The term ‘dementia’ encompasses a diverse group of progressive neurodegenerative disorders, the common feature of which is the deterioration of higher cortical functions. This process not only involves memory deficits and language communication disorders, but also executive dysfunction and loss of emotional control, which ultimately leads to a complete loss of the patient’s independence. Within this group of disorders, Alzheimer’s disease (AD) presents the most serious clinical challenge, characterized by a unique neuropathological triad: the presence of extracellular β-amyloid plaques, intracellular neurofibrillary tangles of tau protein, and widespread dysfunction of cholinergic transmission. The cholinergic hypothesis remains the cornerstone of the current understanding of cognitive impairment in AD. It posits that progressive dementia is caused by the selective degeneration of neurons in the anterior basal forebrain, resulting in a drastic reduction in acetylcholine (ACh) levels in the synaptic cleft. In the absence of a causal treatment, acetylcholinesterase inhibitors (AChEIs) remain the standard of care. Their pharmacological action is based on the inhibition of the AChE enzyme, which allows neurotransmission deficits to be compensated for by prolonging the half-life of acetylcholine at the synapse. This literature review presents a synthesis of the efficacy and safety of classic and novel AChEIs. A comprehensive search of the PubMed, Scopus, and Cochrane Library databases was conducted for clinical data published up to 2026. Evidence from key trials indicates that standard AChEIs induce significant cognitive stabilization compared to placebo, with rivastigmine maximizing daily living parameters via transdermal delivery. However, their therapeutic impact remains strictly symptomatic without arresting neurodegeneration. Conversely, emerging agents like huperzine A and the translation-blocker Posiphen demonstrate disease-modifying potential by modulating CSF biomarkers associated with amyloid and tau proteins. Clinically, while traditional regimens are limited by gastrointestinal toxicities, transitioning toward innovative multi-target structures represents a necessary shift to address both cognitive decline and neurodegeneration.

Opioids comprise a class of substances characterized by a narrow therapeutic window and significant euphoric effects. Opioid-related mortality remains a critical global health issue, primarily resulting from respiratory depression associated with full μ-opioid receptor agonists. Buprenorphine is distinguished by its pharmacological profile as a partial μ-opioid receptor agonist, exhibiting a ceiling effect on both respiratory depression and euphoria. These characteristics render buprenorphine particularly valuable in opioid replacement therapy for opioid use disorder and in the management of both chronic and acute pain. Current literature indicates that, due to these properties, buprenorphine possesses a superior safety profile compared to other opioids. This narrative review evaluates whether buprenorphine can cause fatal overdose despite its protective ceiling effect and examines cases of buprenorphine-related fatalities. The review synthesizes data from pre-clinical, clinical, pharmacological, and toxicological studies. Current literature supports the consensus that the established ceiling effect on respiratory depression does not fully eliminate the risk of fatal overdose. Polysubstance use, particularly co-ingestion of other central nervous system depressants, significantly increases this risk, and most buprenorphine-related deaths involve such combinations. Additionally, buprenorphine’s safety is reduced in vulnerable populations, including opioid-naive individuals, children, and patients with pre-existing respiratory compromise. While buprenorphine alone presents a substantially lower fatality risk compared to other opioids, the ceiling effect is pharmacodynamic rather than absolute, and toxicity or fatal overdose may still occur. Current data gathered from clinical and pre-clinical studies suggest that buprenorphine is safer than full μ-opioid receptor agonists, but it is not without risk. The ceiling effect’s protective benefits depend on context. Therefore, despite its improved safety profile, buprenorphine should not be regarded as risk-free.

Background: Alcohol use disorder (AUD) is a grave mental health condition that can result in significant health and social consequences. The medications Naltrexone and Nalmefene are indicated for the treatment of AUD, with Naltrexone having received the most extensive research attention. Methods: The majority of papers assessing universal measures of alcohol consumption employed two primary metrics: total alcohol consumption (TAC) and the number of days per month where individuals engaged in heavy drinking (HDD). Indicators pertaining to the maintenance of complete abstinence were excluded due to the absence of sufficient data. The safety of both substances was also assessed, as were the frequency of side effects and independent patient dropout. The study also incorporated practical factors of the therapy, such as the route of administration, dosage regimen, and the drug’s patient convenience, which can have a significant impact on adherence to therapy. Results: Nalmefene, administered in an “as needed” regimen, demonstrated statistically significant activity in reducing HDD and total alcohol consumption (TAC) among patients with AUD, particularly those with elevated World Health Organization (WHO) DRL risk. Preliminary findings from the ESENSE1 (Efficacy of Nalmefene in Alcohol Dependence; the first phase III study), ESENSE 2 (Efficacy of Nalmefene in Alcohol Dependence, the second phase III study), and SENSE (the final phase III long term-safety and cost-effectiveness study) studies indicate a substantial decrease in HDD and TAC following the initial month of treatment. These effects persist throughout the subsequent follow-up period. Several Japanese studies have corroborated the effectiveness of Nalmefene, demonstrating its efficacy across both short-term and long-term applications. Furthermore, these studies have substantiated its safety profile, indicating that there is no inherent risk of addiction or the emergence of withdrawal symptoms. The mild nature of adverse events (most commonly nausea and dizziness) led to a relatively low discontinuation rate of Nalmefene treatment. A subsequent study, employing a recognized methodology, corroborated the efficacy of psychosocial support in enhancing treatment outcomes. Meta-analyses demonstrate that Naltrexone exhibits comparable efficacy in reducing the frequency and severity of alcohol consumption. In select populations, the injectable form (LAI) of this pharmaceutical agent facilitates less frequent dosing, which is advantageous for the treatment process. A comparison of Nalmefene and Naltrexone reveals that the latter does not demonstrate a significant impact on the likelihood of individuals returning to heavy alcohol consumption. Conclusions: In the treatment of AUD, both naltrexone and nalmefene have been shown to yield positive outcomes, particularly in terms of reducing the HDD and TAC. According to the World Health Organization (WHO) classification, Nalmefene is indicated for individuals with a high risk of developing serious conditions. It has been demonstrated to produce rapid and sustained results while exhibiting a favorable safety profile, characterized by the absence of significant adverse effects. Naltrexone is a medication that has proven to be effective. LAI may have a positive impact on the efficacy of treatment.