Incidence Of Drug Interactions Research Articles

The Relationship Between the Use of Combination Antidiabetic and Antihipertensive Drug of Classes on the Incidence of Drug Interaction in BPJS Patients

The Relationship Between the Use of Combination Antidiabetic and Antihipertensive Drug of Classes on the Incidence of Drug Interaction in BPJS Patients

Drug interactions and drug-food interactions in patients receiving diabetes mellitus treatment

Drug interaction is the change of a drug's effects by the preceding and/or concurrent administration of a different substance (precipitant drug). Drug interactions may either intensify or weaken the effects that one or both medications are supposed to have. Any drug's therapeutic, preventative, or diagnostic capabilities may change as a result. A major contributing factor to the prevalence and occurrence of adverse medication responses and adverse drug events might be drug interactions. Patients receiving drug combinations or polypharmacy or suffering from co-morbid diseases like diabetes, hypertension, peptic ulcer, fungal infections, and neurodegenerative disorders have a much higher rate of occurrence and incidence of drug interactions. As these patients receive prolonged and multiple treatments, the risk of drug interactions rises. Conclusion: Drug interactions are more likely to occur in diabetes patients who are also getting a mix of medications for diabetic complications. As a result, the frequency of drug interactions is fast increasing. Because of its increasing incidence and the corresponding rise in morbidity and mortality, diabetes mellitus has been regarded as a major public health concern globally. The major goal of this review study is to highlight the different medication interactions that may occur between drugs and foods, as well as to record any unfavorable side effects of other treatments used in conjunction with antidiabetic drugs in diabetic patients.

Rationality of the Antibiotics Use in Pediatric Acute Respiratory Infection Patients at Ssma Hospital in Pontianak, Indonesia

Acute respiratory tract infections (ARI) in children have a high prevalence that can be caused by bacteria or viruses. Antibiotics are prescribed more often than recommendations in the guidelines. This study aims to evaluate the rationality of antibiotic use and the occurrence of drug interactions in pediatric patients diagnosed with ARI at one of the hospitals in Pontianak based on some parameters such as right drug, right dose, and right duration as well as the incidence of drug interactions. Data collection was carried out based on medical record data which was carried out with a total sampling technique, namely taking all data that met the inclusion criteria.This research is a descriptive cross sectional design and retrospective data collection using patient medical records. Samples were taken by total sampling method. The results obtained from 131 patients consisting of 172 visits, right drug (131), right dose (93), and right duration (77).

Polypharmacy and Drug Interactions in Geriatric Patients with Type 2 Diabetes Mellitus at the Internal Medicine Inpatient Installation at RSUP Dr. M. Djamil Padang

One of the diseases commonly suffered by geriatric patients is diabetes mellitus, more than 95% of diabetics suffer from type 2 DM. Type 2 DM has a 2.28 times higher risk in the elderly and a greater risk of suffering from geriatric syndromes, one of them is polypharmacy which can increase the potential for drug interactions. The purpose of this study was to describe polypharmacy and drug interactions and to analyze the correlation between polypharmacy and drug interactions in geriatric patients with type 2 DM at the Internal Medicine Inpatient Installation at RSUP Dr. M. Djamil Padang in 2021. This type of research is non-experimental using a cross sectional method. Retrieval of data is retrospective originating from the patients medical records. A total of 39 samples included in the inclusion criteria showed that the incidence of drug interactions in patients prescribing polypharmacy was 79.49%, with the highest severity of drug interactions was moderate at 74.46%, and the most pattern of drug interaction mechanisms was pharmacodynamics at 78.72%. In this study it can be concluded that there is a strong and significant corelation between polypharmacy and the potential for drug interactions (p=0.000, r=0.570), which means that the more drugs used, the more potential drug-drug interactions.

