Binding studies of promethazine and its metabolites with human serum albumin by high-performance affinity chromatography and molecular docking in the presence of codeine.

"Purple Drank", a soft drink containing promethazine (PMZ) and codeine (COD), has gained global popularity for its hallucinogenic effects. Consuming large amounts of this combination can lead to potentially fatal events. The binding of these drugs to plasma proteins can exacerbate the issue by increasing the risk of drug interactions, side effects, and/or toxicity. Herein, the binding affinity to human serum albumin (HSA) of PMZ and its primary metabolites [N-desmethyl promethazine (DMPMZ) and promethazine sulphoxide (PMZSO)], along with COD, was investigated by high-performance affinity chromatography (HPAC) though zonal approach. PMZ and its metabolites exhibited a notable binding affinity for HSA (%b values higher than 80%), while COD exhibited a %b value of 65%. To discern the specific sites of HSA to which these compounds were bound, displacement experiments were performed using warfarin and (S)-ibuprofen as probes for sites I and II, respectively, which revealed that all analytes were bound to both sites. Molecular docking studies corroborated the experimental results, reinforcing the insights gained from the empirical data. The in silico data also suggested that competition between PMZ and its metabolites with COD can occur in both sites of HSA, but mainly in site II. As the target compounds are chiral, the enantioselectivity for HSA binding was also explored, showing that the binding for these compounds was not enantioselective.

Formulation development and evaluation of nasal in situ gel of promethazine hydrochloride.

OBJECTIVE: The present work aims to develop mucoadhesive thermosensitive nasal in situ gel for Promethazine hydrochloride using quality by design (QbD) approach. It can reduce nasal mucociliary clearance (MCC) and increase residence of the drug on nasal mucosa. This might increase drug absorption to improve bioavailability of the drug as compared to oral dosage form. SIGNIFICANCE: Promethazine hydrochloride is an antiemetic drug administered by oral, parenteral and rectal routes. These routes have poor patient compliance or low bioavailability. Nasal route is a better alternative as it has large surface area, high drug absorption rate and no first pass effect. Its only limitation is short drug retention time due to MCC. By formulating a mucoadhesive in situ gel, the MCC can be reduced, and drug absorption will be prolonged. Thus, improving bioavailability. METHOD: In-situ gel was prepared by cold method having material attributes as concentration of Poloxamer 407 (X1) as gelling agent and hydroxypropyl methyl cellulose K4M (X2) as mucoadhesive agent. Critical Quality Attributes (CQA) were gelation temperature, mucoadhesive force and ex-vivo diffusion. Central composite design (CCD) was adopted for optimization. RESULT: Optimized formulation satisfied all the CQA significant for nasal administration. Moreover, the formulation was found to be stable in accelerated stability studies for 3 months. CONCLUSION: It can be concluded that since the drug can easily permeate through nasal mucosa and can gain access directly in the brain without undergoing first pass metabolism along with increased residence due to mucoadhesion, mucoadhesive in situ gel has potential to increase drug bioavailability.

Promethazine inhibits efflux, enhances antifungal susceptibility and disrupts biofilm structure and functioning in Trichosporon.

Trichosporon spp. are emerging opportunistic fungi associated with invasive infections, especially in patients with haematological malignancies. The present study investigated the in vitro inhibition of efflux pumps by promethazine (PMZ) as a strategy to control T. asahii and T. inkin. Planktonic cells were evaluated for antifungal susceptibility to PMZ, as well as inhibition of efflux. The effect of PMZ was also studied in Trichosporon biofilms. PMZ inhibited T. asahii and T. inkin planktonic cells at concentrations ranging from 32 to 256 µg ml-1. Subinhibitory concentrations of PMZ inhibited efflux activity in Trichosporon. Biofilms were completely eradicated by PMZ. PMZ potentiated the action of antifungals, affected the morphology, changed the amount of carbohydrates and proteins and reduced the amount of persister cells inside biofilms. The results showed indirect evidences of the occurrence of efflux pumps in Trichosporon and opens a perspective for the use of this target in the control of trichosporonosis.

