Male/Female Differences in Pharmacology: Safety Issues with QT-Prolonging Drugs

Using a Model to Design Activity-Based Educational Experiences to Improve Cultural Competency among Graduate Students

To improve the cultural competency of 34 students participating in graduate nutrition counseling classes, the Campinha-Bacote Model of Cultural Competence in the Delivery of Health Care Services was used to design, implement, and evaluate counseling classes. Each assignment and activity addressed one or more of the five constructs of the model, i.e., knowledge, skill, desire, encounters, and awareness. A repeated measure ANOVA evaluated pre- and post-test cultural competence scores (Inventory for Assessing the Process of Cultural Competence among Healthcare Professionals). The overall cultural competence score significantly improved (p < 0.001) from "culturally aware" (68.7 at pre-test) to "culturally competent" (78.7 at post-test). Students significantly improved (p < 0.001) in four constructs of the model including awareness, knowledge, skill, and encounter. Factor analysis indicated that course activities accounted for 83.2% and course assignments accounted for 74.6% of the total variance of cultural competence. An activity-based counseling course encouraging self-evaluation and reflection and addressing Model constructs significantly improved the cultural competence of students. As class activities and assignments aligned well with the Campinha-Bacote Model constructs, the findings of this study can help guide health educators to design effective cultural competence training and education programs.

The GENDER ATTENTION Observational Study: Gender and Hormonal Status Differences in the Incidence of Adverse Events During Cyclosporine Treatment in Psoriatic Patients

Introduction

Female sex has been shown to be a risk factor for the development of adverse drug reactions; however, this has not been studied for cyclosporine (CsA). The aim of this study was to investigate, in Italian dermatological practice, the influence of gender and menopause and related hormones on the incidence of adverse events (AEs) during CsA treatment in psoriatic patients.

Methods

Multicenter, prospective, observational study conducted from May 2011 to June 2013. Patients with plaque psoriasis, undergoing a new CsA administration course, or about to start it, were enrolled in the outpatient clinics of Italian dermatological centers. During the 2–6 months of study duration, patients had to note all AEs that occurred in a diary that was reviewed by the investigators at the follow-up visit. Sex hormone levels were measured within 7 days from the start date of a menstrual cycle.

Results

A total of 969 adult psoriatic patients were enrolled in the study, divided into four cohorts: fertile women and corresponding age-matched men; postmenopausal women and corresponding age-matched men. A significant difference in the percentage of patients with AEs was observed between fertile and postmenopausal women, but not between women and age-matched men. AE incidence rate was about 37% higher in fertile women than in age-matched men and about 18% higher in postmenopausal women than in age-matched men, but differences were not statistically significant. Incidence rate ratio of fertile vs. postmenopausal women was 0.67, reaching statistical significance. AEs were mild or moderate in severity in the great majority of patients of all cohorts and postmenopausal women had significantly less grade 1–2 AEs compared to fertile women, but more grade 3–4 AEs. FSH levels were significantly higher in postmenopausal women reporting no AEs, and DHEA sulfate levels were about 10% higher in men with no AEs, compared to those reporting at least one AE. Cortisol levels were slightly though significantly higher in postmenopausal women with no AE.

Conclusions

A better understanding of sex- and hormone-related influences on drug responses may help to improve drug safety and efficacy, by permitting one to tailor pharmacological treatments to individual subjects or defined patient cohorts.

Funding

Novartis Farma S.p.A., Italy.

Racial susceptibility for QT prolongation in acute drug overdoses

BACKGROUND AND PURPOSE

QT prolongation independently predicts adverse cardiovascular events in suspected poisoning. We aimed to evaluate the association between race and drug-induced QT prolongation for patients with acute overdose.

METHODS

This was a cross-sectional observational study at two urban teaching hospitals. Consecutive adult ED patients with acute drug overdose were prospectively enrolled over a two year period. The primary outcome, long-QT, was defined using standard criteria: QTc>470 ms in females and>460 ms in males. The association between race and drug-induced QT prolongation was tested, considering several confounding variables.

RESULTS

In 472 patients analyzed (46% female, mean age 42.3), QT prolongation occurred in 12.7%. Blacks had two-fold increased odds of drug-induced QT prolongation (OR 2.01, CI 1.03-3.91) and Hispanics had 48% decreased odds of drug-induced QT prolongation (OR 0.52, CI 0.29-0.94).

CONCLUSIONS

We found significant racial susceptibility to drug-induced QT prolongation in this large urban study of acute overdoses.