Potensi Interaksi Polifarmasi Pasien Jantung Koroner (PJK) di Rumah Sakit I.A. Moeis Samarinda

The condition of the heart experiencing changes is called Coronary Heart Disease namely, changes in body cells that encourage organ work. According to the 2018 Basic Health Research, coronary heart disease in Indonesia is 1.5% or is estimated to be 883,447 people and for East Kalimantan it is 1.9% or as many as 13,977 people. The use of a lot of drugs, often occurs in coronary heart patients with additional comorbiditiens that require doctors to prescribe more than one drug to overcome the complaints suffered by the patient. The purpose of this study was to determine the interaction of the use of drug in patients with coronary heart disease and additional comorbidities. The concept was carried out using a random sampling data collection method in the form of taking outpatient prescription data at the cardiac polyclinic for 1 year, from January to December 2021. There were 242 patients, 59.1% male and 40.9% female. The highest comorbidities, of the 7 comorbidities with the most patients being hypertension, amounted to 122 and followed by diabetes mellitus 40 patients. The highest drug interactions were found in 108 clopidogrel and lansoprazole drugs, 31 spironolactone and furosemide drugs, and 26 simvastatin and amlodipine. With the incidence of drug interactions as many as 218 of 242 samples.

Studi Interaksi Obat Pasien Diabetes Melitus Tipe 2 dengan penyakit penyerta : Studi Kasus Rumah Sakit X Gorontalo

Diabetes mellitus (DM) type 2 is a chronic disease caused by insulin that does not work properly or is called insulin resistance. Such a condition causes the emergence of DM comorbidities. The treatment of diabetes mellitus and comorbidities is based on the symptoms that appear, leading to polypharmacy and causing drug-related problems; one of which is drug interactions. This study aimed to determine the correlation between the number of drugs and the incidence of drug interactions. It employed non-experimental research with descriptive analysis design, retrospective data collection. The research sample that met the inclusion criteria consisted of 97 recipe. Further, data were then analyzed univariately using the chi-square test. The results showed the use of the drugs was glimepiride (31%), metformin (24%), insulin aspart + insulin detemir (13.5%), insulin aspart (13.5%), metformin + glimepirid (8%), insulin. + OHO (5%), insulin aspart + insulin glargine (2%), metformin + glibenclamide (1%), a combination of 2 insulin aspart (1%), and metformin + gliclazide (1%). Moreover, the number of drugs used by patients was 2-4 drugs (70%) and ≥5 drugs (30%). Drug interactions based on the mechanism of interaction are unknown (49%), pharmacodynamics (30%), and pharmacokinetics (21%). Drug interactions based on the degree of severity were moderate (76.23%), minor (23.13%), major (1.64%). There was a correlation between the number of drugs in one prescription and the incidence of drug interactions (P = 0.042 0.05).

Effects of psychotropic polypharmacy intervention

Psychotropic polypharmacy, the concurrent use of two or more psychotropic drugs in the same patient, is a common practice in treating patients with psychiatric disorders. Such practices risk an increase in the incidence of drug interaction and adverse effects, as well as a decrease in medication adherence. A meta‐analysis of 26 studies that employed focused medication review with a goal of appropriate de‐prescribing reported significant reductions in the number of psychotropic drugs after the reviews, but there was little evidence of decreased incidence of adverse drug reactions or lower drug costs.

Drug Interactions: A Review

Increased use of drugs as well as polypharmacy has led to increase in incidence of drug interactions. These interactions may lead to medically significant as well as life threatening complications. Not all kind of interactions that can occur with a drug are known. The data in reference safety documents, published literature and safety databases is also limited. Some drugs may also react to certain foods or beverages if taken concomitantly. Most of the interactions come into picture during post-marketing phase of a drug. Latest versions of labelling documents by the manufacturers are informative but not necessarily for newly approved drugs. It is imperative for the healthcare professionals to check for known interactions while prescribing multiple drugs. Detailed diet routine and ongoing medications of subjects also need to be taken into consideration.