In vitro effects of promethazine on cell morphology and structure and mitochondrial activity of azole-resistant Candida tropicalis.

The aim of this study was to evaluate the effect of promethazine on the antifungal minimum inhibitory concentrations against planktonic cells and mature biofilms of Candida tropicalis, as well as investigate its potential mechanisms of cell damage against this yeast species. Three C. tropicalis isolates (two azole-resistant and one azole-susceptible) were evaluated for their planktonic and biofilm susceptibility to promethazine alone and in combination with itraconazole, fluconazole, voriconazole, amphotericin B, and caspofungin. The antifungal activity of promethazine against C. tropicalis was investigated by performing time-kill curve assays and assessing rhodamine 6G efflux, cell size/granularity, membrane integrity, and mitochondrial transmembrane potential, through flow cytometry. Promethazine showed antifungal activity against planktonic cells and biofilms at concentrations of 64 and 128 µg/ml, respectively. The addition of two subinhibitory concentrations of promethazine reduced the antifungal MICs for all tested azole drugs against planktonic growth, reversing the resistance phenotype to all azoles. Promethazine decreased the efflux of rhodamine 6G in an azole-resistant strain. Moreover, promethazine decreased cell size/granularity and caused membrane damage, and mitochondrial membrane depolarization. In conclusion, promethazine presented synergy with azole antifungals against resistant C. tropicalis and exhibited in vitro cytotoxicity against C. tropicalis, altering cell size/granularity, membrane integrity, and mitochondrial function, demonstrating potential mechanisms of cell damage against this yeast species.

Development and characterization of a small electromembrane extraction probe coupled with mass spectrometry for real-time and online monitoring of in vitro drug metabolism.

A small and very simple electromembrane extraction probe (EME-probe) was developed and coupled directly to electrospray ionization mass spectrometry (ESI-MS), and this system was used to monitor in real time in vitro metabolism by rat liver microsomes of drug substances from a small reaction (incubation) chamber (37 °C). The drug-related substances were continuously extracted from the 1.0 mL metabolic reaction mixture and into the EME-probe by an electrical potential of 2.5 V. The extraction probe consisted of a 1-mm long and 350-µm ID thin supported liquid membrane (SLM) of 2-nitrophenyl octyl ether. The drugs and formed metabolites where extracted through the SLM and directly into a 3 µL min(-1) flow of 60 mM HCOOH inside the probe serving as the acceptor solution. The acceptor solution was directed into the ESI-MS-system, and the MS continuously monitored the drug-related substances extracted by the EME-probe. The extraction efficiency of the EME-probe was dependant on the applied electrical potential and the length of the SLM, and these parameters as well as the volume of the reaction chamber were set to the values mentioned above to avoid serious depletion from the reaction chamber (soft extraction). Soft extraction was mandatory in order not to affect the reaction kinetics by sample composition changes induced by the EME-probe. The EME-probe/MS-system was used to establish kinetic profiles for the in vitro metabolism of promethazine, amitriptyline and imipramine as model substances.

Studies on the metabolism of five model drugs by fungi colonizing cadavers using LC-ESI-MS/MS and GC-MS analysis.

