Respiratory effects of the atypical tricyclic antidepressant tianeptine in human models of opioid-induced respiratory depression

Tianeptine as an opiate replacement in a patient on methadone treatment: A case report

Tianeptine, an antidepressant and full µ-opioid receptor agonist, has increased in popularity and has been used as an over-the-counter supplement over the past decade. Due to its well-documented euphoric effects, there exists elevated risk for potential abuse. Buprenorphine-naloxone has been successfully utilized to treat opioid use disorder (OUD) in patients concurrently using tianeptine, limiting withdrawal symptoms and abstinence. However, there is limited evidence on the management of tianeptine use disorder, specifically methadone or naltrexone. The current opioid epidemic, the emerging use of tianeptine, and the lack of physician awareness have emphasized the need for further research on the role of tianeptine in medication-assisted treatment for OUD. This case report aims to demonstrate how medication-assisted therapy can be successfully utilized in a patient with opioid and severe other (tianeptine) drug use disorder.

Opioid Overdose: Limitations in Naloxone Reversal of Respiratory Depression and Prevention of Cardiac Arrest

Opioids are effective analgesics, but they can have harmful adverse effects, such as addiction and potentially fatal respiratory depression. Naloxone is currently the only available treatment for reversing the negative effects of opioids, including respiratory depression. However, the effectiveness of naloxone, particularly after an opioid overdose, varies depending on the pharmacokinetics and the pharmacodynamics of the opioid that was overdosed. Long-acting opioids, and those with a high affinity at the µ-opioid receptor and/or slow receptor dissociation kinetics, are particularly resistant to the effects of naloxone. In this review, the authors examine the pharmacology of naloxone and its safety and limitations in reversing opioid-induced respiratory depression under different circumstances, including its ability to prevent cardiac arrest.

Pharmacology of viable mechanism agnostic respiratory stimulants for the reversal of drug-induced respiratory depression in humans

INTRODUCTION

Drug-induced respiratory depression is potentially fatal and can be caused by various drugs such as synthetic opioids and tranquilizers. The only class of respiratory depressants that has a specific reversal agent are opioids, such as naloxone. These reversal agents have limited utility in situations of polysubstance ingestion with agents from multiple respiratory depressant classes. Hence, there is an unmet need for drugs that stimulate breathing irrespective of the underlying cause of respiratory depression, i.e. mechanism agnostic respiratory stimulants.

AREAS COVERED

In this review, we discuss agnostic respiratory stimulants, tested in humans with promising results, i.e. ampakines, drugs that act at the carotid bodies, N-methyl-D-aspartate receptor antagonist ketamine, and orexin receptor-2-agonist danavorexton, and others that demonstrated positive effects in animals but not yet in humans.

EXPERT OPINION

Rapid, effective rescuing of individuals who overdosed on respiratory depressants saves lives. While naloxone is the preferred drug for reversing opioid-induced respiratory depression, its effectiveness is limited in cases involving non-opioids. While several agnostic respiratory stimulants showed promise in humans, further research is needed to optimize dosing, evaluate safety and efficacy in deeper respiratory depression (apnea). Additionally, future studies should combine agnostic stimulants with naloxone, to improve rapid, effective rescue from drug overdoses.

Inhaled Δ9-tetrahydrocannabinol does not enhance oxycodone-induced respiratory depression: randomised controlled trial in healthy volunteers

BACKGROUND

In humans, the effect of cannabis on ventilatory control is poorly studied, and consequently, the effect of Δ⁹-tetrahydrocannabinol (THC) remains unknown, particularly when THC is combined with an opioid. We studied the effect of THC on breathing without and with oxycodone pretreatment. We hypothesised that THC causes respiratory depression, which is amplified when THC and oxycodone are combined.

METHODS

In this randomised controlled crossover trial, healthy volunteers were administered inhaled Bedrocan® 100 mg (Bedrocan International B.V., Veendam, The Netherlands), a pharmaceutical-grade high-THC cannabis variant (21.8% THC; 0.1% cannabidiol), after placebo or oral oxycodone 20 mg pretreatment; THC was inhaled 1.5 and 4.5 h after placebo or oxycodone intake. The primary endpoint was isohypercapnic ventilation at an end-tidal Pco₂ of 55 mm Hg or 7.3 kPa (V_E55), measured at 1-h intervals for 7 h after placebo/oxycodone intake.

RESULTS

In 18 volunteers (age 22 yr [3]; 9 [50%] female), oxycodone produced a 30% decrease in V_E55, whereas placebo was without effect on V_E55. The first cannabis inhalation resulted in V_E55 changing from 20.3 (3.1) to 23.8 (2.4) L min^-1 (P=0.06) after placebo, and from 11.8 (2.8) to 13.0 (3.9) L min^-1 (P=0.83) after oxycodone. The second cannabis inhalation also had no effect on V_E55, but slightly increased sedation.

CONCLUSIONS

In humans, THC has no effect on ventilatory control after placebo or oxycodone pretreatment.

CLINICAL TRIAL REGISTRATION

2021-000083-29 (EU Clinical Trials Register.).

Carbon dioxide tolerability and toxicity in rat and man: A translational study

Background: Due the increasing need for storage of carbon dioxide (CO₂) more individuals are prone to be exposed to high concentrations of CO₂ accidentally released into atmosphere, with deleterious consequences.

Methods: We tested the effect of increasing CO₂ concentrations in humans (6–12%) and rats (10–50%) at varying inhalation times (10–60 min). In humans, a continuous positive airway pressure helmet was used to deliver the gas mixture to the participants. Unrestrained rats were exposed to CO₂ in a transparent chamber. In both species regular arterial blood gas samples were obtained. After the studies, the lungs of the animals were examined for macroscopic and microscopic abnormalities.

Results: In humans, CO₂ concentrations of 9% inhaled for >10 min, and higher concentrations inhaled for <10 min were poorly or not tolerated due to exhaustion, anxiety, dissociation or acidosis (pH < 7.2), despite intact oxygenation. In rats, concentrations of 30% and higher were associated with CO₂ narcosis, epilepsy, poor oxygenation and, at 50% CO₂, spontaneous death. Lung hemorrhage and edema were observed in the rats at inhaled concentrations of 30% and higher.

Conclusion: This study provides essential insight into the occurrence of physiological changes in humans and fatalities in rats after acute exposure to high levels of CO₂. Humans tolerate 9% CO₂ and retain their ability to function coherently for up to 10 min. These data support reconsideration of the current CO₂ levels (<7.5%) that pose a risk to exposed individuals (<7.5%) as determined by governmental agencies to ≤9%.