Impact of Definitive Drug-Drug Interaction Testing on Medication Management and Patient Care

Assessment of Potential Drug-Drug Interactions of Psycholeptics and Antidepressants in Outpatient Settings

Mental health is an important segment in preserving overall health and represents a significant public health issue. In modern times, mental health disorders have risen, often requiring complex pharmacotherapy and chronic monitoring. The aim of this research was to determine the prevalence and clinical significance of potential psychotropic drug interactions in outpatient settings and compare the differences in potential drug-drug interaction (pDDIs) exposure with age. The psychotropic drugs included antipsychotics-N05A, anxiolytics-N05B, hypnotics and sedatives-N05C, and antidepressants-N06A. This retrospective study analyzed prescribed pharmacotherapy in 492 outpatients who were treated with at least one psychotropic drug. We determined 1.64 prescribed psychotropic drugs per patient and 2.2 pDDIs that involved psychotropic drugs. In total, 2285 pDDIs were recorded, of which almost half (47.6%) were pDDIs with psychotropic drugs. More prescribed psychotropic drugs were found in patients younger than 65 years, and equal exposure to pDDIs of psychotropic drugs (p = 0.5077) was found in both age groups. The most commonly identified psychotropics involved in pDDIs were benzodiazepines, promazine, and zolpidem. The results indicate that psychotropic drug interactions represent important drug-related problems for primary health care. The widespread use of psychotropic drugs and the determined clinical significance of their interactions require pharmacist interventions which can reduce the prevalence of pDDIs and increase patient safety.

CYP2D6 Substrate Dispensing Among Patients Dispensed Mirabegron: An Administrative Claims Analysis

BACKGROUND

Overactive bladder (OAB) is characterized by the presence of bothersome urinary symptoms. Pharmacologic treatment options for OAB include anticholinergics and β3-adrenergic agonists. Use of β3-adrenergic agonists may result in similar treatment efficacy with a decreased side effect profile compared with anticholinergics because high anticholinergic burden is associated with cardiovascular and neurologic side effects. However, the β3-adrenergic agonist mirabegron, one of two approved drugs within this class, is a moderate cytochrome P450 (CYP) 2D6 inhibitor, and coadministration of drugs that are CYP2D6 substrates with mirabegron may lead to adverse drug effects.

OBJECTIVE

The aim of this study was to quantify how often CYP2D6 substrates were dispensed in patients receiving mirabegron among adults of any age and among those ≥ 65 years of age.

METHODS

In this retrospective descriptive analysis, a deidentified administrative claims database in the United States, IQVIA PharMetrics® Plus, was used to identify dispensing claims for CYP2D6 substrates and mirabegron from November 2012 to September 2019. Prevalence of CYP2D6 substrate dispensing was assessed in patients dispensed mirabegron among all adults ≥ 18 years old and additionally among a cohort of those ≥ 65 years old. Patient baseline profiles at the time of mirabegron and CYP2D6 substrate codispensing and at the time of mirabegron dispensing were compared. CYP2D6 substrates were categorized as those with the potential for increased risk of QT prolongation, with anticholinergic properties, with narrow therapeutic index (NTI), contraindicated or having a black box warning when used with CYP2D6 inhibitors, or used for depression or other psychiatric disease. Dispensing data and patient profiles were summarized descriptively.

RESULTS

Overall, 68.5% of adults ≥ 18 years old dispensed mirabegron had overlapping dispensings for one or more CYP2D6 substrate; 60.6% and 53.6% had overlapping dispensings for CYP2D6 substrates with anticholinergic properties or risk of QT prolongation, respectively. CYP2D6 substrates with NTI, contraindicated with CYP2D6 inhibitors, or for psychiatric use were codispensed in 17.7%, 16.6%, and 38.0% of adult mirabegron users, respectively. Mirabegron users receiving one or more concurrent CYP2D6 substrate were more likely to be older, have more comorbidities and baseline polypharmacy, and have increased healthcare resource utilization compared with those without concurrent CYP2D6 substrates. Commonly codispensed CYP2D6 substrates included hydrocodone, oxycodone, tramadol, metoprolol, and tamsulosin. Findings were similar for patients in the older cohort (≥ 65 years old), with 72.1% receiving overlapping CYP2D6 substrates.