Assessment of Prescription Pattern Prescribed to Patients Affected by Rheumatoid Arthritis: A Cross Sectional Health Survey Conducted in Different Hospitals of Bangladesh

Introduction: Rheumatoid arthritis (RA) is a systemic autoimmune disease that affects the joints with variable degrees of severity depending on the patient. As it is a chronic disease and patients have to go through medication for a long period of time, choosing the proper drug is very crucial to avoid irrational use of drug. The present study was designed to evaluate the usual prescription pattern that are prescribed by the physicians, and unveiling the scenario of patient care treating for arthritis.
 Materials and Methods: The current survey-based research study was conducted in seven divisional areas of Bangladesh. Data was collected for Five months periods from September 2020 to January 2021. This cross-sectional study was carried out at a variety of private and governmental hospitals. The study included 300 individuals who had been on antirheumatic medicines for at least six months. Patient demographic details, prescribed drugs, adverse drug reactions, and use of complementary and substitute medicine were used to analyze the pattern of drug use.
 Results and Discussions: The results of the study found that most of the patients are from 40 to 60 years of age. The number of drug prescribed ranges from 3 to 8, with an average of 6.1 medicines per prescription. The most used Disease-modifying antirheumatic drugs (DMARDs) were tofacitinib, glucocorticosteroids were prednisolone and NSAIDs were Aceclofenac group. None of these drugs were prescribed as generic names, rather proprietary names were used.
 Conclusion: Most of the patients are treated with more than one drug to fight against arthritis. So the incidence of drug interaction should be observed carefully. Moreover, both the prescriber and patient should be aware of ensuring rationale use of drug.

1044. The Incidence and Severity of Drug interactions Before and After Switching Antiretroviral Therapy to Bictegravir/Emtricitabine/Tenofovir Alafenamide in Treatment Experienced Patients

BackgroundSwitching antiretroviral therapy (ART) in virally suppressed people with HIV (PWH) can simplify treatment, improve tolerability, and limit long-term toxicity. It can also influence the presence of drug interactions (DIs) in a positive or negative manner among patients receiving concomitant medications (CMs). The extent to which switching ART to bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) influences DIs in treatment-experienced PWH is unclear. The purpose of this study was to assess changes in the incidence and severity of DIs after switching to BIC/FTC/TAF.MethodsThis was a multicenter retrospective cohort study of PWH on ART and at least one prescription CM who switched to BIC/FTC/TAF between 3/2018 and 6/2019. Using the University of Liverpool’s HIV drug interaction checker, two DI analyses were performed for each patient. The first assessed patients’ pre-switch ART regimen with their CM list. The second assessed the same CM list with BIC/FTC/TAF. Each ART-CM combination was given a numerical score of 0 (no or potential weak interaction), 1 (potential interaction), or 2 (contraindicated interaction). Total DI scores for each patient, both before and after switching to BIC/FTC/TAF, were then calculated. A paired t-test analyzed changes in DI scores following ART switches and a linear regression model examined factors contributing to DI score reductions.ResultsA total of 411 patients were included in the analysis (Table 1) of which 236 (57%) had at least one DI present at baseline. On average, patients had a baseline DI score of 1.4 (SD 1.8) and experienced a 1 point reduction (95% CI -1.1,-0.8) after switching to BIC/FTC/TAF (p < 0.0001). After adjusting for demographic variables as well as baseline ART and CM categories in the regression model, switching to BIC/FTC/TAF led to significant DI score reductions in patients receiving CMs for the following conditions: cardiovascular disease, neurologic and psychiatric disorders, chronic pain, inflammation, gastrointestinal and urologic conditions and conditions requiring hormonal therapy (Table 2).Table 1. Descriptive Summary of Baseline Characteristics, n =411. Table 2. Linear Regression for the Difference of DI scores (post – pre), n =376. ConclusionSwitching ART to BIC/FTC/TAF can reduce the incidence of DIs among treatment-experienced PWH who are receiving CMs for a broad range of comorbid conditions.Disclosures Jason J. Schafer, PharmD, MPH, Gilead (Research Grant or Support)Merck (Grant/Research Support, Advisor or Review Panel member)ViiV (Advisor or Review Panel member) Elizabeth Sherman, PharmD, Gilead (Grant/Research Support) Jennifer Cocohoba, PharmD, AAHIVP, BCPS, Viiv (Grant/Research Support)

