Acute lung failure induced by tricyclic antidepressants

Antidepressants activate the lysophosphatidic acid receptor LPA(1) to induce insulin-like growth factor-I receptor transactivation, stimulation of ERK1/2 signaling and cell proliferation in CHO-K1 fibroblasts

Different lines of evidence indicate that the lysophosphatidic acid (LPA) receptor LPA1 is involved in neurogenesis, synaptic plasticity and anxiety-related behavior, but little is known on whether this receptor can be targeted by neuropsychopharmacological agents. The present study investigated the effects of different antidepressants on LPA1 signaling. We found that in Chinese hamster ovary (CHO)-K1 fibroblasts expressing endogenous LPA1 tricyclic and tetracyclic antidepressants and fluoxetine induced the phosphorylation of extracellular signal-regulated kinase1/2 (ERK1/2) and CREB. This response was antagonized by either LPA1 blockade with Ki16425 and AM966 or knocking down LPA1 with siRNA. Antidepressants induced ERK1/2 phosphorylation in human embryonic kidney (HEK)-293 cells overexpressing LPA1, but not in wild-type cells. In PathHunter™ assay measuring receptor-β-arrestin interaction, amitriptyline, mianserin and fluoxetine failed to induce activation of LPA2 and LPA3 stably expressed in CHO-K1 cells. ERK1/2 stimulation by antidepressants and LPA was suppressed by pertussis toxin and inhibition of Src, phosphatidylinositol-3 kinase and insulin-like growth factor-I receptor (IGF-IR) activities. Antidepressants and LPA induced tyrosine phosphorylation of IGF-IR and insulin receptor-substrate-1 through LPA1 and Src. Prolonged exposure of CHO-K1 fibroblasts to either mianserin, mirtazapine or LPA enhanced cell proliferation as indicated by increased [(3)H]-thymidine incorporation and Ki-67 immunofluorescence. This effect was inhibited by blockade of LPA1- and ERK1/2 activity. These data provide evidence that different antidepressants induce LPA1 activation, leading to receptor tyrosine kinase transactivation, stimulation of ERK1/2 signaling and enhanced cell proliferation.

Short inhalation exposures of the isolated and perfused rat lung to respirable dry particle aerosols; the detailed pharmacokinetics of budesonide, formoterol, and terbutaline

There is an increasing interest in using the lung as a route of entry for both local and systemic administration of drugs. However, because adequate technologies have been missing in the preclinical setting, few investigators have addressed the detailed disposition of drugs in the lung following short inhalation exposures to highly concentrated dry powder aerosols. New methods are needed to explore the disposition of drugs after short inhalation exposures, thus mimicking a future clinical use. Our aim was to study the pulmonary disposition of budesonide, formoterol, and terbutaline, which are clinically used for the treatment of bronchial asthma. Using the recently developed DustGun aerosol technology, we exposed by inhalation for approximately 1 min the isolated and perfused rat lung (IPL) to respirable dry particle aerosols of the three drugs at high concentrations. The typical aerosol concentration was 1 mug/mL, and the particle size distribution of the tested substances varied with a MMAD ranging from 2.3 to 5.3 mum. The IPL was perfused in single pass mode and repeated samples of the perfusate were taken for up to 80 min postexposure. The concentration of drug in perfusate and in lung extracts was measured using LC-MS/MS. The deposited dose was determined by adding the amounts of drug collected in perfusate to the amount extracted from the tissues at 80 min. Deposited amounts of budesonide, formoterol fumarate, and terbutaline sulphate were 23 +/- 17, 36 +/- 8, and 60 +/- 3.2 mug (mean +/- SD, n = 3), respectively. Retention in lung tissues at the end of the perfusion period expressed as fraction of deposited dose was 0.19 +/- 0.05, 0.19 +/- 0.06, and 0.04 +/- 0.01 (mean +/- SD, n = 3) for budesonide, formoterol, and terbutaline, respectively. Each short inhalation exposure to the highly concentrated aerosols consumed 1-3 mg powder. Hence, this system can be particularly useful for obtaining a detailed pharmacokinetic characterization of inhaled compounds in drug discovery/development.

