed pills. Implementation rates were classified as nonadherent (<85.8%), suboptimally adherent (≥85.8% but <96.2%), and optimally adherent (≥96.2%), including perfectly adherent (100%). Persistence, ie, time until discontinuation, was analyzed by Kaplan-Meier analysis. Reasons for discontinuation were recorded.

RESULTS

The cohort included 98 patients with relapsing MS, all of whom received a dedicated education session about their medication. Of these 80% were women, 31.6% had fingolimod as first DMT, and 68.4% had switched from other DMTs. The mean implementation rate over 2 years was 98.6% (IQR_1-3 98.51%-98.7%) and did not change significantly over time; 89% of measurements were in the optimally adherent category, 45.6% in the perfectly adherent category. There was one single occurrence of nonadherence. New users of DMTs were 1.29 times more likely to be adherent than experienced users (OR 1.29, 95% CI 1.11-1.51; P<0.001), but not more persistent. Nineteen of 98 patients discontinued fingolimod.

CONCLUSION

The very high implementation rates displayed in this sample of MS patients suggest that facilitation by health care professionals in preserving adherence behavior may be sufficient for the majority of patients. Targeted interventions should focus on patients who are nonadherent or who stop treatment without intention to reinitiate.

Pharmacological interventions into the renin-angiotensin system with ACE inhibitors and angiotensin II receptor antagonists: effects beyond blood pressure lowering

Hypertension is recognized as an important risk factor for cardiovascular morbidity and mortality. Lowering of blood pressure has been shown to minimize the risk of cardiovascular events, with the majority of antihypertensives demonstrating a similar ability to reduce coronary events and stroke for a given reduction in blood pressure. Agents that modify the activity of the renin-angiotensin system (RAS) have been proposed to exhibit additional effects that might go beyond simple blood pressure lowering. The RAS is a crucial system that regulates extracellular fluid volume and blood pressure. Proposed potential benefits of RAS blockade that go beyond blood pressure lowering include a reduction in platelet aggregation and thrombosis, blunting of cardiac and vascular remodeling, favorable metabolic effects and reno- and cerebro-protection. However, factors such as treatment adherence, duration of action of antihypertensive agents and differences in effects on central versus brachial blood pressure may also result in apparent differences in efficacy of different antihypertensives. The aim of this review article is to examine the available data from clinical studies of antihypertensive drugs for evidence of effects that might legitimately be claimed to go beyond simple blood pressure lowering.

Desirability and feasibility of wireless electronic monitoring of medications in clinical trials

Medication nonadherence is a vexing problem in health care necessitating patients and health professionals' efforts to prevent, minimize, or reverse it. Research participants' inconsistent medication taking obscures treatment efficacy and adds costs to biomedical research. Electronic monitoring devices (EMDs), like the Medication Event Monitoring System (MEMS), have grown in sophistication, providing precise, timely insights into individuals' medication-taking patterns across clinical populations. This article reports on the desirability and feasibility study of using a wireless EMD in clinical research to promote adherence to clinical regimens and research protocols. Nonadherence in transplant patients has been linked to late acute rejection and graft loss. High levels of adherence (97.7 %) were documented for six renal transplant recipients for a mean of 6 months (M = 196.1 ± 71.2 days) who indicated acceptance of the technology. MEMS data confirmed the feasibility of using wireless EMDs to monitor medication use. Monitoring provides greater assurance that research studies reflect the biological impact of medications and provide a basis for targeting adherence enhancement efforts within research investigations.

Effectiveness of RHZE-FDC (fixed-dose combination) compared to RH-FDC + Z for tuberculosis treatment in Brazil: a cohort study

Background

In 2009, Brazil was the sole high-burden country to use three drugs [rifampin (R), isoniazid (H) and pyrazinamide (Z)] as the standard treatment for sensitive tuberculosis, with RH in fixed-dose combination (FDC). In December 2009, the country has adopted the FDC four-drug regimen including ethambutol (E). The rationale was the expectation to reduce default and resistance rates, by increasing adherence to treatment and avoiding monotherapy. However, there is no consensus on the superior effectiveness of the RHZE-FDC regimen over RH-FDC + Z. In particular, few studies evaluated its influence on default and smear negativation rates.

Methods

We conducted a historic cohort study to assess the effectiveness of RHZE-FDC for the treatment of tuberculosis in Brazil, measured by the rates of treatment default and smear negativation in the second month of treatment, using secondary data from the national information system known as SINAN-TB.