It is well-known that cadavers may be colonized by microorganisms, but there is limited information if or to what extent these microbes are capable of metabolizing drugs or poisons, changing the concentrations and metabolic pattern of such compounds in postmortem samples. The aim of the present study was to develop a fungal biotransformation system as an in vitro model to investigate potential postmortem metabolism by fungi. Five model drugs (amitriptyline, metoprolol, mirtazapine, promethazine, and zolpidem) were each incubated with five model fungi known to colonize cadavers (Absidia repens, Aspergillus repens, Aspergillus terreus, Gliocladium viride, and Mortierella polycephala) and with Cunninghamella elegans (positive control). Incubations were performed in Sabouraud medium at 25 °C for 5 days. After centrifugation, a part of the supernatants was analyzed by liquid chromatography-tandem mass spectrometry with product ion scanning. Another part was analyzed by full scan gas chromatography-mass spectrometry after extraction and derivatization. All model drugs were metabolized by the control fungus resulting in two (metoprolol) to ten (amitriptyline) metabolites. Of the model fungi, only Abs. repens and M. polycephala metabolized the model drugs: amitriptyline was metabolized to six and five, metoprolol to two and two, mirtazapine to five and three, promethazine to six and nine, and zolpidem to three and four metabolites, respectively. The main metabolic reactions were demethylation, oxidation, and hydroxylation. The presented in vitro model is applicable to studying drug metabolism by fungi colonizing cadavers.

Promethazine Downregulates Wnt/ß-Catenin Signaling and Increases the Biomechanical Forces of the Injured Achilles Tendon in the Early Stage of Healing.

BACKGROUND: Wnt/ß-catenin signaling suppresses the differentiation of cultured tenocytes, but its roles in tendon repair remain mostly elusive. No chemical compounds are currently available to treat tendon injury. HYPOTHESIS: We hypothesized that the inhibition of Wnt/ß-catenin signaling would accelerate tendon healing. STUDY DESIGN: Controlled laboratory study. METHODS: Tendon-derived cells (TDCs) were isolated from rat Achilles tendons. The right Achilles tendon was injured via a dermal punch, while the left tendon was sham operated. A Wnt/ß-catenin inhibitor, IWR-1, and an antihistamine agent, promethazine (PH), were locally and intramuscularly injected, respectively, for 2 weeks after surgery. The healing tendons were histologically and biomechanically evaluated. RESULTS: The amount of ß-catenin protein was increased in the injured tendons from postoperative weeks 0.5 to 2. Inhibition of Wnt/ß-catenin signaling by IWR-1 in healing tendons improved the histological abnormalities and decreased ß-catenin, but it compromised the biomechanical properties. As we previously reported that antihistamine agents suppressed Wnt/ß-catenin signaling in human chondrosarcoma cells, we examined the effects of antihistamines on TDCs. We found that a first-generation antihistamine agent, PH, increased the expression of the tendon marker genes Mkx and Tnmd in TDCs. Intramuscular injection of PH did not improve histological abnormalities, but it decreased ß-catenin in healing tendons and increased the peak force and stiffness of the healing tendons on postoperative week 2. On postoperative week 8, however, the biomechanical properties of vehicle-treated tendons became similar to those of PH-treated tendons. CONCLUSION: IWR-1 and PH suppressed Wnt/ß-catenin signaling and improved the histological abnormalities of healing tendons. IWR-1, however, compromised the biomechanical properties of healing tendons, whereas PH improved them. CLINICAL RELEVANCE: PH is a candidate repositioned drug that potentially accelerates tendon repair.

LYTIC COCKTAIL ATTENUATES CATECHOLAMINE SURGE AFTER SEVERE BURNS BY BLOCKING HISTAMINE H1 RECEPTOR/PKA/CREB/TYROSINE HYDROXYLASE SIGNALING IN CHROMAFFIN CELLS.

ABSTRACT: Severe burns develop a catecholamine surge, inducing severe damage to the organism, raising the possibility of multisystem organ failure, and even death. The mechanisms of catecholamine surge have not been fully elucidated, and few strategies are generally acceptable to reduce catecholamine surge postburn. Thus, it is valuable to investigate the underlying mechanisms of catecholamine surge postburn to develop targeted interventions to attenuate it. We have found that the lytic cocktail alleviates the surge of catecholamine and organ injury after severe burn; however, the underlying mechanisms were still unclear. Moreover, the lytic cocktail has side effects, such as significant arterial hypotension and breathing depression, limiting its clinical application. This study aims to investigate the therapeutic mechanism of the lytic cocktail in regulating catecholamine levels postburn. We find that promethazine, a classic histamine H1 receptor blocker and a component of the lytic cocktail, can effectively reduce catecholamine surge and organ injury postburn. Our study confirms that blood histamine levels increase after severe burns. We find that histamine can amplify the catecholamine surge by elevating tyrosine hydroxylase expression and catecholamine synthesis in chromaffin cells through the histamine H1 receptor/Protein Kinase A /cAMP-response element binding protein signaling pathway. In summary, for the first time, we find that histamine plays a vital role in catecholamine surge postburn. We also confirm that the lytic cocktail effectively alleviates catecholamine surge and organ injury postburn through promethazine.