Assessment of comorbidities in patients with deranged thyroid hormone levels

Background: There is association of deranged thyroid hormone levels with various co-morbidities. Drugs for comorbidity may interact with each other and affect the outcome of treatment. So, this study was planned to find out comorbidities with deranged thyroid hormone levels and various possible drug interactions.Methods: It was a prospective, observational study carried out at tertiary care hospital from November 2017 to June 2018. Thyroid hormonal levels reports were followed in OPD and online information system facility. Drugs interactions were checked by referring standard pharmacology textbooks, review articles and Medscape drug interaction checker. Approval from the Institutional Ethics Committee was taken before initiation of the study. Patients with deranged thyroid hormone levels were included in the study.Results: Study was conducted in 111 patients of thyroid disorders. Spondylitis, asthma, acne cases were seen in hypothyroid patients whereas hypokalemic periodic paralysis, thyroid ophthalmopathy statistically significantly seen in hyperthyroid patients. Various concurrent medications such as calcium, carbamazepine decreases the effects of levothyroxine. For management of comorbidities various drugs are given which also interact among themselves significantly.Conclusions: Diabetes mellites, obesity, spondylitis, lichen planus were more common in hypothyroidism while comorbidities like hypertension, hypokalemic periodic paralysis, thyroid ophthalmopathy were found to be more in hyperthyroidism. Incidence of drug interactions is found to be more with increased use of medications for comorbidities, so physicians should be careful while prescribing them. Due to drug interactions desired effects of drugs given for thyroid disorders may not be observed.

The Incidence and Severity of Drug Interactions Before and After Antiretroviral Therapy Simplification in Treatment-Experienced Patients With HIV Infection.

Background: Current guidelines advocate for antiretroviral therapy (ART) simplification in patients on complicated regimens. Simplifying ART improves patient adherence and quality of life, but changes in drug interactions (DIs) are uncertain. Objective: This study assessed changes in DIs following ART simplification in patients with HIV. Methods: This was an observational, retrospective cohort study of patients attending an urban HIV clinic. Patients were included if they had ART simplification (a decreased number of daily tablets) and ≥1 concomitant medication (CM). Total DI scores were generated for each patient pre-ART simplification and post-ART simplification using an online DI database. Each ART-CM pair labeled as "do not co-administer" was given a score of 2, "potential interaction" a score of 1, or "no interaction" a score of 0. Differences in total DI scores following simplification were analyzed with a Wilcoxon Signed-Rank test. Predictors of DI score reductions were examined with linear regression. Results: A total of 99 patients were included. Their median age was 54 years, and 79% were male. The median durations of HIV infection and ART were 16 and 10 years, respectively. Patients were receiving an average of 4.5 CMs. Median interaction scores presimplification and postsimplification were 3 (interquartile range [IQR], 1-6) and 1 (IQR, 0-2) respectively (P < 0.001). Predictors of score reductions were the patient's number of CMs, discontinuing a protease inhibitor, and switching to a dolutegravir-based regimen. Conclusion and Relevance: ART simplification decreased the incidence of DIs in this analysis of patients with advanced age who had ART experience and polypharmacy.

Effect of Pharmacist Intervention on a Population in Taiwan with High Healthcare Utilization and Excessive Polypharmacy.

