Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ANTIHISTAMINICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2001

Decongestants and antihistamines for acute otitis media in children.

BACKGROUND: Acute otitis media (AOM) is a common and important source of morbidity in children, although most cases resolve spontaneously. While frequently recommended, decongestant and antihistamine therapy is of unclear benefit. OBJECTIVES: To determine the efficacy of decongestant and antihistamine therapy in children with AOM on outcomes of AOM resolution, medication side effects, and complications of AOM. SEARCH STRATEGY: Comprehensive search of Cochrane's Controlled Trials Registry, Medline and Embase was conducted. Bibliographic review and requests for information from study authors and pharmaceutical companies supplemented this. SELECTION CRITERIA: Randomized controlled trials evaluating decongestant (DC) or antihistamine (AH) treatment for children with AOM were included. Patient-oriented outcomes were considered most relevant. There were no quality or language restrictions. DATA COLLECTION AND ANALYSIS: Investigators independently evaluated studies for inclusion, performed validity assessments, and completed data extraction. Dichotomous data were pooled to generate relative risks and numbers needed to treat, and homogeneity was assessed using approximate chi-square tests. MAIN RESULTS: For the combined control groups, healing rates at 2 weeks were high, with rates of persistent AOM <23%. No additional benefit was demonstrated from intervention subgroupings DC, AH, or any medication (DC and/or AH). Only the combined treatment (DC + AH) group demonstrated statistically lower rates of persistent AOM at the 2-week period (RR 0.76, 95% CI, NNT 10.5, 95% CI). No benefit was found for other outcomes including early or late cure rates, symptom resolution, prevention of surgery or other complications. There was an increased risk of medication side effects for those receiving an intervention, which reached statistical significance for the "any medication" and decongestant groupings (NNH 16.6, 14.3 respectively, 95% CI ). Validity subanalyses demonstrated that lower quality studies found benefit, but analysis of those studies with higher validity scores found no benefit to treatment. REVIEWER'S CONCLUSIONS: Given lack of benefit and increased risk of side effects, these data do not support the use of decongestant, antihistamine, or combined DC/AH treatment in children with AOM. The small statistical benefit found in the combination medication group is of small clinical significance and study design may be biasing the results.

Acute Disease↗
PubMed1995

Antihistamine activity, central nervous system and cardiovascular profiles of histamine H1 antagonists: comparative studies with loratadine, terfenadine and sedating antihistamines in guinea-pigs.

BACKGROUND: Sedation limits the clinical utility of classical H1 antihistamines, while newer antihistamines such as loratadine and terfenadine are non-sedating. However, clinical use of the terfenadine has been associated with rare but severe cardiac arrhythmias, in particular torsades de pointes. OBJECTIVE: To establish a quantitative experimental model for assessing the sedating and cardiotoxicity potential of non-sedating and sedating antihistamines. METHODS: Drugs were administered intravenously and the integrated amplitude of the cortical electroencephalogram (EEG) signal was recorded. The threshold dose that depressed EEG activity was compared with the dose required to inhibit by 50% the peripheral bronchospasm elicited by 10 micrograms/kg i.v., of histamine. In separate studies, the electrocardiogram (ECG) and cardiovascular effects of loratadine (30 and 100 mg/kg, i.v.), terfenadine (10 mg/kg, i.v.), promethazine (5 mg/kg, i.v.) and diphenhydramine (20 mg/kg, i.v.) were evaluated. RESULTS: The sedating antihistamines, diphenhydramine and promethazine, depressed the integrated EEG at doses between 0.6 and 2.0 times their peripheral antihistamine doses. Loratadine had no EEG depressant activity at 100 mg/kg, i.v., a dose more than 170 times its ED50 (0.58 mg/kg, i.v.) against histamine bronchospasm. We were unable to evaluate the EEG effects of terfenadine, because it produced cardiovascular collapse at 10 mg/kg, i.v. Loratadine and promethazine did not produce adverse cardiovascular effects, nor did they alter normal ECG activity. Diphenhydramine produced bradycardia followed by a transient hypertensive phase without affecting the QTc interval. In contrast, terfenadine elicited hypotension, bradycardia and significant arrhythmogenic activity, causing a prolongation of the QTc interval and a torsades de pointes--like ventricular arrhythmia. Pharmacokinetic studies after i.v. administration of loratadine (30 and 100 mg/kg) demonstrated plasma levels of loratadine and its major metabolite descarboethoxyloratadine to be several orders of magnitude greater than levels found in humans at the clinical dose of 10 mg. CONCLUSION: The CNS depressant effects of H1 antihistamines are promethazine approximately diphenhydramine >> loratadine = placebo. Of the non-sedating antihistamines, loratadine was devoid of adverse cardiovascular effects whereas terfenadine caused a pronounced disruption of the normal ECG, characterized by a torsades de pointes-like effect.

