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PubMed1997

Antihistamine-containing cough/cold medications present a low hazard in pediatric accidental exposure incidents: analysis of Poison Control Center data.

We studied accidental exposure to pediatric cough/cold medications in children under 6-y-of-age to determine whether the presence of an antihistamine (chlorpheniramine) in the product increased the likelihood for adverse outcomes. General accidental exposure cases reported to the American Association of Poison Control Centers (AAPCC) during 1988-1992 were analyzed for specific over-the-counter cough/cold pediatric products containing identical concentrations of active ingredients except for the presence or absence of chlorpheniramine. These case reports were evaluated for differences in medical outcome, symptom assessment, management site and therapy, as coded by poison control centers participating in the AAPCC Toxic Exposure Surveillance System. A total of 10,289 cases of accidental exposures were evaluated for the specific products included in this analysis. While these cases represented a small percentage of total exposures to these products (approximately 3% of total cases in children under 6-y-of-age reported to the AAPCC for all cough/cold medications during 1988-1992), they provided a unique opportunity to evaluate the impact of the antihistamine component of the formulation. This study demonstrated that the presence of chlorpheniramine did not affect the medical outcome or the extent to which symptoms were reported. Additionally, similar percentages of exposures for these 2 products were managed at the site of the incident, and required either no therapy or only required fluids and observation. There were no notable differences in the percentage of cases which involved more aggressive treatment procedures (activated charcoal, cathartic, lavage). This analysis demonstrates that over-the-counter cough/cold medications containing chlorpheniramine present low potential for hazard in cases of accidental ingestions in young children and do not show an increased likelihood for adverse outcomes of accidental exposures compared to cough/cold medications not containing this antihistamine.

Child↗

PubMed1964

ISOLATION OF AN ANTIHISTAMINIC PRINCIPLE RESEMBLING TOMATINE FROM CROWN GALL TUMORS.

Antihistaminic activity was demonstrated previously in extracts of crown gall tumors by assaying in vivo. A crystalline substance isolated from the crude extracts has now been found to possess a high degree of potency against histamine, acetylcholine, bradykinin, and serotonin when assayed in vitro. The chemical characteristics of the substance resemble closely those of tomatine. When tomatine was investigated, it was found to have biological properties similar to those of the crystalline substances isolated from crown gall tumors. It seems likely that the antihistaminic properties of crown-gall tumor extracts are due to tomatine or a substance which closely resembles it.

Acetylcholine↗

PubMed1999

Effects of antihistamines on fenfluramine-induced depletion of indoles in the brain of rats.

Various effects of chlorpheniramine (CPA), diphenhydramine (DIPH), tripelennamine (TRIP), and pyrilamine (PYRI) on fenfluramine (FEN)-induced depletion of serotonin in the brain of rats were observed to be dependent on body temperature. Levels of 5-HT and 5-HIAA in the frontal cortex, hippocampus, and striatum of rats treated with FEN (10 mg/kg, once or twice daily x 4 days) decreased to approximately 30% (P < 0.01) that of controls with no significant changes after CPA, DIPH, TRIP, and PYRI. Treatment with FEN plus CPA (5, 10, 20 mg/kg) and FEN plus DIPH (20 mg/kg), but not FEN plus TRIP (20 mg/kg) and FEN plus PYRI (20 mg/kg), increased brain serotonin levels 2- to 3-fold more than those treated with FEN plus saline. Treatment with FEN plus CPA and FEN plus DIPH, but not FEN plus TRIP and FEN plus PYRI, decreased rectal temperature with no significant change after FEN. The antihistamines alone decreased temperature at a 1-hour period and enhanced FEN-induced reduction in body weight. Possible mechanisms of the different effects of antihistamines on FEN-induced depletion of serotonin are discussed.

Animals↗

PubMed1999

Effects of antihistamines on 3, 4-methylenedioxymethamphetamine-induced depletion of serotonin in rats.