Simultaneous determination of cyclodol and diprazin by thin layer chromatography and high performance liquid chromatography.

Ciklodol (trihexyphenidil)--the central and peripheral m-cholinoblocker is currently used with other antipsychotic drugs such as phenotiazines and tricycle antidepressants. For the purpose of simultaneous determination of ciklodol and diprazine, were selected two methods of analysis: Thin Layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC). During development of TLC method was studied the 10 visualizing system and 24 mobile systems. For individual or simultaneous determination of ciklodol and diprazine were recommended the following solvents' systems: 1. Toluene-acetone-ethanole-25%NH(4)OH (45:45: 7.5:2.5), 2. Hexane-ethyl acetate (15:5), 3. Chloroform-heptene-25%NH(4)OH (16:3:3), 4. Ethylacetate-hexane (10:10), 5. Acetonitrile-metanol (10:10) and 6.Heptene-chloroform-ethanol-25% NH(4)OH (5:10:3:1). As visualizing systems were chosen: Iodine vapors, blacklight (UV254) and reagent of FNP. Reagent of FNP gives colored spot just with diprazine and it is also could be used for separation of both objects in simultaneous analysis. Developed HPLC method of simultaneous determination of ciklodol and diprazine: like mobile phase is recommended: Acetonitril- 0.05M KH(2)PO4 (55:45) (v/v) +H(3)PO(4) (pH3.5), column EC250 x 4.6mm, with solid phase Nucleosil, flow rate 1ml/min, sample volume 40 microl. In given conditions, the retention time of ciklodol is 6.005min and diprazine 7.227min. Developed method of simultaneous determination and separation of ciklodol and diprazine in respective mixtures could be successfully applied as in the pharmaceutical, as well in the chemical-toxicological laboratories.

Biophysical investigation of promethazine hydrochloride binding with micelles of biocompatible gemini surfactants: Combination of spectroscopic and electrochemical analysis.

Knowledge of binding parameters for drug and surfactant complexations is crucially vital in order to design effective drug carrier systems with requisite features. To this end, this work was designed to demonstrate the biophysical characterization of the interaction of a phenothiazine drug promethazine hydrochloride (PMT) with relatively lower cytotoxic and easily degradable biomimetic micellar self-assemblies of oxy-diester functionalized gemini surfactants (Cm-E2O-Cm, m = 12, 14 and 16), possessing different hydrophobic character. The binding propensity of Cm-E2O-Cm increases upon increasing the hydrophobic tail length as manifested through both intrinsic fluorescence and absorption spectral profiles of PMT ̶ Cm-E2O-Cm, showing 1:1 stoichiometry. Ksv values also follow the trend of increasing hydrophobic character (i.e., C12-E2O-C12 < C14-E2O-C14 < C16-E2O-C16). Moreover, the determined thermodynamic parameters, particularly the positive values of ΔHbo and ΔSbo, reveal that the involved complexations are dominated by the hydrophobic interactions. In addition, micropolarity assay was done to deduce the microenvironmental changes upon PMT ̶ Cm-E2O-Cm complexations. Beside this, comparative appraisal of all the three systems helps to underpin a reasonable knowledge of the effect of structural variation of surfactants on their binding ability with drug which, in turn, may also open new avenues for the designing of potential tunable drug carrier systems.

