Acute intoxication with guaifenesin, diphenhydramine, and chlorpheniramine

Over-the-counter drug use in suicidal/self-harm behavior: Scoping review

Background and aims

Minor physical ailments are treated with over-the-counter (OTC) medications. The availability of OTC drugs helps reduce waiting times and ease the suffering of many. Suicidal behavior includes suicidal ideation, attempts, and completed suicides and affects people of all ages, religions, and cultures. This study aims to review use of OTC drugs for self-harm and suicidal attempts.

Methods

We reviewed English language publications from the beginning of time to October 2021 on OTC drug use for suicidal behavior.

Results

Twenty-seven studies met the eligibility criteria, and 1,816,228 participants were reported in these publications. OTC analgesics and sedatives/hypnotics were frequently used for suicidal behavior. Females and young people mainly were reported to self-harm using OTC medications. An increase in OTC analgesic use for self-harm in adolescents during the school months was reported. Elderly persons use hypnotics more frequently for suicidal attempts. Persons with major psychiatric disorders were reported to use OTC for suicidal behavior.

Conclusion

The available information shows that the prevention strategies should focus on OTC analgesics and hypnotic use among women, the young, the elderly, and persons with mental health disorders.

Role of guaifenesin in the management of chronic bronchitis and upper respiratory tract infections

Guaifenesin, a mucoactive drug, acts by loosening mucus in the airways and making coughs more productive. It is used for relief of wet cough and chest congestion due to the common cold, and remains the only legally marketed expectorant in the US (per OTC Monograph). An ingredient in numerous over-the-counter (OTC) cough/cold medications, guaifenesin has a secondary indication for use in stable chronic bronchitis (professional indication). Clinical pharmacology and patient studies support the clinical utility of guaifenesin in respiratory conditions where mucus hypersecretion is prevalent: acute upper respiratory tract infections (URTIs), stable chronic bronchitis, and possibly rhinosinusitis. Guaifenesin has a well-established and favorable safety and tolerability profile in adult and pediatric populations. Its dosing range (200–400 mg 4-hourly, up to 6× daily) allows flexible dose titration to allow an increase of plasma concentrations. Multiple daily doses are needed to maintain 24-h therapeutic effect with immediate-release formulations. Extended-release guaifenesin tablet formulations are available, providing convenience with 12-hourly dosing and portability compared to liquids. Guaifenesin is considered as a safe and effective expectorant for the treatment of mucus-related symptoms in acute URTIs and stable chronic bronchitis. Its clinical efficacy has been demonstrated most widely in chronic respiratory conditions, where excess mucus production and cough are more stable symptoms. Progress is being made to establish clinical models and measures that are more appropriate for studying symptomatic relief with guaifenesin in acute respiratory infections. This will help generate the up-to-date and high-quality data needed to optimize guaifenesin’s effectiveness in established uses, and in new respiratory indications associated with mucus hypersecretion.

Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review

Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.

Diphenhydramine's role in death investigations: an examination of diphenhydramine prevalence in 2 US geographical areas

PURPOSE

Diphenhydramine (DPH), an over-the-counter first-generation H1 receptor antagonist, is not a common drug of abuse; however, it is encountered in cases of overdose both in the clinical setting and in death investigations. The toxicology laboratories in the Tarrant County Medical Examiner's Office and the District of Columbia Office of The Chief Medical Examiner analyze antemortem and postmortem specimens. Presented are the findings of this evaluation and detailed histories of cases involving DPH.

METHODS

Toxicology reports, autopsy reports, and death investigator narratives were obtained in cases involving DPH at toxic and lethal levels in which this compound was the primary cause or a contributing factor in the death.

RESULTS

Blood concentrations were quantified at a range of 2870 to 21,263 ng/mL. A rare occurrence of DPH abuse via documented intravenous administration leading to death is presented. The cases presented here generally involved much higher concentrations of DPH and an older population than those in previous published data regarding DPH's role in death investigation and abuse.

