Cyclizine induces cytotoxicity and apoptosis in macrophages through the extrinsic and intrinsic apoptotic pathways.

Cyclizine, an over-the-counter and prescription antihistamine, finds widespread application in the prevention and treatment of motion sickness, encompassing symptoms such as nausea, vomiting, dizziness, along with its effectiveness in managing vertigo. However, the overuse or misuse of cyclizine may lead to hallucinations, confusion, tachycardia, and hypertension. The molecular mechanisms underlying cyclizine-induced cytotoxicity and apoptosis remain unclear. During the 24 h incubation duration, RAW264.7 macrophages were exposed to different concentrations of cyclizine. Cytotoxicity was assessed through the lactate dehydrogenase assay. Flow cytometry employing annexin V-fluorescein isothiocyanate and propidium iodide was utilized to evaluate apoptosis and necrosis. Caspase activity and mitochondrial dysfunction were evaluated through a fluorogenic substrate assay and JC-1 dye, respectively. Flow cytometry employing fluorogenic antibodies was utilized to evaluate the release of cytochrome c and expression of death receptor, including tumor necrosis factor-α receptor and Fas receptor. Western blotting was utilized to evaluate the expression of the Bcl2 and Bad apoptotic regulatory proteins. The findings unveiled from the present study demonstrated that cyclizine exerted a concentration-dependent effect on RAW264.7 macrophages, leading to the induction of cytotoxicity, apoptosis, and necrosis. This compound further activated the intrinsic apoptotic pathway by inducing mitochondrial dysfunction, Bcl2/Bad exchange expression, cytochrome c liberation, and activation of caspases contained caspase 3, 8, and 9. Moreover, the activation of the extrinsic apoptotic pathway was observed as cyclizine induced the upregulation of death receptors and increased caspase activities. Based on our investigations, it can be inferred that cyclizine prompts cytotoxicity and apoptosis in RAW264.7 macrophages in a concentration-dependent manner by triggering both the intrinsic and extrinsic apoptotic pathways.

Cyclizine-induced proinflammatory responses through Akt-NFκB pathway in macrophages.

Cyclizine exhibits sedation and treatment of nausea, vomiting, and motion sickness due to antihistaminic and antimuscarinic effects. Cyclizine has the potential for abuse due to the hallucinogenic and euphoric effect. The response of overdose and illegal abuse of cyclizine includes confusion, tremors, chest pain, ataxia, seizures, and lead to suicide. Macrophage plays the important role in the innate immunity. However, over activation of macrophages results in pro-inflammatory responses in peripheral tissues. In the present study, cyclizine was found to enhanced the generation of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6. We further found that secretion of nitrogen oxide (NO) induced by cyclizine via expression of inducible nitric oxide synthases (iNOS). Cyclizine exhibited parallel stimulation of phosphorylation of nuclear factor-κB (NFκB) p65, and its up-stream factor Akt. These results indicated that the expression of pro-inflammatory cytokines, pro-inflammatory mediators, and adhesion molecules would be induced by cyclizine via activation of Akt-NFκB pathway in macrophages.

[Cyclizine is sold in Denmark as an over-the-counter drug and has serious side effects when overdosed].

Cyclizine is sold in Denmark as an over-the-counter drug and affects not only histaminergic but also muscarinergic, serotonergic and α-adrenergic receptors, with side effects such as respiratory depression and cardiac arrhythmias, leading to fatalities. Due to the numerous side effects, it raises questions concerning the status of cyclizine as an over-the-counter drug. Data of healthcare contacts because of cyclizine intoxication in the 2014-2016 period should be analyzed to further illuminate the health risk of cyclizine poisoning.

Inhibitory effect of homochlorcyclizine on melanogenesis in α-melanocyte stimulating hormone-stimulated mouse B16 melanoma cells.

