Cytotoxic and cytocompatible comparison among seven photoinitiators-triggered polymers in different tissue cells

Photoinitiators (PIs) are widely used for photopolymerization in industrial area and recently paid close attention to in biomedical field. However, there are few reports on their toxicity to human health. Here we explored cytotoxicity and cytocompatibilty of seven commercial and industrial-used PIs for developing their potential clinical application. Phenylbis(acyl) phosphine oxides (BAPO), 2-Benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (369), 4,4'-Bis(diethylamino) benzophenone (EMK), Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO), and 2-Isopropylthioxanthone (ITX) caused different extent cytotoxicities to four tissue types of cells at the concentrations of 1 to 50 μM under a non-irradiation condition, of which the BAPO cytotoxicity was the highest, whereas Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPOL) and Methyl benzoylformate (MBF) displayed the lowest cellular toxicity. The cell lines and primary cells appeared highly sensitive to BAPO toxicity, the primary lymphocytes relatively to photoinitiator 369 (369) and EMK toxicities, LO2 cells to EMK and TPO toxicities, the primary lymphocytes and HUVEC-12 cells to MBF toxicity, but only HEK293T cells not to 369 toxicity. Furthermore, these PIs led to increasing cytotoxicity to different extents after exposure to 455 nm blue light, which is consistent with non-irradiation tendency. All the cells presented low sensitivity to TPOL and MBF, of which TPOL-triggered polymer is dramatically superior in its cytocompatibility to MBF, and in its transparency to clinically exclusively-used camphorquinone (CQ). The novel findings indicate that BAPO is the most toxic among the seven PIs, but TPOL and MBF are the least toxic, directing their development and application. Combined their triggered polymer cytocompatibility and color with reported deep curing efficiency, TPOL is more promising to be applied especially to clinical practice.

Studies on the metabolism and toxicological detection of the new designer drug 4′-methyl-α-pyrrolidinobutyrophenone (MPBP) in rat urine using gas chromatography–mass spectrometry

The aim of the presented study was to identify the metabolites of the new designer drug 4'-methyl-alpha-pyrrolidinobutyrophenone (MPBP) in rat urine using GC-MS techniques. After enzymatic hydrolysis, extraction and various derivatizations, seven metabolites of MPBP could be identified suggesting the following metabolic steps: oxidation of the 4'-methyl group to the corresponding alcohol and further oxidation to the respective carboxy compound, hydroxylation of the pyrrolidine ring followed by dehydrogenation to the corresponding lactam or reduction of the keto group to the 1-dihydro compound. A previously published GC-MS-based screening procedure for pyrrolidinophenones involving enzymatic hydrolysis and mixed-mode solid-phase extraction of urine samples allowed detection of MPBP metabolites. Assuming similar metabolism and dosages in humans, an intake of MPBP should be detectable via its metabolites in urine.

Carebastine Almirall Prodesfarma

Carebastine, a histamine H1 antagonist, is under development by Almirall Prodesfarma for the potential treatment of allergic rhinitis, asthma and conjunctivitis. A nasal formulation was submitted for registration in Spain in June 1999 [343595]. It is also in phase III trials for conjunctivitis and phase I trials for asthma [343144,343243]. In a multicentered, multinational, double-blind, placebo-controlled study in patients with symptomatic SAR, patients were assigned a nasal spray formulation of carebastine (2.5 mg/ml) or placebo. Severity scores decreased significantly with carebastine compared to placebo. This findings suggest that carebastine nasal spray has the potential to be of value in the treatment of SAR [282185]. In a multicenter, multinational, double-blind, randomized, placebo-controlled study, patients with seasonal allergic conjunctivitis (SAC) were assigned an eye drop formulation of carebastine (25 mg/ml) or placebo. Carebastine was significantly better than placebo at relieving the effects of SAC, as early as 15 min after administration and the effect lasted for 14 days. Carebastine was well-tolerated and there were no difference in adverse events between the two groups [282897].