Animals↗
PubMed2002

[Comparative antihistamine and anti-allergic effects of various antihistamine preparations].

AIM: To compare antihistaminic and antiallergic activity of antihistaminic drugs of the latest generation (ebastin, cetirisine, fexofenadine, loratadine) and antihistaminic drugs of the first generation (clemastin) in the same patients with pollenosis. MATERIAL AND METHODS: Skin prick-titration with 10-dilution histamine and specific allergen, provocative nasal titration with 2-dilution histamine and allergen before and after a single intake of H1-antagonists were made in 30 patients in stable clinical remission of pollenosis during maximal antihistamine activity of the above drugs. RESULTS: Systemic administration of the known H1-antagonists suppresses histamine sensitivity of both skin and nasal mucosa in the same degree. Drugs with more potent antihistaminic activity (fexofenadin and cetirisin) inhibited allergen-induced reactions more effectively. The order of the tested drugs by suppression of allergen-provoked skin and nasal reactions (by lowering antiallergic activity) is the following: fexofenadin and cetirisin > ebastin and loratadin > clemastin. CONCLUSION: The above drugs of the latest generation seem to posses antiallergic activity not only due to antihistaminic effect but also due to other mechanisms. Different suppressive action of H1-antagonists reflects also individual sensitivity to different drugs. The factor of individual sensitivity of the patients to a pharmacological action of the drug may be crucial in the selection of the most effective medicine for each patient. This is confirmed by the data of individual sensitivity of the patient to antihistaminic and antiallergic action of H1-antagonists. The illustrated method may be helpful for individual selection of H1-antagonists for treatment of patients with allergic diseases.

Adult↗
PubMed1985

New antihistaminic N-heterocyclic 4-piperidinamines. 1. Synthesis and antihistaminic activity of N-(4-piperidinyl)-1H-benzimidazol-2-amines.

The synthesis of a series N-(4-piperidinyl)-1H-benzimidazol-2-amines and the preliminary evaluation of their in vitro and in vivo antihistaminic activity are described. Cyclodesulfurization of (2-aminophenyl)thioureas with mercury(II) oxide resulted in 2-aminobenzimidazole intermediates, which were monoalkylated on the endo-nitrogen atom. After deprotection of the piperidine nitrogen atom with 48% aqueous hydrobromic acid solution, the title compounds were obtained by three different methods, viz. alkylation, reductive amination, or oxirane ring-opening reactions. The in vivo antihistaminic activity was evaluated by the compound 48/80 induced lethality test in rats and histamine-induced lethality test in guinea pigs after oral and/or subcutaneous administration. The duration of action, for a selected number of compounds, was studied in the guinea pig. The phenylethyl derivatives showed the most potent antihistamine properties after oral administration in both animal species.

Administration, Oral↗
PubMed1985

New antihistaminic N-heterocyclic 4-piperidinamines. 2. Synthesis and antihistaminic activity of 1-[(4-fluorophenyl)methyl]-N-(4-piperidinyl)-1H-benzimidazol-2-a mines.

