Promethazine inhibits NMDA-induced currents – New pharmacological aspects of an old drug

Prospective case-control study on pain intensity after the use of promethazine in patients undergoing videothoracoscopy

Objective

Effective and secure pain management following video-assisted thoracoscopic surgery (VATS) is crucial for rapid postoperative recovery. This study evaluated analgesic and sedative effects of sufentanil and promethazine in patient-controlled intravenous analgesia (PCIA) post-thoracic surgery, along with potential adverse reactions.

Methods

In this prospective, randomized, controlled, double-blind, clinical study, 60 patients (American Society of Anesthesiologists status I-III) undergoing VATS were enrolled. The patients were randomized into experimental (Group P) or control (Group C) groups. PCIA was administered post-general anesthesia using a double-blind method. Group P received sufentanil (3 μg/kg) + promethazine (1 mg/kg) + 0.9% sodium chloride solution (100 mL total), while Group C received sufentanil (3 μg/kg) + 0.9% sodium chloride solution (100 mL total). PCIA settings included a 1-mL bolus and 15-min locking time. The primary outcomes were the visual analog scale (VAS) at rest and during coughing and sedation (Ramsay) scores at 6, 12, 24, and 48 h. The secondary outcomes were rescue drug use rate, hemodynamic parameters (mean arterial pressure and heart rate), percutaneous oxygen saturation, respiratory rate, and occurrence of adverse reactions.

Results

Group P exhibited lower resting and coughing VAS scores at 6, 12, 24, and 48 h, plus decreased incidence of nausea and vomiting within 48 h post-surgery compared with Group C (p < 0.05). No significant differences were observed in pruritus, sedation (Ramsay) scores, mean arterial pressure, heart rate, oxygen saturation, or respiratory rate between the two groups (p > 0.05).

Discussion

The combination of sufentanil and promethazine for postoperative intravenous analgesia could effectively reduce adverse effects such as nausea and vomiting, contributing to postoperative pain relief.

Modulation of NLRP3 inflammasome-related-inflammation via RIPK1/RIPK3-DRP1 or HIF-1α signaling by phenothiazine in hypothermic and normothermic neuroprotection after acute ischemic stroke

BACKGROUND

Inflammation and subsequent mitochondrial dysfunction and cell death worsen outcomes after revascularization in ischemic stroke. Receptor-interacting protein kinase 1 (RIPK1) activated dynamin-related protein 1 (DRP1) in a NLRPyrin domain containing 3 (NLRP3) inflammasome-dependent fashion and Hypoxia-Inducible Factor (HIF)-1α play key roles in the process. This study determined how phenothiazine drugs (chlorpromazine and promethazine (C + P)) with the hypothermic and normothermic modality impacts the RIPK1/RIPK3-DRP1 and HIF-1α pathways in providing neuroprotection.

METHODS

A total of 150 adult male Sprague-Dawley rats were subjected to 2 h middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion. 8 mg/kg of C + P was administered at onset of reperfusion. Infarct volumes, mRNA and protein expressions of HIF-1α, RIPK1, RIPK3, DRP-1, NLRP3-inflammation and cytochrome c-apoptosis were assessed. Apoptotic cell death, infiltration of neutrophils and macrophages, and mitochondrial function were evaluated. Interaction between RIPK1/RIPK3 and HIF-1α/NLRP3 were determined. In SH-SY5Y cells subjected to oxygen/glucose deprivation (OGD), the normothermic effect of C + P on inflammation and apoptosis were examined.

RESULTS

C + P significantly reduced infarct volumes, mitochondrial dysfunction (ATP and ROS concentration, citrate synthase and ATPase activity), inflammation and apoptosis with and without induced hypothermia. Overexpression of RIPK1, RIPK3, DRP-1, NLRP3-inflammasome and cytochrome c-apoptosis were all significantly reduced by C + P at 33 °C and the RIPK1 inhibitor (Nec1s), suggesting hypothermic effect of C + P via RIPK1/RIPK3-DRP1pathway. When body temperature was maintained at 37 °C, C + P and HIF-1α inhibitor (YC-1) reduced HIF-1α expression, leading to reduction in mitochondrial dysfunction, NLRP3 inflammasome and cytochrome c-apoptosis, as well as the interaction of HIF-1α and NLRP3. These were also evidenced in vitro, indicating a normothermic effect of C + P via HIF-1α.

