Pharmacokinetic modeling of over-the-counter drug diphenhydramine self-administered in overdoses in Japanese patients admitted to hospital

Postmortem distribution of etizolam in various autopsy samples using the surrogate analyte approach (SAA) method

Etizolam, a type of anxiolytic drug, is the most commonly abused drug among hypnotic/anxiolytic medications in Japan. Although there have been reports on the postmortem identification of etizolam in the blood, the detailed distribution of etizolam among organs in an abuse case has not been reported. In this study, we examined etizolam concentrations in the blood and organs obtained from etizolam-related autopsy cases using the surrogate analyte approach (SAA) method, which can be analytically used without blank samples. Target compounds were extracted from samples using the QuEChERS method and filtrated with Captiva ND Lipids. Then, the eluates were analyzed by LC-MS/MS. Etizolam-d₃ was used as a stable isotope-labeled surrogate compound with this quantification approach. A strong linear correlation was observed for each sample, showing a correlation coefficient value at least 0.99. The right heart, left heart, and femoral vein blood etizolam concentrations ranged from 85.2 to 178.2 ng/mL, while this concentration was 592.0 ng/g in liver tissue. Here, we could determine the etizolam concentration in various autopsy samples using LC-MS/MS. In addition, this work demonstrated that the SAA method can be successfully applied to various human samples.

Integration of Ontogeny-Based Changes for Predicting the Exposure of Diphenhydramine in the Pediatric Population: A PBPK Modeling Approach

BACKGROUND

Diphenhydramine is an anti-tussive used periodically to treat seasonal colds, contact dermatitis, and anaphylactic reactions. This study aimed to develop a physiologically based pharmacokinetic (PBPK) model of diphenhydramine in predicting its systemic exposure among healthy pediatrics (children and adolescents) by leveraging data files from adults (young and elderly).

METHODS

The data profiles comprising serum/plasma concentration over time and parameters related to diphenhydramine were scrutinized via exhaustive literature analysis and consolidated in the PK-Sim software version 11.1. This modeling methodology commences with developing an adult model and then translating it to the pediatrics which compares the predicted concentration-time datasets with the reported values.

RESULTS

The accuracy of model anticipations was then assessed for each pharmacokinetics (PK) variable, i.e., the area under the curve from 0 to infinity (AUC0-∞), maximal serum/plasma concentration (Cmax), and clearance of the diphenhydramine in plasma (CL) by employing the predicted/observed ratios (Rpre/obs), and average fold error (AFE), which fell within the pre-defined benchmark of 2-fold. The predicted and observed Cmax values for pediatrics were 3-fold greater in comparison to the young adults following a 25 mg dose depicting a need to monitor dosage schedules among children closely.

CONCLUSIONS

These model-based anticipations confirmed the authenticity of the developed pediatric model and enhanced the comprehension of developmental variations on PK of diphenhydramine. This may assist healthcare professionals in ensuring the significance of lifespan applicability in personalized dose regimens, promoting therapeutic efficacy and minimizing side effects in chronic conditions among children.

Prospective multicenter study of the epidemiological features of emergency patients with overdose of over-the-counter drugs in Japan

Aim

To investigate the epidemiological characteristics of patients presenting to the emergency department with an overdose of over-the-counter (OTC) drugs.

Methods

A questionnaire survey was conducted to examine the sociodemographic characteristics of patients with OTC drugs overdoses visiting emergency departments at eight sites across the country. The patients were divided into "habitual" and "nonhabitual" groups according to their history of OTC drugs overdose. Student's t-test or Welch's t-test was performed for numerical variables, and Pearson's χ 2 test was performed for dichotomous and nominal variables between the two groups.

Results

Of the 124 patients included in this study, 79% were women. The habitual (26.6%) and the nonhabitual (73.4%) groups showed no differences in sex, occupation, cohabitants, history of mental illness, or history of alcohol consumption or smoking; however, those in the habitual group were significantly younger. The proportion of OTC drugs obtained from physical stores was higher in the habitual group, whereas the nonhabitual group used more household medicines. Suicide and self-harm were more common reasons for overdose in the nonhabitual group. Antipyretic analgesics were significantly more common in the nonhabitual group, whereas antitussive expectorants and antihistamines were significantly more common in the habitual group.

Conclusion

This is the first multicenter study to determine the status of OTC drugs overdose patients treated at emergency departments of medical facilities in Japan. To prevent new overdoses of OTC drugs, continued detailed epidemiologic studies of patient backgrounds and drug acquisition routes, and investigation of the components of OTC drugs that cause dependency are necessary.

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.