Interaction of promethazine and adiphenine to human hemoglobin: A comparative spectroscopic and computational analysis.

The binding nature of amphiphilic drugs viz. promethazine hydrochloride (PMT) and adiphenine hydrochloride (ADP), with human hemoglobin (Hb) was unraveled by fluorescence, absorbance, time resolved fluorescence, fluorescence resonance energy transfer (FRET) and circular dichroism (CD) spectral techniques in combination with molecular docking and molecular dynamic simulation methods. The steady state fluorescence spectra indicated that both PMT and ADP quenches the fluorescence of Hb through static quenching mechanism which was further confirmed by time resolved fluorescence spectra. The UV-Vis spectroscopy suggested ground state complex formation. The activation energy (Ea) was observed more in the case of Hb-ADP than Hb-PMT interaction system. The FRET result indicates the high probability of energy transfer from ß Trp37 residue of Hb to the PMT (r=2.02nm) and ADP (r=2.33nm). The thermodynamic data reveal that binding of PMT with Hb are exothermic in nature involving hydrogen bonding and van der Waal interaction whereas in the case of ADP hydrophobic forces play the major role and binding process is endothermic in nature. The CD results show that both PMT and ADP, induced secondary structural changes of Hb and unfold the protein by losing a large helical content while the effect is more pronounced with ADP. Additionally, we also utilized computational approaches for deep insight into the binding of these drugs with Hb and the results are well matched with our experimental results.

Hydroxyzine, promethazine and thioridazine interaction with phospholipid monomolecular layers at the air-water interface.

In this work the interaction of Hydroxyzine, Promethazine and Thioridazine with Langmuir films of dipalmitoylphosphatidylcholine (dpPC) and dipalmitoylphosphatidic acid (dpPA), is studied. Temporal variations in lateral surface pressure (pi) were measured at different initial pi (pi(i)), subphase pH and drug-concentration. Drugs with the smallest (PRO) and largest (HYD) molecular size exhibited the lowest adsorption (k(a)) and the highest desorption (k(d)) rate constant values, respectively. The affinity binding constants (K(b)) obtained in monolayers followed the same profile (K(b,PRO) < K(b,HYD) < K(b,THI)) of the egg-PC/water partition coefficients (P) determined in bilayers. The drug concentration required to reach the half-maximal Deltapi at pi(i) = 14 mN/m (K(0.5)), was very sensitive to pH. The maximal increment in pi upon drug incorporation into the monolayer (deltapi(max)) will depend on the phospholipid collapse pressure (pi(c)), the monolayers's compressibility and drug's size, shape and charge. The higher pi(c) of dpPC lead to higher pi(cut-off) values (maximal pi allowing drug penetration), if compared with dpPA. In dpPC and dpPA pi(cut-off) decreased as a function of the molecular size of the uncharged drugs. In dpPA, protonated drugs became electrostatically trapped at the monolayer surface hence drug penetration, monolayer deformation and pi increase were impaired and the correlation between pi(cut-off) and drug molecular size was lost.

Studies on drug metabolism by fungi colonizing decomposing human cadavers. Part II: biotransformation of five model drugs by fungi isolated from post-mortem material.