CONCLUSION

Hypothermic and normothermic neuroprotection of C + P involve different pathways. The normothermic effect was mediated by HIF-1α, while hypothermic effect was via RIPK1/RIPK3-DRP1 signaling. This provides a theoretical basis for future precise exploration of hypothermic and normothermic neuroprotection.

Exploring the interactions of antihistamine with retinoic acid receptor beta (RARB) by molecular dynamics simulations and genome-wide meta-analysis

Kaposi sarcoma (KS) is one of the most common AIDS-related malignant neoplasms, which can leave lesions on the skin among HIV patients. These lesions can be treated with 9-cis-retinoic acid (9-cis-RA), an endogenous ligand of retinoic acid receptors that has been FDA-approved for treatment of KS. However, topical application of 9-cis-RA can induce several unpleasant side effects, like headache, hyperlipidemia, and nausea. Hence, alternative therapeutics with less side effects are desirable. There are case reports associating over-the-counter antihistamine usage with regression of KS. Antihistamines competitively bind to H1 receptor and block the action of histamine, best known for being released in response to allergens. Furthermore, there are already dozens of antihistamines that are FDA-approved with less side effects than 9-cis-RA. This led our team to conduct a series of in-silico assays to determine whether antihistamines can activate retinoic acid receptors. First, we utilized high-throughput virtual screening and molecular dynamics simulations to model high-affinity interactions between antihistamines and retinoic acid receptor beta (RARβ). We then performed systems genetics analysis to identify a genetic association between H1 receptor itself and molecular pathways involved in KS. Together, these findings advocate for exploration of antihistamines against KS, starting with our two promising hit compounds, bepotastine and hydroxyzine, for experimental validation study in the future.

Mechanisms of NMDA Receptor Inhibition by Sepimostat-Comparison with Nafamostat and Diarylamidine Compounds

N-methyl-D-aspartate (NMDA) receptors are inhibited by many amidine and guanidine compounds. In this work, we studied the mechanisms of their inhibition by sepimostat-an amidine-containing serine protease inhibitor with neuroprotective properties. Sepimostat inhibited native NMDA receptors in rat hippocampal CA1 pyramidal neurons with IC50 of 3.5 ± 0.3 µM at -80 mV holding voltage. It demonstrated complex voltage dependence with voltage-independent and voltage-dependent components, suggesting the presence of shallow and deep binding sites. At -80 mV holding voltage, the voltage-dependent component dominates, and we observed pronounced tail currents and overshoots evidencing a "foot-in-the-door" open channel block. At depolarized voltages, the voltage-independent inhibition by sepimostat was significantly attenuated by the increase of agonist concentration. However, the voltage-independent inhibition was non-competitive. We further compared the mechanisms of the action of sepimostat with those of structurally-related amidine and guanidine compounds-nafamostat, gabexate, furamidine, pentamidine, diminazene, and DAPI-investigated previously. The action of all these compounds can be described by the two-component mechanism. All compounds demonstrated similar affinity to the shallow site, which is responsible for the voltage-independent inhibition, with binding constants in the range of 3-30 µM. In contrast, affinities to the deep site differed dramatically, with nafamostat, furamidine, and pentamidine being much more active.

