Digging up the human genome: current progress in deciphering adverse drug reactions

The Transporter-Mediated Cellular Uptake and Efflux of Pharmaceutical Drugs and Biotechnology Products: How and Why Phospholipid Bilayer Transport Is Negligible in Real Biomembranes

Over the years, my colleagues and I have come to realise that the likelihood of pharmaceutical drugs being able to diffuse through whatever unhindered phospholipid bilayer may exist in intact biological membranes in vivo is vanishingly low. This is because (i) most real biomembranes are mostly protein, not lipid, (ii) unlike purely lipid bilayers that can form transient aqueous channels, the high concentrations of proteins serve to stop such activity, (iii) natural evolution long ago selected against transport methods that just let any undesirable products enter a cell, (iv) transporters have now been identified for all kinds of molecules (even water) that were once thought not to require them, (v) many experiments show a massive variation in the uptake of drugs between different cells, tissues, and organisms, that cannot be explained if lipid bilayer transport is significant or if efflux were the only differentiator, and (vi) many experiments that manipulate the expression level of individual transporters as an independent variable demonstrate their role in drug and nutrient uptake (including in cytotoxicity or adverse drug reactions). This makes such transporters valuable both as a means of targeting drugs (not least anti-infectives) to selected cells or tissues and also as drug targets. The same considerations apply to the exploitation of substrate uptake and product efflux transporters in biotechnology. We are also beginning to recognise that transporters are more promiscuous, and antiporter activity is much more widespread, than had been realised, and that such processes are adaptive (i.e., were selected by natural evolution). The purpose of the present review is to summarise the above, and to rehearse and update readers on recent developments. These developments lead us to retain and indeed to strengthen our contention that for transmembrane pharmaceutical drug transport "phospholipid bilayer transport is negligible".

Adverse Reactions to Medications: Concept Analysis and Development of a New Risk Nursing Diagnosis

PURPOSE

To analyze the concept of adverse reaction to medications and to develop the new nursing diagnosis Risk for Adverse Reactions to Medications.

METHODS

Concept analysis using Walker and Avant's eight step method.

FINDINGS

Thirty-three articles indexed in four databases were included. The components of the new nursing diagnosis were determined, including possible nursing outcomes and interventions.

CONCLUSIONS

The concept analysis supported the development of the new nursing diagnosis Risk for Adverse Reactions to Medications, which may help nurses to evaluate and identify patients susceptible to adverse reactions.

IMPLICATIONS FOR NURSING PRACTICE

The establishment of this nursing diagnosis will provide nurses an opportunity to implement interventions to anticipate and effectively intervene with patients at risk for this condition.

Pharmacogenomics of Medications Commonly Used in the Intensive Care Unit

In the intensive care unit (ICU) setting, where highly variable and insufficient drug efficacies, as well as frequent and unpredictable adverse drug reactions (ADRs) occur, pharmacogenomics (PGx) offers an opportunity to improve health outcomes. However, PGx has not been fully evaluated in the ICU, partly due to lack of knowledge of how genetic markers may affect drug therapy. To fill in this gap, we conducted a review to summarize the PGx information for the medications commonly encountered in the ICU.

HLA Alleles and CYP2C9*3 as Predictors of Phenytoin Hypersensitivity in East Asians

To develop a pre-emptive genetic test that comprises multiple predisposing alleles for the prevention of phenytoin-related severe cutaneous adverse reactions (SCARs), three sets of patients with phenytoin-SCAR and drug-tolerant controls from Taiwan, Thailand, and Japan, were enrolled for this study. In addition to cytochrome P450 (CYP)2C9*3, we found that HLA-B*13:01, HLA-B*15:02, and HLA-B*51:01 were significantly associated with phenytoin hypersensitivity with distinct phenotypic specificities. Strikingly, we showed an increase in predictive sensitivity of concurrently testing CYP2C9*3/HLA-B*13:01/HLA-B*15:02/HLA-B*51:01 from 30.5-71.9% for selecting the individuals with the risk of developing phenytoin-SCAR in Taiwanese cohorts, accompanied by a specificity of 77.7% (combined sensitivity, 64.7%; specificity, 71.9% for three Asian populations). Meta-analysis of the four combined risk alleles showed significant associations with phenytoin-SCAR in three Asian populations. In conclusion, combining the assessment of risk alleles of HLA and CYP2C9 potentiated the usefulness of predictive genetic tests to prevent phenytoin hypersensitivity in Asians.

Epigenetic mechanisms of importance for drug treatment

There are pronounced interindividual variations in drug metabolism, drug responses, and the incidence of adverse drug reactions. To a certain extent such variability can be explained by genetic factors, but epigenetic modifications, which are relatively scarcely described so far, also contribute. It is known that a novel class of drugs termed epidrugs intervene in the epigenetic control of gene expression, and many of these are now in clinical trials for disease treatment. In addition, disease prognosis and drug treatment success can be monitored using epigenetic biomarkers. Here we review these novel aspects in pharmacology and address intriguing future opportunities for gene-specific epigenetic editing.