This study investigated the effects of chlorpheniramine (CPA, 10-25 mg/kg), diphenhydramine (DIPH, 20 mg/kg), tripelennamine (TRIP, 20 mg/kg), and pyrilamine (PYRI, 20 mg/kg) on 3, 4-methylenedioxymethamphetamine (MDMA, 20 mg/kg x 2)-induced hyperthermia and depletion of indoles in rat brains, on the uptake of serotonin and dopamine into rat synaptosomes, on the binding affinity of CPA for biogenic amine transporters in the synaptosomes of rat brain, and on the scavenging hydroxyl free radicals activity. Rats were treated with two injections of MDMA, CPA, DIPH, TRIP, PYRI, and saline, alone or in combination of MDMA with one of the antihistamines, 6 h apart and sacrificed 5 days later. Rectal temperature was measured prior to and hourly following the drug injections for 13 h. As compared to saline controls, MDMA increased body temperature and decreased levels of indoles, measured by HPLC, in several brain regions of rats. CPA attenuated and DIPH had no effect on MDMA-induced hyperthermia, yet both attenuated the depletion of indoles, whereas PYRI and TRIP potentiated these effects. CPA inhibited the binding of [(3)H]paroxetine and [(3)H]nisoxetine to the synaptosomes of cerebral cortex and of [(3)H]win 35,428 to the synaptosomes of striatum. CPA, DIPH, TRIP, and PYRI inhibited [(3)H]serotonin uptake. CPA, PYRI, and TRIP, but not DIPH, scavenge hydroxyl radicals. Possible mechanisms of the different effects of the antihistamines on MDMA-induced hyperthermia and depletion of serotonin are discussed. Published 1999 Wiley-Liss, Inc.

Adrenergic Uptake Inhibitors↗

PubMed2004

Cetirizine from topical phosphatidylcholine liposomes: evaluation of peripheral antihistaminic activity and systemic absorption in a rabbit model.

This study was performed to assess the peripheral H(1)-antihistaminic activity and extent of systemic absorption of cetirizine from liposomes applied to the skin. Cetirizine was incorporated into small unilamellar vesicles (SUV) and multilamellar vesicles (MLV) prepared using L-alpha-phosphatidylcholine, and into Glaxal Base (GB), used as the control. In a randomized, cross-over study, each formulation, containing 10 mg of cetirizine, was applied to depilated areas on the backs of six rabbits (3.08+/-0.05 kg). Histamine-induced wheal tests and blood sampling were performed before cetirizine application and at designated times for up to 24 h. Compared with the baseline, histamine-induced wheal formation was suppressed by cetirizine in SUV and MLV from 0.5-24 h and by cetirizine in GB from 0.5-8 h, p</=0.05. Maximum wheal suppression by cetirizine in SUV and MLV ranged from 90.6%+/-4.9% to 89.0%+/-3.8% and 98.0%+/-1.3% to 94.0%+/-2.3%, respectively, from 6 to 8 h. The plasma cetirizine AUC of 201+/-24.2 ng.h/ml from SUV was lower than from PC-MLV, 334.6+/-65.1 ng.h/ml and from GB, 248.3+/-34.6 ng.h/ml. After 24 h, the percent of the cetirizine dose remaining on the backs of the rabbits from SUV was lower than from both MLV and GB, p</=0.05. In this model, cetirizine from both SUV and MLV had excellent topical H(1)-antihistaminic effects, while systemic exposure to cetirizine from SUV was reduced.

Administration, Topical↗

PubMedDate not supplied

Prolonged effect of an H1-receptor blocker antihistamine on the histamine content of white blood cells and mast cells.

Hormonal imprinting usually takes place perinatally at the first encounter between the developing receptor and its target hormone, determining the future binding capacity of the receptor for life. Molecules similar to a hormone can cause faulty imprinting also with life-long consequences. Hormone production of the imprinted cell is also durably influenced. In cytogenic organs imprinting can also be provoked in adulthood. At present the effect of a single terfenadine treatment in adult rats on the histamine content of peritoneal cells (lymphocytes, mast cells and the monocyte-macrophage-granulocyte group), white blood cells (lymphocytes, granulocytes, monocytes) and thymic lymphocytes was studied 3 weeks after treatment to clarify the effect of prolonged treatment with an antihistamine in adulthood. The cells were studied by flow cytometric analysis. Peritoneal mast cells contained significantly more and thymic lymphocytes significantly less histamine than controls. In the other cells the differences were not significant. The results support earlier observations on the effect of antihistamines on mast cell histamine release (inhibition) and call attention to the fact that this effect is durable (hormonal imprinting provoked in adults).

Animals↗

PubMed1987

[Pyrrolidone and piperidone derivatives with antihistaminic and antianaphylactic activities. Synthesis and pharmacological study].

The preparation of several derivatives to oxatomide (A), with the benzimidazolinone moiety replaced by another heterocyclic residue is described. In some cases changes to the basic chain of (A) were also considered. All the new compounds were evaluated as antihistaminics (H1) and antianaphylactics. The derivatives where the heterocyclic moiety was an unsubstituted or phenylsubstituted 2-pyrrolidone or 2-piperidone residue showed antihistaminic and antianaphylactic activities similar to those of oxatomide while modification of the basic side chain with elimination of the benzhydryl group, gave a complete loss of activity. The pharmacological screening was completed by the evaluation of the barbiturate induced sleep prolongation and of acute toxicity.