Mechanisms of NMDA receptor inhibition by diarylamidine compounds

Pentamidine, diminazene and 4',6-diamidino-2-phenylindole (DAPI) are antiprotozoal diarylamidine compounds. In the present work, we have studied their action on native N-methyl-D-aspartate (NMDA) receptors in rat hippocampal pyramidal neurons. All three compounds inhibited NMDA receptors at -80 mV holding voltage with IC₅₀ of 0.41 ± 0.08, 13 ± 3 and 3.1 ± 0.6 μM, respectively. The inhibition by pentamidine was strongly voltage-dependent, while that of DAPI was practically voltage-independent. Inhibition by diminazene had both voltage-dependent and voltage-independent components. Diminazene and DAPI demonstrated tail currents and overshoots suggesting "foot-in-the-door" mechanism of action. In contrast, pentamidine was partially trapped in the closed NMDA receptor channels. Such difference in the mechanism of action can be explained by the difference in the 3D structure of compounds. In the pentamidine molecule, two benzamidine groups are connected with a flexible linker, which allows the molecule to fold up and fit in the cavity of a closed NMDA receptor channel. Diminazene and DAPI, in contrast, have an extended form and could not be trapped.

Comparison of Haloperidol, Promethazine, Trifluoperazine, and Chlorpromazine in Terms of Velocity and Durability of the Sedation among Acute Aggressive Patients: A Randomized Clinical Trial

Background:

Knowledge and skill about sedation of aggressive patients is necessary for each psychiatrist. The purpose of this study was comparing the velocity and durability of sedation induced by the haloperidol, trifluoperazine, promethazine, and chlorpromazine in aggressive patients.

Materials and Methods:

This randomized clinical trial was done on 76 aggressive patients referred to Psychiatry Emergency Service of Noor Hospital of Isfahan University of Medical Sciences that were randomly divided into four groups of haloperidol, promethazine, chlorpromazine, and trifluoperazine. Patients were evaluated at 30 min intervals for aggressive symptoms, and if they did not respond to intervention after the first 30 min or if they showed aggression again, a same dose of the injected drug was prescribed. The length of sedation time was recorded for each patient.

Results:

Seventy-six patients with the mean age of 31.89 ± 8.73 years were participated and 63.2% of them were male. Response to intervention after the first injection was seen in 40.8% and 59.2% needed the second injection. The mean time needed for obtaining sedation was 17.38 ± 8.23 and 19.66 ± 4.64 min after the first and second injection, respectively. The mean times of sedation induction were not significantly related to age, gender, type of substance used, type of aggression, and type of psychiatric disorder. Considering the type of drugs, there was no significant difference between velocity and durability effect of sedation after the first and second injection.

Conclusion:

Comparing the velocity and durability of sedative effect of the four studied drugs on acute aggressive patients, did not show any significant difference between them.

Abuse and Intentional Misuse of Promethazine Reported to US Poison Centers: 2002 to 2012

OBJECTIVE

Promethazine abuse has been reported. The objective was to investigate promethazine abuse/misuse in the United States.

METHODS

An 11-year retrospective review was conducted of promethazine abuse and intentional misuse cases without co-ingestants in persons 10 years and older reported to the National Poison Data System. Data were stratified by product (promethazine-alone [PA] or co-formulation [PC]) and evaluated for demographics, toxicity, management sites, and outcomes.

RESULTS

There were 354 single product abuse or misuse exposures-95 PA and 259 PC. Over the 11-year timeframe, the annual exposure rate per 100,000 population doubled. Exposures were most prevalent among 10 to 19 years old and young adults (20s), accounting for 69.5% of PA and 57.5% of PC cases. Clinical effects due to PA included drowsiness (43.2%), tachycardia (7.4%), agitation (13.7%), confusion (13.7%), slurred speech (12.6%), hallucinations (7.4%), dizziness (7.4%), and hypertension (5.3%). Drowsiness (53.4%) and tachycardia (20.8%) were more frequent with PC. There were significant differences between PA and PC in management site (P = 0.0078). Management sites for PA and PC, respectively, were emergency department (37.9%, 55.6%), non-health care facility (33.7%, 14.7%), critical care unit (8.4%, 11.2%), non-critical care unit (7.4%, 7.3%), psychiatry (2.1%, 4.2%), and other/unknown (10.5%, 7.0%). Outcomes for PA and PC, respectively, were no effect (21.0%, 12.4%), minor (58.9%, 53.7%), moderate (17.9%, 32.0%), and major effects (2.1%, 1.9%).