Results

The RHZE-FDC had a protective effect against treatment default compared to RH-FDC + Z, reducing it by 14%. However, it was not possible to show an effect of the RHZE-FDC on the rate of second month smear negativation. In addition to the regimen, other well-studied individual characteristics, such as older age (over 38 years) and higher education occupation were also protective against default. Conversely, alcoholism increased the probability of defaulting. These programmatic findings suggests the benefits of RHZE-FDC over RH-FDC + Z.

Conclusion

Our analysis of a cohort database in a high burden country shows that compared to RH-FDC + Z, RHZE-FDC reduces the default rates, independently of other influencing individual or health service factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0820-4) contains supplementary material, which is available to authorized users.

A hybrid Markov chain-von Mises density model for the drug-dosing interval and drug holiday distributions

Lack of adherence is a frequent cause of hospitalizations, but its effects on dosing patterns have not been extensively investigated. The purpose of this work was to critically evaluate a novel pharmacometric model for deriving the relationships of adherence to dosing patterns and the dosing interval distribution. The hybrid, stochastic model combines a Markov chain process with the von Mises distribution. The model was challenged with electronic medication monitoring data from 207 hypertension patients and against 5-year persistence data. The model estimates distributions of dosing runs, drug holidays, and dosing intervals. Drug holidays, which can vary between individuals with the same adherence, were characterized by the patient cooperativity index parameter. The drug holiday and dosing run distributions deviate markedly from normality. The dosing interval distribution exhibits complex patterns of multimodality and can be long-tailed. Dosing patterns are an important but under recognized covariate for explaining within-individual variance in drug concentrations.

Linking the population pharmacokinetics of tenofovir and its metabolites with its cellular uptake and metabolism

Empirical pharmacokinetic models are used to explain the pharmacokinetics of the antiviral drug tenofovir (TFV) and its metabolite TFV diphosphate (TFV-DP) in peripheral blood mononuclear cells. These empirical models lack the ability to explain differences between the disposition of TFV-DP in HIV-infected patients vs. healthy individuals. Such differences may lie in the mechanisms of TFV transport and phosphorylation. Therefore, we developed an exploratory model based on mechanistic mass transport principles and enzyme kinetics to examine the uptake and phosphorylation kinetics of TFV. TFV-DP median C_max from the model was 38.5 fmol/10⁶ cells, which is bracketed by two reported healthy volunteer studies (38 and 51 fmol/10⁶ cells). The model presented provides a foundation for exploration of TFV uptake and phosphorylation kinetics for various routes of TFV administration and can be updated as more is known on actual mechanisms of cellular transport of TFV.

The value of nurses’ tailored communication when discussing medicines: Exploring the relationship between satisfaction, beliefs and adherence

Numerous studies of various populations and settings link patient–provider communication or beliefs to medication adherence. A better understanding of this interplay may help to improve patient-centred communication. To predict adherence, this study used the Beliefs about Medicines Questionnaire and indications of the quality of the nurse’s communication in terms of patient satisfaction. Patient satisfaction with the information provided and the degree to which the information was tailored to them were related to adherence via the patient’s beliefs. This study supports the argument that tailoring is an effective strategy for improving adherence via beliefs and can contribute to medical education and to adherence interventions.

Successful Projection of the Time Course of Drug Concentration in Plasma During a 1-Year Period From Electronically Compiled Dosing-Time Data Used as Input to Individually Parameterized Pharmacokinetic Models

Pharmacokinetic studies rely on blood sampling at times relative to predefined dosing intervals. Intensive sampling is often done under direct observation of dose taking, which, though costly, virtually eliminates uncertainty about actual dosing times. In contrast, the sparse sampling done in population pharmacokinetic studies relies on patient-reported times of dosing, the accuracy of which the authors sought to assess by adding electronic monitoring to the usual patient reporting of dosing times. The study involved 35 antiretroviral-naive, human immunodeficency virus-infected patients and was designed to assess the safety, tolerability, pharmacokinetics, and antiviral activity of prescribed lopinavir/ritonavir (800/200 mg qd or 400/100 mg bid), stavudine, and lamivudine. The present research reports the pharmacokinetic analysis that results from taking into account the patients' actual dosing histories. Intensive sampling for plasma lopinavir concentrations was done at week 3, and 4 additional predose (trough) concentrations were measured during the next 12 months. Convergence was achieved by fitting a simple 1-compartment pharmacokinetic model, with first-order absorption and elimination, to the sparse sampling data, using electronic monitoring-reported times. In contrast, convergence was not achieved using the simple model when steady state was assumed, and the times for the last qd dose or the last 2 bid doses, as reported by the patient, were used as model input. Estimated individual pharmacokinetic parameters were then combined with electronic dosing histories to project each patient's internal drug exposure over long periods of time. This strategy may provide a basis for greatly increasing the informational yield and utility of conventional therapeutic drug monitoring.