Risk factors for the development of pneumonia in acute psychotropic drugs poisoning

Background/Aim. Pneumonia is the most frequent complication in acute psychotropic drugs poisoning, which results in substantial morbidity and mortality, but which also increases the costs of treatment. Risk factors for pneumonia are numerous: age, sex, place of the appearance of pneumonia, severity of underlying disease, airway instrumentation (intubation, reintubation, etc). The incidence of pneumonia varies in poisoning caused by the various groups of drugs. The aim of this study was to determine the incidence and risk factors for pneumonia in the patients with acute psychotropic drugs poisoning. Methods. A group of 782 patients, out of which 614 (78.5%) with psychotropic and 168 (21.5%) nonpsychotropic drug poisoning were analyzed prospectively during a two-year period. The diagnosis of pneumonia was made according to: clinical presentation, new and persistent pulmonary infiltrates on chest radiography, positive nonspecific parameters of inflammation, and the microbiological confirmation of causative microorganisms. To analyze predisposing risk factors for pneumonia, the following variables were recorded: sex, age, underlying diseases, endotracheal intubation, coma, severity of poisoning with different drugs, histamine H2 blockers, corticosteroids, mechanical ventilation, central venous catheter. The univariate analysis for pneumonia risk factors in all patients, and for each group separately was done. The multivariate analysis was performed using the logistic regression technique. Results. Pneumonia was found in 94 (12.02%) of the patients, 86 of which (91.5%) in psychotropic and 8 (8.5%) in nonpsychotropic drug poisoning. In the psychotropic drug group, pneumonia was the most frequent in antidepressant (47%), and the rarest in benzodiazepine poisoning (3.8%). A statistically significant incidence of pneumonia was found in the patients with acute antidpressant poisoning (p < 0.001). Univariate analysis showed statistical significance for the following parameters: sex (p < 0.05), chronic alcohol intake (p < 0.05), underlying diseases (p < 0.01), central venous catheter (p < 0.05) vasopressors (p < 0.05), coma (p < 0.001), H2 blockers (p < 0.001) and corticosteroids (p < 0.001). The multivariate analysis retained endotracheal intubation and antidepressant drug poisoning as an independent risk factor for pneumonia. Conclusion. Using univariate and multivariate analysis, risk factors for developing pneumonia were disclosed. Some of these factors may be modified by simple medical procedures, thus the incidence and mortality rate of pneumonia in drug poisoning might be substantially reduced.

Photo-distributed neutrophilic drug eruption and adult respiratory distress syndrome associated with antidepressant therapy

Drug reactions are well-known complications of antidepressant therapy, often related to photosensitization. Herein is reported a singular case of antidepressant (amoxapine and citalopram) and anxiolytic related (perphenazine) photo-distributed neutrophilic dermatosis and adult respiratory distress syndrome (ARDS). The clinicopathologic findings displayed overlapping features with drug-induced Sweet's syndrome, acute generalized exanthematous pustulosis (AGEP), and so-called sterile neutrophilic folliculitis with perifollicular vasculopathy. Of the three medications, only amoxapine has been associated with AGEP. Treatment with high-dose systemic corticosteroids and cessation of drug therapy was followed by rapid resolution of the cutaneous eruption and respiratory distress. The possibility that neutrophil infiltration of the lung and/or accumulation of neutrophils in the skin and blood served as a source for reactive oxygen species, leading to lung injury and subsequent ARDS, is discussed.

Pegylated interferon and ribavirin-induced interstitial pneumonitis with ARDS

A 49-year-old man with cirrhosis due to hepatitis C virus developed interstitial pneumonitis documented by surgical lung biopsy specimen evaluation after two weekly doses of pegylated interferon-alpha(2)b in combination with ribavirin. He developed ARDS and died after 26 days of hospitalization from multisystem organ failure. This case suggests that interstitial pulmonary disease can occur with pegylated interferon-alpha(2)b therapy.

