Gender differences in drug toxicity

Sex-dimorphic adverse drug reactions to immune suppressive agents in inflammatory bowel disease

AIM: To analyze sex differences in adverse drug reactions (ADR) to the immune suppressive medication in inflammatory bowel disease (IBD) patients.

METHODS: All IBD patients attending the IBD outpatient clinic of a referral hospital were identified through the electronic diagnosis registration system. The electronic medical records of IBD patients were reviewed and the files of those patients who have used immune suppressive therapy for IBD, i.e., thiopurines, methotrexate, cyclosporine, tacrolimus and anti-tumor necrosis factor agents (anti-TNF); infliximab (IFX), adalimumab (ADA) and/or certolizumab, were further analyzed. The reported ADR to immune suppressive drugs were noted. The general definition of ADR used in clinical practice comprised the occurrence of the ADR in the temporal relationship with its disappearance upon discontinuation of the medication. Patients for whom the required information on drug use and ADR was not available in the electronic medical record and patients with only one registered contact and no further follow-up at the outpatient clinic were excluded. The difference in the incidence and type of ADR between male and female IBD patients were analyzed statistically by χ² test.

RESULTS: In total, 1009 IBD patients were identified in the electronic diagnosis registration system. Out of these 1009 patients, 843 patients were eligible for further analysis. There were 386 males (46%), mean age 42 years (range: 16-87 years) with a mean duration of the disease of 14 years (range: 0-54 years); 578 patients with Crohn’s disease, 244 with ulcerative colitis and 21 with unclassified colitis. Seventy percent (586 pts) of patients used any kind of immune suppressive agents at a certain point of the disease course, the majority of the patients (546 pts, 65%) used thiopurines, 176 pts (21%) methotrexate, 46 pts (5%) cyclosporine and one patient tacrolimus. One third (240 pts, 28%) of patients were treated with anti-TNF, the majority of patients (227 pts, 27%) used IFX, 99 (12%) used ADA and five patients certolizumab. There were no differences between male and female patients in the use of immune suppressive agents. With regards to ADR, no differences between males and females were observed in the incidence of ADR to thiopurines, methotrexate and cyclosporine. Among 77 pts who developed ADR to one or more anti-TNF agents, significantly more females (54 pts, 39% of all anti-TNF treated women) than males (23 pts, 23% of all anti-TNF treated men) experienced ADR to an anti-TNF agent [P = 0.011; odds ratio (OR) 2.2, 95%CI 1.2-3.8]. The most frequent ADR to both anti-TNF agents, IFX and ADA, were allergic reactions (15% of all IFX users and 7% of all patients treated with ADA) and for both agents a significantly higher rate of allergic reactions in females compared with males was observed. As a result of ADR, 36 patients (15% of all patients using anti-TNF) stopped the treatment, with significantly higher stopping rate among females (27 females, 19% vs 9 males, 9%, P = 0.024).

CONCLUSION: Treatment with anti-TNF antibodies is accompanied by sexual dimorphic profile of ADR with female patients being more at risk for allergic reactions and subsequent discontinuation of the treatment.

Toxicogenomic analysis suggests chemical-induced sexual dimorphism in the expression of metabolic genes in zebrafish liver

Differential gene expression in two sexes is widespread throughout the animal kingdom, giving rise to sex-dimorphic gene activities and sex-dependent adaptability to environmental cues, diets, growth and development as well as susceptibility to diseases. Here, we present a study using a toxicogenomic approach to investigate metabolic genes that show sex-dimorphic expression in the zebrafish liver triggered by several chemicals. Our analysis revealed that, besides the known genes for xenobiotic metabolism, many functionally diverse metabolic genes, such as ELOVL fatty acid elongase, DNA-directed RNA polymerase, and hydroxysteroid dehydrogenase, were also sex-dimorphic in their response to chemical treatments. Moreover, sex-dimorphic responses were also observed at the pathway level. Pathways belonging to xenobiotic metabolism, lipid metabolism, and nucleotide metabolism were enriched with sex-dimorphically expressed genes. We also observed temporal differences of the sex-dimorphic responses, suggesting that both genes and pathways are differently correlated during different periods of chemical perturbation. The ubiquity of sex-dimorphic activities at different biological hierarchies indicate the importance and the need of considering the sex factor in many areas of biological researches, especially in toxicology and pathology.

