Nurse empowerment through Pharmacogenetics*

Objective: to verify the existence of elements that justify the use of pharmacogenetics by the Brazilian nurse. Method: this is a quantitative, cross-sectional, observational, descriptive study, whose final sample was 67 individuals. The participants were healthy at the time of the study and reported a history of previous use and the occurrence of adverse effects by drugs commonly used and metabolized by CYP2C9. We collected 4 mL of venous blood for subsequent DNA extraction by salting out method and genotyping of the CYP2C9*2 and CYP2C9*3 polymorphisms, using Polymerase Chain Reaction in real time using Taqman assays. Results: the use of drugs metabolized by CYP2C9 was frequent (more than 75% of the individuals have already used between 2 or 4 of these drugs). Regarding adverse events, there were 19 perceived symptomatic occurrences associated with drugs metabolized by CYP2C9. The allele frequency of the polymorphism * 2 and * 3 in the population studied was 11.1% and 7.5%, respectively, and there was a coincidence between the presence of alleles of low enzyme activity and the occurrence of adverse effects. Conclusion: there are elements that justify the adoption of pharmacogenetics in the nursing care to reduce the occurrence of adverse reactions to drugs metabolized by CYP2C9.


Introduction
It is estimated that the so-called Adverse Drug Reactions (ADRs), which are between the 4 th and 6 th biggest causes of mortality in the USA, result in a percentage of hospital admissions around or above 10% in several countries and lead to a 15 to 20% of the hospital budget is spent to deal with complications resulting from medication use (1) . All ADRs are harmful, unintended response and the result of using a therapeutic dose of any medication. The consequences resulting from ineffective treatments or hospitalizations for drug poisoning are enormous and show the great importance of personalization and rationalization in the use of medications for both patients and health professionals (2) . The main causes for drug poisoning at therapeutic doses involve drug-drug interactions, drug-food interactions, patient health conditions (for example, liver or kidney failure) and the individual's genetic characteristics (3) .
The metabolism of drugs in the human body occurs mainly through the hepatic cytochrome P450 (CYP) system (4) . These enzymes can have their activity and expression modulated by endogenous factors, such as genetic polymorphisms (2)(3)5) , which are variations in the genetic code of individuals. These are hereditary characteristics, explaining family vulnerabilities to toxic reactions in the use of certain drugs (3) .
Of the liver enzymes of cytochrome P450, the The importance of polymorphisms is clear when considering a drug with a narrow therapeutic window such as Warfarin. This anticoagulant can lead to hemorrhagic events in patients with alleles associated with reduced metabolism of the warfarin, for example, CYP2C9 * 2 and * 3 (8)(9)(10)(11) . In several countries, genetic testing prior to drug administration is already adopted to establish the correct dose of warfarin (9)(10) , and efforts are being made to adapt this to the Brazilian reality (8,11) . This has been studied from a multiprofessional point of view, but it is important to understand how nurses can use this tool in their daily lives.
The nursing professional is responsible for performing many competencies, among which we highlight three central care activities: 1) medication administration, 2) the nurse's management skills, important, among other things, to identify the cost-benefit of a health action, and 3) the education of the patient about the illness he/ she has. These skills can be improved by incorporating pharmacogenetics in the nursing process (12) .
It is assumed that the Nursing Process is a method to systematize care and thus, in addition to allowing personalization of care, it unites nurses, patients, family and community. The Nursing Process is classified into five sequential and interrelated steps: data collection, diagnosis, planning, implementation and evaluation (13) . Studies have identified that the nursing process is capable of providing autonomy for the professional nurse, given that it enables the planning and organization of the actions of this team, enabling improvement and efficiency in the care provided, reduction of complications, length of stay in the hospital and the cost of care (14) . Pharmacogenetics can be incorporated in almost all stages of the nursing process. In the data collection stage, it allows the health team to detect the individual's genetic data, outlining a diagnosis that will guide care planning (12) . Thus, in the same way that it is necessary to obtain local information to adapt concepts of pharmacogenetics to our population that has a mixed ethnic origin (8,11) , it is necessary to understand whether and how this knowledge can be applied to the nurse's daily life.
In other countries, there is already evidence that this is important in this professional's daily life, such as the use of genetic biomarkers in the care of diabetic (15) and schizophrenic patients (16) , in the treatment of pain (3) , in the treatment of cancer (17) , but there is still no clear evidence that this is relevant in our context.  (18) , and we have used this material to make the population aware of the use and importance of pharmacogenetics, with the intention that patients take the demand to health professionals and they start using pharmacogenetics on a routine basis.