Patients with high healthcare utilization are at increased risk of polypharmacy and drug interactions. This study investigated the changes in the number of medications, drug interactions and interaction severity in high frequency outpatients with polypharmacy at hospitals and clinics in Taiwan after home pharmaceutical care, to understand the effectiveness of interventions by pharmacists. This was a retrospective observational study. Cases with excessive polypharmacy (10+ drugs) were selected from the Pharmaceutical Care Practice System database of the Taiwan Pharmacist Association in 2017. After the home care intervention, the number of drug types used decreased 1.89-fold (p < 0.001), and the number of medications fell 61.6%. The incidence of drug interaction was 93.82%. In an average case, the incidence of drug interaction after the pharmacist intervention decreased 0.6-fold (p < 0.001). The drug most commonly causing interactions was aspirin, followed by diclofenac; also common were three used in diabetes, two psycholeptics and two beta blockers. Among 22 cases of severe drug interaction, seven resulted in increased risk of extrapyramidal symptoms and neuroleptic malignant syndrome. By analyzing the relationship between the side effects of individual drugs and the pharmacokinetic Tmax, a sequential thermal zone model of adverse drug reactions can be established, the value of which could prompt physicians and pharmacists to intervene in order to prevent adverse events. It is concluded that home pharmaceutical care by pharmacists can significantly reduce the number of medications and interactions in patients with excessive polypharmacy and high healthcare utilization.

DRUG-RELATED PROBLEMS IN HOSPITALIZED GERIATRIC PATIENTS WITH DIABETES MELLITUS

Objective: This study aimed at analyzing drug-related problems (DRPs) in hospitalized geriatric patients with diabetes mellitus.Methods: We prospectively collected data of 26 hospitalized geriatric patients at the Gatot Soebroto Army Hospital (age, &gt;60 year) who underwentinpatient treatment for at least 1 month between February and April 2015. Readable data were obtained from prescriptions, medical records, andindex card/nurses records. We obtained data on 299 drug treatments for 26 patients and identified 166 DRPs. These were analyzed based on thePharmaceutical Care Network Europe Version 6.2.Results: The percentage of treatment effectiveness (50.6%) and adverse drug reactions (49.4%) was predominantly due to an inappropriate drug–drug or drug–food combination, including the incidence of drug interactions (20.4%).

STUDI FARMAKOVIGILAN OBAT ANTIHIPERTENSI PADA PASIEN HIPERTENSI RAWAT JALAN DI DR. A. DADI TJOKRODIPO BANDAR LAMPUNG PERIODE OKTOBER–NOVEMBER 2021

Hypertension, also known as high blood pressure, is systolic pressure140 and diastolic pressure 80 mmHg. The more blood pressure is pumped by the heart and the narrower the arteries, the higher the blood pressure. This study aims to determine the occurrence of adverse drug reactions in hypertensive patients in RSD DR. A. Dadi Tjokrodipo Bandar Lampung. This research is a descriptive research with total sampling method. Collecting data by looking at the patient's medical record data. The results showed that the female sex was more dominant in suffering from hypertension, namely 20 female patients (62.5%) and 12 male patients (37.5%). The highest age characteristics were found in the age range of 46-55 years as many as 14 patients (43.75%). The most characteristic of hypertension was in the case of stage 2 hypertension with a total of 17 patients (53.12%). The highest pattern of drug use was amlodipine (37.5%). The incidence of drug interactions was 10 cases (31.25%) with minor severity. The highest incidence of ADR was in the "moderately probable" 1-4 with a total of 15 cases (46.87%). Keywords: ADR, hypertension, drug interactions, antihypertensive drugs

A Review on Drug-Drug and Drug-Food Interactions in Patients During the Treatment of Diabetes Mellitus