The synthesis of a series of 1-[(4-fluorophenyl)methyl]-N-(4-piperidinyl)-1H-benzimidazol-2-ami nes and the preliminary evaluation of their in vivo antihistamine activity are described. The title compounds were obtained starting from either 1, 4, 10, or 55 by different synthetic methods. Substitution on the phenyl nucleus of the benzimidazole ring (84-87) was achieved by two different approaches. The in vivo antihistamine activity was evaluated by the compound 48/80 induced lethality test in rats and the antihistamine-induced lethality test in guinea pigs after oral and/or subcutaneous administration. The duration of action was studied in the guinea pig for three compounds (4, 51, and 55). Compound 51, "astemizole", was also studied in histamine- and serotonin-induced cutaneous reaction and for mydriatic activity in the rat and tested for peripheral and central effects not related to histamine antagonism in a variety of systems. Astemizole has been selected for clinical investigation.

Administration, Oral↗
PubMed2001

Neuroimaging of histamine H1-receptor occupancy in human brain by positron emission tomography (PET): a comparative study of ebastine, a second-generation antihistamine, and (+)-chlorpheniramine, a classical antihistamine.

AIMS: Sedation induced by antihistamines is widely recognized to be caused by their penetration through the blood-brain-barrier and the consequent occupation of brain histamine H1-receptors. We previously studied the mechanism of sedation caused by antihistamines using positron emission tomography (PET). Recently, we revealed the nonsedative characteristic of ebastine, a second-generation antihistamine, with cognitive performance tests. In the present study, H1-receptor occupation by ebastine was examined in the human brain using PET. METHODS: Ebastine 10 mg and (+)-chlorpheniramine 2 or 6 mg were orally given to healthy male volunteers. PET scans with [11C]-doxepin, a potent H1-receptor antagonist, were conducted near tmax of respective drugs. Other volunteers in the control group also received PET scans. The binding potential of doxepin (BP = Bmax/Kd) for available brain H1-receptors was imaged on a voxel-by-voxel basis through graphical analysis. By setting regions of interest, the H1-receptor occupancy of drugs was calculated in several H1-receptor rich regions. RESULTS: Brain distribution of radioactivity after ebastine treatment was similar to that without any drugs. However, after the oral administration of 2 mg (+)-chlorpheniramine, the level was lower than after ebastine and nondrug treatments. Graphical analysis followed by statistical parametric mapping (SPM96) revealed that H1-receptor rich regions such as cortices, cingulate gyrus and thalamus were regions where the BPs after ebastine were significantly higher than after (+)-chlorpheniramine (2 mg). H1-receptor occupancies in cortex were approximately 10% by ebastine and > or = 50% by either dose of (+)-chlorpheniramine (95% confidence interval for difference in the mean receptor occupancies: 27%, 54% for 2 mg and 35%, 62% for 6 mg vs ebastine, respectively). Receptor occupancies increased with increasing plasma concentration of (+)-chlorpheniramine, but not with concentration of carebastine, an active metabolite of ebastine. CONCLUSIONS: Ebastine (10 mg orally) causes brain histamine H1-receptor occupation of approximately 10%, consistent with its lower incidence of sedative effect, whereas (+)-chlorpheniramine occupied about 50% of brain H1-receptors even at a low but sedative dose of 2 mg; occupancy of (+)-chlorpheniramine was correlated with plasma (+)-chlorpheniramine concentration.

Adult↗
PubMed1991

Optical isomers of rocastine and close analogues: synthesis and H1 antihistaminic activity of its enantiomers and their structural relationship to the classical antihistamines.

The enantiomers of 2-[2-(dimethylamino)ethyl]-3,4-dihydro-4-methylpyrido[3,2-f]-1,4- oxazapine-5(2H)-thione (rocastine) and two of its more potent analogues were prepared with an enantiomeric purity of greater than 99.9%. The antihistaminic activity of these compounds was assessed by their ability to block histamine-induced lethality in guinea pigs and to inhibit [3H]mepyramine binding to guinea pig cortex. In this series, compounds having the R configuration at the 2-position are at least 300 times more potent than the S isomers. Conformational analysis and molecular modeling suggest that rocastine can adopt a conformation in which the pyridine ring, ether oxygen, and protonated amine functions are positioned similarly to the corresponding elements of the probable binding conformers of some of the more classical antihistamines. This conformation, boatlike in the oxazepine ring with the side chain quasi-equatorial and folded back toward the ring, is the likely binding conformer at the histamine H1 receptor, and the available structure-activity relationship data is consistent with this interpretation.

