Clinical significance of pharmacokinetic drug interactions with over-the-counter (OTC) drugs

Primary care electronic medication record discrepancies in patients starting treatment at a hospital-based ambulatory care pharmacy and impact on prevalence of potential drug-drug interactions

OBJECTIVE

Our objective was to evaluate the prevalence of discrepancies between primary care electronic medication records (EMR) and patient reported medication (PRM) in ambulatory patients starting a hospital dispensing treatment (HDT) at a hospital-based ambulatory care pharmacy (HACPh). Our secondary aims were to analyse factors associated with the presence of discrepancies and their impact on the prevalence of potential drug-drug interactions (DDIs) with the HDT.

METHODS

Retrospective study including 230 patients starting a HDT at the HACPh. Pharmacists interviewed patients and PRM was compared with EMR. Discrepancies were classified as omissions (medication in the PRM not present in the EMR) and commissions (medication active in the EMR that the patients were not taking). Potential DDIs with the HDT were screened, and univariate and multivariate analyses were performed to detect factors associated with the presence of discrepancies.

RESULTS

We identified 221 discrepancies in 116 (50.4%) patients. Being visited by three or more medical specialties (OR 1.93, 95% CI 1.11 to 3.37) and attending private healthcare (OR 4.36, 95% CI 1.14 to 16.72) in the 12 months before the study inclusion were the factors independently associated with the presence of discrepancies. Among patients with commissions (n=91), 15.4% had a potential DDI between the HDT and one medication from the EMR that they were not taking at that moment. Among patients with omissions (n=45), 11.1% had a potential DDI between the HDT and a medication in the PRM not present in the EMR.

CONCLUSIONS

About 40% of patients had one or more medications in the EMR which they were not taking and one fifth used medications that were not listed in the EMR. EMR should not be used as the only source of information when screening for DDIs, especially in patients followed by different medical specialties or combining private and public healthcare.

Prevalence and impacts of self-medication in a disadvantaged setting: the importance of multi-dimensional health interventions

Background

Self-medication is recognized as an effective form of treatment and is increasingly encouraged to treat minor illnesses. However, misuse of self-medication leaves devastating impacts on human health and causes antimicrobial resistance. Using medication without a prescription among farmers could cause more severe effects on their health than non-farm workers since they suffer from several occupational hazards such as excessive exposure to pesticides.

Methods

A cross-sectional study was conducted in 197 residents living in Moc Chau from August to September. A structured questionnaire and face-to-face were used to collecting data. The multivariate logistic model was applied to indicate associated factors with the self-medication.

Results

The prevalence of self-medication among farmers was 67%. Pain relievers (66.7%) and antibiotics (32.5%) were the types of medicines that were the most commonly purchased and used without a medical prescription. Ethnics and health status also significantly affected the self-medication practice as well as the purchase and use of antibiotics. The distance to travel to a medical center and the dangerous or difficult travel, participants with arthritis or inpatient treatment had significantly associated with buying and using the medicine and antibiotics without the medical prescription of farmers.

Conclusion

Our research highlights a considerably high prevalence of self-medication among farmers residing in the mountainous area of Vietnam. Individual factors such as ethnics, health status, distance to health centers, and dangerous or difficult travel were found to be related to the SM practice as well as the purchase and use of antibiotics. From that, the current study suggests interventions. For instance, official guidelines are needed to raise awareness and minimize the disadvantages of self-medication; and digital health technologies should be applied to reduce the gap in healthcare service between mountainous and other areas of Vietnam.

Over-The-Counter Remedies in Older Adults: Patterns of Use, Potential Pitfalls, and Proposed Solutions

Over-the-counter (OTC) products such as pharmaceuticals, dietary supplements, vitamins, and herbal remedies are widely available and copiously used by older adults for health maintenance and symptom management. Owing to physiology, multimorbidity, and polypharmacy, this population is particularly vulnerable to inappropriate use of OTC products, adverse effects, and drug interactions. While OTC pharmaceuticals are bound by FDA-approved standards, dietary supplements are regulated differently, resulting in variable quality and increased possibility for adulteration. Internationally, standards for OTC products vary widely. Accessible educational information, improved provider-patient communication, and revision of regulatory policy could improve safety for older adult users of OTC products.

