Gas chromatography nitrogen phosphorous detection (GC-NPD) assay of tofisopam in human plasma for pharmacokinetic evaluation

Inhibitory Actions of Antidepressants, Hypnotics, and Anxiolytics on Recombinant Human Acetylcholinesterase Activity

Alzheimer's disease (AD) is accompanied by behavioral and psychological symptoms of dementia (BPSD), which is often alleviated by treatment with psychotropic drugs, such as antidepressants, hypnotics, and anxiolytics. If these drugs also inhibit acetylcholinesterase (AChE) activity, they may contribute to the suppression of AD progression by increasing brain acetylcholine concentrations. We tested the potential inhibitory effects of 31 antidepressants, 21 hypnotics, and 12 anxiolytics on recombinant human AChE (rhAChE) activity. At a concentration of 10-4 M, 22 antidepressants, 19 hypnotics, and 11 anxiolytics inhibited rhAChE activity by <20%, whereas nine antidepressants (clomipramine, amoxapine, setiptiline, nefazodone, paroxetine, sertraline, citalopram, escitalopram, and mirtazapine), two hypnotics (triazolam and brotizolam), and one anxiolytic (buspirone) inhibited rhAChE activity by ≥20%. Brotizolam (≥10-6 M) exhibited stronger inhibition of rhAChE activity than the other drugs, with its pIC50 value being 4.57 ± 0.02. The pIC50 values of the other drugs were <4, and they showed inhibitory activities toward rhAChE at the following concentrations: ≥3 × 10-6 M (sertraline and buspirone), ≥10-5 M (amoxapine, nefazodone, paroxetine, citalopram, escitalopram, mirtazapine, and triazolam), and ≥3 × 10-5 M (clomipramine and setiptiline). Among these drugs, only nefazodone inhibited rhAChE activity within the blood concentration range achievable at clinical doses. Therefore, nefazodone may not only improve the depressive symptoms of BPSD through its antidepressant actions but also slow the progression of cognitive symptoms of AD through its AChE inhibitory actions.

Occurrence, detection and ecotoxicity studies of selected pharmaceuticals in aqueous ecosystems- a systematic appraisal

Pharmaceutical compounds (PCs) have globally emerged as a significant group of environmental contaminants due to the constant detection of their residues in the environment. The main scope of this review is to fill the void of information on the knowledge on the African occurrence of selected PCs in environmental matrices in comparison with those outside Africa and their respective toxic actions on both aquatic and non-aquatic biota through ecotoxicity bioassays. To achieve this objective, the study focused on commonly used and detected pharmaceutical drugs (residues). Based on the conducted literature survey, Africa has the highest levels of ciprofloxacin, sulfamethoxazole, lamivudine, acetaminophen, and diclofenac while Europe has the lowest of all these PC residues in her physical environments. For ecotoxicity bioassays, the few data available are mostly on individual groups of pharmaceuticals whereas there is sparsely available data on their combined forms.

Development of a simple HPLC-DAD multi-analyte procedure and its application in cases evaluated by the Poison Control Center of São Paulo, Brazil

This work describes a simple approach to overcome challenges in emergency toxicological analysis, using liquid-liquid extraction and high-performance liquid chromatography coupled with a diode-array detector (HPLC-DAD). A rapid procedure has been developed, for the extraction and detection of 19 analytes from the following drug classes: analgesics, benzodiazepines, antidepressants, anticonvulsants and drugs of abuse. These substances are relevant in the context of emergency toxicology in Brazil. The method has been validated according to international guidelines by establishing parameters such as lower limit of quantification, sensitivity, linearity, accuracy and precision. The intra and inter-day precision values, at the lowest concentration levels, have always been less than 20% considering its relative standard deviation. As for accuracy values, these have also been satisfactory (above 81.3%). This method was successfully applied in 201 blood samples from patients with suspected poisoning of the Poison Control Center of São Paulo (PCC-SP), Brazil. Finally, the developed method has shown to be relevant for emergency toxicology due to its high sensitivity and it could be also very useful in both fields of clinical and forensic toxicology.

The atypical anxiolytic drug, tofisopam, selectively blocks phosphodiesterase isoenzymes and is active in the mouse model of negative symptoms of psychosis

Tofisopam is a member of the 2,3-benzodiazepine compound family which is marketed for the treatment of anxiety in some European countries. In contrast to classical 1,4-benzodiazepines, the compound does not bind to the benzodiazepine binding site of the γ-aminobutyric acid receptor and its psychopharmacological profile differs from such compounds. In addition to anxiolytic properties, antipsychotic effects are reported. We now show that tofisopam, 50 mg/kg intraperitoneally (i.p.), administered in parallel to repeated doses of dizocilpine 0.2 mg/kg i.p. can ameliorate dizocilpine-induced prolongation of immobility, which is considered to be a model of negative symptoms of psychosis. We further show that tofisopam acts as an isoenzyme-selective inhibitor of phosphodiesterases (PDEs) with highest affinity to PDE-4A1 (0.42 μM) followed by PDE-10A1 (0.92 μM), PDE-3 (1.98 μM) and PDE-2A3 (2.11 μM). The data indicate that tofisopam is an interesting candidate for the adjuvant treatment of psychosis with focus on negative symptoms. Combined partial inhibition of PDE-4 and PDE-10 as well as PDE-2 may be the underlying mechanism to this activity. Due to the good safety profile of tofisopam as evident from long-term use of this agent in patients, it may be concluded that dual or triple inhibition of PDE isoenzymes with additive or synergistic effects may be an interesting approach to pharmacological activity, resulting in active compounds with beneficial safety profile. Dose-limiting side effects such as emesis induced by selective inhibition of PDE-4 may be prevented by such strategies.