Evaluation of demographic factors that influence acute radiation response

Casualty estimation tools are critical in planning for nuclear event scenarios. Current consequence assessment models based on healthy adult males may not adequately represent the population. To develop an understanding of the impact of demographic variables on casualty estimates, human data was surveyed to identify key demographic factors that affect acute radiation response. Information on in utero exposures, gender, age, and comorbidity status was collected from atomic bomb survivors, radiation accidents, and clinical oncology. Burn and trauma studies were also examined to gain insight into the impact of demographic variables on acute injury outcomes. Fetal radiation sensitivity is well documented; increased mortality or malformations are observed depending on gestational age. A greater incidence of radiation syndrome was observed among male atomic bomb survivors. Trauma data show increased mortality in males, apparently due to immunological differences between genders. Limited data suggest vulnerability in the very young and old due to immunological status and comorbidities, respectively. Certain genetically susceptible subpopulations demonstrate marked increased sensitivity to radiation exposure. Interaction of radiation and comorbid conditions has not been well studied; however, burn and trauma data indicate that comorbidities negatively impact response to acute injury. Key factors evaluated together with their prevalence indicate the importance of modeling demographic variability in casualty estimations. Also they can help identify vulnerable subpopulations and provide insight on treatment requirements.

Sex Differences in the Expression of Drug-Metabolizing and Transporter Genes in Human Liver

Human sex differences in the gene expression of drug metabolizing enzymes and transporters (DMETs) introduce differences in drug absorption, distribution, metabolism and excretion, possibly affecting drug efficacy and adverse reactions. However, existing studies aimed at identifying dimorphic expression differences of DMET genes are limited by sample size and the number of genes profiled. Focusing on a list of 374 DMET genes, we analyzed a previously published gene expression data set consisting of human male (n=234) and female (n=193) liver samples, and identified 77 genes showing differential expression due to sex. To delineate the biological functionalities and regulatory mechanisms for the differentially expressed DMET genes, we conducted a co-expression network analysis. Moreover, clinical implications of sex differences in the expression of human hepatic DMETs are discussed. This study may contribute to the realization of personalized medicine by better understanding the inter-individual differences between males and females in drug/xenobiotic responses and human disease susceptibilities.

The intersection of neurotoxicology and endocrine disruption

Endocrine disruption, the guiding theme of the 27th International Neurotoxicology Conference, merged into the neurotoxicology agenda largely because hormones help steer the process of brain development. Although the disruption motif first attracted public health attention because of reproductive anomalies in both wildlife and humans, the neurobehavioral implications had been planted decades earlier. They stemmed from the principle that sex differences in behavior are primarily the outcomes of differences in how the brain is sexually differentiated during early development by gonadal hormones (the Organizational Hypothesis). We also now understand that environmental chemicals are capable of altering these underlying events and processes. Among those chemicals, the group labeled as endocrine disrupting chemicals (EDCs) offers the clearest evidence of such selectivity, a consequence of their actions on the endogenous sex steroids, androgens and estrogens. Two EDCs in particular offer useful and intriguing examples. One is phthalate esters. The other is bisphenol A. Both agents are used extensively in plastics manufacture, and are pervasive in the environment. Both are produced in immense quantities. Both are found in almost all humans. Phthalates are considered to function in essence as anti-androgens, while bisphenol A is labeled as an estrogen. Their associations with brain sexual differentiation are reviewed and further questions noted. Both EDCs produce a wider spectrum of health effects, however, than would be extrapolated simply from their properties as anti-androgens and estrogens. Obesity is one example. Further complicating their assessment as health risks are questions about nonmonotonic dose-response functions and about transgenerational effects incurred via epigenetic mechanisms. All these facets of endocrine disruption are pieces of a puzzle that challenge neurotoxicologists for solutions.