A new taxonomy for describing and defining adherence to medications

Interest in patient adherence has increased in recent years, with a growing literature that shows the pervasiveness of poor adherence to appropriately prescribed medications. However, four decades of adherence research has not resulted in uniformity in the terminology used to describe deviations from prescribed therapies. The aim of this review was to propose a new taxonomy, in which adherence to medications is conceptualized, based on behavioural and pharmacological science, and which will support quantifiable parameters. A systematic literature review was performed using MEDLINE, EMBASE, CINAHL, the Cochrane Library and PsycINFO from database inception to 1 April 2009. The objective was to identify the different conceptual approaches to adherence research. Definitions were analyzed according to time and methodological perspectives. A taxonomic approach was subsequently derived, evaluated and discussed with international experts. More than 10 different terms describing medication-taking behaviour were identified through the literature review, often with differing meanings. The conceptual foundation for a new, transparent taxonomy relies on three elements, which make a clear distinction between processes that describe actions through established routines ('Adherence to medications', 'Management of adherence') and the discipline that studies those processes ('Adherence-related sciences'). 'Adherence to medications' is the process by which patients take their medication as prescribed, further divided into three quantifiable phases: 'Initiation', 'Implementation' and 'Discontinuation'. In response to the proliferation of ambiguous or unquantifiable terms in the literature on medication adherence, this research has resulted in a new conceptual foundation for a transparent taxonomy. The terms and definitions are focused on promoting consistency and quantification in terminology and methods to aid in the conduct, analysis and interpretation of scientific studies of medication adherence.

A new taxonomy for describing and defining adherence to medications

Interest in patient adherence has increased in recent years, with a growing literature that shows the pervasiveness of poor adherence to appropriately prescribed medications. However, four decades of adherence research has not resulted in uniformity in the terminology used to describe deviations from prescribed therapies. The aim of this review was to propose a new taxonomy, in which adherence to medications is conceptualized, based on behavioural and pharmacological science, and which will support quantifiable parameters. A systematic literature review was performed using MEDLINE, EMBASE, CINAHL, the Cochrane Library and PsycINFO from database inception to 1 April 2009. The objective was to identify the different conceptual approaches to adherence research. Definitions were analyzed according to time and methodological perspectives. A taxonomic approach was subsequently derived, evaluated and discussed with international experts. More than 10 different terms describing medication-taking behaviour were identified through the literature review, often with differing meanings. The conceptual foundation for a new, transparent taxonomy relies on three elements, which make a clear distinction between processes that describe actions through established routines ('Adherence to medications', 'Management of adherence') and the discipline that studies those processes ('Adherence-related sciences'). 'Adherence to medications' is the process by which patients take their medication as prescribed, further divided into three quantifiable phases: 'Initiation', 'Implementation' and 'Discontinuation'. In response to the proliferation of ambiguous or unquantifiable terms in the literature on medication adherence, this research has resulted in a new conceptual foundation for a transparent taxonomy. The terms and definitions are focused on promoting consistency and quantification in terminology and methods to aid in the conduct, analysis and interpretation of scientific studies of medication adherence.

Adherence, compliance and persistence to oral antineoplastic therapy: a review focused on chemotherapeutic and biologic agents

INTRODUCTION

To date, orally administered chemotherapy and biologic agents represent a significant percentage of all antineoplastic treatments in several types of cancer, which are most likely to increase in the near future. In this scenario, the issue of adherence and persistence to oral therapy is a key issue since poor compliance to oral antineoplastic treatments may negatively influence patients' clinical outcomes and, in turn, cause an increase in costs, number of hospitalizations and time spent in the hospital.