Pharmacokinetic-pharmacodynamic analysis of the arrhythmogenic potency of a novel antiallergic agent, ebastine, in rats

Ebastine (EBS), a novel nonsedative antiallergic agent, is similar to terfenadine in its chemical structure. However, clinical arrhythmogenicity of EBS remains controversial. In this study, we evaluated the possible arrhythmogenic potency of EBS as assessed by QT prolongation from a pharmacokinetic-pharmacodynamic viewpoint in comparison with that of terfenadine. EBS was intravenously infused into anesthetized rats at a rate of 3.0 or 10 mg/kg/h for 60 min, and electrocardiographic effects were continuously monitored from lead II. The plasma concentrations of EBS and its major metabolite, carebastine, were also measured under the same conditions. When intravenously administered, EBS exhibited QT prolongation in an infusion rate-dependent manner, with a lag time. Pharmacokinetic-pharmacodynamic analysis of EBS based on the effect-compartment model revealed values of EC50, Emax and EC(10 ms), (where 10 ms of QT prolongation was evoked) of 0.73 microg/mL, 12.5 ms and 2.90 microg/mL, respectively. The EC(10 ms) value of EBS was five times higher than that of terfenadine reported previously (Ohtani et al., J. Pharm. Pharmacol., 49, 458-462 (1997)). In conclusion, EBS was suggested to be less arrhythmogenic than terfenadine.

Cardiotoxic and drug interaction profile of the second generation antihistamines ebastine and terfenadine in an experimental animal model of torsade de pointes

Second generation antihistamines are widely used because of their efficacy in treating allergic disorders without significant sedative side effects. Recent clinical evidence shows that some of the early prototypes in this class, namely terfenadine and astemizole, have the potential for producing torsade de pointes, a rare form of ventricular arrhythmia that is life-threatening. Important questions have been raised as to whether this is a property shared by newer, recently-introduced second generation antihistamines. The objective of this study was to characterize and compare the ECG and cardiovascular effects of terfenadine (CAS 50679-08-8) and ebastine (CAS 90729-43-4), a new second generation antihistamine, in an experimental animal model predictive of the cardiotoxic proclivity of these agents. Also, the drug interaction effect of the antifungal drug ketoconazole (CAS 65277-42-1) was evaluated, which blocks hepatic first-pass biotransformation of ebastine and terfenadine leading to increased cardiotoxity of terfenadine in man, on the ECG effects of terfenadine and ebastine in this animal model. Terfenadine (10 mg/kg) and ebastine (50 mg/kg) were administered intravenously to anesthetized guinea pigs. Electrocardiographic (ECG) and cardiovascular parameters (blood pressure and heart rate) were measured during the course of the experiment. The ECG wave form was analyzed to determine QTc interval, PR interval, QRS interval and heart rate. In separate studies in conscious guinea pigs, the effect of oral ketoconazole (200 mg) on the ECG effects of oral terfenadine (60 mg) and ebastine (10 mg) was studied. Terfenadine (10 mg/kg) and ebastine (50 mg/kg) produced significant prolongation of the QTc interval and disruption of the ECG signal when given intravenously to anesthetized guinea pigs. The ECG effects were characterized by large amplitude, morphologically aberrant T-waves, and instances of arrhythmogenic activity. Both drugs produced pronounced bradycardia and hypotension. In conscious animals, pretreatment with oral ketoconazole significantly enhanced the QTc interval prolongation effects of terfenadine and ebastine. Oral terfenadine and ebastine, when given alone at the doses tested, were devoid of adverse QTc interval prolongation effects in the conscious guinea pig. In separate studies in conscious guinea pigs, oral loratadine (10 mg; CAS 79794-75-5) given alone or in animals pretreated with ketoconazole did not affect ECG parameters. The present studies show that terfenadine and ebastine share similar cardiotoxic properties characterized by QTc interval prolongation, bradycardia, hypotension and proarrhythmogenic activity in the anesthetized guinea pig. In addition, pretreatment with ketoconazole enhances the QTc interval effect of both drugs, most likely due to the accumulation of parent compound that occurs after blockade of hepatic metabolism by CYP3A4. In conclusion, our findings indicate that ebastine and terfenadine display similarities in their inherent potential for cardiotoxic and adverse drug interaction effects. In contrast, loratadine is devoid of adverse ECG and drug interaction effects.