Prevalence of Drug Resistance and Associated Mutations in a Population of HIV-1(+) Puerto Ricans: 2006-2010

This is a continuation of our efforts to maintain a record of the evolution of HIV-1 infection in Puerto Rico by monitoring the expression levels of antiretroviral drug-resistance-associated mutations. Samples from 2,500 patients from 2006–2010 were analyzed using the TruGene HIV-1 genotyping kit and the OpenGene DNA sequencing system. Results show that 58.8% of males and 65.3% of females had HIV-1 with resistance to at least one medication. The average number of HIV mutations was 6.0 in males and 6.1 in females. Statistically significant differences between men and women were recorded in the levels of HIV-1 expressed mutations and antiretroviral drug resistance. The most prevalent antiretroviral medication resistance shifted from zalcitabine to nevirapine and efavirenz in the five-year period. M184V and L63P were the dominant mutations for the reverse transcriptase and the protease genes, respectively, but an increase in the incidence of minority mutations was observed.

Human pluripotent stem cells for modeling toxicity

The development of xenobiotics, driven by the demand for therapeutic, domestic and industrial uses continues to grow. However, along with this increasing demand is the risk of xenobiotic-induced toxicity. Currently, safety screening of xenobiotics uses a plethora of animal and in vitro model systems which have over the decades proven useful during compound development and for application in mechanistic studies of xenobiotic-induced toxicity. However, these assessments have proven to be animal-intensive and costly. More importantly, the prevalence of xenobiotic-induced toxicity is still significantly high, causing patient morbidity and mortality, and a costly impediment during drug development. This suggests that the current models for drug safety screening are not reliable in toxicity prediction, and the results not easily translatable to the clinic due to insensitive assays that do not recapitulate fully the complex phenotype of a functional cell type in vivo. Recent advances in the field of stem cell research have potentially allowed for a readily available source of metabolically competent cells for toxicity studies, derived using human pluripotent stem cells harnessed from embryos or reprogrammed from mature somatic cells. Pluripotent stem cell-derived cell types also allow for potential disease modeling in vitro for the purposes of drug toxicology and safety pharmacology, making this model possibly more predictive of drug toxicity compared with existing models. This article will review the advances and challenges of using human pluripotent stem cells for modeling metabolism and toxicity, and offer some perspectives as to where its future may lie.

Gene, ethnic and gender influences predisposition of adverse drug reactions to artesunate among Malaysians

CONTEXT

Artesunate (AS) and amodiaquine (AQ) are two prodrugs widely used as antimalarial agents and are metabolized by the CYP P450 2A6 (CYP 2A6) and CYP P450 2C8 (CYP 2C8) enzymes, respectively.

OBJECTIVE

In this study, we aim to investigate the association of both genes on AS and AQ's tolerabilities in the hope of identifying a pharmacogenetic approach that could be useful in prediction and prevention of adverse drug reactions (ADRs) among Malaysian population.

MATERIALS AND METHODS

In this randomized crossover study, loose and AS/AQ formulations were administered to normal healthy volunteers (n = 24) over two study phases. The drugs' tolerabilities (incidence of facial flushing, giddiness, headache, nausea, abdominal discomfort, progression of liver enzymes and neutrophil counts) were compared between the two treatment arms. Volunteers were also genotyped for the CYP2C8 and CYP2A6 variants.

RESULTS

The frequency of the CYP2A6*1B, CYP2A6*4, CYP2A6*8 and CYP2A6*9 alleles were 54.2%, 16.7%, 4.2% and 10.4%, respectively. No mutations for CYP2C8 gene were, however, detected. Most (96%) of the subjects were of the Malay ethnicity. Subjects having the CYP2A6*1B variants responsible for ultra rapid metabolism of AS suffered a significantly higher incidence of ADRs.

DISCUSSION

Our study is the first to report that CYP2A6 genotyping influences AS's ADR. Gender also plays a role where females reported more incidences of nausea (p < 0.05).

CONCLUSION

It is concluded that genetic polymorphisms of CYP2A6 as well as gender influence the side effect profiles of subjects receiving AS among this Malaysian population.

Gender and manganese exposure interactions on mouse striatal neuron morphology

Gender differences in sensitivity and toxicokinetics of multiple metals have been identified in humans. A recent study suggested that young girls performed worse on intellectual exams than young boys exposed to manganese (Mn) in the environment. Animal studies have shown that Mn exposure causes differential effects on behavior in male compared to female mice. We hypothesized that in response to Mn exposure striatal Mn accumulation and/or striatal medium spiny neuron (MSN) morphology show gender-dependent effects. We evaluated the contribution of gender to neuropathology by examining striatal MSN morphology in male and female mice exposed to Mn. We found that gender played a significant role in alterations of striatal MSN morphology in mice exposed to Mn. Gender-dependent changes were strongest when striatal Mn levels were elevated 24h following the final Mn exposure. Nevertheless, gender-dependent alterations in neuron morphology were still present 3 weeks after the final Mn exposure. Gender differences in neuron morphology were not due to differential striatal Mn accumulation between genders. We conclude that although gender does not affect striatal Mn accumulation, MSN morphology is differentially sensitive to elevated Mn levels.