The histamine receptor H1 antagonist homochlorcyclizine (HC) has been widely used as an antihistamine agent for the treatment of allergies. However, the effect of HC on skin pigmentation is not known. In the present study, we investigated the inhibitory effect of HC on melanogenesis in mouse B16 melanoma cells. Our results showed that HC inhibited melanogenesis in either α-melanocyte stimulating hormone (α-MSH)- or 3-isobutyl-1-methylxanthin (IBMX)-stimulated B16 cells in a dose-dependent manner. Despite the strong inhibition of melanogenesis by HC, it was surprisingly found that HC did not reduce either cellular or melanosomal tyrosinase activity in α-MSH-stimulated B16 cells. In addition, HC also did not directly inhibit either murine or mushroom tyrosinase activity in the cell-free system. Moreover, western blotting and reverse-transcription polymerase chain reaction (RT-PCR) analyses respectively confirmed that HC did not downregulate levels of tyrosinase protein and its mRNA in α-MSH-stimulated B16 cells. These results clearly demonstrated that HC inhibits melanogenesis of B16 cells by a mechanism other than reduction of the cellular tyrosinase activity. From the present study, HC was proven to be a good candidate as a skin-whitening agent for treatment of skin hyperpigmentation, and this generic drug might be suitable for use in combination with other depigmenting agents due to its unique inhibition mechanism.

Synthesis and in vitro antiproliferative activity of novel 1-benzhydrylpiperazine derivatives against human cancer cell lines.

In order to explore the antiproliferative effect associated with the piperazine framework, several 1-benzhydrylpiperazine derivatives 8(a-d), 9(a-d) and 10(a-h) were synthesized. Variation in the functional group at N-terminal of the piperazine led to three sets of compounds, bearing the sulfonyl, amide and thiourea, respectively. Their chemical structures were confirmed by (1)H NMR, LCMS, IR and elemental analysis. The antiproliferative effect of the compounds were evaluated in vitro using the MTT colorimetric method against one normal cell line (NF-103 skin fibroblast cells) and four human cancer cell lines (MCF-7 breast carcinoma cell line, HepG-2 hepatocellular carcinoma cell line, HeLa cervix carcinoma cell line and HT-29 colon carcinoma cell line) for the time period of 24 h. Among the series, four compounds exhibited interesting growth inhibitory effects against all four cell lines.

Histamine H1-receptor antagonists, promethazine and homochlorcyclizine, increase the steady-state plasma concentrations of haloperidol and reduced haloperidol.

The effects of histamine H1-receptor antagonists, promethazine and homochlorcyclizine, both of which are inhibitors of CYP2D6, on the steady-state plasma concentrations (Css) of haloperidol and reduced haloperidol were studied in 23 schizophrenic inpatients receiving haloperidol, 12 to 36 mg/d, for 2 to 29 weeks. Promethazine, 150 mg/d, in 11 patients and homochlorcyclizine, 60 mg/d, in the others were coadministered for at least 1 week. Blood sampling was performed before and during coadministration of promethazine or homochlorcyclizine and 1 week after the discontinuation, together with clinical assessments by Brief Psychiatric Rating Scale (BPRS) and Udvalg for kliniske undersogelser (UKU) side effect rating scale. The Css (mean +/- SD) of haloperidol and reduced haloperidol during promethazine coadministration (27.6 +/- 24.9 and 8.6 +/- 13.2 ng/mL) were significantly higher than those before the coadministration (12.7 +/- 10.8 and 5.0 +/- 6.0 ng/mL; P < 0.01) or 1 week after the discontinuation (15.6 +/- 14.8 and 5.8 +/- 7.9 ng/mL; P < 0.05). The Css of haloperidol and reduced haloperidol during homochlorcyclizine coadministration (14.9 +/- 8.1 and 6.4 +/- 5.4 ng/mL) were also significantly higher than those before the coadministration (10.9 +/- 7.2 and 3.8 +/- 3.6 ng/mL; P < 0.01) or 1 week after the discontinuation (12.9 +/- 7.4 and 4.8 +/- 4.1 ng/mL; P < 0.05). No change in BPRS or UKU score was found throughout the study. Thus, the current study suggests that coadministration of clinical doses of promethazine and homochlorcyclizine increases the Css of haloperidol and reduced haloperidol via the inhibitory effects on the CYP2D6-catalyzed metabolism of haloperidol and reduced haloperidol.

The effects of scopolamine and cyclizine on visual-vestibular interaction in humans.