The present study investigated the in vitro metabolic capacity of 28 fungal strains isolated from post-mortem material towards five model drugs: amitriptyline, metoprolol, mirtazapine, promethazine, and zolpidem. Each fungal strain was incubated at 25 °C for up to 120 h with each of the five models drugs. Cunninghamella elegans was used as positive control. Aliquots of the incubation mixture were centrifuged and 50 µL of the supernatants were diluted and directly analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with product ion scanning. The remaining mixture was analyzed by full scan gas chromatography-mass spectrometry (GC-MS) after liquid-liquid extraction and acetylation. The metabolic activity was evaluated through the total number of detected metabolites (NDM) produced in each model and fungal strains and the percentage of parent drug remaining (%RPD) after up to five days of incubation. All the tested fungal strains were capable of forming mammalian phase I metabolites. Fungi from the normal fungal flora of the human body such as Candida sp., Geotrichum candidum, and Trichosporon asahii) formed up to seven metabolites at %RPD values greater than 52% but no new fungal metabolites (NFM). In contrast, some airborne fungal strains like Bjerkandera adusta, Chaetomium sp, Coriolopsis sp., Fusarium solani and Mucor plumbeus showed NDM values exceeding those of the positive control, complete metabolism of the parent drug in some models and formation of NFM. NFM (numbers in brackets) were detected in four of the five model drugs: amitriptyline (18), metoprolol (4), mirtazapine (8), and zolpidem (2). The latter NFM are potential candidates for marker substances indicating post-mortem fungal metabolism.

CYP2D6 is the principal cytochrome P450 responsible for metabolism of the histamine H1 antagonist promethazine in human liver microsomes.

To determine which cytochrome P450 form is involved in the promethazine [10-(2-dimethylaminopropyl) phenothiazine] metabolism, in vitro analysis using human liver microsomes were performed. Promethazine was mainly biotransformed to ring-hydroxylated, S-oxidized and N-demethylated metabolites. The promethazine hydroxylase in human liver microsomes was inhibited by SKF-525A, propranolol, sparteine, quinidine and anti-CYP2D6 serum suggesting involvement of a P450 related to CYP2D6. Lineweaver-Burk plots for the hydroxylation, S-oxidation and N-demethylation indicated that the hydroxylation occurred with a low K(m) value in human liver microsomes. Microsomes from genetically-engineered human B-lymphoblastoid cells expressing CYP2D6 hydroxylated promethazine most efficiently as compared to other P450 forms, indicating that it was the principal P450 responsible for the metabolism of promethazine in human liver microsomes. The inhibition of CYP2D6-catalysed bufuralol 1'-hydroxylase by various histamine H3 antagonists including promethazine suggested that promethazine and some other histamine H1 antagonists could be inhibitors of this P450 in human liver microsomes.

Variations in the bioavailability of thiazinamium methylsulfate.

Bioavailability after oral administration of the anticholinergic drug thiazinamium methylsulfate (Multergan), a phenothiazine derivative with a quaternary ammonium group in the molecule, has been studied in patients and volunteers by measuring the drug concentrations in plasma or the excretion of the parent drug in urine. The relative bioavailability as compared to intramuscular injection seems to be of the order of 10%. Much more of the drug is absorbed, however, but is metabolized during the first liver passage. Moreover, there seems to be a substantial interindividual variation in the bioavailability of the drug. Studies in a group of eight volunteers showed that there is also a substantial intraindividual variation, but its magnitude is smaller than that of the interindividual variation.

Horseradish peroxidase-catalyzed sulfoxidation of promethazine and properties of promethazine sulfoxide.

Promethazine sulfoxide was obtained with a quantitative yield in a horse radish peroxidase-catalyzed reaction of promethazine and hydrogen peroxide and was also prepared by direct chemical synthesis. The enzymatic sulfoxidation of promethazine was studied in vitro as a function of pH, promethazine, and hydrogen peroxide concentration. Promethazine sulfoxide inhibits with an apparent K(i) of 59.7 microM at pH 5.5 the enzymatic reaction, followed spectrophotometrically, polarographically, potentiometrically, and luminometrically. The reaction was also inhibited by ascorbic acid (K(i) 26.8 microM) and glutathione (K(i) 41.8 microM). The spectrophotometric techniques employed, together with ESR spectrometry, allowed the identification of at least three radical species formed in the course of the reaction. Promethazine sulfoxide is devoid of the antioxidant effect exhibited by promethazine on rat brain synaptosomes. The sulfoxide also lacks photosensitizing action, while retaining the neuroleptic effect of the parent compound.

Clinical pharmacokinetics of H1-receptor antagonists (the antihistamines).

