Trapping of adrenergic decongestant drugs into cellular endomembrane compartments: Toxicological and pharmacological consequences

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Should Excess Topical Decongestant Use Raise a Red Flag? Rhinitis Medicamentosa and Opioid Use Disorder

OBJECTIVE

The objective of this study was to determine whether patients with rhinitis medicamentosa (RM) have an increased odds of having an opioid use disorder (OUD) and which characteristics may predict this association.

METHODS

The authors conducted a retrospective case control study of patients 18 years and older who presented to the otolaryngology clinic at an academic medical center from January 2013 through December 2017. Cases, defined as patients who presented with excessive decongestant nasal spray usage based on history, were matched to control patients who presented with chronic rhinitis and did not report regular nasal decongestant usage. The charts were reviewed for patients that carried a problem of opioid abuse, identified using ICD-9 codes 304.XX or ICD-10 codes F11.XX. The primary outcome of this study was the odds of having an OUD. Secondary outcomes were assessed by summary statistics.

RESULTS

One hundred and thirty-one cases of RM were matched to 1871 controls of chronic rhinitis. Seven cases (5.3%) and 24 (1.3%) controls had a diagnosis of OUD, consistent with an odds ratio of 3.98 for opioid abuse in patients with RM (95% CI: 1.47-9.71). Oxymetazoline was used by 85.5% (n = 112) of patients with RM. Thirty-six patients (27.1%) with RM underwent nasal surgery following a diagnosis of RM, of which twenty patients (55.6%) were prescribed opioids following the procedure.

CONCLUSIONS

RM is associated with increased odds of having an OUD.

Cation trapping by cellular acidic compartments: beyond the concept of lysosomotropic drugs

"Lysosomotropic" cationic drugs are known to concentrate in acidic cell compartments due to low retro-diffusion of the protonated molecule (ion trapping); they draw water by an osmotic mechanism, leading to a vacuolar response. Several aspects of this phenomenon were recently reexamined. (1) The proton pump vacuolar (V)-ATPase is the driving force of cationic drug uptake and ensuing vacuolization. In quantitative transport experiments, V-ATPase inhibitors, such as bafilomycin A1, greatly reduced the uptake of cationic drugs and released them in preloaded cells. (2) Pigmented or fluorescent amines are effectively present in a concentrated form in the large vacuoles. (3) Consistent with V-ATPase expression in trans-Golgi, lysosomes and endosomes, a fraction of the vacuoles is consistently labeled with trans-Golgi markers and protein secretion and endocytosis are often inhibited in vacuolar cells. (4) Macroautophagic signaling (accumulation of lipidated and membrane-bound LC3 II) and labeling of the large vacuoles by the autophagy effector LC3 were consistently observed in cells, precisely at incubation periods and amine concentrations that cause vacuolization. Vacuoles also exhibit late endosome/lysosome markers, because they may originate from such organelles or because macroautophagosomes fuse with lysosomes. Autophagosome persistence is likely due to the lack of resolution of autophagy, rather than to nutritional deprivation. (5) Increased lipophilicity decreases the threshold concentration for the vacuolar and autophagic cytopathology, because simple diffusion into cells is limiting. (6) A still unexplained mitotic arrest is consistently observed in cells loaded with amines. An extended recognition of relevant clinical situations is proposed for local or systemic drug administration.

Dissociation of the vacuolar and macroautophagic cytopathology from the cytotoxicity induced by the lipophilic local anesthetic bupivacaine

Local anesthetics, like many other cationic drugs, induce a vacuolar and macroautophagic cytopathology that has been observed in vivo and in various cell types; some also induce cytotoxicity of mitochondrial origin (apoptosis and necrosis) and it is not known whether the 2 types of toxicity overlap or interact. We compared bupivacaine with a more hydrophilic agent, lidocaine, for morphological, functional, and toxicological responses in a previously exploited nonneuronal system, primary smooth muscle cells. Bupivacaine induced little vacuolization (≥2.5 mmol/L, 4 h), but elicited autophagic accumulation (≥0.5 mmol/L, 4 h) and was massively cytotoxic at 2.5–5 mmol/L (4–24 h), the latter effect being unabated by the V-ATPase inhibitor bafilomycin A1. Lidocaine exerted little cytotoxicity at and below 5 mmol/L for 24 h, but intensely induced the V-ATPase-dependent vacuolar and autophagic cytopathology. Bupivacaine was more potent than lidocaine in disrupting mitochondrial potential, as judged by Mitotracker staining (significant proportions of cells affected in the 1–5 and 5–10 mmol/L concentration ranges, respectively). The addition of mitochondrial-inactivating toxins antimycin A and oligomycin to lidocaine (2.5 mmol/L) reproduced the profile of bupivacaine action (low intensity of vacuolization and retained autophagic accumulation). The high potency of bupivacaine as a mitochondrial toxicant eclipses the benign vacuolar and autophagic response seen with more hydrophilic local anesthetics.