How pharmacogenomics (PG) are changing practice: implications for prescribers, their patients, and the healthcare system (PG series part I)

Variability of Pharmacogenomics Information in Drug Labels Approved by Different Agencies and Its Ethical Implications

AIMS

The aim of this study was to determine if there are discrepancies among various agency-approved labels for the same active ingredient and where the labels approved by the Turkish Medicines and Medical Devices Agency (TMMDA) stand regarding the inclusion of PGx and discuss these ethical implications.

BACKGROUND

The efficacy and safety of drugs can be improved by rational prescription and personalization of medicine for each patient. Pharmacogenomics information (PGx) in drug labels (DL) is one of the important tools for the personalization of medications because genetic differences may affect both drug efficacy and safety. Providing adequate PGx to patients has ethical implications.

OBJECTIVE

To evaluate PGx in the DLs approved by TMMDA and other national agencies provided by the Pharmacogenomics Knowledgebase.

METHODS

DL annotations from the Pharmacogenomics Knowledgebase and DLs approved by the TMMDA were analyzed according to information and action levels, which are "testing required", "testing recommended", "actionable", and "informative".

RESULTS

There are 381 drugs listed in PharmGKB drug label annotations with pharmacogenomics information and 278 of these have biomarkers. A total of 242 (63.5%) drugs are approved and available in Turkey. Of these, 207 (85.5%) contain the same information as in or similar to that in the labels approved by the other agencies. The presence and level of information varied among the DLs approved by different agencies. The inconsistencies may have an important effect on the efficacy and the safety of drugs.

CONCLUSION

These findings suggest a need for the standardization of PGx information globally because it may not only affect the efficacy and safety of medications but also essential ethical rules regarding patient rights by violating not sufficiently sharing all available information.

Charting and Handling Genetic Test Results: How They Differ From Most Laboratory Results

Genetic tests, unlike most other laboratory tests, are trait rather than state tests. That means the results almost always stay the same. Exceptions to this rule are discussed in this column. Trait tests require documentation in such a way that they are not buried in the chart and forgotten, as usually happens with state (or point-in-time tests) such as serum potassium levels. Genetic test results and their implications should be explained to the patient in as much detail as possible and also shared and discussed with all health care providers treating the patient. This column explains the rationale for and the means to accomplish the goals of optimally charting and disseminating the results of such tests.

Knowledge of the Pharmacology of Antidepressants and Antipsychotics Yields Results Comparable With Pharmacogenetic Testing

Several companies offer pharmacogenetic testing for psychiatry on the basis of the claim that the outcome of drug selection is better when guided by such testing than when such testing is not used. This column examines the results of the GeneSight Psychotropic Test which groups various antidepressants and antipsychotics into 3 bins: green ("use as directed"), yellow ("use with caution"), and red ("use with increased caution and more frequent monitoring"). The authors examined how frequently the same drugs appeared in these different bins in 19 patients. They found that of the 22 antidepressants evaluated, 2 were virtually always (>90%) in the green bin: desvenlafaxine and levomilnacipran; and 8 were almost never (≤10.5%) in the green bin: citalopram, duloxetine, escitalopram, fluoxetine, fluvoxamine, mirtazapine, paroxetine, and sertraline. Of the 16 antipsychotics evaluated, they found that 4 were virtually always (>90%) in the green bin: asenapine, lurasidone, paliperidone, and ziprasidone; and 2 were almost never (≤10.5%) in the green bin: chlorpromazine and thioridazine. What was common among those drugs almost always in the green bin versus those almost never in the green bin were newer versus older marketed drugs and those not dependent versus dependent on oxidative metabolism for their clearance. The authors concluded that the results of this pharmacogenetic testing could be predicted on the basis of knowledge of the pharmacology of the drugs, particularly whether their clearance was dependent on oxidative drug metabolism.