Adult respiratory distress syndrome and renal failure associated with citalopram overdose

A 45-year-old man ingested 3000 mg of citalopram hydrobromide (2400 mg citalopram). He presented to the Emergency Department 2 hours post-ingestion with a pulse of 100 beats/min and blood pressure of 120/80 mmHg. His electrocardiogram (ECG) was normal. Chest X-ray showed bilateral shadowing, with no evidence of aspiration of gastric contents. Shortly after, he had three tonic-clonic seizures, requiring intravenous diazepam. Eight hours post-ingestion he became oliguric with deteriorating renal function, despite normal arterial and central venous pressures. He became increasingly hypoxic, with chest X-ray changes compatible with adult respiratory distress syndrome (ARDS). Despite treatment with 100% oxygen and continuous positive airway pressure, his gas exchange continued to deteriorate, requiring intubation and ventilation. His renal function also deteriorated with a peak creatinine of 492 micromol/L on day 4 in the absence of rhabdomyolysis. There was complete spontaneous recovery of renal function after 2 weeks. A peak plasma total citalopram (R+S enantiomers) concentration of 1.92 mg/L was recorded 2 hours post-ingestion. Total norcitalopram concentrations continued to rise up to 24 hours post-ingestion. Citalopram has been associated with seizures, ECG abnormalities, rhabdomyolysis and coma after overdose. The renal and respiratory complications seen in this patient have not been reported previously.

A study of mechanisms underlying amitriptyline-induced acute lung function impairment

In this study possible mechanisms underlying the vaso- and bronchoconstriction caused by the tricyclic antidepressant drug amitriptyline in isolated rat lungs were investigated. Some features here are similar to those apparent in adult respiratory distress syndrome and acute lung injury. Amitriptyline exposure (50 and 100 microM) caused a dose-related, pronounced, and rapid vaso- (50 microM, 30 min, p < 0.001 and 100 microM, 30 min, p < 0.001) and bronchoconstriction (50 microM, 30 min, p = 0.01 and 100 microM, 30 min, p < 0.001). The maximal noted decrease in perfusion flow was 28 +/- 2.9% at 25 min and 80 +/- 4.5% at 30 min for 50 and 100 microM amitriptyline, respectively. The maximal noted decrease in airway conductance was 29 +/- 4.7% at 25 min and 68 +/- 5.0% at 30 min. To investigate mechanisms thought to be involved in amitriptyline-induced lung function impairment, lungs were treated with several different substances including antiinflammatory agents, antioxidants, inhibitors of enzymes involved in the arachidonic acid cascade, physiological antagonists, and neurogenic antagonists. A significant reduction of amitriptyline-induced vasoconstriction was observed when lungs were treated with the protein kinase inhibitor staurosporine (3 microM, 30 min, p < 0.001), the NO-donor S-nitrosoglutathione (100 microM, 30 min, p < 0.001) and the combined endothelin A/endothelin B receptor antagonist PD 145065. This latter inhibitor caused a significant attenuation of late vasoconstriction (1 microM, 60 min, p = 0.03). The amitriptyline-induced bronchoconstriction was attenuated by the beta(2)-agonist salbutamol (1 microM, 30 min, p = 0.03) and the platelet-activating factor antagonist WEB2086 (10 microM, 30 min, p = 0.03). Staurosporine had an initial protective effect on bronchoconstriction (3 microM, 5 min, p = 0.003), while PD145065 significantly decreased bronchoconstriction 60 min after start of amitriptyline exposure (1 microM, 30 min, p = 0.003). This indicates that endothelin as well as platelet activating factor and protein kinase activation are important in mediating amitriptyline-induced lung function impairment in our experimental model and perhaps also in acute lung injury.