CONCLUSIONS

Promethazine-alone abuse/misuse most frequently resulted in minor outcomes, and less than 20% required medical admission. Abuse/misuse of PC resulted in a higher frequency of health care facility treatment and a trend toward more moderate outcomes. These differences are most likely attributed to the co-formulate.

Binding of phenothiazines into allosteric hydrophobic pocket of human thioredoxin 1

Thioredoxins are multifunctional oxidoreductase proteins implicated in the antioxidant cellular apparatus and oxidative stress. They are involved in several pathologies and are promising anticancer targets. Identification of noncatalytic binding sites is of great interest for designing new allosteric inhibitors of thioredoxin. In a recent work, we predicted normal mode motions of human thioredoxin 1 and identified two major putative hydrophobic binding sites. In this work we investigated noncovalent interactions of human thioredoxin 1 with three phenotiazinic drugs acting as prooxidant compounds by using molecular docking and circular dichroism spectrometry to probe ligand binding into the previously predicted allosteric hydrophobic pockets. Our in silico and CD spectrometry experiments suggested one preferred allosteric binding site involving helix 3 and adopting the best druggable conformation identified by NMA. The CD spectra showed binding of thioridazine into thioredoxin 1 and suggested partial helix unfolding, which most probably concerns helix 3. Taken together, these data support the strategy to design thioredoxin inhibitors targeting a druggable allosteric binding site.

Ondansetron and promethazine have differential effects on hypothermic responses to lithium chloride administration and to provocative motion in rats

We recently reported that provocative motion (rotation in a home cage) causes hypothermic responses in rats, similar to the hypothermic responses associated with motion sickness in humans. Many stimuli inducing emesis in species with an emetic reflex also provoke hypothermia in the rat, therefore we hypothesized that a fall in body temperature may reflect a “nausea-like” state in these animals. As rats do not possess an emetic reflex, we employed a pharmacological approach to test this hypothesis. In humans, motion- and chemically-induced nausea have differential sensitivity to anti-emetics. We thus tested whether the hypothermia induced in rats by provocative motion (rotation at 0.7 Hz) and by the emetic LiCl (63 mg/kg i.p.) have a similar differential pharmacological sensitivity. Both provocations caused a comparable robust fall in core body temperature (−1.9 ± 0.3°C and −2.0 ± 0.2°C for chemical and motion provocations, respectively). LiCl⁻induced hypothermia was completely prevented by ondansetron (2mg/kg, i.p., a 5-HT₃ receptor antagonist that reduces cancer chemotherapy-induced nausea and vomiting), but was insensitive to promethazine (10 mg/kg, i.p., a predominantly histamine-H₁ and muscarinic receptor antagonist that is commonly used to treat motion sickness). Conversely, motion-induced hypothermia was unaffected by ondansetron but promethazine reduced the rate of temperature decline from 0.20 ± 0.02 to 0.11 ± 0.03°C/min (P < 0.05) with a trend to decrease the magnitude. We conclude that this differential pharmacological sensitivity of the hypothermic responses of vestibular vs. chemical etiology in rats mirrors the observations in other pre-clinical models and humans, and thus supports the idea that a “nausea-like” state in rodents is associated with disturbances in thermoregulation.

Open channel block of NMDA receptors by diphenhydramine

BACKGROUND AND PURPOSE

Diphenhydramine is a well known H1-receptor antagonist that plays a major role in clinical practice. Nowadays, diphenhydramine is primarily applied to prevent nausea but also its sedative and analgesic effects are of clinical importance. As other drugs mediating sedative and analgesic properties partly operate via the inhibition of glutamate receptors, we tested the hypothesis that diphenhydramine, as well interacts with excitatory ionotropic glutamate receptors.

EXPERIMENTAL APPROACH

Electrophysiological patch-clamp experiments were performed on glutamate receptors which were heterologously expressed in human TsA cells.