Gender-related differences on P-glycoprotein-mediated drug intestinal transport in rats

Objectives

Evidence of sex-related differences on drug pharmacokinetics and pharmacodynamics are markedly increasing. The aim of this study was to characterize the influence of gender on P-glycoprotein (P-gp)-mediated drug intestinal transport using two ex-vivo methodological approaches.

Methods

To study the comparative tissue uptake of ivermectin, intestinal sacs (distal jejunum/ileum) of male and female Wistar rats were incubated with ivermectin (0.5 µm) (a P-gp substrate) in the presence or absence of PSC833 (10 µm) (a P-gp inhibitor). Additionally, sex-based differences in the bidirectional transport of Rhodamine 123 (Rho 123; 5 µm) incubated either alone or with PSC833 (10 µm) were examined in diffusion chambers.

Key findings

The ivermectin accumulation in the everted gut sacs was higher in female compared with male intestine. The presence of PSC833 increased ivermectin accumulation profiles both in male and female rats. However, a greater response to transport modulation was observed in male compared with female animals. Similar results were obtained for Rho 123, where a higher absorption was measured in the intestine of females. PSC833 decreased Rho 123 intestinal secretion in animals of both sexes with a greater inhibition in male.

Conclusions

Substantial sex-related differences were observed on the ivermectin and Rho 123 active intestinal transport. Likewise, the PSC833-mediated modulation had a differential impact between male and female animals. Further work is needed to clarify the mechanisms underlying this phenomenon, which may have considerable pharmacological and clinical relevance.

Sex-related differences in hospital admissions attributed to adverse drug reactions in the Netherlands

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Women are more at risk for developing adverse drug reactions (ADRs) due to differences in pharmacokinetics, pharmacodynamics and drug use. ADRs regularly lead to hospital admissions.

WHAT THIS STUDY ADDS

There are differences between the sexes in hospital admissions attributed to ADRs. The risk of being hospitalized with an ADR varies between the sexes in the type of reaction and the causative drug.

AIM

Adverse drug reactions (ADRs) are a major burden in health care, regularly leading to hospital admission, morbidity or death. Women tend to have a higher risk of adverse drug reactions with a 1.5 to 1.7-fold greater risk than men. Our primary aim was to study differences in ADR-related hospitalizations between the sexes.

METHODS

We conducted a nationwide study of all ADR-related hospitalizations in the period between 2000 and 2005 in the Netherlands, which were selected from all 9,287,162 hospital admissions in this period. ADR-drug group combinations with at least 50 admissions in one of the sexes were selected. Relative risks and confidence intervals were calculated with respect to total admissions and total prescriptions with men as reference.

RESULTS

In total, 0.41% of the 4,236,368 admissions in men (95% CI 0.40, 0.42%) and 0.47% of the 5,050,794 admissions in women (95% CI 0.46, 0.48%) were attributed to an ADR by medical specialists (57% of all ADR-related admissions were in women). Differences between the sexes in risk for ADR-related hospitalization were found for antineoplastic and immunosuppressive drugs, antirheumatics, anticoagulants and salicylates, cardiovascular and neurological drugs, steroids and antibiotics. In certain drug categories, risks for hospitalization changed after taking into account total drug prescriptions.

CONCLUSION

In all different drug classes, significant differences exist between the sexes in ADR-related hospital admissions. Cardiovascular drugs account for the most pronounced differences between men and women. More research is needed to explain the clear sex differences in ADR-related hospital admissions.

Sex differences in drug disposition

Physiological, hormonal, and genetic differences between males and females affect the prevalence, incidence, and severity of diseases and responses to therapy. Understanding these differences is important for designing safe and effective treatments. This paper summarizes sex differences that impact drug disposition and includes a general comparison of clinical pharmacology as it applies to men and women.