CONCLUSIONS

As people seek legal alternative drugs to abuse and with the ease of obtaining information via online forums, there is a potential to see an increase in the number of cases involving excessive use of DPH.

Postmortem distribution of guaifenesin concentrations reveals a lack of potential for redistribution

Therapeutic (or non-toxic) postmortem guaifenesin blood and liver concentrations have not been previously described. Peripheral blood guaifenesin concentrations were compared to central blood and liver concentrations in eight medical examiner cases. Specimens were initially screened for alcohol and simple volatiles, drugs of abuse, alkaline, and acid/neutral drugs. Guaifenesin, when detected by the acid/neutral drug screen, was subsequently confirmed and quantified by a high performance liquid chromatography procedure. Data suggest that postmortem guaifenesin peripheral blood concentrations may be considered non-toxic to at least 5.4mg/L with liver concentrations to at least 7.0mg/kg. Overall, guaifenesin concentrations ranged from 1.9 to 40mg/L in peripheral blood, 2.2-150mg/L in central blood, and 2.6-36mg/kg in liver. The median guaifenesin central blood to peripheral blood ratio was 1.1 (N=8). Similarly, liver to peripheral blood ratios showed a median value of 0.9L/kg (N=5). Given that a liver to peripheral blood ratio less than 5L/kg is consistent with little to no propensity for postmortem redistribution, these data suggest that guaifenesin is not prone to substantial postmortem redistribution.

Effects of antihistamines on the function of human α7-nicotinic acetylcholine receptors

Effects of the histamine H₁ receptor (H1R) antagonists (antihistamines), promethazine (PMZ), orphenadrine (ORP), chlorpheniramine (CLP), pyrilamine (PYR), diphenhydramine (DPH), citerizine (CTZ), and triprolidine (TRP) on the functional properties of the cloned α7 subunit of the human nicotinic acetylcholine receptor expressed in Xenopus oocytes were investigated. Antihistamines inhibited the α7-nicotinic acetylcholine receptor in the order PYR>CLP>TRP>PMZ>ORP≥DPH≥CTZ. Among the antihistamines, PYR showed the highest reversible inhibition of acetylcholine (100 µM)-induced responses with IC₅₀ of 6.2 µM. PYR-induced inhibition was independent of the membrane potential and could not be reversed by increasing the concentration of acetylcholine. Specific binding of [¹²⁵I] α-bungarotoxin, a selective antagonist for α7-nicotinic acetylcholine receptor, was not changed in the presence of PYR suggesting a non-competitive inhibition of nicotinic receptors. In line with functional experiments, docking studies indicated that PYR can potentially bind allosterically with the α7 transmembrane domain. Our results indicate that the H₂-H₄ receptor antagonists tested in this study (10 µM) showed negligible inhibition of α7-nicotinic acetylcholine receptors. On the other hand, H₁ receptor antagonists inhibited the function of human α7-nicotinic acetylcholine receptor, with varying potencies. These results emphasize the importance of α7-nicotinic acetylcholine receptor for future pharmacological/toxicological profiling.

Acute renal failure after ingestion of guaifenesin and dextromethorphan

BACKGROUND

Guaifenesin is a common nonprescription medication that has been implicated in drug-induced nephrolithiasis. Dextromethorphan, a nonprescription antitussive found in some guaifenesin-containing preparations, is increasingly recognized as a substance of abuse by many youth and young adults. Renally excreted medications known to have poor solubility in urine have the potential to precipitate when ingested in large quantity, leading to acute obstruction of the ureters and renal failure.

OBJECTIVE

We describe the case of a 22-year-old male who developed severe bilateral flank pain, hematuria, and oliguria after an isolated recreational ingestion of guaifenesin and dextromethorphan.

CASE REPORT

The patient was found to have bilateral ureteral obstruction and acute renal failure, suspected to be secondary to precipitation of medication metabolites in the urine.

