Paroxetine hydrochloride

Development and pharmacological evaluation of liposomes and nanocapsules containing paroxetine hydrochloride

Depression is one of the most common psychiatric disorders. Nanotechnology has emerged to optimize the pharmacological response. Therefore, the aim of this work was to develop and characterize liposomes and nanocapsules containing paroxetine hydrochloride and evaluate their antidepressant-like effect using the open field and tail suspension tests in mice. Liposomes and nanocapsules were prepared using the reverse-phase evaporation and nanoprecipitation methods, respectively. The particle size of the formulation ranged from 121.81 to 310.73 nm, the polydispersity index from 0.096 to 0.303, the zeta potential from -11.94 to -34.50 mV, the pH from 5.31 to 7.38, the drug content from 80.82 to 94.36 %, and the association efficiency was 98 %. Paroxetine hydrochloride showed slower release when associated with liposomes (43.82 %) compared to nanocapsules (95.59 %) after 10 h. In Vero cells, in vitro toxicity showed a concentration-dependent effect for paroxetine hydrochloride nanostructures. Both nanostructures decreased the immobility time in the TST at 2.5 mg/kg without affecting the number of crossings in the open field test, suggesting the antidepressant-like effect of paroxetine. In addition, the nanocapsules decreased the number of groomings, reinforcing the anxiolytic effect of this drug. These results suggest that the nanostructures were effective in preserving the antidepressant-like effect of paroxetine hydrochloride even at low doses.

Paroxetine-Overview of the Molecular Mechanisms of Action

In the 21st century and especially during a pandemic, the diagnosis and treatment of depression is an essential part of the daily practice of many family doctors. It mainly affects patients in the age category 15–44 years, regardless of gender. Anxiety disorders are often diagnosed in children and adolescents. Social phobias can account for up to 13% of these diagnoses. Social anxiety manifests itself in fear of negative social assessment and humiliation, which disrupts the quality of social functioning. Treatment of the above-mentioned disorders is based on psychotherapy and pharmacotherapy. Serious side effects or mortality from antidepressant drug overdose are currently rare. Recent studies indicate that paroxetine (ATC code: N06AB), belonging to the selective serotonin reuptake inhibitors, has promising therapeutic effects and is used off-label in children and adolescents. The purpose of this review is to describe the interaction of paroxetine with several molecular targets in various points of view including the basic chemical and pharmaceutical properties. The central point of the review is focused on the pharmacodynamic analysis based on the molecular mechanism of binding paroxetine to various therapeutic targets.

Inhibition of G Protein-Coupled Receptor Kinase 2 Promotes Unbiased Downregulation of IGF1 Receptor and Restrains Malignant Cell Growth

The ability of a receptor to preferentially activate only a subset of available downstream signal cascades is termed biased signaling. Although comprehensively recognized for the G protein-coupled receptors (GPCR), this process is scarcely explored downstream of receptor tyrosine kinases (RTK), including the cancer-relevant insulin-like growth factor-1 receptor (IGF1R). Successful IGF1R targeting requires receptor downregulation, yet therapy-mediated removal from the cell surface activates cancer-protective β-arrestin-biased signaling (β-arr-BS). As these overlapping processes are initiated by the β-arr/IGF1R interaction and controlled by GPCR-kinases (GRK), we explored GRKs as potential anticancer therapeutic targets to disconnect IGF1R downregulation and β-arr-BS. Transgenic modulation demonstrated that GRK2 inhibition or GRK6 overexpression enhanced degradation of IGF1R, but both scenarios sustained IGF1-induced β-arr-BS. Pharmacologic inhibition of GRK2 by the clinically approved antidepressant, serotonin reuptake inhibitor paroxetine (PX), recapitulated the effects of GRK2 silencing with dose- and time-dependent IGF1R downregulation without associated β-arr-BS. In vivo, PX treatment caused substantial downregulation of IGF1R, suppressing the growth of Ewing's sarcoma xenografts. Functional studies reveal that PX exploits the antagonism between β-arrestin isoforms; in low ligand conditions, PX favored β-arrestin1/Mdm2-mediated ubiquitination/degradation of IGF1R, a scenario usually exclusive to ligand abundancy, making PX more effective than antibody-mediated IGF1R downregulation. This study provides the rationale, molecular mechanism, and validation of a clinically feasible concept for "system bias" targeting of the IGF1R to uncouple downregulation from signaling. Demonstrating system bias as an effective anticancer approach, our study reveals a novel strategy for the rational design or repurposing of therapeutics to selectively cross-target the IGF1R or other RTK. SIGNIFICANCE: This work provides insight into the molecular and biological roles of biased signaling downstream RTK and provides a novel "system bias" strategy to increase the efficacy of anti-IGF1R-targeted therapy in cancer.

Efficacy and tolerability of paroxetine in adults with social anxiety disorder: A meta-analysis of randomized controlled trials

OBJECTIVE

The present study aimed to estimate the comprehensive efficacy and tolerability of paroxetine in adult patients with social anxiety disorder (SAD).