This article reviews clinical pharmacokinetic data on the H1-receptor antagonists, commonly referred to as the antihistamines. Despite their widespread use over an extended period, relatively little pharmacokinetic data are available for many of these drugs. A number of H1-receptor antagonists have been assayed mainly using radioimmunoassay methods. These have also generally measured metabolites to greater or lesser extents. Thus, the interpretation of such data is complex. After oral administration of H1-receptor antagonists as syrup or tablet formulations, peak plasma concentrations are usually observed after 2 to 3 hours. Bioavailability has not been extensively studied, but is about 0.34 for chlorpheniramine, 0.40 to 0.60 for diphenhydramine, and about 0.25 for promethazine. Most of these drugs are metabolised in the liver, this being very extensive in some instances (e.g. cyproheptadine and terfenadine). Total body clearance in adults is generally in the range of 5 to 12 ml/min/kg (for astemizole, brompheniramine, chlorpheniramine, diphenhydramine, hydroxyzine, promethazine and triprolidine), while their elimination half-lives range from about 3 hours to about 18 days [cinnarizine about 3 hours; diphenhydramine about 4 hours; promethazine 10 to 14 hours; chlorpheniramine 14 to 25 hours; hydroxyzine about 20 hours; brompheniramine about 25 hours; astemizole and its active metabolites about 7 to 20 days (after long term administration); flunarizine about 18 to 20 days]. They also have relatively large apparent volumes of distribution in excess of 4 L/kg. In children, the elimination half-lives of chlorpheniramine and hydroxyzine are shorter than in adults. In patients with alcohol-related liver disease, the elimination half-life of diphenhydramine was increased from 9 to 15 hours, while in patients with chronic renal disease that of chlorpheniramine was very greatly prolonged. Little, if any, published information is available on the pharmacokinetics of these drugs in neonates, pregnancy or during lactation. The relatively long half-lives of a number of the older H1-receptor antagonists such as brompheniramine, chlorpheniramine and hydroxyzine suggest that they can be administered to adults once daily.

A peroxidase-catalyzed sulfoxidation of promethazine.

Lactoperoxidase, when incubated with increasing amounts of promethazine (P) and promethazine sulfoxide (PO) catalyzes the formation of promethazine sulfoxide accompanied by oxygen consumption. An intermediate radical of PO can be detected by electron spin resonance (ESR). Catalase or superoxide dismutase do not inhibit the reaction while dopamine does. The lactoperoxidase-catalyzed formation of dopaminochrome in the presence of hydrogen peroxide is inhibited by P. Both P and PO inhibit acetyl- and butyrylcholinesterase. Purified enzymes were used throughout the study and horseradish peroxidase but not myeloperoxidase had an activity similar to that of lactoperoxidase.

Binding of antagonists of H1 and H2 histamine receptors to peripheral blood lymphocytes of atopic and healthy subjects.

The binding of the antagonists of histamine H1 and H2 receptors by peripheral blood lymphocytes from atopic and healthy subjects was investigated. We found that lymphocytes from atopic subjects showed statistically significant decrease in the binding of H2 receptor antagonist - ranitidine. In addition, lymphocytes from atopic and control subjects had similar capacity of binding of H1 receptor antagonist - promethazine. The ratio of the amount of H1 and H2 antagonists, bound to lymphocytes from atopic and healthy subjects, was calculated. The difference between the values in the group of atopic (2.55) and control subjects (1.55) was statistically significant.

Specific immunotherapy stimulates the binding of histamine H2 receptor antagonist by lymphocytes.

The binding of antagonists of histamine receptors H1 (promethazine) and H2 (ranitidine) by peripheral blood lymphocytes from pollinotics was determined before and after the course of immunotherapy. We found that lymphocytes from atopic subjects showed significant decrease in the binding of H2 receptor antagonist as compared to control subjects. Specific immunotherapy induced statistically significant increase in H2 receptor antagonist binding, which correlated with the improvement of clinical symptoms.