AREAS COVERED

The issue of adherence to new oral chemotherapeutic and/or biologic agents has not been deeply evaluated and data published in medical literature are quite scarce. Adherence is a multidimensional phenomenon, which may be influenced by patient- and health-care provider-related factors, anticancer therapy itself, education and socioeconomic aspects. Patients' selection plays, therefore, a key role in maximizing adherence and persistence to oral therapies. Treating health-care practitioners should first evaluate patient reliability to avoid prescribing oral treatments to patients with socioeconomic and medical conditions, which may predict poor adherence.

EXPERT OPINION

Adherence and persistence to new oral biologic agents, which are linked to several side effects and whose use is constantly widening, should represent a main endpoint of clinical research in the nearest future.

Does blood glucose monitoring increase prior to clinic visits in children with type 1 diabetes?

OBJECTIVE

To assess the occurrence of white coat adherence in families with children who have type 1 diabetes.

RESEARCH DESIGN AND METHODS

Blood glucose data were downloaded from meters of 72 children, aged 2-11 years, with type 1 diabetes at four consecutive clinic visits. Generalized estimating equations were used to analyze patterns of blood glucose monitoring (BGM) during the 28 days before each clinic visit.

RESULTS

More frequent BGM was associated with better glycemic control. Evidence of a white coat adherence effect, with BGM frequency increasing before a clinic visit, was found only among children with low A1C levels.

CONCLUSIONS

Highly motivated families who frequently monitor their child's blood glucose increased the frequency of BGM before the child's clinic visit. The additional monitoring may benefit the child by providing the physician with a wealth of blood glucose information to guide recommendations.

Compliance descriptors: analysis and evaluation in terms of therapeutic effect

The aim of this work was to evaluate the performance of various compliance parameters in order to identify those which best assess the impact of compliance on therapeutic issues. We will discuss the particularities and restrictions of these parameters by considering two criteria, namely sensitivity index and reliability, which respectively describe strength and robustness of the relationship between these parameters and compliance. Using real and virtual data, performance analysis of compliance parameters was carried out for drugs whose pharmacokinetic properties govern the time course of their actions. Within this context, it was found that the percentage of taken doses (PTD), the most widely used parameter, poorly performed in the evaluation of the therapeutic impact of compliance. On the other hand, the adjusted percentage of correct doses (PCD*) which we propose here, showed the best reliability, making it the most appropriate parameter for the comparison of different compliance patterns. The percentage of correct doses (PCD) has, in its turn, the highest sensitivity index and thus should be preferred for the assessment of changes in compliance. Hence, a perfect parameter for the evaluation of compliance impact cannot be universally identified since each parameter can have its own characteristic advantages and limitations. The methodology proposed here is general enough to be adapted for similar drug classes to evaluate their compliance descriptors.

Performance of Cpred/Cobs concentration ratios as a metric reflecting adherence to antidepressant drug therapy

BACKGROUND

Nonadherence is very common among subjects undergoing pharmacotherapy for schizophrenia and depression. This study aimed to evaluate the performance of the ratio of the nonlinear mixed effects pharmacokinetic model predicted concentration to observed drug concentration (ratio of population predicted to observed concentration (Cpred/Cobs) and ratio of individual predicted to observed concentration (Cipred/Cobs) as a measure of erratic drug exposure, driven primarily by variable execution of the dosage regimen and unknown true dosage history.

METHODS

Modeling and simulation approaches in conjunction with dosage history information from the Medication Event Monitoring System (MEMS, provided by the "Depression: The search for treatment relevant phenotypes" study), was applied to evaluate the consistency of exposure via simulation studies with scenarios representing a long half-life drug (escitalopram). Adherence rates were calculated based on the percentage of the prescribed doses actually taken correctly during the treatment window of interest. The association between Cpred/Cobs, Cipred/Cobs ratio, and adherence rate was evaluated under various assumptions of known dosing history.

RESULTS

Simulations for those scenarios representing a known dosing history were generated from historical MEMS data. Simulations of a long half-life drug exhibited a trend for overprediction of concentrations in patients with a low percentage of doses taken and underprediction of concentrations in patients taking more than their prescribed number of doses. Overall, the ratios did not predict adherence well, except when the true adherence rates were extremely high (greater than 100% of prescribed doses) or extremely low (complete nonadherence). In general, the Cipred/Cobs ratio was a better predictor of adherence rate than the Cpred/Cobs ratio. Correct predictions of extreme (high, low) 7-day adherence rates using Cipred/Cobs were 73.8% and 64.0%.