Anaphylaxis↗

PubMed2006

Role of chemical structure in stereoselective recognition of beta-blockers and H1-antihistamines by human serum transferrin in capillary zone electrophoresis.

Studies on chiral resolution of beta-blocker and H1-antihistamine drugs by CZE using human serum transferrin are described. The drugs with different structures passed a pseudostationary protein zone in a coated capillary applying the partial filling method for the chiral separation. In this study we screened 15 compounds; most of them showed longer migration time, indicating an interaction with transferrin. Stereoselective interaction was observed only for five beta-blockers (celiprolol, talinolol, mepindolol, bopindolol, and oxprenolol) and for one H1-antihistamine (brompheniramine). The most important finding was that very small differences in the chemical structure of the drug resulted in significant changes in the stereoselective recognition. Resolution of mepindolol enantiomers was observed showing the essential role of one methyl group compared to pindolol, which is not resolved by transferrin. Bopindolol, also a derivative of pindolol having bigger difference in the structure, showed more experienced separation. The very slight difference between alprenolol and oxprenolol was also revealed with these methods, since only oxprenolol enantiomers, having an extra oxygen in the structure, are resolved. Determining the migration order of the eutomers and distomers (chlorpheniramine, brompheniramine) we can deduct conclusions about the role of serum proteins in the delivery of drugs within the body.

Adrenergic beta-Antagonists↗

PubMed2002

The effects of a sedative antihistamine, d-chlorpheniramine, on visuomotor spatial discrimination and regional brain activity as measured by positron emission tomography (PET).

Although most people taking antihistamines have experienced sedation and impaired performance, the neural correlates of these sedative properties are not well understood in man. Brain imaging can be used to demonstrate how regional brain activities are altered during such sedative effects. The aim of this study was to visualize the brain mechanism of impaired visuomotor spatial cognition with orally administered d-chlorpheniramine, a first-generation sedative antihistamine, using H(2) (15)O and positron emission tomography (PET). Normal subjects were randomly assigned to two groups (chlorpheniramine and placebo) and performed a spatial discrimination task after the oral administration of 6 mg d-chlorpheniramine or a placebo. The administration of d-chlorpheniramine impaired visuomotor spatial discrimination and altered cortical and subcortical activity. Decreased and increased activities were observed in the right parietal cortex (BA 40) which is related to visuomotor spatial cognition and the posterior cingulate cortex which constitutes the attention system of the brain, respectively. In particular, the brain activities of BA 40 were negatively and positively correlated to those of bilateral caudate nuclei and the dorsolateral prefrontal cortex, respectively. These findings clearly suggest that the alteration in the cortical and subcortical activity contributes to impaired spatial cognition caused by treatment with d-chlorpheniramine.

Adult↗

PubMed1991

Pharmacology of non-sedating H1 antihistamines.

A review of the preclinical pharmacology of non-sedating H1 antihistamines includes comparative data on potency, duration of action, side effect liability, especially CNS depressant and anticholinergic activity and new approaches that may further enhance the efficacy of these newer compounds. Data discussed mainly involve studies in which multiple comparative agents were used and usually include astemizole, cetirizine, loratadine and terfenadine. New research approaches include the combination of PAF inhibition with antihistamine activity and the inhibitory effects these compounds may have on cellular influx in allergic diseases.

Animals↗

PubMed1995

Lack of interaction between two antihistamines, mizolastine and cetirizine, and ethanol in psychomotor and driving performance in healthy subjects.

The pharmacodynamic interaction between mizolastine, a new H1 antihistamine, and ethanol was assessed in a randomized, double-blind, three-way crossover, placebo-controlled study. Eighteen healthy young male volunteers received mizolastine 10 mg, or cetirizine 10 mg or placebo once daily for 7 days with a 1-week wash-out interval. An oral dose of ethanol or ethanol placebo, given 2 h after dosing on days 5 or 7 of each treatment period, was administered to achieve a peak blood alcohol concentration (BAC) of 0.7 g/l then maintained for 1 h by two further doses of ethanol. Driving ability and psychomotor performance were evaluated using actual and simulated driving tests, critical flicker fusion threshold (CFF), adaptive tracking and divided attention (DAT) tasks. Ethanol produced a significant decrement in all tasks up to 5.5 h after administration: an increase in steering movements of 4.6, in lateral deviation of 0.45 m, in braking reaction time of 80 ms, in driving test and DAT performance of + 3.2; and a decrease in CFF and in tracking speed of 2.6 m.s-1. Neither mizolastine nor cetirizine significantly impaired driving ability or arousal (CFF) compared with the placebo. However, both drugs significantly impaired DAT performance 6:00 h post-dose (increase of + 2.1 for mizolastine and + 2.4 for cetirizine). The tracking speed was significantly decreased 7:50 h after mizolastine administration (-1.3 m.s-1) and more consistently from 1:30 to 7:50 h after cetirizine administration (-1.4 m.s-1). No significant adverse interaction, i.e. potentiation, occurred between ethanol and either antihistamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Bone cement implantation syndrome. A prospective randomised trial for use of antihistamine blockade.