The aim of the present study was to investigate the effects of scopolamine (1.5 mg, transdermal patch) and cyclizine (50 mg tablet), at the doses usually used for the relief of motion sickness, on postural sway, optokinetic nystagmus (OKN) and circularvection (CV) in humans, using a within-subjects, double-blind, placebo-controlled design. Scopolamine and cyclizine were found to have no significant suppressive effect on these aspects of visual-vestibular interaction. Postural sway and CV were not significantly affected by either drug treatment; OKN SPV was significantly increased (p < 0.05), although OKN amplitude and frequency were unaffected. These results suggest that scopolamine and cyclizine, at doses used for the relief of motion sickness, may have minimal suppressive effects on these aspects of visual-vestibular interaction.

Structure-activity relationships of alkylamines that inhibit rat liver hydroxysteroid sulfotransferase activities in vitro.

Tetraalkylammonium salts having n-propyl to n-amyl side chains inhibited rat liver sulfotransferase (ST) activities toward dehydroepiandrosterone and cortisol, but not ST activity toward 2-naphthol, whereas trialkylamines having ethyl to n-amyl side chains inhibited ST activity toward dehydroepiandrosterone, but not ST activities toward cortisol and 2-naphthol. A comparison of I50 values, which represent inhibitor concentration resulting in 50% inhibition of dehydroepiandrosterone ST activity, revealed that the values for the tetraalkylammonium salts were 0.015 to 0.017 mM, whereas the values for the trialkylamines were 0.20 to 0.33 mM. Introduction of hydrophilic groups such as hydroxyl, thiol, nitrile and acetamide groups or substitution by methyl and allyl groups in the alkyl side chains markedly diminished the inhibitory effect of triethylamine. These data indicate that ethyl to n-amyl side chains are a prerequisite for the alkylamine-type inhibitor. Tertiary amine drugs such as imipramine, dimenhydrinate, cyclizine, chlorpromazine and promethazine inhibited ST activities toward dehydroepiandrosterone and cortisol similar to the tetraalkylammonium salts, although the drugs were weaker inhibitors of hydroxysteroid ST activities. These results imply that in addition to trialkylamine side chains, the other portion of the drugs may participate in the inhibition of hydroxysteroid ST activities.

Effect of first-pass metabolism on enantioselective pharmacokinetics after oral administration of (+)-, (-)- and racemic homochlorcyclizine to rats.

The enantioselective relationship between the pharmacokinetics and hepatic metabolism of homochlorcyclizine hydrochloride (HCZ) was investigated using rats. There were no significant differences in blood concentrations between the three forms after intravenous administration (5 mg/kg) of (+)-, (-)- and racemic HCZ. On the other hand, there were significant differences in the pharmacokinetics between (-)- and (+)-HCZ and between (-)- and racemic HCZ after oral administration (50 mg/kg) of these three forms. The Cmax and AUC0-infinity of (-)-HCZ were lower than those of (+)-isomer and racemate, and its CLo was clearly higher than the others. The (+)-isomer and racemate showed no significant differences in their pharmacokinetic parameters. At a lower dose (10 mg/kg), however, no enantiomeric differences were found in the pharmacokinetic parameters of (+)- and (-)-HCZ. Also examined was the cytochrome p-450-dependent-oxidative metabolism of (+)-, (-)- and racemic HCZ in vitro using rat liver 9000 x g supernatant fraction. The in vitro metabolism of (-)-HCZ was extremely fast, compared with those of the (+)-isomer and the racemate. The Vmax in vitro showed a good correlation with the CLo in vivo after oral administration (50 mg/kg) of all three forms of HCZ. In vitro study of enantiomeric inhibition of the metabolism showed that (+)-HCZ was a competitive inhibitor of (-)-HCZ metabolism, with a Ki of 6.96 microM. (-)-HCZ was also a competitive inhibitor of (+)-HCZ metabolism, with a Ki of 20.4 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Method for optical resolution of racemic homochlorcyclizine and comparison of optical isomers in antihistamine activity and pharmacokinetics.