CONCLUSIONS

This case highlights the potential for acute renal failure secondary to guaifenesin and dextromethorphan abuse.

Toxicological identification of diphenhydramine (DPH) in suicide

Diphenhydramine (DPH), an H1-antihistamine, is identified during postmortem toxicological analyses on a relatively rare but still regular basis. This study examines suicidal intoxications with DPH by analyzing blood and gastric content concentration levels. Twenty cases of DPH intoxications within a 10-year period (2000-2010) were discovered by screening the autopsy records of the Institute of Legal Medicine and Forensic Sciences (ILMFS) in Berlin, Germany. In four cases, DPH levels were lower than 1 μg/mL and hence were not considered likely to be responsible for causing death. In 11 cases, DPH played a role in the fatal episode, and five of these cases were monointoxications. Considering that more than 8,000 autopsies were performed by the ILMFS within the time period under examination, there is only one monointoxication case every 2 years, which makes it a rare occurrence. In two of these intoxications, DPH was only measured in toxic but not "lethal" concentrations in blood, with a concentration of 5 μg/mL being generally used as the cut off between categories according to forensic literature. This raises the question as to whether a strict boundary for a "lethal" blood concentration, as suggested in some literature, can be set and applied in any of these cases. This study shows that an individual interpretation of each case is of utmost importance for correct classification. A thorough toxicological analysis of peripheral venous blood and gastric content, as well as a detailed work-up of the death circumstances, are the basis of an exact interpretation of intoxications with DPH.

Acute pulmonary edema associated with naphazoline ingestion

In published reports of naphazoline ingestion, clinical effects are hypertension, bradycardia, pallor, diaphoresis, and respiratory distress. We report three cases of acute pulmonary edema after the intentional ingestion of naphazoline-containing antiseptic first aid liquid. These cases presented with altered mental status, hypertension, bradycardia, and diaphoresis. Chest x-ray on admission revealed acute pulmonary edema. Two cases required mechanical ventilation. All of these clinical effects resolved within 24 hours and the patients were discharged with no sequelae. Since naphazoline stimulates the peripheral alpha-2 adrenergic receptor, we speculate that intense vasoconstriction may have elevated cardiac afterload and left atrial-ventricular blood volume and caused acute pulmonary edema.

Intoxication with over-the-counter antitussive medication containing dihydrocodeine and chlorpheniramine causes generalized convulsion and mixed acidosis

We report a 35-year-old man who was referred to our hospital with generalized convulsion and mixed acidosis presumably caused by abuse of SS-BRON tablets, an over-the-counter (OTC) antitussive medication sold in Japan. These tablets contain dihydrocodeine phosphate, methylephedrine, chlorpheniramine, and caffeine. Although it is difficult to discern which component caused these symptoms, it seems that dihydrocodeine phosphate or methylephedrine was involved in the addiction to SS-BRON and chlorpheniramine may have caused the generalized convulsion. It should be recognized that an OTC antitussive, which is quite easy to obtain, can be abused and subsequently induce serious intoxication.

Selective inhibition of Kir currents by antihistamines

In the present study, the effects of antihistamines on inwardly rectifying potassium (Kir) channels expressed in Xenopus oocyte were investigated using two-electrode voltage clamp technique. Firstly, effects of antihistamines on two members of Kir2.0 sub-family, Kir2.1 and Kir2.3 were compared. For antihistamines that selectively block histamine H(1) receptor, the first-generation antihistamines mepyramine and diphenhydramine inhibited Kir2.3 current by 25.0+/-2.9% and 17.3+/-0.7% at concentrations of 100 microM, respectively. In contrast, the second- and third-generation antihistamines astemizole and desloratadine were completely devoid of any inhibitory effect on Kir2.3 current. Histamine H(2) receptor antagonist cimetidine, at 100 microM, failed to inhibit Kir2.3 current. On the other hand, Kir2.1 current was not sensitive to any of these drugs. The mepyramine-induced inhibition of Kir2.3 current was significantly reduced by a single point mutation in Kir2.3 (Kir2.3(I213L)), which enhances Kir2.3-PIP(2) interaction. Secondly, the effect of mepyramine was also tested on Kir3.4*, another member of Kir family. 100 microM mepyramine produced a 30.3+/-4.6% inhibition on Kir3.4* current. These results suggest that the first-generation histamine H(1) receptor antagonists selectively inhibit Kir currents. The inhibitory effect of antihistamines on Kir currents may be involved in their neuronal and cardiac toxic effects caused by drug overdosing.