CONCLUSION

This simulation study demonstrated the limitations of the Cpred/obs and Cipred/obs ratios as metrics for actual dosage intake history, and identified that use of MEMS dosing history monitoring combined with sparse pharmacokinetic sampling is a more reliable approach.

Imatinib treatment in chronic myelogenous leukemia: What have we learned so far?

Imatinib mesylate is currently the standard therapy for chronic myelogenous leukemia patients. Despite the remarkable results achieved with imatinib, the emergence of resistance to this drug has become a significant problem. Actually, two other second-generation tyrosine kinase inhibitors have been used for resistant/intolerant patients to imatinib. With the availability of oral tyrosine kinase inhibitors for the treatment of chronic myelogenous leukemia, questions relating to adherence to prescribed therapy have become an important issue. It has been demonstrated that the effectiveness of the treatment with imatinib requires high compliance to the prescribed dose of the drug for an indefinite period of time, whereas reduced adherence to therapy has been associated with delay in achieving cytogenetic or molecular response and/or possible development of resistance. The aim of this review is to discuss the importance of adherence, and the possible tools that we have to measure it, to improve our knowledge on possible underlying causes of non-adherence and the impact of non-adherence on hospitalization risk and healthcare cost through a systematic review of the data published to date.

Compliance with inhalatory therapy: an increasingly recognized clinical outcome

Compliance with medications is one of the major issues encountered in medical practice in the treatment of many chronic diseases, as it represents the interface between the effectiveness of the drug regimen and management of the disease. Noncompliance with inhalatory therapy could be the leading cause of poor disease control and increased morbidity in conditions, such as asthma or chronic obstructive pulmonary disease. The strongest predictors of compliance are represented by the marital status, age and education of the patient, however, more research is needed in this field. Psychological factors are also known to play a role, as does the medication regimen. Assessment methods most commonly used for inhalatory therapy are self-reporting and canister weight but electronic diaries and electronic monitoring devices are more promising and reliable. Educational interventions and disease self-management plans are known to be effective in improving compliance but more specific strategies must be established. Special attention is required in children and the elderly since the compliance-related issues in these populations are more complex.

Interventions to improve adherence to lipid lowering medication

BACKGROUND

Lipid lowering drugs are still widely underused, despite compelling evidence about their effectiveness in the treatment and prevention of cardiovascular disease. Poor patient adherence to a medication regimen is a major factor in the lack of success in treating hyperlipidaemia. In this updated review we focus on interventions which encourage patients at risk of heart disease or stroke to take lipid lowering medication regularly.

OBJECTIVES

To assess the effects of interventions aimed at improved adherence to lipid lowering drugs, focusing on measures of adherence and clinical outcomes.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 1), MEDLINE, EMBASE, PsycINFO and CINAHL (March 2008). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of adherence-enhancing interventions for lipid lowering medication in adults for both primary and secondary prevention of cardiovascular disease in an ambulatory setting looking at adherence, serum lipid levels, adverse effects and health outcomes. Studies were selected independently by two review authors.

DATA COLLECTION AND ANALYSIS

Data were extracted and assessed by two review authors following criteria outlined by the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

Three additional studies were found in the update and, in total, 11 studies were included in this review. The studies included interventions that caused a change in adherence ranging from -3% to 25% (decrease in adherence by 3% to increase in adherence by 25%). Patient re-enforcement and reminding was the most promising category of interventions, investigated in six trials of which four showed improved adherent behaviour of statistical significance (absolute increase: 24%, 9%, 8% and 6%). Other interventions associated with increased adherence were simplification of the drug regimen (absolute increase 11%) and patient information and education (absolute increase 13%). The methodological and analytical quality of some studies was low and results have to be considered with caution.

AUTHORS' CONCLUSIONS

At this stage, reminding patients seems the most promising intervention to increase adherence to lipid lowering drugs. The lack of a gold standard method of measuring adherence is one major barrier in adherence research. More reliable data might be achieved by newer methods of measurement, more consistency in adherence assessment and longer duration of follow up. More recent studies have started using more reliable methods for data collection but follow-up periods remain too short. Increased patient-centredness with emphasis on the patient's perspective and shared decision-making might lead to more conclusive answers when searching for tools to encourage patients to take lipid lowering medication.

Unused medications at home — reasons and costs

Objectives

To examine types and quantities of unused medications in a sample of households and to investigate reasons for the unused medications and associated factors, including costs.