Prediction of individual response to antidepressants and antipsychotics: an integrated concept

In both clinical trials and daily practice, there can be substantial inter- and even intraindividual variability in response--whether beneficial or adverse--to antidepressants and antipsychotic medications. So far, no tools have become available to predict the outcome of these treatments in specific patients. This is because the causes of such variability are often not known, and when they are, there is no way of predicting the effects of their various potential combinations in an individual. Given this background, this paper presents a conceptual framework for understanding known factors and their combinations so that eventually clinicians can better predict what medication(s) to select and at what dose they can optimize the outcome for a given individual. This framework is flexible enough to be readily adaptable as new information becomes available. The causes of variation in patient response are grouped into four categories: (i) genetics; (ii) age; (iii) disease; and (iv) environment (internal). Four cases of increasing complexity are used to illustrate the applicability of this framework in a clinically relevant way In addition, this paper reviews tools that the clinician can use to assess for and quantify such inter- and intraindividual variability. With the information gained, treatment can be adjusted to compensate for such variability, in order to optimize outcome. Finally, the limitations of existing antidepressant and antipsychotic therapy and the way they reduce current ability to predict response is discussed.

The package insert: who writes it and why, what are its implications, and how well does medical school explain it?

The package insert, which is jointly authored by the U.S. Food and Drug Administration and the manufacturer of the drug, is a summary of all of the preclinical and clinical data accumulated during the successful development of a new drug. Despite the role of the package insert in the safe practice of medicine, prescribers often minimize, overlook, or misunderstand its importance, suggesting a gap in their training. An anonymous, three-question survey was administered to third year medical students (N=34) from two medical schools to assess how well they had been educated about the evidence-based origin, purpose, and implications of the package insert. The results indicate a deficiency in their medical education, and the authors contrast the student responses with the facts. These results underscore the need to revise medical school curricula to provide future prescribers with more education about the importance of the package insert and the relationship between pharmaceutical companies, the U.S. Food and Drug Administration, and prescribers.

Pharmacogenomics in the nursing literature: an integrative review

BACKGROUND

Pharmacogenomics is a rapidly growing component of personalized health care, and nurses must be competent to deliver genomic-focused nursing care.

METHODS

We conducted an integrative review of pharmacogenomics in the nursing literature. A comprehensive search of the nursing literature was conducted using the key words pharmacogenomics and pharmacogenetics. A total of 47 unique articles were included.

RESULTS

Articles represented mainly narrative reviews, with limited discussions of the implications for nursing practice, education, or research. As such, they provide limited direction for advancing either clinical practice or scientific inquiry.

CONCLUSIONS

This review serves as a call to action for more systematic and empirical publications addressing pharmacogenomics in nursing practice, education, and research. Nurses must be involved in and contribute to interdisciplinary conversations and burgeoning clinical practice initiatives related to pharmacogenomics.

Outliers on the dose-response curve: if the problem is not concentration, then what?

This column addresses the two primary reasons some patients do not respond as usual to a medication. Such patients may not benefit either because they are uniquely sensitive to the adverse effects of the drug and/or because the drug does not work on the correct mechanism of action to treat the illness. This column explains and reviews these concepts and provides a rationale for using such information prospectively to increase the likelihood of an optimal outcome with the prescribed treatment.

Challenges for trainees in psychiatry and early career psychiatrists

Psychiatry as a discipline will undergo major changes in the coming years. Although changes can be particularly stimulating and challenging from an intellectual, scientific and social viewpoint, the new generations of psychiatrists must be prepared to face these changes and deal with them appropriately. Paradigms which have represented the foundations of psychiatry in the last century now need a major revision. In particular, both trainees in psychiatry and early career psychiatrists need to (1) (re)discover psychopathology, (2) improve mental healthcare through integrated treatments, (3) identify and treat new syndromes, (4) promote an image of psychiatry with patients at the heart of care and as advocates for each other by fighting stigma and promoting the recruitment in psychiatry by medical students. These can be achieved by increasing involvement in institutions and organizations to influence the agenda. In this paper the possible contribution of trainees and early career psychiatrists is discussed and recommendations are made in order to set a new agenda for early career psychiatrists who will still be practising 2-3 decades from now.