International Journal of Pharmacology and Clinical Sciences,2015,4,4,98-105.DOI:10.5530/ijpcs.4.4.6Published:Dec 2015Type:Review articlesAuthors:Sonu, Gopal Sharma, SL. Harikumar, and Silvia Navis Author(s) affiliations:Sonu1, Gopal Sharma1, SL. Harikumar2, Silvia Navis3* 1M.Pharm students, Sahauran, Mohali-140104, Punjab, INDIA. 2Department of Pharmacology, Dean, University School of Pharmaceutical Sciences, Rayat-Bahra University, Sahauran, Mohali-140104, Punjab, INDIA. 3Department of Pharmaceutics, Rayat and Bahra Institute of Pharmacy, Sahauran, Mohali-140104, Punjab, INDIA. Abstract:Drug interaction is defined as the modification of the effects of a drug (object drug) by the prior and/or the concomitant administration of another drug (precipitant drug). Drug interaction may either increase or decrease the intended effect of one or both drugs. It may transform the diagnostic, preventive or therapeutic activity of any drug. Drug-interactions can be an extremely main contributory factor for the incidence and occurrence of adverse drug reactions and adverse drug events. The rate of occurrence and incidence of drug interactions is much higher in patients receiving combinations of drugs or poly-pharmacy or suffered from co-morbidity of diseases such as diabetes, hypertension, peptic ulcer, fungal infections and neurodegenerative disorders, which require prolong and multi treatments and the risk of drug interaction will increase as they are treated with multi-therapies. It is concluded that diabetic patients are at higher risk for drug interaction as receiving a combination of therapies for diabetic complications as well, so that the rate of occurrence of drug interaction is rapidly amplifying. Diabetes mellitus has been considered as a foremost public health challenge around the world because of its high prevalence and associated increase in morbidity and mortality. The main objective of this review study is to highlights the various drug interactions likely drug-drug and drug-food interactions as well as reports unwanted effects of other treatment associated with antidiabetic agents in the diabetic patients. Keywords:Adverse drug reactions, Diabetes Mellitus, Drug Interaction, Drug-drug Interaction, Drug-food Interaction, PolypharmacyView:PDF (334.22 KB) PDFClick here to download the PDF file. Images These agents can be used moderately in safety with almost all

Polypharmacy Treatment of Hypertensionin Public Health Centers

Background : Hypertension is one of the most prominent global diseases. Despite the availability of effective therapies, hypertension remains poorly controlled in Indonesia. In many cases, patient’s noncompliance may be attributable to the low patients’ knowledge, attitude, and life-style practices such as polypharmacy. Polypharmacy is defined as the administration of many drugs at in one prescription. Polypharmacy increases expenses, possible adverse reaction to a single agent, incidence of drug interactions, and decreases patient’s compliance This study aimed to identify the practice of polypharmacy in hypertension treatment in primary health centers. Methods : A cross-sectional descriptive observational study was carried out on 60 patients from two primary health centers in Jatinangor, West Java, Indonesia in October 2013. Sociodemographic profile, degree of hypertension, types of antihypertensive drugs, concomitant drugs given together with antihypertensive drugs, and treatment compliance data were collected and presented in tables and figures. Results : The incidence of hypertension was more common among male patients compared to female patients. Thirty-three patients (55%) have low compliance to their medication. Twenty-nine patients (48%) received single drug and 31 patients (52%) received more than one drugs. Conclusions : The percentage of polypharmacy practice in treating hypertension in primary health centers is 52%. The most frequently prescribed anti-hypertensive are angiotensin-converting enzyme (ACE) inhibitors and calcium-channel blockers (CCB). Most of hypertensive patients have low compliance to therapy. [AMJ.2016;3(4):633–9] DOI: 10.15850/amj.v3n4.951

Pharmaceutical intervention assessment in the identification and management of drug interactions in an intensive care unit

