Effects of pretreatment with 8018 on the toxicokinetics of soman in rabbits and distribution in mice

Mechanism of penehyclidine hydrochloride on a dysmenorrhea rat model

Primary dysmenorrhea affects the quality of life in young women, particularly school and work performance. This study investigated the mechanisms of penehyclidine hydrochloride (PHC) efficacy on a rat model of primary dysmenorrhea. The model was induced by injecting both estradiol benzoate and oxytocin. Different doses of PHC were administrated intraperitoneally following estradiol benzoate administration. Writhing scores were assessed, and pathological changes of the uterus were observed via hematoxylin and eosin staining. Western blot and real-time PCR were used to evaluate the expression level of the M₃ receptor, both TLR₃ and TLR₄ in uterine tissue, and the level of Ca²⁺ was measured in uterine tissues. Writhing scores significantly decreased in the PHC treatment group compared to model, and PHC alleviated the occurrence of edema or necrosis in the uteri compared to model group. PHC can decrease the M₃ receptor, TLR₃ , TLR₄ expression, and the Ca²⁺ level compared to the model group. PHC is a potential candidate for the future treatment of primary dysmenorrhea due to its ability to attenuate muscarinic receptors and TLRs. Preclinical Research & Development.

Neuroprotective effect of penehyclidine hydrochloride on focal cerebral ischemia-reperfusion injury

Penehyclidine hydrochloride can promote microcirculation and reduce vascular permeability. However, the role of penehyclidine hydrochloride in cerebral ischemia-reperfusion injury remains unclear. In this study, in vivo middle cerebral artery occlusion models were established in experimental rats, and penehyclidine hydrochloride pretreatment was given via intravenous injection prior to model establishment. Tetrazolium chloride, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling and immunohistochemical staining showed that, penehyclidine hydrochloride pretreatment markedly attenuated neuronal histopathological changes in the cortex, hippocampus and striatum, reduced infarction size, increased the expression level of Bcl-2, decreased the expression level of caspase-3, and inhibited neuronal apoptosis in rats with cerebral ischemia-reperfusion injury. Xanthine oxidase and thiobarbituric acid chromogenic results showed that penehyclidine hydrochloride upregulated the activity of superoxide dismutase and downregulated the concentration of malondialdehyde in the ischemic cerebral cortex and hippocampus, as well as reduced the concentration of extracellular excitatory amino acids in rats with cerebral ischemia-reperfusion injury. In addition, penehyclidine hydrochloride inhibited the expression level of the NR1 subunit in hippocampal nerve cells in vitro following oxygen-glucose deprivation, as detected by PCR. Experimental findings indicate that penehyclidine hydrochloride attenuates neuronal apoptosis and oxidative stress injury after focal cerebral ischemia-reperfusion, thus exerting a neuroprotective effect.

Characterization of the effect of penehyclidine hydrochloride on muscarinic receptor subtypes mediating the contraction of guinea-pig isolated gastrointestinal smooth muscle

Objectives

The aim was to characterize the effect of penehyclidine hydrochloride, which mediates the relaxation of guinea-pig isolated gastrointestinal smooth muscle, on muscarinic receptor subtypes.

Methods

Radioimmune assay was used to determine cAMP levels in isolated guinea-pig gastrointestinal smooth muscle to compare the selective effects of penehyclidine hydrochloride on muscarinic receptor subtypes.

Key findings

The results indicated that the relaxing effect of penehyclidine hydro-chloride on isolated gastrointestinal smooth muscle contraction induced by acetylcholine was stronger than that of atropine (based on PA2 values). In the radioimmune assay, penehyclidine hydrochloride increased the cAMP content in isolated guinea-pig stomach smooth muscle and decreased the cAMP content in isolated guinea-pig intestinal smooth muscle, but the difference was not statistically significant at a dose of 10 μmol/1.

Conclusions

The results suggest that penehyclidine hydrochloride has little or no effect on M2 receptor subtypes in guinea-pig gastrointestinal smooth muscle.

Underlying mechanism of penehyclidine hydrochloride on isolated rat uterus

We investigated the underlying mechanisms of penehyclidine hydrochloride (PHC), a novel selective anticholinergic drug on isolated rat uterus. The method of radio-immunity assay was further employed to determine cyclic adenosine mono phosphate (cAMP) levels in isolated rat uterus for comparing with selective effect on muscarinic receptor subtypes. In the assay, PHC could decrease the content of cAMP in isolated rat uterus, but the difference was not statistically significant at dose of 10 mumol/L. In conclusion, our results suggested that PHC has no or poor effect on M(2) receptor subtypes in isolated rat uterus.