Method

A cross-sectional survey of a random sample of 931 households in the Songkhla province of Thailand. The households were visited and interviews were conducted with owners of unused medication using a structured questionnaire. Unused medications were collected, identified and quantified and their costs were calculated. Descriptive analysis of the type and amount of unused medications was conducted, including the characteristics of the owners and their reasons for having unused medications. Logistic regression analysis was used to examine factors associated with having unused medications.

Key findings

A total of 1,004 unused medication items were identified from 523 respondents who had unused medications. Oral dosage forms comprised 95.6% of all items, and totalled 14,297 doses. The median number of unused medications per household was 2. The most common therapeutic categories were musculoskeletal conditions, infections and the respiratory system. Thirty-seven per cent of all unused medications needed to be used continuously. The most frequently cited reason for having unused medications was that patients believed their symptoms or disease had resolved, and thus that the medications were no longer needed. Younger patients and those who had no chronic disease were more likely to cite this reason. The average cost of unused medications per household was 0.8 Euro.

Conclusions

This study has documented the types and quantities of unused medications and found that their costs were modest. Patients' perceptions of the need for, and effectiveness of, medication were the most frequent reasons for having unused medications. Age, gender and chronic disease were significantly associated with respondents' reported reasons for having unused medications.

Adherence to antiparkinson medication in a multicenter European study

Two small studies reported suboptimal therapy adherence in Parkinson's disease. We conducted a larger multicenter European study to assess medicine-taking behavior. Parkinson's disease patients taking dopaminergic therapy were enrolled in 8 centers in 5 countries, and disease severity and demographics recorded. Antiparkinson drug adherence was measured for 4 weeks using electronic monitoring bottles which record the date and time of cap opening (Aardex, Switzerland). One hundred twelve patients, mean age 65 years (standard deviation (SD) 10), with Parkinson's disease for 7.7 (SD 8.2) years completed the study. Total median adherence (doses taken/doses prescribed) was 97.7% (interquartile range [IQ] 90.6-100), days adherence (correct dose days) was 86.2% (IQ 61.1-96.2) and timing adherence (doses taken at correct time intervals) was 24.4% (IQ 5.3-56.5). Fourteen patients (12.5%) took less than 80% of prescribed doses, which was defined as suboptimal adherence. Patients with satisfactory adherence took a median of 8 mg/day (IQ 0-33) less than their prescribed dose of levodopa (P = NS), while suboptimal adherence patients took a median of 481 mg/day (IQ 205-670) less than their prescribed dose (P = 0.0006). The Parkinson motor score was significantly higher in patients with suboptimal adherence at 29 (IQ 20-40), versus those with satisfactory adherence at 19 (IQ 13-26), P = 0.005. Once daily drugs had significantly better adherence when compared with drugs prescribed more frequently (P < 0.0001). Suboptimal therapy adherence is associated with significant deviation from prescribed levodopa doses, despite greater Parkinson's motor severity. Optimizing oral medication intake has a potential role in maximizing the therapy response in Parkinson's disease.

Cost-related prescription nonadherence in the United States and Canada: a system-level comparison using the 2007 International Health Policy Survey in Seven Countries

BACKGROUND

Prior research indicates that residents of the United States are nearly twice as likely as Canadian residents to report cost-related nonadherence (CRNA) (ie, being unable to fill > or =1 prescription due to cost). However, these kinds of national comparisons obscure important within-country differences in insurance coverage.

OBJECTIVE

This study was designed to compare rates of CRNA across major financing systems for prescription drugs in the United States and Canada.

METHODS

This study used the 2007 International Health Policy Survey in Seven Countries (supported by the US Commonwealth Fund) to estimate rates of CRNA in the following health systems: Canadian compulsory coverage (Quebec), Canadian senior and social assistance coverage (Ontario), Canadian income-based coverage (British Columbia, Manitoba, and Saskatchewan), Canadian mixed coverage (all other provinces), US private coverage (employer-based or individual insurance), US senior and social assistance coverage (Medicare and/or Medicaid), and US no coverage (uninsured).