METHODS

We conducted a comprehensive literature review of the PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, and ClinicalTrials databases for eligible randomized controlled trials (RCTs). The efficacy outcome was the mean change of different kinds of scale scores as well as response and remission rates. The secondary outcome was tolerability, defined as the discontinuation rate and the incidence of adverse events (AEs).

RESULTS

Our meta-analysis included 13 RCTs. Mean changes in the Liebowitz Social Anxiety Scale (LSAS) total score, fear and avoidance subscale of LSAS scores were all significantly greater in patients with SAD that received paroxetine compared to those received placebo (total: MD = 13.46, 95%CI 10.59-16.32, P < .00001; fear: MD = 6.76, 95%CI 4.89-8.62, P < .00001; avoidance: MD = 6.54, 95%CI 4.63-8.45, P < .00001). Response and remission rates were both significantly greater in patients with SAD that received paroxetine compared to those received placebo (response: OR = 3.02, 95%CI 2.30-3.97, P < .00001; remission: OR = 3.14, 95%CI 2.25-4.39, P < .00001). There was no significant difference in discontinuation rate due to any reason between two groups (OR = 1.06, 95%CI 0.81-1.39, P = .65). Discontinuation rate due to AEs was higher in paroxetine than placebo group (OR = 3.41, 95%CI 2.45-4.72, P < .00001) whereas the rate due to lack of efficacy was higher in placebo as compared with paroxetine group (OR = 0.14, 95%CI 0.09-0.22, P < .00001). The incidence of any AE was significantly increased in patients that received paroxetine (OR = 1.83, 95%CI 1.43-2.35, P < .00001).

CONCLUSION

Paroxetine was an effective and well-tolerated treatment option for adult patients with SAD.

Blockage of Autophagic Flux and Induction of Mitochondria Fragmentation by Paroxetine Hydrochloride in Lung Cancer Cells Promotes Apoptosis via the ROS-MAPK Pathway

Cancer cells are characterized by malignant proliferation and aberrant metabolism and are thereby liable to the depletion of nutrients and accumulation of metabolic waste. To maintain cellular homeostasis, cancer cells are prone to upregulating the canonical autophagy pathway. Here, we identified paroxetine hydrochloride (Paxil) as a late autophagy inhibitor and investigated its killing effect on lung cancer cells and with a xenograft mouse model in vivo. Upregulated LC3-II and p62 expression indicated that Paxil inhibited autophagy. Acid-sensitive dyes (e.g., LysoTracker and AO staining) indicated reduced lysosomal acidity following Paxil treatment; consequently, the maturation of the pH-dependent hydroxylases (e.g., cathepsin B and D) substantially declined. Paxil also induced the fragmentation of mitochondria and further intensified ROS overproduction. Since the autophagy pathway was blocked, ROS rapidly accumulated, which activated JNK and p38 kinase. Such activity promoted the localization of Bax, which led to increased mitochondrial outer membrane permeability. The release of Cytochrome c with the loss of the membrane potential triggered a caspase cascade, ultimately leading to apoptosis. In contrast, the clearance of ROS by its scavenger, NAC, rescued Paxil-induced apoptosis accompanied by reduced p38 and JNK activation. Thus, Paxil blocked the autophagic flux and induced the mitochondria-dependent apoptosis via the ROS-MAPK pathway.

A Novel Testing Approach for Oxidative Degradation Dependent Incompatibility of Amine Moiety Containing Drugs with PEGs in Solid-State

Reactive impurities originating from excipients can cause drug stability issues, even at trace amounts. When produced during final dosage form storage, they are especially hard to control, and often, factors inducing their formation remain unidentified. Oxidative degradation dependent formation of formaldehyde and formic acid is responsible for N-methylation and N-formylation of amine-moiety-containing drug substances. A very popular combination of polyethylene glycols and iron oxides, used in more than two-thirds of FDA-approved tablet formulation drugs in 2018, was found to be responsible for increased concentrations of N-methyl impurity in the case of paroxetine hydrochloride. We propose a novel testing approach for early identification of potentially problematic combinations of excipients and drug substances. The polyethylene glycol 6000 degradation mechanism and kinetics in the presence of iron oxides is studied. The generality of the proposed stress test setup in view of the susceptibility of amine-moiety-containing drug substances to N-methylation and N-formylation is evaluated.