Sex differences in drug effects: interaction with sex hormones in adult life

In recent years, it has become clear that women and men may differ for drug response. Also, there is an increasing recognition on the role of sex hormones on pharmacokinetics and pharmacodynamics as mechanism accounting for sex differences in drug effects.In women, the phases of menstrual cycle, of reproductive life and fluctuations in the concentrations of sexual steroids on pharmacokinetics and pharmacodynamics must be considered. Furthermore, the use of oral contraceptives or hormonal replacement therapy, the sex hormone-related changes in total body water or in the amount of fat influence the overall effect of drugs.On the contrary, the influence of androgens on drug effects is minimal because of the even plasma levels of these hormones in adult males.Nevertheless, since women have been scarcely included in the early phases of clinical trials, the results obtained in men have been often translated to women and their exact response to drugs is still not well known.The available evidence suggests that sex hormones influence drug absorption, distribution, metabolism, pharmacodynamics, and adverse effects. For instance, many cardiovascular drugs are metabolized by enzymes of the cytochrome P450 mono-oxygenases system, which is more expressed in females than in males, showing sex differences in drug response.Upcoming pharmacological research should aim to further clarify the influence of sex hormones on drug effects and, for this purpose, to increase the number of women enrolled in all phases of clinical trials. An evidence-based pharmacotherapy in women is therefore auspicable for women's health.

[Sex differences in cardiovascular drug targeting]

Women and men differ in drug needs and drug metabolism. Usually women are smaller and lighter and have a higher body fat percentage and lower kidney function. Primary drug-metabolizing enzymes in the intestinal wall and liver, which are part of the cytochrome P450 family, have different activities in men and women. Their substrates (beta-blockers, blockers of calcium channels such as nifedipine and verapamil, cyclosporine, and many others) are metabolized differently. Sex differences were observed after administration of digitalis, which is often overdosed in women. Furthermore, beta-blockers are found at higher plasma levels in women and ACE inhibitors cause more side effects in women than in men. In women, acetylsalicylic acid provides effective primary prophylaxis against stroke but not myocardial infarction. In men, these drugs have opposite effects. Anticoagulants and thrombolytics often lead to bleeding complications in women, QT prolonging drugs produce more frequently arrhythmia. It is therefore very important to control drugs following approval and to look out for these differences between men and women.

Sex and the cardiovascular system: the intriguing tale of how women and men regulate cardiovascular function differently

The ability to recognize and appreciate from a reproductive standpoint that males and females possess different attributes has been long standing. Only more recently have we begun to look more deeply into both the similarities and differences between men and women, as well as between boys and girls, with respect to the structure and function of other organ systems. This article focuses on the cardiovascular system, with examples of sex differences in the control of coronary function, blood pressure, and volume. Recognizing the differences between the sexes with respect to cardiovascular function facilitates understanding of the mechanisms whereby homeostasis can be achieved using different contributions or components of the living system. Furthermore, recognition of the differences as well as the similarities permits the design of appropriate diagnostic instruments, recognition of sex-specific pathophysiology, and implementation of appropriate treatment of cardiovascular disease in men and women.

Therapeutic implications of the gender-specific aspects of cardiovascular disease

The manifestations of cardiovascular diseases differ between men and women, as do outcomes after therapeutic interventions. It is important that those involved in drug discovery and development, as well as disease treatment, are aware of these differences because such variations are likely to have an increasing role in therapeutic decisions in the future. Here, I review gender differences in the most frequent cardiovascular diseases and their underlying sex-dependent molecular pathophysiology, and discuss gender-specific effects of current cardiovascular drugs and the implications for novel strategies for drug development.

Pharmacokinetic-pharmacodynamic modeling in the data analysis and interpretation of drug-induced QT/QTc prolongation

In this review, factors affecting the QT interval and the methods that are currently in use in the analysis of drug effects on the QT interval duration are overviewed with the emphasis on (population) pharmacokinetic-pharmacodynamic (PK-PD) modeling. Among which the heart rate (HR) and the circadian rhythm are most important since they may interfere with the drug effect and need to be taken into account in the data analysis. The HR effect or the RR interval (the distance between 2 consecutive R peaks) effect is commonly eliminated before any further analysis, and many formulae have been suggested to correct QT intervals for changes in RR intervals. The most often used are Bazett and Fridericia formulae introduced in 1920. They are both based on the power function and differ in the exponent parameter. However, both assume the same exponent for different individuals. More recent findings do not confirm this assumption, and individualized correction is necessary to avoid under- or overcorrection that may lead to artificial observations of drug-induced QT interval prolongation. Despite the fact that circadian rhythm in QT and QTc intervals is a well-documented phenomenon, it is usually overlooked when drug effects are evaluated. This may result in a false-positive outcome of the analysis as the QTc peak due to the circadian rhythm may coincide with the peak of the drug plasma concentration. In view of these effects interfering with a potential drug effect on the QTc interval and having in mind low precision of QT interval measurements, a preferable way to evaluate the drug effect is to apply a population PK-PD modeling. In the literature, however, there are only a few publications in which population PK-PD modeling is applied to QT interval prolongation data, and they all refer to antiarrhythmic agents. In this review, after the most important sources of variability are outlined, a comprehensive population PK-PD model is presented that incorporates an individualized QT interval correction, a circadian rhythm in the individually corrected QT intervals, and a drug effect. The model application is illustrated using real data obtained with 2 compounds differing in their QT interval prolongation potential. The usefulness of combining data of several studies is stressed. Finally, the standard approach based on the raw observations and formal statistics, as described in the Preliminary Concept paper of the International Conference on Harmonization, is briefly compared with the method based on population PK-PD modeling, and the advantages of the latter are outlined.