CONCLUSIONS

Codispensing of CYP2D6 substrates, especially those with anticholinergic properties or risk of QT prolongation, was common among adults and older adults receiving mirabegron. Results highlight the need for improved awareness of CYP2D6 substrate prescribing among patients receiving pharmacologic treatment for OAB that inhibits the CYP2D6 pathway.

Clinical Opportunities for Germline Pharmacogenetics and Management of Drug-Drug Interactions in Patients With Advanced Solid Cancers

PURPOSE

Precision medicine approaches, including germline pharmacogenetics (PGx) and management of drug-drug interactions (DDIs), are likely to benefit patients with advanced cancer who are frequently prescribed multiple concomitant medications to treat cancer and associated conditions. Our objective was to assess the potential opportunities for PGx and DDI management within a cohort of adults with advanced cancer.

METHODS

Medication data were collected from the electronic health records for 481 subjects since their first cancer diagnosis. All subjects were genotyped for variants with clinically actionable recommendations in Clinical Pharmacogenetics Implementation Consortium guidelines for 13 pharmacogenes. DDIs were defined as concomitant prescription of strong inhibitors or inducers with sensitive substrates of the same drug-metabolizing enzyme and were assessed for six major cytochrome P450 (CYP) enzymes.

RESULTS

Approximately 60% of subjects were prescribed at least one medication with Clinical Pharmacogenetics Implementation Consortium recommendations, and approximately 14% of subjects had an instance for actionable PGx, defined as a prescription for a drug in a subject with an actionable genotype. The overall subject-level prevalence of DDIs and serious DDIs were 50.3% and 34.8%, respectively. Serious DDIs were most common for CYP3A, CYP2D6, and CYP2C19, occurring in 24.9%, 16.8%, and 11.7% of subjects, respectively. When assessing PGx and DDIs together, approximately 40% of subjects had at least one opportunity for a precision medicine-based intervention and approximately 98% of subjects had an actionable phenotype for at least one CYP enzyme.

CONCLUSION

Our findings demonstrate numerous clinical opportunities for germline PGx and DDI management in adults with advanced cancer.

An Overview of Clinically Imperative and Pharmacodynamically Significant Drug Interactions of Renin-Angiotensin-Aldosterone System (RAAS) Blockers

INTRODUCTION

Hypertension is a leading cause of cardiovascular disease and chronic kidney disease, resulting in premature death and disability. The Renin-Angiotensin-Aldosterone System (RAAS) blockers, including Angiotensin-Converting Enzyme (ACE) inhibitors or Angiotensin Receptor Blockers (ARBs), are used as first-line antihypertensive therapy to treat hypertensive patients with comorbidities, including diabetes, ischemic heart disease, heart failure, and chronic kidney disease. The use of RAS blockers is associated with the risks, such as hyperkalemia, angioedema, etc. The drugs potentiating them interact pharmacodynamically, resulting in adverse consequences. This review article focuses on the clinically important drug interactions of RAAS blockers.

MATERIALS AND METHODS

The electronic databases, such as Medline/PubMed Central/PubMed, Google Scholar, ScienceDirect, Cochrane Library, Directory of Open Access Journals (DOAJ), Embase, and reference lists were searched to identify relevant articles.

RESULTS

The risk of hyperkalemia may be enhanced potentially in patients receiving a RAS blocker and potassium-sparing diuretics, potassium supplements, trimethoprim, adrenergic betablockers, antifungal agents, calcineurin inhibitors, pentamidine, heparins or an NSAID, concomitantly. The patients taking ACE inhibitors and mTOR inhibitors, DPP4 inhibitors, alteplase, or sacubitril/valsartan concurrently may be at increased risk of developing angioedema.

CONCLUSION

Clinicians, pharmacists, and other healthcare practitioners should be accountable for medication safety. To avoid adverse implications, prescribers and pharmacists must be aware of the drugs that interact with RAAS blockers.

