Severe loperamide toxicity associated with the use of cimetidine to potentiate the “high”

An Opioid Hiding in Plain Sight: Loperamide-Induced False-Positive Fentanyl and Buprenorphine Immunoassay Results

BACKGROUND

Loperamide (Imodium®), a commonly used anti-diarrheal, is a mu opioid receptor agonist that, like all opioids, reduces gastrointestinal tract peristalsis. Loperamide is considered to have low abuse potential as it does not produce an analgesic or euphoric effect due to low bioavailability and first-pass metabolism. However, reports of individuals misusing loperamide through the use of super-therapeutic doses, alone or in combination with P-glycoprotein and/or CYP450 enzyme inhibitors, is increasing. We hypothesized that loperamide could potentially cross-react with laboratory immunoassay drug screens.

METHODS

Drug-free urine was spiked with loperamide or its principal metabolite, N-desmethyl loperamide (dLop), and assayed on multiple fentanyl and buprenorphine assays. Fentanyl immunoassay screen-positive results at one institution were examined by high-resolution mass spectrometry (MS) for the presence of loperamide and quantified by liquid chromatography- tandem MS when positive.

RESULTS

Loperamide produced positive results on the Thermo DRI Fentanyl and Immunalysis Fentanyl assays at concentrations greater than 5.72 mg/L and 23.7 mg/L. dLop generated positive results for the Thermo DRI and Immunalysis fentanyl assays at concentrations exceeding 6.9 mg/L and 35.7 mg/L. dLop also produced positive buprenorphine results on the Thermo CEDIA buprenorphine assay at concentrations exceeding 12.2 mg/L. High-resolution MS analysis of 225 fentanyl immunoassay positives (Thermo DRI) yielded 5 specimens containing loperamide and/or dLop, 4 of which contained measurable quantities of fentanyl in addition to loperamide/dLop.

CONCLUSIONS

Laboratories using these assays should be aware of the potential for false-positive screening results due to the presence of high concentrations of loperamide and its metabolite dLop.

Effects of opioid receptor agonist and antagonist medications on electrocardiogram changes and presentation of cardiac arrhythmia: review article

BACKGROUND/PURPOSE

Mortality associated with prescription opioids has significantly increased over the past few decades and is considered a global pandemic. Prescribed opioids can cause cardiac arrhythmias, leading to fatal outcomes and unexpected death, even in the absence of structural cardiac disease. Despite the extent of cardiac toxicity and death associated with these medications, there is limited data to suggest their influences on cardiac electrophysiology and arrhythmias, with the exception of methadone. The goal of our review is to describe the possible mechanisms and to review the different ECG changes and arrhythmias that have been reported.

METHODS

A literature search was performed using Google Scholar, PubMed, Springer, Ovid, and Science Direct to identify studies that demonstrated the use of prescription opioids leading to electrocardiogram (ECG) changes and cardiac arrhythmias.

RESULTS

Many of the commonly prescribed opioid medications can uniquely effect the ECG, and can lead to the development of various cardiac arrhythmias. One of the most significant side effects of these drugs is QTc interval prolongation, especially when administered to patients with a baseline risk for QTc prolongation. A prolonged QTc interval can cause lethal torsades de pointes and ventricular fibrillation. Obtaining an ECG at baseline, following a dosage increase, or after switching an opioid medication, is appropriate in patients taking certain prescribed opioids. Opioids are often used first line for the treatment of acute and chronic pain, procedural sedation, medication opioid use disorders, and maintenance therapy.

CONCLUSIONS

To reduce the risk of cardiac arrhythmias and to improve patient outcomes, consideration of accurate patient selection, concomitant medications, electrolyte monitoring, and vigilant ECG monitoring should be considered.

Pharmacological Aspects of Over-the-Counter Opioid Drugs Misuse

Several over-the-counter (OTC) drugs are known to be misused. Among them are opioids such as codeine, dihydrocodeine, and loperamide. This work elucidates their pharmacology, interactions, safety profiles, and how pharmacology is being manipulated to misuse these common medications, with the aim to expand on the subject outlined by the authors focusing on abuse prevention and prevalence rates. The reviewed literature was identified in several online databases through searches conducted with phrases created by combining the international non-proprietary names of the drugs with terms related to drug misuse. The results show that OTC opioids are misused as an alternative for illicit narcotics, or prescription-only opioids. The potency of codeine and loperamide is strongly dependent on the individual enzymatic activity of CYP2D6 and CYP3A4, as well as P-glycoprotein function. Codeine can also be utilized as a substrate for clandestine syntheses of more potent drugs of abuse, namely desomorphine (“Krokodil”), and morphine. The dangerous methods used to prepare these substances can result in poisoning from toxic chemicals and impurities originating from the synthesis procedure. OTC opioids are generally safe when consumed in accordance with medical guidelines. However, the intake of supratherapeutic amounts of these substances may reveal surprising traits of common medications.

The unsuspected threat of three opioid-like substitutes

The opioid epidemic has left its toll on the United States with millions suffering from an opioid use disorder and tens of thousands dying from overdoses each year. With intentions to combat the crisis, health providers have been prescribing less opioids, which resulted in an unintentional increase in the abuse of other opioid-like substances. Three emerging drugs of abuse have been noted in the literature as having increased abuse potential in light of recent trends. Kratom, an herbal supplement, gabapentin, a prescription nerve pain and anticonvulsant medication, and loperamide, an over-the-counter antidiarrheal medication. These have all displayed opioid-like properties at high doses and used to alleviate opioid withdrawal. Healthcare clinicians and patients might not be aware of the potential risks involved with misusing or abusing these opioid substitutes. This article discusses the increased usage of kratom, gabapentin, and loperamide, the abuse potential, adverse effects and withdrawal symptoms of each drug, and nursing implications that impact inpatient safety and management.