Machine Learning Prediction of the Three Main Input Parameters of a Simplified Physiologically Based Pharmacokinetic Model Subsequently Used to Generate Time-Dependent Plasma Concentration Data in Humans after Oral Doses of 212 Disparate Chemicals

Physiologically based pharmacokinetic (PBPK) modeling has the potential to play significant roles in estimating internal chemical exposures. The three major PBPK model input parameters (i.e., absorption rate constants, volumes of the systemic circulation, and hepatic intrinsic clearances) were generated in silico for 212 chemicals using machine learning algorithms. These input parameters were calculated based on sets of between 17 and 65 chemical properties that were generated by in silico prediction tools before being processed by machine learning algorithms. The resulting simplified PBPK models were used to estimate plasma concentrations after virtual oral administrations in humans. The estimated absorption rate constants, volumes of the systemic circulation, and hepatic intrinsic clearance values for the 212 test compounds determined traditionally (i.e., based on fitting to measured concentration profiles) and newly estimated had correlation coefficients of 0.65, 0.68, and 0.77 (p < 0.01, n = 212), respectively. When human plasma concentrations were modeled using traditionally determined input parameters and again using in silico estimated input parameters, the two sets of maximum plasma concentrations (r = 0.85, p < 0.01, n = 212) and areas under the curve (r = 0.80, p < 0.01, n = 212) were correlated. Virtual chemical exposure levels in liver and kidney were also estimated using these simplified PBPK models along with human plasma levels. These results indicate that the PBPK model input parameters for humans of a diverse set of compounds can be reliability estimated using chemical descriptors calculated using in silico tools.

Pharmacokinetics of caffeine self-administered in overdose in a Japanese patient admitted to hospital

Background

Caffeine (0.1 g) is used as a central nervous system stimulant and as a nontoxic phenotyping probe for cytochrome P450 1A2. However, an increasing number of suicide attempts by caffeine overdose have been recently reported.

Case presentation

A 25-year-old woman (body weight, 43 kg) who intentionally took an overdose of 5.9 g caffeine as a suicide attempt was emergently admitted to Kyoto Medical Center. The plasma concentrations of caffeine and its primary metabolite, N-demethylated paraxanthine, in the current case were 100 and 7.3 μg/mL, 81 and 9.9 μg/mL, 63 and 12 μg/mL, and 21 and 14 μg/mL, at 12, 20, 30, and 56 h after oral overdose, respectively. The observed apparent terminal elimination half-life of caffeine during days 1 and 2 of hospitalization was 27 h, which is several times longer than the reported normal value. This finding implied nonlinearity of caffeine pharmacokinetics over such a wide dose range, which could affect the accuracy of values simulated by a simplified physiologically based pharmacokinetic model founded on a normal dose of 100 mg. Low serum potassium levels (2.9 and 3.5 mM) on days 1 and 2 may have been caused by the caffeine overdose in the current case.

Conclusions

The patient underwent infusion with bicarbonate Ringer’s solution and potassium chloride and was discharged on the third day of hospitalization despite taking a potentially lethal dose of caffeine. The virtual plasma exposures of caffeine estimated using the current simplified PBPK model were higher than the measured values. The present results based on drug monitoring data and additional pharmacokinetic predictions could serve as a useful guide in cases of caffeine overdose.

Pharmacokinetics of loxoprofen in a self-administered overdose in a Japanese patient admitted to hospital

Background

Loxoprofen is a propionic acid derivative and is the most widely prescribed non-steroidal anti-inflammatory drug in Japan. Loxoprofen is generally considered to be relatively nontoxic.

Case presentation

A 33-year-old man (body weight, 55 kg) who intentionally took an overdose of 100 tablets of loxoprofen (6000 mg) as a suicide attempt was emergently admitted to Kyoto Medical Center. On arrival, the patient was suffering disorders of consciousness. His plasma concentrations of loxoprofen and its reduced trans-alcohol metabolite were 52 and 24 μg/mL, 3.7 and 2.3 μg/mL, 0.81 and 0.54 μg/mL, and 0.015 and 0.011 μg/mL, respectively, at 4, 26, 50, and 121 h after the oral overdose. The observed apparent terminal elimination half-life of loxoprofen during days 1 and 2 of hospitalization was in the range 6–12 h, which is several times longer than the reported normal value. This finding implied nonlinearity of loxoprofen pharmacokinetics over the current 100-fold dose range, which could affect the accuracy of values simulated by a simplified physiologically based pharmacokinetic (PBPK) model founded on data from a normal dose of 60 mg. The reasons for the delayed eliminations from plasma of loxoprofen and its trans-alcohol metabolite in this case are uncertain, but slight renal impairment (low eGFR values) developed on the second and third hospital days and could be a causal factor.

Conclusions

Because the patient’s level of consciousness had gradually improved, he was discharged on the fourth day of hospitalization. The virtual plasma exposures of loxoprofen and its reduced trans-alcohol metabolite estimated using the current simplified PBPK model were lower than the measured values in the overdose case. The present results based on drug monitoring data and pharmacokinetic predictions could serve as a useful guide in cases of loxoprofen overdose.