Investigating Potential Drug-Drug Interactions from Greek e-Prescription Data

BACKGROUND

The prevalence of potential drug-drug interactions (pDDIs) is indicative of the prevalence of actual drug-drug interactions and prescription quality. However, they are significantly understudied in Greece.

OBJECTIVE

To determine the prevalence of pDDIs among outpatients and identify factors associated with their occurrence.

METHODS

Anonymous e-prescription data between 2012 and 2017 were obtained from community pharmacies in Thessaloniki, Greece. Patients taking more than one medication for at least three months were included. pDDIs were identified and categorized depending on their clinical significance using Drug Interactions Checker. Crude and adjusted odds ratios (ORs) with accompanying 95% confidence intervals (CIs) of risk factors of pDDIs occurrence were identified using multivariable logistic regression.

RESULTS

During the study period, 6,000 anonymous e-prescriptions (1,000 per year) satisfying the inclusion criteria, were collected. The overall prevalence of major pDDIs was 17.4% (63.0% for moderate pDDIs). The most common major pDDIs were between amlodipine and simvastatin (22.8% of major interactions) followed by clopidogrel and omeprazole (6.4% of major interactions). Polypharmacy (≥5 concomitantly received medications) was associated with an increased risk of major pDDIs (adjusted OR, 5.72; 95% CI, 4.87-6.72); no associations were observed regarding age, sex and number of prescribing physicians.

CONCLUSION

The prevalence of pDDIs in this study was higher than previously reported in other European countries, with polypharmacy being a potential risk factor. Those results argue for a need for improvement in the area of prescribing in Greece.

Randomized Trial to Improve Primary Care Patient Management and Patient Outcomes Using a Drug-Drug Interaction Test: Confirmation of the DECART Simulated Patient Clinical Utility Trial Results

Drug–drug interactions (DDIs) are a serious problem in the healthcare system, leading to excess healthcare utilization and costs. We conducted a second prospective randomized, controlled trial to further establish the real-world clinical utility of a novel assay that objectively identifies potentially serious DDIs in real-world patients. Re-recruiting primary care physicians (PCPs) from our first randomized, controlled, simulated-patients study on DDIs, we experimentally introduced a definitive, urine-based mass spectrometry test intervention that the physicians could use when caring for their eligible patients. Patients were eligible if taking four or more prescription medications or suspected of taking other non-prescribed substances with potential medication interactions. The primary outcome was whether DDI testing changed clinical care. We explored a secondary outcome to see if the change in practice improved symptoms in patients with potential DDIs. A total of 169 control and 162 intervention patients were enrolled in the study, and their medical records were abstracted. In real-world patients, intervention physicians identified and/or treated a DDI at 3.0x the rate in their patient population compared to controls (21.6% vs. 7.1%, p < 0.001). Intervention physicians were more likely to discontinue or adjust the interacting agent compared to controls (62.9% vs. 8.3%, p = 0.001), and patient-reported symptoms also significantly declined (29.6% vs. 20.1%, p = 0.045). These results were nearly identical to concurrent measurements that used simulated patients, wherein intervention was more likely to both make a DDI diagnosis (56.3% vs. 21.6%, p < 0.001) and stop the interacting medications (58.3% versus 26.6%, p < 0.001). Bringing a new diagnostic test to market, particularly for an under-recognized clinical problem, requires robust data on both clinical validity and clinical utility. The results of this follow-up study showed that the use of DDI testing in real-world patients significantly improved (1) primary care patient management of drug interactions and (2) patient outcomes.