KEY RESULTS

Diphenhydramine inhibits NMDA-mediated membrane currents in a reversible and concentration-dependent manner at clinically relevant concentrations. The inhibition occurred in a noncompetitive manner. Diphenhydramine did not compete with NMDA or glycine for their binding sites and half-maximal inhibition was obtained around 25 μM diphenhydramine, independent of the subunit composition. The inhibition was caused by a classical open channel blocking mechanism and varied strongly with the membrane potential. Our results suggest that diphenhydramine most probably interacts with the Mg2+ binding site or a very closely related area of the channel pore.

CONCLUSION AND IMPLICATIONS

The data presented here provide evidence that the NMDA receptor antagonism of diphenhydramine contribute to its sedative and potentially LTP-related effects like analgesia and amnesia.

Chloral hydrate, chloral hydrate--promethazine and chloral hydrate -hydroxyzine efficacy in electroencephalography sedation

OBJECTIVE

To compare efficacy and safety of chloral hydrate (CH), chloral hydrate and promethazine (CH + P) and chloral hydrate and hydroxyzine (CH + H) in electroencephalography (EEG) sedation.

METHODS

In a parallel single-blinded randomized clinical trial, ninety 1-7 y-old uncooperative kids who were referred to Pediatric Neurology Clinic of Shahid Sadoughi University, Yazd, Iran from April through August 2012, were randomly assigned to receive 40 mg/kg of chloral hydrate or 40 mg/kg of chloral hydrate and 1 mg/kg of promethazine or 40 mg/kg of chloral hydrate and 2 mg/kg of hydroxyzine. The primary endpoint was efficacy in sufficient sedation (obtaining four Ramsay sedation score) and successful completion of EEG. Secondary endpoint was clinical adverse events.

RESULTS

Thirty nine girls (43.3 %) and 51 boys (56.7 %) with mean age of 3.34 ± 1.47 y were assessed. Sufficient sedation and completion of EEG were achieved in 70 % (N = 21) of chloral hydrate group, in 83.3 % (N = 25) of CH + H group and in 96.7 % (N = 29) of CH + P group (p = 0.02). Mild clinical adverse events including vomiting [16.7 % (N = 5) in CH, 6.7 % (N = 2) in CH + P, 6.7 % (N = 2) in CH + H], agitation in 3.3 % of CH + P (N = 1) group and mild transient hypotension in 3.3 % of CH + H (N = 1) group occurred. Safety of these three sedation regimens was not statistically significant different (p = 0.14).

CONCLUSIONS

Combination of chloral hydrate-antihistamines can be used as the most effective and safe sedation regimen in drug induced sleep electroencephalography of kids.

Effects of promethazine or dexamethasone pretreatment on mivacurium-induced histamine release in children

OBJECTIVE

To determine the effects of pretreatment with either promethazine or dexamethasone on mivacurium-induced histamine release in children.

METHODS

Eighty ASA I-II children (4-10 years of age) scheduled for tonsillectomy and/or adenoidectomy were randomly divided into 4 groups (n = 20 per group) designated as either the rocuronium, mivacurium, dexamethasone (DXM), or promethazine group. Children in the DXM and promethazine groups were treated separately with intramuscular DXM 0.2 mg·kg(-1) or promethazine 0.5 mg·kg(-1) injections 60 min before operation. Radial artery blood samples were collected to quantify plasma histamine concentrations 1 min before and 1, 3, and 5 min after administration of the relaxant. Mean arterial pressure (MAP), heart rate (HR), and skin flushing were recorded at the same time.

RESULTS

No significant decreases in plasma histamine concentrations were observed between groups; however, more stable MAP and HR and less skin flushing were observed in DXM group participants compared with individuals in the mivacurium group (P < 0.05). By contrast, children in the promethazine group had significantly decreased plasma histamine concentrations and stable MAP and HR (without a significant increase in HR) compared with patients in mivacurium group. In addition, skin flushing was significantly decreased compared with that observed in the rocuronium group (P < 0.05).

CONCLUSIONS

Pretreatment with promethazine significantly decreased mivacurium-induced histamine release in children and provided stable hemodynamics during administration of anesthesia.