Results
Regarding sociodemographic data (  Table 2 shows the reported data regarding the use of drugs metabolized by CYP2C9 enzyme. The most common types of drugs used by the participants were non-steroidal anti-inflammatory drugs. Therefore, the most common adverse effect was stomach pain, which is usual in this class. Our data indicate that the sample, although not subjected to chronic treatments, was exposed almost completely (98.5%) to drugs that were metabolized by CYP2C9 (   Table 3 shows the frequency of the genotypes obtained in the present study and Table 4   The allele frequency of the CYP2C9 * 2 and CYP2C9 * 3 polymorphism in the study population was 11.1% and 7.5%, respectively (    Regarding the feasibility of genetic testing within a university extension program, Table 5 provides an estimate of costs. This was a very interesting scenario, since it was possible to take advantage of a pre-existing structure that is usually focused on research and postgraduate studies.

Discussion
The clinical implementation of pharmacogenetics is a challenge worldwide and has been very well accepted in cases where: 1) the evidence of the genetic association is reproducible and consistent, and 2) the clinical consequences of the presence of a certain allele are serious, for example, slow metabolizers using drugs with a narrow therapeutic window (8,11) . For the implementation, tests are required for each local population, and most of the scientific evidence is from Caucasian and North American populations. In fact, in North American society and on the European continent, the adoption of pharmacogenetics has been a reality for some years (19)(20) , for example, with the recommendation of genotyping of the * 2 and * 3 alleles in patients before starting therapy with various drugs such as Warfarin, Abacavir and Tamoxifen. In addition, the area of oncology is intensively incorporating the study of the genetic bases of cancer and, consequently, specific pharmacological approaches for patients with certain risk alleles (17) .
The challenge of implementing pharmacogenetics in clinical practice has several obstacles (8,11) , which have to patients (23)(24) .
In the present study, the allele frequencies of the CYP2C9 * 2 and * 3 polymorphisms that we found were similar to the frequencies found in the three main Brazilian studies with this theme (25)(26)(27) , which also found that the Caucasian population has a frequency of variant alleles 2 to 3 times higher than the black population.
allelic frequency in Brazilians of the CYP2C9 enzyme polymorphisms studied here is similar to that found in the European Caucasian population since the statistical tests did not show significant difference between these populations, although more than 20% of the population in this study declare themselves to be non-white.
The alleles studied here are primarily responsible for leading to a decrease in CYP2C9 activity, It is interesting to note that 26% of the ADRs reported here occurred in patients with slow CYP2C9 alleles. This demonstrates that complex phenotypes such as pharmacogenetics are affected in a multifactorial way, that is, the genotype has no determinant relation to the phenotype (as in the case of monogenic diseases, for example) (33)(34) . Several factors, such as treatment time, concomitant use of other substrates for the same enzyme, dose, age and health status, among other factors, are also associated with ADRs (35) . This explains why part of the patients with slow alleles did not have ADRs even when exposed to drugs that are substrates of CYP2C9, as well as the appearance of ADRs in noncarriers of the * 2 and * 3 alleles of CYP2C9.
The results reported here showed that stomach pain was the most common adverse event presented by the study participants, and that Aspirin was the drug most associated with the occurrence of adverse effects, which is in agreement with the literature (36)  specifically intense urticaria. This is similar to that found by other authors (37) who, when analyzing the genotypes of 148 patients with urticaria associated with the use of Aspirin and 260 control subjects, found a significantly higher allele frequency of the * 2 and * 3 alleles in the group that reported urticaria intolerant to Aspirin.
The second drug most commonly used by the population in this study, and the second most related to the occurrence of adverse events, was Diclofenac.
Although studies indicate that the use of this drug is common and generally well tolerated in the clinic, a research (38) has already reported that the presence of genetic variants of the CYP2C9 enzyme, more specifically the CYP2C9 * 2 and CYP2C9 * 3 allele, considerably increases the risk of gastrointestinal disorders, including bleeding, during the use of NSAID other than Aspirin.
In our study, two individuals, heterozygous for the * 2 allele, reported adverse reactions related to the use of Diclofenac, an NSAID, being one with allergic reaction and one with stomach pain.
In our results, an individual, heterozygous for the * 3 allele, reported an adverse reaction to the use of the drug Losartan, characterized as an allergic reaction (cough and throat irritation). A similar association has been found previously (39) , relating the presence of the CYP2C9. Other researchers (40) , studying 59 Caucasian individuals with chronic kidney disease and chronic use of Losartan, found allelic frequencies of the * 2 and * 3 variants of 5% and 6%, respectively, whose presence was directly related to an increase in proteinuria and in the non-reduction of systolic and diastolic blood pressure, confirming the need for studies on the role of the enzyme CYP2C9 and its variants not only in preventing adverse events from antihypertensive therapy with Losartan, as well as its effectiveness in clinical practice.
In the sample of this study, 9.1% said they use current implying a high desire to consume medicines, one of the most important symbols of health in this society (2,41) .
The results found in this study help to confirm this trend, since it was almost unanimous (98.5%) the previous or current use of medications metabolized by the enzyme CYP2C9.
In Brazil, it is estimated that 23% of the population consumes 60% of the national production of medicines, especially people over 60, whose other common characteristic is polypharmacy, that is, the use of four or more medicines (42) . In our study, polypharmacy was verified in more than 75% of the research participants.