RESULTS

Adults in the United States were far more likely than adults in Canada to report CRNA (23.1% vs 8.0%; chi(2) = 147.4; P < 0.001). Seniors (> or =65 years of age) were less likely than younger adults (<65 years) to report CRNA in both the United States (9.2% vs 25.8%; chi(2) = 64.3; P < 0.001) and Canada (4.6% vs 8.7%; chi(2) = 14.9; P < 0.001), presumably due to categorical eligibility for prescription drug insurance. Comparative analyses therefore focused on working-age adults (<65 years). Adults in Quebec (who have compulsory drug coverage) were only half as likely as those in Ontario to report CRNA (odds ratio [OR] = 0.5; 95% CI, 0.3-0.8). Uninsured adults in the United States were >7 times as likely to report CRNA (OR =7.2; 95% CI, 5.0-10.5), and adults with public insurance (OR = 2.2; 95% CI, 1.4-3.5) and private insurance (OR = 2.2; 95% CI, 1.6-3.0) were >2 times as likely to report CRNA.

CONCLUSIONS

After stratifying by age and simultaneously adjusting for sex, household income, and chronic illness, large differences in CRNA were found between and within countries. Even in a compulsory prescription insurance system like that in Quebec, 4.4% of working-age adults reported CRNA. However, these rates were low compared with CRNA rates for working-age adults in the United States who lack any health insurance (43.3%).

The effect of reporting methods for dosing times on the estimation of pharmacokinetic parameters of escitalopram

The objective of this study was to compare population pharmacokinetic models of escitalopram developed from dosage times recorded by a medication event monitoring system (MEMS) versus the reported times from patients with diagnosed depression. Seventy-three patients were prescribed doses of 10, 15, or 20 mg escitalopram daily. Sparse blood samples were collected at weeks 4, 12, 24, and 36 with 185 blood samples obtained from the 73 patients. NONMEM was used to develop a population pharmacokinetic model based on dosing records obtained from MEMS prior to each blood sample time. A separate population pharmacokinetic analysis using NONMEM was performed for the same population using the patient-reported last dosing time and assuming a steady-state condition as the model input. Objective function values and goodness-of-fit plots were used as model selection criteria. The absolute mean difference in the last dosing time between MEMS and patient-reported times was 4.48 +/- 10.12 hours. A 1-compartment model with first-order absorption and elimination was sufficient for describing the data. Estimated oral clearance (CL/F) to escitalopram was statistically insensitive to reported dosing methods (MEMS vs patient reported: 25.5 [7.0%] vs 26.9 [6.6%] L/h). However, different dosing report methods resulted in significantly different estimates on the volume of distribution (V/F; MEMS vs patient reported: 1000 [17.3%] vs 767 [17.5%] L) and the absorption rate constant K(a) (MEMS vs patient reported: 0.74 [45.7%] vs 0.51 [35.4%] h(-1)) for escitalopram. Furthermore, the parameters estimated from the MEMS method were similar to literature reported values for V/F ( approximately 1100 L) and K(a) ( approximately 0.8-0.9 h(-1)) arising from traditional pharmacokinetic approaches.

Telemetric monitoring in the behavior sciences

This article reviews recent advances in telemetrics, a class of wireless information systems technology that can collect and transmit a wide variety of behavioral and environmental data remotely. Telemetrics include wearable computers that weave on-body sensors into articles of clothing, ubiquitous computers that embed sensors and transmitters seamlessly into the environment, and handheld devices, such as mobile phones and personal digital assistants, that can record cognitive and affective states. Examples of telemetric applications are provided to illustrate how this technology has been used in the behavioral sciences to unobtrusively and repeatedly gather physiological, behavioral, environmental, cognitive, and affective data in natural settings. Special issues relating to privacy and confidentiality, practical considerations, and statistical and measurement challenges when telemetrics are used are also discussed.

Bromide as marker for drug adherence in hypertensive patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Insufficient drug adherence is an important reason for inadequate blood pressure control. Currently, methods that measure drug adherence objectively are lacking. Objective methods are needed to help improve blood pressure control and outcome in hypertensive patients.

WHAT THIS STUDY ADDS

Potassium bromide added to antihypertensive drugs can be used to monitor drug adherence in individual patients. However, although this method is objective, it is rather time-, cost- and work-consuming. AIMS Adherence to antihypertensive medication is essential for adequate long-term control of blood pressure (BP). This study investigated different methods of measuring adherence in hypertensive patients.

METHODS

Patients were included if BP was insufficiently controlled on monotherapy. After a placebo period patients were treated with trandolapril 2 mg/verapamil SR 180 mg (TV). BP was determined using a mercury sphygmomanometer and ambulatory BP monitoring. Adherence was measured by capsule counting, electronic registration of pill-box openings and by measuring serum bromide concentrations. Potassium bromide was added to each TV capsule.