Imipramine inhibits Cl(-) secretion by desensitization of beta-adrenergic receptors in calu-3 human airway cells

Recent investigations have found that tetracyclic antidepressants like imipramine (IMP) have high-affinity sites not only in brain but also in mammalian lung. In the present study, we examined the effects of IMP on the Cl(-) secretion produced by isoproterenol (ISP), a beta-adrenergic receptor (beta-AR) agonist, in Calu-3 human airway cells. ISP applied in the basolateral solution generated a sustained short-circuit current that was abolished by diphenylamine-2-carboxylate, a Cl(-) channel blocker. IMP (0.01-1 mM) applied in the apical or basolateral solution for 30 min significantly inhibited the ISP-induced responses in a concentration-dependent manner, and the inhibitory effects of this drug were remarkable when applied from the apical rather than the basolateral side. ISP-induced responses were mimicked by forskolin- and 8-bromo-cyclic AMP-induced ones, but which were insensitive to IMP. These results indicate that IMP desensitizes the beta-AR on the basolateral membrane from the cytosolic side in Calu-3 cells.

Drug-induced inflammatory responses to the lung

A number of drugs can induce lung toxicity. The lung manifestations can range from more acute responses such as an acute ARDS-like reaction, seen occasionally at overdosing of drugs to more insidious reactions, which can occur during conventional drug treatment. In many of these cases inflammation is an important component in the pathophysiology of drug induced lung toxicity. Very little is known about the mechanisms and initial events of drug-induced injury. In this review a couple of mechanistic aspects, related to drug induced lung injury, will be discussed such as reactive oxygen species (ROS)-generation, mediator release and disturbances in lung phospholipid turnover.

Amitriptyline-induced release of endothelin-1 in isolated perfused and ventilated rat lungs

We have previously shown that tricyclic antidepressants can induce vaso- and bronchoconstriction as well as oedema formation in isolated perfused lungs. This is an effect similar to that seen clinically in adult respiratory distress syndrome. In order to investigate whether endothelin can be a mediator of this reaction, isolated perfused rat lungs were exposed to 0.1 mM amitriptyline via the pulmonary circulation, perfusate was collected and endothelin-1 present in the perfusate and lavage fluids was determined by radioimmunoassay. A significant increase in perfusate concentration of endothelin-1 was noted, with the highest release seen within the first 10 min. of exposure. Histamine and thromboxane have also been proposed as mediators in induction of adult respiratory distress syndrome. However, no increased amounts of these mediators were detected in the perfusate. Experiments where lungs were exposed to exogenous endothelin-1(0.1-1 nmol), both via the perfusate and via intratracheal instillation were conducted. Similar effects as observed with amitriptyline (0.1 mM) on lung function and perfusion flow were detected. In conclusion, the detection of endothelin-1 release in our lung model proposes a role for endothelin-1 in amitriptyline-induced vaso- and bronchoconstriction and possibly in adult respiratory distress syndrome type reaction. Further studies with this model are interesting in order to elucidate mechanisms behind the complex issue of adult respiratory distress syndrome-induction.

Amitriptyline-induced loss of tight junction integrity in a human endothelial--smooth muscle cell bi-layer model

Tricyclic antidepressants can, when taken in overdose, cause serious pulmonary failure such as the adult respiratory distress syndrome (ARDS). In this study we have examined the effects of some tricyclic antidepressants (amitriptyline, imipramine, nortriptyline and desipramine) on the viability and morphology of human endothelial and smooth muscle cells derived from umbilical cord. Effects of amitriptyline on endothelial cell fluidity, as well as permeability changes to an endothelial-smooth muscle cell bi-layer, were also studied. The tricyclic antidepressants induced acute, sub-lethal toxicity in both cell types above 100 microM as assessed by the MTT reduction assay. Morphological changes were also observed at these concentrations. Such changes were, however, absent at 33 microM and below. Amitriptyline did, however, cause a concentration-dependent fall in the electrical resistance of an endothelial-smooth muscle cell bi-layer, with significant effects already evident at 33 microM. All of these observed effects were fairly rapid and appeared within 5-15 min of exposure. The rapidity of these permeabilisation effects suggests potential membrane perturbations, since tricyclic antidepressants are lipophilic molecules with affinity for cell membranes. However, fluorescence anisotropy measurements showed no significant difference in membrane fluidity between amitriptyline-treated and control endothelial cells. Collectively, these data point to specific mechanisms of action of amitriptyline, and probably also the other tricyclic antidepressants studied, on endothelial permeability, which is a hallmark of ARDS. The data suggest that increased endothelial permeability could be due to impaired tight junction function.