Therapeutic failures and the occurrence of adverse events related to drugs contribute to the strong frequency and prevalence of hospital admissions. In this regard, a study conducted in three tertiary teaching hospitals in Japan found that approximately two thirds of adverse events and medication errors occurred in the ordering/ separation phase, followed by monitoring (18.7%), administration (14% ) and dispensation (2.33%), greatly increasing the length of hospital stay (43) .
In this way, our study brings clear evidence that the genotyping of the * 2 and * 3 alleles is relevant in our population, and supports the application of the concepts of pharmacogenetics for the planning and administration of drugs, the dose of which can be evaluated in the context of "extensive metabolizers", "intermediate metabolizers" and "slow metabolizers" to have a more accurate assessment of the risk that the patient is exposed in relation to ADRs.
We ratify that the administration of drugs is a fundamental care of the nursing professional and that it requires constant innovation within the nursing process.
A domain of knowledge is necessary, which is complex because it involves drug interactions, mechanism of action and clinical complications arising from adverse effects. This is the competence of the nurse since he/ she is the professional responsible for knowing the patient's clinical history and needs to check the medical prescription before administering the medication (44) .
Pharmacogenetics comes to add and subsidize nursing and patient empowerment (45) .
From the point of view of public health management, nurses have a crucial role in assessing the cost-benefit of applying this approach in professional practice. In fact, the urgent need to conduct this type of research in Brazil is clear (8,11) . In the present study, we tried to envision the role that the public university can play in promoting the beginning of the application of pharmacogenomics in the single health system by offering these tests at for CYP2D6, and that these costs could be significantly reduced by pharmacogenetic tests prior to the start of therapy with antipsychotics and antidepressants (48) . higher than when compared to hospitalization without these events occurring (49) . The estimated total cost of hospitalization related to adverse events from 2008 to 2011 in the USA was US$ 142 billion. In 2011 alone, the total cost of hospitalization related to ADRs was estimated at US$ 38.9 billion (49) .
In addition to the financial value, we know how The third axis of application of the data presented in this work concerns the educational role that nurses play when passing on knowledge to the patient and other professionals of the multidisciplinary health team.
Advocating for the patient is one of the most important care and one of the most well-known functions of the nursing professional (50) . The nurse has the opportunity to appropriate pharmacogenomic knowledge, educate the patient (providing the possibility of empowering him/her), and assist the multidisciplinary team in personalizing the therapy in such a way as to increase the effectiveness and safety of the pharmacological treatment (51) .
A key to health promotion since the Ottawa Charter in 1986, empowerment, can be understood as a process of training individuals and communities to take greater control over individual, socioeconomic and environmental factors that affect health (52) . Among the individual factors, we can infer that there are genetic information and the right to obtain and use that information. Given the real possibility and the powerful implications of the growth in the use of genetic information, it is necessary to educate the population in a general way, which, in addition to lacking basic notions of genetics and pharmacology, still needs to pay attention to ethical, family, social, legal and financial aspects that this information affects (53) .
It is important to highlight that the nursing process is characterized as a powerful opportunity to strengthen educational competence, essential in the nurse's work process (54)(55) . The nursing process can contribute in this sense, to the extent that it favors direct educational actions with patients and family members regarding adequate treatment, as well as important associated signs and symptoms.
A study developed in institutions in the state of Espírito Santo identified that actions taken with patients in a superficial way can disqualify the other stages of the nursing process (56) . On the other hand, a research carried out in Hungary has shown that empowered patients, identified as literate and trained, reported better health status compared to any other group of patients (57) .
Empowerment also takes place with respect for nurses in all their levels of performance, since the domain of certain knowledge drives them towards a more effective and efficient health decision-making (21,(58)(59) . In fact, there is evidence that the use of pharmacogenetics in countries where this is implemented positively impacts the care process for both the nurse and the patient (60) .
Through teaching and pharmacogenetic empowerment, we will also be contributing to the formation of more sensitive health professionals, capable of perceiving each individual as unique and, in this way, adapting their form of assistance for each person, transforming the care relationship to the extent that the individual becomes an active subject of his/her treatment. It is also important to increasingly adhere to the nursing process, so that patients and family members can be educated so that they are protagonists of their own care process.
As a limitation of the study, we highlight that the relatively small sample does not allow the detection of rare alleles, but this was not a problem, since the providing a service to society. Cost analyses involving the private sector are necessary, including salaries, training, acquisition of equipment and fixed costs such as electricity, water, physical space, among others.

Conclusion
There are elements that point not only to the relevance, but also to the feasibility of applying pharmacogenetics in the context of Brazilian nursing.
There is evidence of favorable cost-benefit and potential to benefit patients who could avoid adverse reactions to drugs.