RESULTS

Thirty patients participated in the study. Treatment with TV significantly lowered office BP and ambulatory BP. Results for electronic monitoring and adherence based on bromide measurements were comparable. Adherence was slightly higher when assessed by capsule counting.

CONCLUSIONS

Measuring serum bromide concentrations may be suitable for assessment of adherence to drug therapy giving comparable results to electronic monitoring. Using capsule counting, electronic monitoring and measurement of bromide concentrations, nonadherent patients were identified.

Integrated pharmacokinetics and pharmacodynamics in drug development

Drug development is a complex, lengthy and expensive process. Pharmaceutical companies and regulatory authorities have recognised that the drug development process needs optimisation for efficiency in view of the return on investments. Pharmacokinetics and pharmacodynamics are the two main principles determining the relationship between dose and response. This article provides an update on integrated approaches towards drug development by linking pharmacokinetics, pharmacodynamics and disease aspects into mathematical models. Gradually, a transition is taking place from a rather empirical approach towards a modelling- and simulation-based approach to drug development. The main learning phases should be phases 0, I and II, whereas phase III studies should merely have a confirmatory purpose. In model-based drug development, mechanism-based mathematical models, which are iteratively refined along the path of development, incorporate the accumulating knowledge of the investigational drug, the disease and their mutual interference in different subsets of the target population. These models facilitate the design of the next study and improve the probability of achieving the projected efficacy and safety endpoints. In this article, several theoretical and practical aspects of an integrated approach towards drug development are discussed, together with some case studies from different therapeutic areas illustrating the application of pharmacokinetic/pharmacodynamic disease models at different stages of drug development.

Adherence to warfarin assessed by electronic pill caps, clinician assessment, and patient reports: results from the IN-RANGE study

BACKGROUND

Patient adherence to warfarin may influence anticoagulation control; yet, adherence among warfarin users has not been rigorously studied.

OBJECTIVE

Our goal was to quantify warfarin adherence over time and to compare electronic medication event monitoring systems (MEMS) cap measurements with both self-report and clinician assessment of patient adherence.

DESIGN

We performed a prospective cohort study of warfarin users at 3 Pennsylvania-based anticoagulation clinics and assessed pill-taking behaviors using MEMS caps, patient reports, and clinician assessments.

RESULTS

Among 145 participants, the mean percent of days of nonadherence by MEMS was 21.8% (standard deviation+/-21.1%). Participants were about 6 times more likely to take too few pills than to take extra pills (18.8 vs. 3.3%). Adherence changed over time, initially worsening over the first 6 months of monitoring, which was followed by improvement beyond 6 months. Although clinicians were statistically better than chance at correctly labeling a participant's adherence (odds ratio = 2.05, p = 0.015), their estimates often did not correlate with MEMS-cap data; clinicians judged participants to be "adherent" at 82.8% of visits that were categorized as moderately nonadherent using MEMS-cap data (>or=20% nonadherence days). Similarly, at visits when participants were moderately nonadherent by MEMS, they self-reported perfect adherence 77.9% of the time.

CONCLUSIONS

These results suggest that patients may benefit from adherence counseling even when they claim to be taking their warfarin or the clinician feels they are doing so, particularly several months into their course of therapy.

Adherence to topical therapy increases around the time of office visits

BACKGROUND

The efficacy of topical medications is limited by non-adherence. Interventions to improve adherence to topical treatments are not well characterized.

OBJECTIVE

To assess the impact of office visits on patients' adherence to topical treatment.

METHODS

Twenty-nine subjects enrolled in a clinical trial for psoriasis and were followed for up to 8 weeks. Subjects were told to apply 6% salicylic acid gel twice daily. Electronic monitors were used to assess adherence. Results were compared to adherence in clinical trials of hand dermatitis and atopic dermatitis.

RESULTS

Adherence rates were significantly higher around the time of office visits (P < .05).

LIMITATIONS

This is a small study in a limited patient population. The study was observational and not a randomized trial of the effect of increased office visits.

CONCLUSION

Frequent follow-up visits in clinical trials increase patients' adherence to medications. The use of a follow-up visit shortly after initiating treatment may be an effective way to boost patients' use of their medication and achieve better treatment outcomes.