Overactive Bladder Prescribing Considerations: The Role of Polypharmacy, Anticholinergic Burden, and CYP2D6 Drug‒Drug Interactions

Overactive bladder (OAB) is a common disorder in the general population, and the prevalence increases with age. Adults with OAB typically have a greater number of comorbid conditions, such as hypertension, depression, and dementia, compared with adults without OAB. Subsequent to an increased number of comorbidities, adults with OAB take a greater number of concomitant medications, which may increase the risk of potentially harmful drug‒drug interactions. There are two important considerations for many of the medications approved for the treatment of OAB in the USA: anticholinergic burden and potential for drug‒drug interactions, notably related to cytochrome P450 (CYP) 2D6, which is responsible for the metabolism of approximately 25% of all drugs. A substantial number of drugs used for the treatment of OAB and comorbid conditions (e.g., cardiovascular and neurologic disorders) are CYP2D6 substrates or inhibitors. Furthermore, a substantial number of drugs with CYP2D6 properties also have strong anticholinergic properties. Here, we review polypharmacy associated with OAB and its common comorbidities, identify drugs with reported anticholinergic properties, and provide an overview of clinically relevant drug‒drug interactions in the treatment of OAB as they relate to CYP2D6 metabolism. This review aims to provide clinicians with essential information necessary for making treatment decisions when managing OAB.

Potentially inappropriate medications involved in drug-drug interactions at hospital discharge in Croatia

Background The potentially inappropriate medications (PIMs) and drug-drug interactions (DDIs) can significantly affect patient safety in the elderly, especially at transition of health care. Objective The aim of this study is to evaluate PIMs involved in potentially clinically significant DDIs in prescribed pharmacotherapy of elderly patients at hospital discharge. Setting Internal Medicine Clinic of University Hospital Dubrava, Zagreb, Croatia. Method During a 16-month period, the pharmacotherapy data were assessed using Lexicomp Online screening software to identify category C (monitor drug therapy), D (consider therapy modification) and X (avoid combination) DDIs. The European Union (EU)(7)-PIM criteria were applied to detect inappropriately prescribed medications involved in DDIs. Clinical pharmacists obtained data from patients' medical records and patient/caregiver interviews. Main outcome measure The incidence of PIMs involved in potentially clinically significant DDIs. Results A total of 364 consecutive elderly patients were enrolled in the study. The mean number of prescription medications at discharge was 9.3. Overall, 2833 potentially clinically significant DDIs were identified: 2445 (86.3%) of them were category C, 347 (12.3%) category D and 41 (1.4%) were category X interactions. A total of 1164 PIMs were involved in 31.2% of category C interactions, 60.2% of category D interactions and 43.9% of category X interactions. The most frequent PIMs involved in potentially clinically significant DDIs were tramadol, benzodiazepines, moxonidine, vildagliptin and metoclopramide. Conclusion A very high incidence of DDIs in elderly patients and a high incidence of PIMs involved in DDIs was determined at hospital discharge.

Peripheral Opioid Receptor Antagonists for Opioid-Induced Constipation: A Primer on Pharmacokinetic Variabilities with a Focus on Drug Interactions

Opioid analgesics remain a treatment option for refractory acute and chronic pain, despite their potential risk for abuse and adverse events (AEs). Opioids are associated with several common AEs, but the most bothersome is opioid-induced constipation (OIC). OIC is often overlooked but has the potential to affect patient quality of life, increase associated symptom burden, and impede long-term opioid compliance. The peripherally acting µ-receptor antagonists (PAMORAs) are a class of drugs that include methylnaltrexone, naloxegol, and naldemedine. Collectively, each is approved for the treatment of OIC. PAMORAs work peripherally in the gastrointestinal tract, without impacting the central analgesic effects of opioids. However, each has unique pharmacokinetic properties that may be impacted by coadministered drugs or food. This review focuses on important metabolic and pharmacokinetic principals that are pertinent to drug interactions involving µ-opioid receptor antagonists prescribed for OIC. It highlights subtle differences among the PAMORAs that may have clinical significance. For example, unlike naloxegol or naldemedine, methylnaltrexone is not a substrate for CYP3A4 or p-glycoprotein; therefore, its plasma concentration is not altered when coadministered with concomitant medications that are CYP3A4 or p-glycoprotein inducers or inhibitors. With a better understanding of pharmacokinetic nuances of each PAMORA, clinicians will be better equipped to identify potential safety and efficacy considerations that may arise when PAMORAs are coadministered with other medications.