Bone cement implantation syndrome (BCIS) is characterised by hypotension, hypoxaemia, cardiac arrhythmias, cardiac arrest or any combination of these, leading to death in 0.6-1% of patients. One of the mechanisms suggested to explain these complications is diffuse microembolisation of the lungs as a consequence of extrusion of the bone marrow content by the pressurised bone cement. By reducing intramedullary pressure and changing the operative technique, BCIS can be diminished, but deaths still occur. An anaphylactoid mechanism as a major factor in BCIS is receiving renewed attention since increased plasma histamine levels were recently demonstrated after the implantation of bone cement and a prosthesis. Therefore, we conducted a prospective, randomised study to demonstrate the potential benefit of histamine-receptor-blocking agents in patients undergoing cemented hip arthroplasty. Thirty patients were divided into two groups: group 1, the control group, received no histamine-receptor-blocking agents; group 2, the antihistamine group, received H1 and H2-receptor-blocking agents in standard dosages preoperatively. Both groups were comparable concerning age, sex and physical status (ASA criteria). There was no hospital mortality in either group. Thirteen patients of group 1 demonstrated a sudden fall by more than 10% of their blood pressure, level of PaO2 or both. Fourteen patients of group 2 showed similar changes. The mean decrease of blood pressure in group 1 was 14.6 mmHg (SD 36.8) and in group 2 20.5 mmHg (SD 33.43). The difference is not significant (P = 0.65). The mean decrease of PaO2 in group 1 was 30.5 mmHg (SD 30.5) and in group 2 33.4 mmHg (SD 34.1). The difference is not significant (P = 0.81). Overall, we found even a slight disadvantage for patients receiving antihistamine drugs (statistically not significant). Therefore, histamine-receptor-blocking agents do not have a prophylactic potential in BCIS.

Bone Cements↗

PubMed1988

Identification of phenothiazine antihistamines and their metabolites in urine.

Identification of the phenothiazine antihistamines alimemazine, dimetotiazine, isothipendyl, mequitazine, oxomemazine, promethazine, thiethylperazine, triflupromazine and their metabolites in urine is described. After acid hydrolysis of the conjugates, extraction and acetylation the urine samples were analysed by computerized gas chromatography-mass spectrometry. Using ion chromatography with the selective ions m/z 58, 72, 100, 114, 124, 128, 141, and 199 the possible presence of phenothiazine antihistamines and/or their metabolites was indicated. The identity of positive signals in the reconstructed ion chromatograms was confirmed by a visual or computerized comparison of the stored full mass spectra with the reference spectra. The ion chromatograms, reference mass spectra and gas chromatographic retention indices (OV-101) are documented. The procedure presented is integrated in a general screening procedure (general unknown analysis) for several groups of drugs.

Animals↗

PubMed1986

Antihistamines: impaired performance and the tendency to sleep.

The central effects of various antihistamines were studied using a variety of tests of performance, including visuo-motor co-ordination and dynamic visual acuity, as well as paper and pencil tests and critical flicker fusion. The possible relationship between performance and sedation was also studied using digit symbol substitution and latencies to drowsy sleep. There was high degree of correlation between drowsiness, as indicated by the relative ease with which individuals fell asleep over the day, and impaired performance, but it was not possible to establish the relationship for each time of the day. These findings lend some support to the suggestion that impaired performance with antihistamines may be a non-specific effect of sedation.

Adult↗

PubMed1993

Terfenadine: a mixture of equipotent antihistamine enantiomers without a clear 'isomeric ballast'.

Terfenadine was the first non-sedating histamine H1 receptor antagonist and one of the most frequently prescribed H1 antihistamines. Terfenadine has one asymmetric centre in the molecule and is currently used as a racemate. Different methods and approaches for obtaining pure enantiomers of terfenadine are summarized and discussed in the present paper. Studies on antihistamine activity of the enantiomers, their side-effects on the central nervous system, calcium channel affinity and metabolism are also reviewed and analysed.

Animals↗

PubMed1989

Rocastine (AHR-11325), a rapid acting, nonsedating antihistamine.