It is estimated there are thousands of combinations of drugs, which may generate various adverse drug events, including drug interactions (DI). To assess the contribution of pharmacist to identification and management of DI in an intensive care unit (ICU). A longitudinal study was conducted in the ICU of a private hospital in the city of Aracaju-SE, between 2008 and 2009. The prevalence and clinical relevance of DI was assessed by two clinical pharmacists. Demographic data and clinical information of patients hospitalized in the period of the study were obtained from medical records. At the end of the study 137 medical records were analyzed, with a predominance of female patients (55.4%), average age of 66 (±7.0) years. 6,085 prescriptions were collected during the study period, in which 2,455 drugs prescribed. Of these, 175 prescriptions contained clinically relevant DI, 178 of moderate severity and 35 of major severity, 213 DI in total. The clinical pharmacists prepared reports for the physicians, which enabled the reduction of 40% of all DI. Data from this study suggest that pharmacist’s contribution may have reduced the incidence of DI, providing more familiarity of physicians on clinically relevant information and improving the quality of prescriptions in the ICU.

Role of clinical pharmacists to prevent drug interactions in cancer outpatients: a single-centre experience.

Cancer patients are especially vulnerable to drug interactions, which may alter the efficacy and toxicity of treatment, leading to severe clinical consequences. Determine the incidence of such interactions in patients receiving chemotherapy, as well as to identify the drugs most frequently involved, investigate the influence of the pharmacist's interventions and verify the degree of acceptance of pharmacist's recommendations by the medical team. The oncology department of a Spanish tertiary hospital. During 3 months, all the drug interactions in the regular combined with treatment for cancer were analysed using two databases, and recommendations were made when clinically significant interactions (CSI) were identified. Incidence of CSI in oncology outpatients; drugs involved in CSI. Of the 75 patients included, 31 (41%) presented CSI. Most interactions were among drugs included in the patient's usual treatment. The principal drug groups involved in CSI were cytostatic agents, antiemetics and antidepressants. The hospital pharmacist intervened on 20 occasions (35% of the patients presenting drug interactions). These interventions mainly focused on recommendations to modify or discontinue drug prescriptions, and were followed in 94% of cases. The incidence of drug interactions in cancer patients is high, and they most often involve medications to treat comorbid conditions. The pharmacist, as a member of the multidisciplinary team, can contribute significantly by checking the treatment prescribed and detecting interactions, to reduce medication-related problems and to optimise drug therapy for these patients.

Incidence of drug interaction when using proton pump inhibitor and warfarin according to cytochrome P450 2C19 (CYP2C19) genotype in Japanese.

The US Food and Drug Administration has suggested that proton pump inhibitors (PPIs) increase the international normalized ratio (INR) when used concomitantly with warfarin (WF) because of being metabolized by cytochrome P450 2C19 (CYP2C19). We assessed whether CYP2C19 genotypes and type of PPI accentuated the drug interaction. The study group was 82 patients who needed WF after surgery and had their CYP2C19 genotypes analyzed in advance. We randomly divided them into two groups: group I (n = 41) included patients who had lansoprazole 15 mg/day and group II (n = 41) included patients who had rabeprazole 10 mg/day. The dose of WF was controlled by the doctor in charge as a target INR of 1.6 to 2.6 during the 2 months after surgery. The maximum INR was significantly higher in group I (3.36 ± 0.98) than in group II (2.29 ± 0.55, p < 0.0001). The incidence of over-INR (> 3.5) was significantly higher in group I (15 cases) than in group II (2 cases, p = 0.0001). Several bleeding events complicated 10 patients in group I, but none in group II (p = 0.015). Logistic regression analysis revealed that over-INR (odds ratio [OR] 3.58, 95% confidence interval [CI]: 3.48-368.25, p < 0.0001), and pair of lansoprazole and CYP2C19 intermediate metabolizer (OR 2.39, 95% CI: 1.108-29.491, p = 0.0009) were independent predictors of bleeding events. If a patient has had the intermediate metabolizer CYP2C19 genotype and concomitant use of WF and a PPI after open heart surgery, lansoprazole intensifies the effects of WF and is associated with bleeding events.