Histamine H1 antagonists block M-currents in dissociated rat cortical neurons

We investigated the effects of histamine H1 antagonists on acutely dissociated neurons from the rat cortex using the patch-clamp technique. First-generation antihistamines, such as pyrilamine, d-chlorpheniramine, diphenhydramine, and ketotifen, suppressed M-currents in a concentration-dependent manner with respective half-inhibition concentrations (C50) of 35.9, 48.5, 34.8, and 47.8 microM at a holding potential of -26.5 mV. Astemizole, a second-generation antihistamine, inhibited M-currents with a C50 of 18.1 microM, but cetirizine did not do so, up to a concentration of 300 microM. Neither ranitidine nor cimetidine, both H2 antagonists, suppressed M-currents. The C50 of pyrilamine significantly decreased with membrane hyperpolarization, suggesting that it acts directly on M channel pores. The inhibition of M channels may be involved in the neurotoxic effects of histamine H1 antagonist overdose.

Preanalytic aspects in postmortem toxicology

The preanalytic phase has been recognized to have a substantial role for the quality and reliability of analytical results, which very much depend on the type and quality of specimens provided. There are several unique challenges to select and collect specimens for postmortem toxicology investigation. Postmortem specimens may be numerous, and sample quality may be quite variable. An overview is given on specimens routinely collected as well as on alternative specimens that may provide additional information on the route of administration, a long term or a recent use/exposure to a drug or poison. Autolytic and putrefactive changes limit the selection and utility of specimens. Some data from case reports as well as experimental investigations on drug degradation and/or formation during putrefaction are discussed. Diffusion processes as well as postmortem degradation or formation may influence ethanol concentration in autopsy specimens. Formalin fixation of specimens or embalmment of the corpse may cause considerable changes of initial drug levels. These changes are due to alterations of the biological matrix as well as to dilution of a sample, release or degradation of the drug or poison. Most important seems a conversion of desmethyl metabolites to the parent drug. Some general requirements for postmortem sampling are given based on references about specimen collection issues, for a harmonized protocol for sampling in suspected poisonings or drug-related deaths does not exist. The advantages and disadvantages of specimen preservation are shortly discussed. Storage stability is another important issue to be considered. Instability can either derive from physical, chemical or metabolic processes. The knowledge on degradation mechanisms may enable the forensic toxicologist to target the right substance, which may be a major break down product in the investigation of highly labile compounds. Although it is impossible to eliminate all interfering factors or influences occurring during the preanalytic phase, their consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample.

Severe manifestations of coricidin intoxication

CoricidinHBP (Schering-Plough Health Care Products, Inc, Memphis, TN) is a popular over-the-counter product abused by teenagers for its potent euphoric properties. Clinically significant signs and symptoms after ingestion are usually short-lived and commonly include tachycardia, hypertension, somnolence, and agitation. We report 2 cases of severe toxicity from CoricidinHBP in adolescents that required prolonged hospitalization. The first case demonstrates prolonged anticholinergic complications from a suicidal attempt with CoricidinHBP. The second case demonstrates significant acetaminophen-induced hepatotoxicty from recreational use of CoricidinHBP Maximum Strength Flu. Adolescent abuse of these products is encouraged because of the easily accessible medium of the Internet. The significant morbidity seen in our cases clearly demonstrates the need for vigilance by health care professionals regarding the abuse of over-the-counter products.