Over-the-counter medications. Do you know what your patients are taking?

Drug-Drug Interactions With Over-The-Counter Medicines: Mind the Unprescribed

BACKGROUND

This review provides a summary of the currently available clinical data on drug-drug interactions (DDIs) involving over-the-counter (OTC) medicines. It aims to educate and increase awareness among health care providers and to support decisions in daily practice.

METHODS

An extensive literature search was performed using bibliographic databases available through PubMed.gov. An initial structured search was performed using the keywords "drug-drug-interaction AND (over-the-counter OR OTC)," without further restrictions except for the language. The initial results were screened for all described DDIs involving OTC drugs, and further information was gathered specifically on these drugs using dedicated database searches and references found in the bibliography from the initial hits.

RESULTS

From more than 1200 initial hits (1972-June 2021), 408 relevant publications were screened for DDIs involving OTC drugs, leading to 2 major findings: first, certain types of drug regimens are more prone to DDIs or have more serious DDI-related consequences, such as antiretroviral, anti-infective, and oral anticancer therapies. Second, although most DDIs involve OTC drugs as the perpetrators, some prescription drugs (statins or phosphodiesterase-5 inhibitors) that currently have OTC status can be identified as the victims in DDIs. The following groups were identified to be frequently involved in DDIs: nonsteroidal anti-inflammatory drugs, food supplements, antacids, proton-pump inhibitors, H2 antihistamines, laxatives, antidiarrheal drugs, and herbal drugs.

CONCLUSIONS

The most significant finding was the lack of high-quality evidence for commonly acknowledged interactions. High-quality interaction studies involving different phenotypes in drug metabolism (cytochrome P450) and distribution (transporters) are urgently needed. This should include modern and critical drugs, such as oral anticancer medications and direct oral anticoagulants.

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.

Drug-drug interactions among recently hospitalised patients – frequent but mostly clinically insignificant

OBJECTIVE

Patients use and store considerable amounts of drugs. The aim of the present study was to identify potential drug-drug interactions between drugs used by patients recently discharged from the hospital and, subsequently, to estimate the clinical implications of these interactions.

METHODS

Patients were visited within 1 week following their discharge from hospital and interviewed about their drug use. Stored products were inspected. We used a bibliography (Hansten and Horn; Wolters Kluwer Health, St. Louis, Mo., 2004) to identify and classify potential drug-drug interactions.

RESULTS

In total, 83 surgical and 117 medical patients (n = 200) were included in the survey, of which 139 (70%) were women. The median age was 75 years (range: 24-100 years). Patients stored 2119 medications at home (median: nine per patient; range: 2-44) and used 1622 medications daily or on demand (median: eight per patient; range: 1-24). With respect to those drugs used daily or on demand, 476 potential interactions were identified (126 patients); none were class 1 (always avoid drug combination) and 25 were class 2 (usually avoid combination; 24 patients). Eleven of the potential class 2 interactions involved over-the-counter products (aspirin and ginkgo biloba). Of the 52 drugs involved in potential class 2 interactions, 50 had been used for more than 1 month. According to the hospital case notes, none of the potential class 2 interactions had actually caused adverse effects.

CONCLUSION

Although potential drug-drug interactions are highly prevalent, serious and clinically significant interactions are rare among recently hospitalised patients.

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.

Review article: over-the-counter drugs and the gastrointestinal tract

An increasing number of drugs are becoming available over-the-counter, empowering patients to treat them- selves. Although drugs presently available over-the-counter are generally safe, there are issues of safety and possible delays in diagnosis of serious conditions. Therefore it is vital that patients are made aware of the indications and limitations of over-the-counter drugs through improved communication and education. Pharmacists and drug companies will have an increasingly important role in giving information and advice to patients. This review looks at the present and future of over-the-counter medication, highlighting the safety aspects.

Relationships between prescription and non-prescription drug use in an elderly population

This paper explores, at an epidemiological level, the relationship between categories of over-the-counter (OTC) and prescribed (Rx) drugs in a community-resident elderly population. A total of 2818, randomly selected, older adults were interviewed at home about their use of prescribed and non-prescribed medication and other health-related factors. For comparative purposes OTC drugs were classified into 16 therapeutic groups-identical to those used by other researchers; prescribed drugs were classified into 45 British National Formulary (BNF) therapeutic sub-categories. Analyses revealed significant association between certain BNF categories and OTC categories, which may have a clinical explanation. These include a 3-fold increase (P<0.01) of OTC laxative use by those prescribed an antidepressant, and a 4-fold increase (P<0.001) in OTC antacid use among those prescribed oral corticosteroids. Our findings may indicate an attempt by older people to control side effects of prescription medicines with OTC preparations. This study, in part, supports the call by the Royal College of Physicians for further research to determine the effect of interactions (be they pharmacological, behavioural or otherwise) between OTC and prescribed medicines.

Self-administration of medication by patients and family members during hospitalization

The current trend of shorter hospital stays has heightened concern about the adequacy of preparation of patients and their families to understand and follow prescribed medication regimens properly following discharge. Cooperative Care, an education-intensive unit incorporating a living-in family member or friend acting as a 'care partner,' has had a self-administration of medication program (SAM) for the past 16 years. This paper describes SAM and reports on two studies of its effectiveness. The first was a 1-week survey of all patients (151) admitted to the unit. 126 (83.4%) were taking a mean of five medications, with a range of one to 17. Of those, 102 (80.9%) were able to participate in SAM independently, and 11 (8.7%) were on SAM with supervision by their care partners. The second study reviewed medication administration errors within Cooperative Care and the traditional nursing units of Tisch Hospital over a 4-year period (1991-1994). Cooperative Care accounted for 19.4% of discharges (22,164/114,206) and 10.3% of patient days (97,037/944,230), but only 4.6% of medication errors (80/1723). The medication error rate per 1000 discharges was 3.6 for Cooperative Care, and 17.8 for the traditional units. Comparative error rates per 10,000 medication orders were 3.06 at Cooperative Care and 4.01 on the traditional units. 74.8% of Cooperative Care patients were on SAM, but only 30% of the errors were attributed to patients or care partners. The other errors were attributed to nursing staff (50%), equipment defects (12.5%) or pharmacists (5%). Our data indicate that SAM during hospitalization is a safe and effective modality of care.