Animals↗
PubMed1985

New antihistaminic N-heterocyclic 4-piperidinamines. 3. Synthesis and antihistaminic activity of N-(4-piperidinyl)-3H-imidazo[4,5-b]pyridin-2-amines.

To study the bioisosteric replacement of a 2-pyridyl ring for a phenyl nucleus in astemizole, a series of N-(4-piperidinyl)-3H-imidazo[4,5-b]pyridin-2-amines was synthesized and evaluated. The title compounds were obtained starting from either 8a or 8b by four synthetic methods. The in vivo antihistamine activity was evaluated by the compound 48/80-induced lethality test in rats and the histamine-induced lethality test in guinea pigs after oral and/or subcutaneous administration. Compound 37, the isostere of astemizole, showed the most potent antihistaminic properties in the rat. However, astemizole is superior to 37 as to duration of action and total potency.

Administration, Oral↗
PubMed1983

[Guanidinothiazoles with H2-antihistaminic activity. 12: H2-antihistamines].

In studies on H2-antihistaminics, guanidinothiazoles were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium. Whereas the N,N'-disubstituted cyanoguanidines 3 and 5 possess stronger H2-activity than tiotidine, the 5-substituted 4-pyrimidinones 7a, b proved to be as effective as the reference substance.

Animals↗
PubMed1983

[Racemic guanidinothiazoles with H2-antihistaminic activity. 13 H2-antihistaminics].

In studies on H2-antihistaminics with cyclic guanidine structure, side-chain branched racemic guanidinothiazoles were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium. A simple synthesis of alpha-branched guanidinothiazoles is described. Of the prepared substances the racemic 14a, b in particular show high H2-antagonistic activity.

Animals↗
PubMed1984

[Synthesis and H2-antihistaminic effect of N,N'-bisheteroaryl N,N'-bisheteroaryl-substituted cyanoguanidines and 2-nitro-1,1-ethenediamines. 17. H2-antihistaminics].

In studies on structure-activity relationships of histamine H2-receptor antagonists, cyanoguanidines and 2-nitro-1,1-ethendiamines, which contain the heterocyclic rings of ranitidine and cimetidine twofold, were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium and on the histamine stimulated acid secretion of the anaesthetized rat. While the N,N'-disubstituted keten-N,N-acetales 8 and 11 possess markedly stronger H2-antagonistic activity than Ranitidine, the analogously substituted cyanoguanidines 3b and 6 proved to be as effective as the reference substance. The substances 3a and 13, with unsubstituted C-5 position of one heterocyclus, showed lower potency.

Animals↗
PubMed1979

[Synthesis and H2-antihistaminic activity of ring methylated metiamide analogues. 4th communication: H2-antihistaminic agents (author's transl)].

In studies on structure-activity relationships of histamine H2-receptor antagonists, the influence of different imidazole ring methylation on the H2-antagonist activity was investigated. 2-Methyl-, 5-methyl-, 2,5-dimethyl- and unsubstituted analogues of metiamide were prepared and tested. While 5-methyl- and unmethylated analogues with a thiourea group proved to be quite active, the 2-methyl- and 2,5-dimethyl-derivatives, as well as those with a urea group, had only low H2-antihistaminic activity.

Animals↗
PubMed1982

[Synthesis and h2-antihistaminic activity of n,n'-bisimidazole-substituted thioureas, cyanoguanidines and 2-nitro-1,1-ethenediamines 10. C: H2-antihistaminics].

In studies on structure-activity relationships of histamine H2-receptor antagonists, N,N'-bis(2-[(4-imidazolyl)-methylthio]-ethyl)-substituted thioureas, cyanoguinidines, and 2-nitro-1,1-ethenediamines with different C-5 methylation of the imidazole rings were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium and the stimulated gastric acid secretion of the anaesthetized rat. When tested on isolated guinea-pig atrium, substances with both C-5 positions methylated (5b, 7b, 9b) proved to be up to seven times more active than metiamide, whereas inhibition of gastric acid secretion turned out to be less marked. While equally methylated thioureas and cyanoguanidines showed same potency, the 2-nitro-1,1-ethenediamines clearly possessed lower activity.

Animals↗