Rocastine [AHR-11325, 2-[2-(dimethylamino)ethyl]-2,3-dihydro-4-methylpyrido-[3,2-f]-1,4- oxazepine-5(4H)-thione (E)-2-butenedioate)] is a rapid-acting, potent, nonsedating antihistamine. In guinea pigs challenged with a lethal dose of histamine, rocastine is as effective [based on 1 hr. oral, protective dose (PD50S)] as brompheniramine, chlorpheniramine, pyrilamine, and promethazine and superior to astemizole, diphenhydramine, terfenadine, and oxatomide. Rocastine has a faster onset of action than does terfenadine; rocastine being as effective with a 15 min pretreatment time (PD50 = 0.13 mg/kg) as it is with a 1 hr pretreatment time (PD50 = 0.12 mg/kg), while the 15 min PD50 of terfenadine (PD50 = 44.0 mg/kg) is 22 times greater than the 1 hr PD50 (PD50 = 1.93 mg/kg). Against aerosolized histamine, rocastine was 7.12 x, 2.63 x, and equipotent to pyrilamine in preventing histamine-induced prostration at pretreatment times of 1,3, and 6 hr, respectively. Rocastine protected guinea pigs from collapse induced by aerosolized antigen; rocastine was approximately 36 x more potent (based on 1 hr PD50) than diphenhydramine and as potent as oxatomide and terfenadine. Rocastine did not alter the EEG of cats at doses in vast excess (150x) of its antihistaminic dose nor did it potentiate yohimbine toxicity in mice. Further, rocastine possesses no anticholinergic, antiadrenergic, or antiserotonergic properties in vitro. Rocastine is a selective, nonsedating, H1-antagonist with a rapid onset of action.

Anaphylaxis↗

PubMed1989

Arabinogalactan- and dextran-induced ear inflammation in mice: differential inhibition by H1-antihistamines, 5-HT-serotonin antagonists and lipoxygenase blockers.

Intravenous injection of arabinogalactan or dextran together with pontamine sky-blue dye into mice increased vascular permeability and led to marked blueing of the ears. Arabinogalactan caused a rapidly progressing ear blueing (maximal coloration 20-30 min after injection). This response was suppressed by pretreating the animals with the histamine H1-antihistamines levocabastine and loratadine. In contrast, dextran induced a slowly evolving ear inflammation (maximal coloration 60-90 min after injection), which was blocked by the 5-HT-serotonin antagonists cinanserin, metergoline and ritanserin. Furthermore, the dextran reaction was inhibited by the lipoxygenase (LO)/cyclooxygenase (CO) inhibitors BW540C, BW755C and phenidone and by the specific 5-LO inhibitor AA-861. Both arabinogalactan and dextran responses were inhibited by aprotinin, a kallikrein inhibitor, and the mixed H1/5-HT antagonists astemizole and azatadine. The inflammogenic activity of the polysaccharides was not affected by administration of the CO inhibitors indomethacin and suprofen, the thromboxane synthetase inhibitor dazoxiben, the H2-antihistamines cimetidine and ranitidine, the anticholinergics isopropamide or the PAF-antagonist L-652, 731. These data indicate the existence of distinctive endogenous molecules that mediate the pinnal extravasation reaction to both polysaccharides: histamine for arabinogalactan, serotonin and lipoxygenase-derived arachidonic acid metabolites for dextran.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗

PubMed1989

Food-induced histaminosis under diamine oxidase (DAO) blockade in pigs: further evidence of the key role of elevated plasma histamine levels as demonstrated by successful prophylaxis with antihistamines.

Using a recently established porcine model, it was clearly shown that oral histamine administration is extremely dangerous in the presence of diamine oxidase (DAO) blockade. Due to the severity of the symptoms (20% death) and the clinical relevance, further interest has been focussed on strategies to prevent or alleviate food induced histaminosis. In a randomized controlled trial, 10 pigs under DAO blockade were challenged with oral histamine (60 mg). Half of these animals received a prophylactic premedication with a combination of H1- and H2-receptor antagonists. As expected, all animals developed a massive increase in plasma histamine levels, with significantly higher values in the control group (median: 123 ng/ml) compared to the antihistamine group (median: 32 ng/ml). In contrast, clinical symptoms were only observed in the control group. The maximum fall in mean arterial pressure (hypotension) was 60 mmHg (median for control group) but only 15 mmHg (median) under antihistamine pretreatment. These results firstly provide further evidence for the causal role of histamine in the new disease concept and secondly enable us to investigate appropriate therapeutic measures for patients at risk.

Amine Oxidase (Copper-Containing)↗