Chronic melperone administration does not enhance oral movements in rats

Melperone and haloperidol were compared in a rat model for tardive dyskinesia. Drugs were given chronically for 12 months with the drinking water and the frequency of oral movements was measured at monthly intervals. Haloperidol (0.2 and 0.4 mg/kg/d) produced an increase in vacuous chewing movements, whereas melperone (2.4, 5.1 and 11.0 mg/kg/d) did not differ from untreated controls.

Comparison of the metabolism and pharmacokinetics of metbufen and itanoxone and their analogues in rats

Metbufen, II, itanoxone, I, and two other derivatives of gamma-aryl-gamma-keto-substituted butyric acids labelled with 14C in their carbonyl group were synthesized for a metabolic investigation in rats. Profound changes in pharmacokinetic parameters, most specifically in the distribution, elimination, and metabolic pathways, were induced by substitution in the aromatic nucleus or changes in saturation of the aliphatic chain. The metabolites isolated from plasma and urine were identified by gas chromatography and mass spectrometry, by comparison with chemical controls, revealing the processes of metabolism of these structural analogues. This difference in metabolism further understanding of the diversity of biological effects inherent in these compounds.

Mutagenicity evaluation of azaperone in the Salmonella/microsome test

Azaperone was evaluated for its mutagenic potential by the Salmonella/microsome test. No mutagenic activity towards six S. typhimurium strains could be evidenced with azaperone at doses up to 2,000 micrograms/plate, either without or with metabolic activation at usual test conditions. Higher concentrations of liver post-mitochondrial fraction from Aroclor 1254 (ARO)-pretreated rats did not reveal any increase in the number of revertants towards S. typhimurium strains TA1537, TA1538 and TA98. Moreover, a plate-incorporation test with liver post-mitochondrial fractions from mice pretreated with phenobarbital (PB) and a liquid preincubation test with liver post-mitochondrial fractions from rats pretreated with ARO also failed to reveal any mutagenic action of azaperone towards S. typhimurium strain TA98. Thus, none of the tests used provided any indication of azaperone having a mutagenic action.

Pharmacokinetic and metabolic study of itanoxone in the crab Pachygrapsus marmoratus (Decapoda, Brachyura): comparative study with clofibric acid

The LD50 of itanoxone injected i.v. in the crab Pachygrapsus marmoratus is 144 mg/kg. Hypolipidemic drug distribution is distinct according to organ and sex. The fixation power of muscle is comparatively low. Ovary radioactivity is higher than in the testicles. Itanoxone storage is large in the hepatopancreas. Metabolism, increasing over time, is not noticeably different according to sex. Two metabolites, chlorobiphenylcarboxylic acid and chlorobiphenylacetic acid, found in crab, are also identified in rat and man. The pharmacokinetic and metabolic study of itanoxone and clofibric acid in the crab shows a difference between the two drugs. Itanoxone metabolism and fixation is higher than clofibric acid.

[4-aminobutyrophenones with hypotensive activity]

A series of new butyrophenones was synthesized, the aim being to reduce neuroleptic activity and enhance the hypotensive effects of this class of drugs. The compounds were screened for toxicity according to the Irwin scheme and tested in anaesthetized cats for their effects on systemic arterial pressure. The most interesting compound, i.e. 1-(4'-fluorobenzoyl)-3-pyrrolidinyl-propane, was tested also in anaesthetized rabbits, cats, and dogs and in concious dogs. Moreover its central nervous system effects were tested in rats and mice. The compound proved practically devoid of neurological effects and showed interesting hypotensive activity.

Some basic ketones with central nervous system depressant activity

Some γ-(4-benzyl-4-hydroxypiperidino)-butyrophenones and related compounds have been prepared and screened for central nervous system depressant activity. One of the more active, γ-(4-p-chlorobenzyl-4-hydroxypiperidino)-p-fiuorobutyrophenone, was selected for further study and in experimental animals was found to have effects on the central nervous system similar to both those of chlorpromazine and of haloperidol.