A Novel Bromine-Containing Paroxetine Analogue Provides Mechanistic Clues for Binding Ambiguity at the Central Primary Binding Site of the Serotonin Transporter

The serotonin transporter (SERT) is the primary target for the selective serotonin reuptake inhibitors (SSRIs). However, the structural basis for the extraordinarily high binding affinity of the widely prescribed SSRI, paroxetine, to human SERT (hSERT) has not yet been fully elucidated. Our previous findings unveiled a plausible ambiguity in paroxetine's binding orientations that may constitute an integral component of this SSRI's high affinity for hSERT. Herein, we investigate factors contributing to paroxetine's high affinity by modifying both the ligand and the protein. We generated a series of bromine (Br)-containing derivatives and found that the one in which the 4-F of paroxetine had been replaced with the chemically similar but more electron-rich Br atom (13) had the highest affinity. By comparatively characterizing the binding of paroxetine and 13 to both wild type (WT) and a construct harboring a paroxetine-sensitive mutation in the binding cavity, we identified a mechanistic determinant responsible for the pose ambiguity of paroxetine, which can guide future drug design.

Paroxetine versus other anti-depressive agents for depression

BACKGROUND

Paroxetine is the most potent inhibitor of the reuptake of serotonin of all selective serotonin reuptake inhibitors (SSRIs) and has been studied in many randomised controlled trials (RCTs). However, these comparative studies provided contrasting findings and systematic reviews of RCTs have always considered the SSRIs as a group, and evidence applicable to this group of drugs might not be applicable to paroxetine alone. The present systematic review assessed the efficacy and tolerability profile of paroxetine in comparison with tricyclics (TCAs), SSRIs and newer or non-conventional agents.

OBJECTIVES

1. To determine the efficacy of paroxetine in comparison with other anti-depressive agents in alleviating the acute symptoms of Major Depressive Disorder.2. To review acceptability of treatment with paroxetine in comparison with other anti-depressive agents.3. To investigate the adverse effects of paroxetine in comparison with other anti-depressive agents.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis Review Group's Specialized Register (CCDANCTR, to 30 September 2012), which includes relevant randomised controlled trials from the following bibliographic databases: The Cochrane Library (all years), EMBASE (1974 to date), MEDLINE (1950 to date) and PsycINFO (1967 to date). Reference lists of relevant papers and previous systematic reviews were handsearched. Pharmaceutical companies marketing paroxetine and experts in this field were contacted for supplemental data.

SELECTION CRITERIA

All randomised controlled trials allocating participants with major depression to paroxetine versus any other antidepressants (ADs), both conventional (such as TCAs, SSRIs) and newer or non-conventional (such as hypericum). For trials which had a cross-over design, only results from the first randomisation period were considered.

DATA COLLECTION AND ANALYSIS

Two review authors independently checked eligibility and extracted data using a standard form. Data were then entered in RevMan 5.2 with a double-entry procedure. Information extracted included study and participant characteristics, intervention details, settings and efficacy, acceptability and tolerability measures.

MAIN RESULTS

A total of 115 randomised controlled trials (26,134 participants) were included. In 54 studies paroxetine was compared with older ADs, in 21 studies with another SSRI, and in 40 studies with a newer or non-conventional antidepressant other than SSRIs. For the primary outcome (patients who responded to treatment), paroxetine was more effective than reboxetine at increasing patients who responded early to treatment (Odds Ratio (OR): 0.66, 95% Confidence Interval (CI) 0.50 to 0.87, number needed to treat to provide benefit (NNTb) = 16, 95% CI 10 to 50, at one to four weeks, 3 RCTs, 1375 participants, moderate quality of evidence), and less effective than mirtazapine (OR: 2.39, 95% CI 1.42 to 4.02, NNTb = 8, 95% CI 5 to 14, at one to four weeks, 3 RCTs, 726 participants, moderate quality of evidence). Paroxetine was less effective than citalopram in improving response to treatment (OR: 1.54, 95% CI 1.04 to 2.28, NNTb = 9, 95% CI 5 to 102, at six to 12 weeks, 1 RCT, 406 participants, moderate quality of evidence). We found no clear evidence that paroxetine was more or less effective compared with other antidepressants at increasing response to treatment at acute (six to 12 weeks), early (one to four weeks), or longer term follow-up (four to six months). Paroxetine was associated with a lower rate of adverse events than amitriptyline, imipramine and older ADs as a class, but was less well tolerated than agomelatine and hypericum. Included studies were generally at unclear or high risk of bias due to poor reporting of allocation concealment and blinding of outcome assessment, and incomplete reporting of outcomes.

AUTHORS' CONCLUSIONS

Some possibly clinically meaningful differences between paroxetine and other ADs exist, but no definitive conclusions can be drawn from these findings. In terms of response, there was a moderate quality of evidence that citalopram was better than paroxetine in the acute phase (six to 12 weeks), although only one study contributed data. In terms of early response to treatment (one to four weeks) there was moderate quality of evidence that mirtazapine was better than paroxetine and that paroxetine was better than reboxetine. However there was no clear evidence that paroxetine was better or worse compared with other antidepressants at increasing response to treatment at any time point. Even if some differences were identified, the findings from this review are better thought as hypothesis forming rather than hypothesis testing and it would be reassuring to see the conclusions replicated in future trials. Finally, most of included studies were at unclear or high risk of bias, and were sponsored by the drug industry. The potential for overestimation of treatment effect due to sponsorship bias should be borne in mind.