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Effect of cefadroxil on antigen-induced bronchial hyperresponsiveness and eosinophil accumulation in lung from sensitized guinea pigs.

Boichot E, Richard MP, Paubert-Braquet M.

Bio-Inova Research Laboratory, Plaisir, France.

The effect of a semi-synthetic cephalosporin, Cefadroxil, on antigen-induced bronchial hyperresponsiveness and eosinophil accumulation in lungs from sensitized guinea pigs was investigated and compared to the effects of Cetirizine and Ketotifen. When aerosol-sensitized guinea pigs were pretreated 1 h before the antigen challenge with Cefadroxil (100 mg/kg i.p.) a partial but significant inhibition of the bronchial hyperresponsiveness to aerosolized acetylcholine chloride was observed. Furthermore, the treatment of guinea pigs (115 mg/kg, per os) 24 and 1 h before ovalbumin challenge also significantly reduced bronchial hyperresponsiveness. In contrast, no significant inhibition was noted when the guinea pigs were treated by a single dose of Cefadroxil (115 mg/kg per os) 1 h before challenge. Pretreatment of the guinea pigs with Cetirizine (1 mg/kg per os) or Ketotifen (0.1 mg/kg per os) completely inhibited the antigen-induced bronchial hyperresponsiveness. Cefadroxil (100 mg/kg i.p.) slightly inhibited the accumulation of eosinophils in the peribronchial area induced by antigen challenge. In contrast, no significant reduction was noted when the guinea pigs were treated per os with Cefadroxil (115 mg/kg), Cetirizine (1 or 10 mg/kg) or Ketotifen (0.1 mg/kg). These results show that Cefadroxil is effective in reducing antigen-induced bronchial hyperresponsiveness, an effect independent of a reduction in the pulmonary inflammation, namely eosinophil accumulation in lung.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8400889&dopt=Abstract cetirizine Zyrtec



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A pharmacokinetic evaluation of the second-generation H1-receptor antagonist cetirizine in very young children.

Desager JP, Dab I, Horsmans Y, Harvengt C.

Department of Internal Medicine, Universite Catholique de Louvain, Belgium.

The pharmacokinetics of the second-generation H1-receptor antagonist cetirizine was studied in eight children younger than 4 years of age who were treated with a single dose of cetirizine solution (5 mg). These children were hospitalized with suspected allergic respiratory problems or recurrent respiratory tract infections. Blood samples were collected at 1/2, 1, 1 1/2, 2, 4, 6, 8, 12, and 24 hours, and a 24-hour urine collection was performed in five of the samples. The findings obtained in children were compared with those obtained in 16 healthy young adults (mean +/- SD, 24.6 +/- 4.1 years) who received a single 20 mg dose. Cetirizine was absorbed more slowly in children (p = 0.006; mean +/- SD, 1.44 +/- 1.12 hours) than in adults (0.62 +/- 0.22 hours). The plasma elimination half-life of cetirizine was significantly shorter in children (p < 0.001; 4.91 +/- 0.6 hours) than in adults (8.6 +/- 2.1 hours), and the clearance rate was significantly higher in children (p < 0.001; 1.48 +/- 0.41 ml/min/kg) than in adults (0.80 +/- 0.17 ml/min/kg). Urinary excretion of unchanged cetirizine was significantly lower in children (p < 0.001; 37.8% +/- 5.2%; n = 5) than in adults (57.7% +/- 11.8%). Therefore the metabolism of cetirizine is faster in young children than in adults. This effect must be taken into account in future pharmacodynamic studies in this age group.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8477559&dopt=Abstract cetirizine Zyrtec



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Cetirizine exerts anti-inflammatory effects on human neutrophils.

Koller M, Hilger RA, Rihoux JP, Konig W.

Medizinische Mikrobiologie und Immunologie, AG Infektabwehrmechanismen, Ruhr-Universitat Bochum, Germany.

Leukotrienes are potent lipid mediators involved in acute and chronic inflammatory processes and allergic inflammation. Cetirizine is an H1-receptor antagonist used in the treatment of allergic symptoms. We analyzed the effect of cetirizine on the formation of leukotriene B4 (LTB4) after stimulation of human peripheral blood neutrophils. The inflammatory mediators were analyzed after cellular activation with different stimuli: the Ca ionophore A23187, which bypasses membranous signal transduction elements; the bacterial peptide formyl-methionine-leucyl-phenylalanine (fMLP), which activates cells by binding to a GTP-protein (G-protein)-coupled receptor, and with sodium fluoride (NaF), which directly activates G-proteins. After cellular preincubation with cetirizine, the amounts of LTB4 generated from neutrophil granulocytes decreased significantly when the cells were subsequently stimulated with either fMLP or NaF, in contrast to stimulations with the Ca ionophore. The data provide evidence that cetirizine exerts anti-inflammatory effects apart from H1 antagonism.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8645978&dopt=Abstract cetirizine Zyrtec



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Comparative analysis of the cardiotoxicity proclivities of second generation antihistamines in an experimental model predictive of adverse clinical ECG effects.

Hey JA, del Prado M, Sherwood J, Kreutner W, Egan RW.

Schering Plough Research Institute, Allergy, Kenilworth, New Jersey, USA.