The accuracy of self-reported drug ingestion histories in emergency department patients

Inaccuracies in self-reports may lead to duplication of therapy, failure to appreciate non-compliance leading to exacerbation of chronic medical conditions, or inaccurate research conclusions. Our objective is to determine the accuracy of self-reported drug ingestion histories in patients presenting to an urban academic emergency department (ED). We conducted a prospective cohort study in ED patients presenting for pain or nausea. We obtained a structured drug ingestion history including all prescription drugs, over-the-counter medication (OTC) drugs, and illicit drugs for the 48 hours prior to ED presentation. We obtained urine comprehensive drug screens (CDS) and determined self-report/CDS concordance. Fifty-five patients were enrolled. Self-reported drug ingestion histories were poor in these patients; only 17 (30.9%) of histories were concordant with the CDS. For the individual drug classes, prescription drug-CDS was concordant in 32 (58.2%), OTC-CDS was concordant in 33 (60%), and illicit drug-CDS was concordant in 45 (81.8%) of subjects. No demographic factors predicted an accurate self-reported drug history. Sixteen patients had drugs detected by CDS that were unreported by history. Nine of these 16 included an unreported opioid. In conclusion, self-reported drug ingestion histories are often inaccurate and resources are needed to confirm compliance and ensure unreported drugs are not overlooked.

Self-medication with over-the-counter drugs and complementary medications in South Australia's elderly population

Background

A number of surveys have examined use of complementary and alternative medicines (CAM) in Australia. However, there are limited Australian data on use of CAM and over-the-counter (OTC) medicines in the elderly population. The main aims of this study were to examine self-medication practices with CAM and OTC medicines among older Australians and variables associated with their use.

Methods

The Australian Longitudinal Study of Ageing (ALSA) is an ongoing multidisciplinary prospective study of the older population which commenced in 1992 in South Australia. Data collected in 4 waves of ALSA between 1992 and 2004 were used in this study with a baseline sample of 2087 adults aged 65 years and over, living in the community or residential aged care. OTC medicines were classified according to the World Health Organization Anatomical Therapeutic Chemical (ATC) classification. CAM were classified according a modified version of the classification adopted by the Therapeutics Goods Administration (TGA) in Australia.

Results

The prevalence of CAM or OTC use ranged from 17.7% in 2000-2001 to 35.5% in 2003-2004. The top classes of CAM and OTC medicines used remained relatively constant over the study period. The most frequent classes of CAM used were vitamins and minerals, herbal medicines and nutritional supplements while the most commonly used OTC were analgesics, laxatives and low dose aspirin. Females and those of younger age were more likely to be CAM users but no variable was associated with OTC use.

Conclusion

Participants seemed to self-medicate in accordance with approved indications, suggesting they were informed consumers, actively looking after their own health. However, use of analgesics and aspirin are associated with an increased risk of adverse drug events in the elderly. Future work should examine how self-medication contributes to polypharmacy and increases the risk of adverse drug reactions.

The use of non-prescription medicines by general practitioner attendees

PURPOSE

Against a background of increasing availability and use of non-prescription medicines, this study set out to explore: use of such medicines by patients seeing their general practitioner (GP); frequency of GP enquiry about such use; and frequency of recommendations to use a non-prescription medicine.

METHOD

Patients attending four general practices in Aberdeen, Scotland, completed separate questionnaires (before and after seeing their GP).

RESULTS

Some 461 individuals waiting to see their GP were invited to participate: 427 (93%) completed the pre-consultation questionnaire and 305 (71% of questionnaires issued) completed the post-consultation questionnaire. Almost half (45%) of all participants reported using non-prescription medicines in the 7 days prior to visiting their doctor; with 20% of the medicines purchased from non-pharmacy retail outlets. Thirteen per cent of participants were asked about their use of non-prescribed medicines by their GP. Eight per cent of participants were recommended to use a non-prescription medicine by their GP.

CONCLUSION

Although there was a high level of recent use of non-prescribed medicines by the general practice attenders, relatively few reported being asked about such use, or were recommended to use such medicines by their GP.

Switching of Prescription Drugs to Over-the-Counter Status

Prescription medicines are increasingly being switched to over-the-counter (OTC, nonprescription) status in the developed world, with the support of government policy. These changes may provide greater choice for individuals and offer potential savings in government spending on health while expanding the market for pharmaceutical companies. However, there is concern regarding the safety of these reclassifications. Elderly people are the largest consumers of prescription and OTC medicines and are more vulnerable to drug adverse effects and the risks of multiple or inappropriate medications. Commonly purchased agents such as NSAIDs have recognised adverse effects which have been shown to be more common in the elderly. Furthermore, all sedatives, including antihistamines, have a propensity to cause falls in older people. As many doctors do not ask patients about OTC medicine use, problems related to use of these drugs may go undetected. Furthermore, the increased availability of OTCs may result in a delay in patients consulting medical practitioners for potentially serious conditions, although this has not so far been investigated. In the UK, the recent switch of a low-dose HMG-CoA reductase inhibitor (statin) to OTC status has caused concern. Although there might theoretically be some benefits from improved access to medications used in primary and secondary prevention of heart disease, the actual outcomes of use of this reduced dose of the statin will be difficult or impossible for patients or practitioners to monitor. OTC drug use implies a mutual responsibility for communication between patients and health professionals that in practice is not always achieved. Epidemiological research is needed to investigate patterns of OTC use and evaluate the potential risks of OTC medicines in elderly people. Governments, regulatory bodies, professionals and the drug industry have a responsibility to ensure that robust systems are in place if the increased use of OTC medicines by elderly people is to be safe and effective.