Embryo-fetal development toxicity of prenatal exposure to penequine hydrochloride intramuscularly in rats

The potential for penequine hydrochloride to induce maternal and embryo-fetal developmental toxicity was evaluated in Wistar rats. The drug was administered intramuscularly (i.m.) at dose levels of 0, 10, 30 or 50mg/kg/day to groups of pregnant rats from day 6 to 15 of gestation. All dams were observed for maternal body weights, food consumption and any abnormal change, and subjected to caesarean-section on gestation day (GD) 20; all fetuses obtained from caesarean-section were assessed by external inspection, visceral and skeletal examinations. In the 50mg/kg/day group, maternal toxicity included an increase in the incidence of abnormal clinical signs, and decrease in the body weight and body weight gain. Developmental toxicity included an increase in the postimplantation loss, a decrease in the litter size, and a reduction in the gravid uterus weight. In addition, a statistically non-significant increase in the incidence of fetal external, visceral, and skeletal alterations including malformations and variations were seen in high-dose group. There were no treatment-related findings in maternal clinical and intrauterine observations, and fetal morphological examinations in mid-, low-dose and control groups. Thus, under the conditions of this study, the no-observed-adverse-effect-level (NOAEL) and lowest-observed-adverse-effect-level (LOAEL) of penequine hydrochloride for both maternal and embryo-fetal toxicity in the Wistar rats were considered to be 30mg/kg/day and 50mg/kg/day, which are approximately 900 and 1500 above the therapeutic dosage, respectively.

Fertility and early embryonic development toxicity of penequine hydrochloride in mice

Penequine hydrochloride, a novel anticholinergic agent, was developed as an effective treatment for organophosphorus intoxication. The potential for penequine hydrochloride to induce fertility and early embryonic developmental toxicity was evaluated in AMMS-1 mice. Totally 320 healthy, sexual mature and nulliparous AMMS-1 mice were orally treated with the chemical in drinking water at dose levels of 0, 2.5, 12.5 and 62.5 mg/L from 60 days before cohabitation to successful copulation in 160 males and from two weeks before cohabitation to GD 6 in 160 females, respectively. All the parental mice were observed for body weights, water consumption and any abnormal change during treatment period. Caesarean sections were carried out on day 14 of pregnancy in half assumed-pregnant females, and all the intrauterine data were recorded. Pups naturally delivered by the other half females were weighed, and examined for viability, sex ratio and gross malformations. About 7 days after cohabitation period, all the paternal males were examined for epididymal and testicular weights, sperm number and sperm motility. The decreases in fertility/fecundity indices and maternal weight gain were found at high-dose level in both caesarean sections and natural delivery observations. The primary developmental toxicity of the chemical included decreases in relative organ (epididymis, liver and lung) weights at mid- and high-dose levels in pups on postnatal day (PND) 35. The cause of both the decreased fertility/fecundity indices in F0 males and the decreased relative organ weights in F1 pups are not well known but are presently under investigation. Under the experimental conditions, penequine hydrochloride did not produce any adverse effects (expect the decreases in certain relative organ weights) up to and including 12.5 mg/L (2.53 mg/kg/day in males and 2.19 mg/kg/day in females) corresponding to approximately 72 times above anticipated dosage in human.

The pre- and post-natal toxicity of penequine hydrochloride in mice

Penequine hydrochloride, a novel anticholinergic agent, was developed as an effective treatment for organophosphorus intoxication (e.g., soman poisoning). The current study was performed to assess the potential pre- and post-natal toxicity of penequine hydrochloride in mice. Approximately 120 timed-pregnant mice were assigned to four dose groups (n=30 per group). Dams were exposed orally to 0, 2.5, 12.5, 62.5 mg/L penequine hydrochloride in drinking water from gestation day 6 to lactation day 21. The F1 generation mice, which were not exposed directly to penequine hydrochloride as pups or as adults, were bred to produce F2 generation fetuses for the fertility test of the F1 population. Various pre- and post-natal measurements, including neurobehavioral tests, were performed with the F0 and F1 mice. Among the significant findings were decreases in water consumption, viability, organ weights and delay of physical landmarks in 62.5 mg/L groups. With the exception of treatment-unrelated abnormality in surface righting reflex in the F1 generation, penequine hydrochloride did not produce any adverse effects at doses up to and including 12.5 mg/L (equal to 2.5 mg/kg/day in mice) that were at least 75 times of human therapeutic dosage.

Synthesis of the optical isomers of a new anticholinergic drug, penehyclidine hydrochloride (8018)

A practical diastereoselective synthetic method for 8018 enantiopure isomers is described. The intramolecular asymmetric epoxidation of mono-sulfonate 4 was applied for the execution of the synthesis of the key chiral building block for the first time. The isomers were obtained with 70-76% yields in 99-100% ee.