A method was developed for semi-preparative scale enantioseparation of racemic homochlorcyclizine (HCZ) by high performance liquid chromatography (HPLC) on Chiralcel OD column. The best resolution was achieved using an eluent composed of n-hexane plus 0.2 M isopropylamine. By this method, about 5.0 mg of racemic HCZ could be resolved completely in one run. The optical purity of the enantiomers were both greater than 99.9%. The studies of antihistamine activity on guinea pig ileum demonstrated that l-HCZ is significantly more potent than d- and racemic HCZ. The pharmacokinetics of d- and l-HCZ after oral administration to rats also differed. The successful resolution of racemic HCZ permits comparison of the pharmacokinetics and antihistamine activity of the enantiomers.

Effect of H1 blockers alone and in combination with morphine to produce antinociception in mice.

Antinociception was assessed in male CD-1 mice by a modification of Haffner's tail-clamp procedure. The H1 blockers, including an ethylenediamine (pyrilamine), an ethanolamine (diphenhydramine), a phenothiazine (methdilazine), a piperazine (cyclizine) and an alkylamine (chlorpheniramine), all produced antinociception when given alone to mice and also caused potentiation when combined with morphine.

Effects of antiemetics on the acquisition and recall of radiation- and lithium chloride-induced conditioned taste aversions.

A series of experiments were run to evaluate the effect of antiemetics on the acquisition and recall of a conditioned taste aversion induced by exposure to ionizing radiation or by injection of lithium chloride. Groups of male rats were exposed to 100 rad gamma radiation or 3 mEq/kg lithium chloride following consumption of a 10% sucrose solution. They were then injected with saline or with one of three antiemetics (prochlorperazine, trimethobenzamide, or cyclizine) at dose levels that have been reported to be effective in attenuating a previously acquired lithium chloride-induced taste aversion. The pretreatments with antiemetics had no effect on the acquisition or recall of either the lithium chloride- or radiation-induced taste aversion. The data suggest that antiemetics do not disrupt lithium chloride-induced taste aversions as previously reported, nor do they effect radiation-induced taste aversion learning.

A comparison of triprolidine and cyclizine on histamine (H1) antagonism, subjective effects and performance tests in man.

1 The effects of triprolidine and cyclizine on the histamine skin response, performance tests and subjective effects were examined in a controlled, double-blind study in eight healthy volunteers. 2 Triprolidine was considerably more potent that cyclizine in inhibiting the skin response to histamine. Significant inhibition of flare size occurred at 1, 2 an 4 h after triprolidine 2.5 mg. A smaller but significant reduction occurred at 2 and 4 h after cyclizine 100 mg but not after the 50 mg dose. 3 Cyclizine 100 mg produced a significant increase in reaction time at 4.5 h compared with lactose. Smaller though non significant increases followed triprolidine and cyclizine 50 mg. 4 Subjective effects were seen only after cyclizine 100 mg when subjects were significantly more drowsy, feeble, muzzy, lethargic and dreamy than after lactose dummy. No significant changes followed triprolidine 2.5 mg or cyclizine 50 mg. 5 It was concluded that while cyclizine has antihistamine properties, these are weak compared with triprolidine, and are not seen with doses sufficiently low to avoid central nervous system impairment.

The effects of some drugs on the caloric induced nystagmus.

A striking difference between the two anticholinergic drugs was observed. Atropine only modified the eye speed of the slow phase (mes), whereas scopolamine modified both parameters measured, mes and duration. Amphetamine and caffeine prolonged the duration, leaving the mes unchanged. All antiemetic drugs inhibited both parameters. It is concluded that the effect of a drug on the caloric reaction gives insufficient information in the preclinical evaluation of vestibulo-suppressive drugs.

The effect of cyclizine hydrochloride on lower oesophageal sphincter pressure in man.

Gastro-oesophageal reflux and pulmonary aspiration of acid gastric content remain significant causes of morbidity and mortality. A drug which increases lower oesophageal sphincter (LOS) tone would reduce this hazard. The effect of LOS function of intravenous cyclizine (25 mg), in half the recommended adult dose, was investigated in 8 volunteers. Cyclizine increased the LOS pressure by an average of 14,4 cm H2O (P less than 0,005). Cyclizine, like metoclopramide, has a desirable functional effect on the LOS. Both drugs are, in addition, potent anti-emetics. On the grounds of these pharmacological properties they are recommended in the preparation of patients for emergency surgery.