Over-the-counter analgesics in older adults: a call for improved labelling and consumer education

The use of analgesics increases with age and on any given day 20-30% of older adults take an analgesic medication. Over-the-counter (OTC) analgesics are generally well tolerated and effective when taken for brief periods of time and at recommended dosages. However, their long-term use, use at inappropriately high doses, or use by persons with contraindications may result in adverse effects, including gastrointestinal haemorrhage, cardiovascular toxicity, renal toxicity and hepatotoxicity. Many OTC drugs are also available through a prescription, for a broader range of indications and for longer durations of use and wider dose ranges, under the assumption that healthcare providers will help patients make safe choices about analgesics. Safe and effective use of medications is one of the greatest challenges faced by healthcare providers in medicine. More than 60% of people cannot identify the active ingredient in their brand of pain reliever. Additionally, about 40% of Americans believe that OTC drugs are too weak to cause any real harm. As a result of a recent US FDA policy, the conversion of prescription to OTC medications will result in a 50% increase of OTC medications. To reduce the risks of potential adverse effects from OTC drug therapy in older adults, we propose that the use of analgesics will be enhanced through the use of patient and healthcare provider education, as well as improved labelling of OTC analgesics. Improved labelling of OTC analgesics may help consumers distinguish common analgesic ingredients in a wide variety of preparations and facilitate informed decisions concerning the use of OTC drugs.

The use of over-the-counter drugs among surgical and medical patients

INTRODUCTION

An increasing number of drugs are sold directly to the consumers without a prescription from pharmacies and from non-pharmacies such as supermarkets and gas stations.

AIM OF STUDY

To analyse the consumption of over-the-counter drugs (OTCs) among patients recently discharged from two hospital departments. Furthermore, to describe where the drugs had been bought and to which extent OTCs used prior to admission were recorded in the hospital files.

METHOD

Patients were visited within 1 week after discharge and interviewed about OTC use. Home inventories were inspected. Hospital files and discharge letters were examined.

RESULTS

In totally, 83 surgical and 117 medical patients were included (n=200). Whereas the home inventories of 187 patients comprised 587 OTCs, 13 patients (7%) stored no OTCs. Of the patients, 134 (67%) used OTCs daily and 132 patients (66%) used OTCs on demand; 79 patients (40%) stored a total of 157 OTCs not currently used. Analgesics were used by 138 patients (78%). Acetaminophen was the OTC used most frequently. Of the 240 OTCs used daily, 238 (99%) had been purchased from pharmacies and 169 (70%) had been prescribed. Of the 430 OTCs used daily or on demand, 348 (81%) had been recommended verbally or prescribed by health care professionals. Among the 206 OTCs used daily prior to admission, 162 (79%) were recorded in hospital files, whereas only 41 (24%) of 173 OTCs used on demand were recorded.

CONCLUSION

Two of three surgical and medical patients use OTCs daily. Most OTCs are used with the consent of health care professionals and are purchased from pharmacies. Pre-admission OTC use is incompletely recorded in the hospital files. If information was systematically collected from pharmacies and general practitioners, the number of recall biases concerning OTC use in the medication histories may be reduced.

Monitoring self-medication

Self-medication, using non-prescription drugs, is beneficial to patients, healthcare professionals, the pharmaceutical industry and governments. Although many non-prescription medications are effective, misuse and abuse of these products can arise. Monitoring of specific populations and products, in addition to data recording and educating and informing patients, may go some way towards promoting safe and effective self-medication.

Pharmacovigilance of over-the-counter products based in community pharmacy: methodological issues from pilot work conducted in Hampshire and Grampian, UK

PURPOSE

The incidence of serious adverse events from non-prescription medicines remains to be established. The aim of this initial pilot work, using an observational cohort design, was to determine the feasibility of conducting a pharmacovigilance study of a non-prescription medicine, based in community pharmacies.