Terfenadine and astemizole belong to the second generation histamine H1 antagonists and are widely prescribed for allergic and upper respiratory diseases. The popularity of the newer H1 antihistamines is due to their ability to provide relief from allergic symptoms without the undesirable side effect of sedation commonly associated with first generation H1 receptor antagonists such as diphenhydramine and promethazine. Recent clinical evidence that the second generation histamine H1 antagonists terfenadine and astemizole have the potential for inducing life threatening ventricular arrhythmias has raised questions as to whether other drugs in this class have similar cardiotoxic potential. The objective of this study was to evaluate and compare the arrhythmogenic potential of a series of second generation antihistamines in a quantitative experimental model predictive of adverse ECG effects in man. Antihistamines were given intravenously and electrocardiographic (ECG) and cardiovascular parameters (blood pressure and heart rate) were measured. The ECG wave form was analyzed to determine QTc interval, PR interval, QRS interval and heart rate. To determine the relative cardiotoxic potential of the antihistamines, the lowest dose producing significant prolongation of the QTc interval was compared with the dose required to inhibit by 50% the peripheral bronchospasm elicited by histamine at 10 micrograms/kg i.v. (antihistamine ED50). The second generation antihistamines studied were astemizole (CAS 68844-77-9), carebastine (CAS 90729-42-3), cetirizine hydrochloride (CAS 83881-52-1), ebastine (CAS 90729-43-4), norastemizole (CAS 75970-99-9), terfenadine (CAS 50679-08-8) and terfenadine carboxylate (CAS 83799-24-0). The second generation antihistamines astemizole, ebastine and terfenadine produced pronounced dose-dependent QTc interval prolongation effects. These arrhythmogenic effects occurred at doses that were between 1 and 4 times their respective peripheral antihistamine doses. These drugs produced significant disruption of the ECG wave form including large amplitude, morphologically aberrant T-waves and, in some cases, torsades de pointes-type arrhythmias. In contrast, terfenadine carboxylate (100 mg/kg i.v.), norastemizole (20 mg/kg, i.v.) and carebastine (50 mg/kg, i.v.), the major metabolites of terfenadine, astemizole and ebastine, were largely devoid of adverse ECG effects. Similarly, cetirizine (20 mg/kg, i.v.) was also found to not alter ECG or cardiovascular function. These findings demonstrate that terfenadine, astemizole and ebastine exhibit significant arrhythmogenic effects including QTc interval prolongation, bradycardia and distortion of the ECG morphology in the guinea pig. The relative cardiotoxicity of these antihistamines based on the separation of antihistamine activity and adverse ECG effects was similar for terfenadine and astemizole, but slightly less for ebastine. In this model carebastine, cetirizine, loratadine, norastemizole and terfenadine carboxylate are devoid of QTc prolongation effects. Given the structural similarity of terfenadine and ebastine it is not surprising that these drugs produce significant cardiotoxicity in this animal model. Taken together, these results indicate that the ability to cause QTc interval prolongation and the proclivity for producing arrhythmias is not a class effect and is seen only with some second generation nonsedating antihistamines.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8720304&dopt=Abstract cetirizine Zyrtec



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Characterization of a primate model of asthma using anti-allergy/anti-asthma agents.

Turner CR, Andresen CJ, Smith WB, Watson JW.

Department of Immunology and Infectious Diseases, Pfizer Central Research Groton, CT 06340, USA.

The following study was performed to further characterize a primate model of asthma using classes of drugs that target allergy (pyrilamine, cetirizine), are bronchodilators for the treatment of asthma (salbutamol, salmeterol) or are anti-inflammatory (dexamethasone). These drugs were examined for their ability to inhibit acute, antigen-induced bronchoconstriction, the development of airway hyperresponsiveness (AHR) and the infiltration of leukocytes into the lungs of atopic cynomolgus monkeys (Macaca facsicularis) using a 10-day, multiple antigen (Ag) challenge protocol. All compounds except dexamethasone and cetirizine significantly (p < 0.05) reduced acute, Ag-induced bronchoconstriction (salbutamol: 74.2%, salmeterol: 52.6%%, pyrilamine: 62.4% inhibition) compared to vehicle control trials. Only dexamethasone and salmeterol prevented the development of AHR to methacholine challenge by 90.4 +/- 6.81% and 85.7 +/- 5.61% respectively. Dexamethasone significantly reduced the Ag-induced increase in BAL eosinophils by 85.9 +/- 8.53%. Cetirizine reduced the eosinophil response in 5 of 6 monkeys and salmeterol demonstrated a trend towards reduced eosinophil increases after multiple Ag challenge, but neither of these were statistically significant. These results further illustrate the utility of this model in predicting compound effects against several relevant functional endpoints that are consistent with the effects of similar classes of compounds in humans.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8737747&dopt=Abstract cetirizine Zyrtec



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High-performance thin-layer chromatography for the determination of cetirizine in human plasma and its use in pharmacokinetic studies.

Pandya KK, Bangaru RA, Gandhi TP, Modi IA, Modi RI, Chakravarthy BK.

Research & Development Centre, Cadila Laboratories Ltd, Ahmedabad, India.

A rapid and sensitive high-performance thin-layer chromatography (HPTLC) assay has been developed for the measurement of cetirizine in human plasma and its utility for pharmacokinetic study has been evaluated. In the proposed HPTLC method, protein-bound cetirizine was freed by proteolysis of plasma proteins by incubating the plasma with 0.35% pepsin and then extracting with 2 mL pH 5.0 phosphate buffer, followed by 4 mL chilled chloroform. The chloroform layer was separated and concentrated. An aliquot of the extract was then spotted on precoated silica-gel 60 F254 plates using a Camag Linomat IV autosampler. Quantification was with the help of a dual-wavelength TLC scanner. The proposed method had a recovery of 98% and the lowest amount of cetirizine that could be detected was 50 ng. The method was applied for the determination of the plasma levels and pharmacokinetic parameters of cetirizine after oral administration of two marketed preparations in healthy volunteers and the pharmacokinetic parameters determined by the proposed method were in agreement with previously reported values.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8799876&dopt=Abstract cetirizine Zyrtec