METHOD

Community pharmacists from Grampian, Scotland, and Hampshire, England, recruited user-purchasers of ibuprofen. Exposure data were collected from a series of self-completed questionnaires. Outcome data were any new symptoms, use of concomitant medication and subsequent health-care utilization.

RESULTS

A total of 1021 eligible customers were recruited, 6.4% (466/7320) and 48.2% (555/1152) by the Hampshire and Grampian networks respectively. The cohorts differed with regard to age, smoking and socio-economic status, reason for purchase and recommendation, and duration of use. The two cohorts reported different use of concomitant medication (46.0 and 65.5%), asthma (7.2 and 10.5%), stomach/peptic ulcer (3.5 and 2.1%), a higher prevalence of gastrointestinal symptoms post-compared to pre-purchase (12.9 vs. 7.2%, p = 0.0006 and 8.8 vs. 5.8%, p = 0.034), ingestion of doses in excess of the licensed non-prescription dose by 5.1 and 3.9%, and discontinuation of treatment because the medicine upset them by 4.5 and 3.1%, respectively. Most participants did not seek medical advice for their symptoms.

CONCLUSION

Greater vigilance is required for adverse events that may be attributable to non-prescription product use. Development of pharmacovigilance models using community pharmacies is one means of systematically collecting information regarding drug safety. Further work is needed to identify a method which maximizes patient recruitment whilst maintaining acceptable follow-up rates.

Benefits and risks of self medication

Self medication is becoming an increasingly important area within healthcare. It moves patients towards greater independence in making decisions about management of minor illnesses, thereby promoting empowerment. Self medication also has advantages for healthcare systems as it facilitates better use of clinical skills, increases access to medication and may contribute to reducing prescribed drug costs associated with publicly funded health programmes. However, self medication is associated with risks such as misdiagnosis, use of excessive drug dosage, prolonged duration of use, drug interactions and polypharmacy. The latter may be particularly problematic in the elderly. Monitoring systems, a partnership between patients, physicians and pharmacists and the provision of education and information to all concerned on safe self medication, are proposed strategies for maximising benefit and minimising risk.

Clinically significant pharmacokinetic interactions between dietary caffeine and medications

Caffeine from dietary sources (mainly coffee, tea and soft drinks) is the most frequently and widely consumed CNS stimulant in the world today. Because of its enormous popularity, the consumption of caffeine is generally thought to be safe and long term caffeine intake may be disregarded as a medical problem. However, it is clear that this compound has many of the features usually associated with a drug of abuse. Furthermore, physicians should be aware of the possible contribution of dietary caffeine to the presenting signs and symptoms of patients. The toxic effects of caffeine are extensions of their pharmacological effects. The most serious caffeine-related CNS effects include seizures and delirium. Other symptoms affecting the cardiovascular system range from moderate increases in heart rate to more severe cardiac arrhythmia. Although tolerance develops to many of the pharmacological effects of caffeine, tolerance may be overwhelmed by the nonlinear accumulation of caffeine when its metabolism becomes saturated. This might occur with high levels of consumption or as the result of a pharmacokinetic interaction between caffeine and over-the-counter or prescription medications. The polycyclic aromatic hydrocarbon-inducible cytochrome P450 (CYP) 1A2 participates in the metabolism of caffeine as well as of a number of clinically important drugs. A number of drugs, including certain selective serotonin reuptake inhibitors (particularly fluvoxamine), antiarrhythmics (mexiletine), antipsychotics (clozapine), psoralens, idrocilamide and phenylpropanolamine, bronchodilators (furafylline and theophylline) and quinolones (enoxacin), have been reported to be potent inhibitors of this isoenzyme. This has important clinical implications, since drugs that are metabolised by, or bind to, the same CYP enzyme have a high potential for pharmacokinetic interactions due to inhibition of drug metabolism. Thus, pharmacokinetic interactions at the CYP1A2 enzyme level may cause toxic effects during concomitant administration of caffeine and certain drugs used for cardiovascular, CNS (an excessive dietary intake of caffeine has also been observed in psychiatric patients), gastrointestinal, infectious, respiratory and skin disorders. Unless a lack of interaction has already been demonstrated for the potentially interacting drug, dietary caffeine intake should be considered when planning, or assessing response to, drug therapy. Some of the reported interactions of caffeine, irrespective of clinical relevance, might inadvertently cause athletes to exceed the urinary caffeine concentration limit set by sports authorities at 12 mg/L. Finally, caffeine is a useful and reliable probe drug for the assessment of CYP1A2 activity, which is of considerable interest for metabolic studies in human populations.