Zyrtec
Measurement of interstitial cetirizine concentrations in human skin: correlation of drug levels with inhibition of histamine-induced skin responses.

Petersen LJ, Church MK, Rihoux JP, Skov PS.

Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark.

BACKGROUND: The purpose of the present study was to measure the concentrations of cetirizine in the extracellular water compartment in intact human skin and assess simultaneously inhibition of histamine-induced wheal and flare reactions. METHODS: Skin cetirizine levels were collected by the microdialysis technique and analyzed by high-pressure liquid chromatography with mass spectrometry detection. Skin levels in 20 subjects were compared to plasma levels for 4 h after a single oral dose of 10 or 20 mg of cetirizine. Skin prick tests were performed with histamine 100 mg/ml. RESULTS: Plasma cetirizine levels increased within 30 min to reach peak values of 315+/-10 and 786+/-45 ng/ml 90-120 min after administration of 10 and 20 mg of cetirizine. This was followed by a slow decline. In the skin, dialysate cetirizine levels (non-protein-bound fraction only) peaked at 1.6+/-0.1 and 2.4+/-0.3 ng/ml at 120-180 min. In vivo recovery of cetirizine was 14.4+/-4.3%. It was estimated that the non-protein-bound concentration of cetirizine in the skin was 50-70% of corresponding plasma values. Both 10- and 20-mg doses of cetirizine inhibited wheal and flare reactions over 240 min. The time vs concentration profile of cetirizine in skin dialysate paralleled the inhibition of skin reactions, but no significant correlations were found between individual cetirizine levels in skin or plasma with wheal and flare reactions. CONCLUSIONS: Cetirizine concentrations in the skin could be monitored by the microdialysis technique. The results indicate no simple linear correlation between cetirizine skin levels and inhibition of skin reactions.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10435475&dopt=Abstract cetirizine Zyrtec



Zyrtec
Role of histamine release in nonspecific vasodilatation during anodal and cathodal iontophoresis.

Horiuchi Y, Droog EJ, Henricson J, Wikstrom T, Lennquist S, Sjoberg F.

The Burns Unit, Department of Hand and Plastic Surgery, University Hospital, Linkoping, Sweden.

Nonspecific vasodilatation during iontophoresis is an important confounding factor in experimental pharmacology. In this investigation, we studied the involvement of sensory nerves and histamine-related reactions in causing nonspecific vasodilatation in a model of anodal and cathodal iontophoresis of sodium chloride. Firstly, we applied a mixture of local anesthetic (EMLA) cream to confirm its suppressive effect on nonspecific vasodilatation and to measure its efficacy in three different dosages (duration: 1, 2, and 3 h). We then investigated the role of histamine in nonspecific vasodilatation by giving an oral antihistamine drug (cetirizine) to subjects who had and had not been given EMLA. We found substantial suppression of the nonspecific vasodilatation in all EMLA-treated groups (all dosages) compared with untreated controls (with suppression rates of 60-65%). Dosage had no significant effect. A further suppression of nonspecific vasodilatation was seen after oral cetirizine during anodal and cathodal iontophoresis in both EMLA-treated and untreated groups. The antihistamine effect was most pronounced during anodal iontophoresis. These results suggest a histaminergic increase in perfusion that may be independent of neurogenic mechanisms and depend on polarity (anode or cathode). Local nerve blocks (EMLA) together with cetirizine may therefore be used to reduce nonspecific vasodilatation in both anodal and cathodal iontophoresis.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15020210&dopt=Abstract cetirizine Zyrtec



Zyrtec
Assessing patient satisfaction with desloratadine after conversion from loratadine, fexofenadine, or cetirizine.

Glass D, Harper A.

Harris Interactive Healthcare Division, New York City, New York 10003, USA. dglass harrisinteractive.com

A number of prescription and nonprescription nonsedating antihistamines are available for the treatment of allergic rhinitis. From a managed care perspective, determining the extent to which a medication conversion to desloratadine from loratadine, fexofenadine, or cetirizine results in maintained or increased patient satisfaction with allergy care would be informative for formulary decision makers and other budget holders. To that end, a survey was undertaken of patient medication assessments after a switch in antihistamines. On average, patients who converted to desloratadine from loratadine, fexofenadine, or cetirizine reported increased satisfaction with desloratadine treatment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15038691&dopt=Abstract cetirizine Zyrtec



Zyrtec
Is it important to correct apparent drug tissue concentrations for blood contamination in the dog?

Giudicelli C, Dricot E, Moati F, Strolin-Benedetti M, Giudicelli JF.

Departement de Pharmacologie, Faculte de Medecine Paris-Sud, 63, rue Gabriel Peri, 94276 Le Kremlin-Bicetre, France. christine.giudicelli kb.u-psud.fr

The goal of this study was to quantify in the dog the error that is made in assessing drug tissue concentrations when no correction for blood contamination is performed and hence to determine in which organs such a correction should be made. The organs investigated were the heart, the brain, the liver and the skeletal muscle, and the test drug used was the H1-antihistamine, cetirizine (0.1 or 0.6 mg/kg/day for 3 days, orally, n = 6 dogs). Radiolabelled serum albumin was used to quantitate blood trapped in the tissues. Blood and tissue samplings were performed 2 h after the last drug administration. Mean (+/-SEM) volumes of blood trapped in the liver, heart, muscle and brain were 263 +/- 12, 91 +/- 3, 27 +/- 1 and 20 +/- 2 microL/g, respectively. Apparent tissue/blood concentration ratios of cetirizine were 2.39 +/- 0.33, 1.11 +/- 0.09, 0.77 +/- 0.07 and 0.37 +/- 0.05 in the four organs. When correction for residual blood is not performed, cetirizine concentrations are underestimated (-13.6 +/- 3.2%) in the liver, slightly overestimated (+4.7 +/- 1.5 to +6.3 +/- 2.8%) in the brain, and neither over nor underestimated in the heart and muscle. Simulation data over a wide range of theoretical drug tissue/blood concentration ratios indicate that in the dog: (a) for the liver, correction of apparent tissue concentration for residual blood should be performed when the drug tissue/blood concentration ratio achieved is <0.8 or >4, (b) for the heart, correction should be made when this ratio is < or =0.4 and (c) for the brain and muscle, no correction is necessary unless the ratio is < or =0.1.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15147279&dopt=Abstract cetirizine Zyrtec



Zyrtec
[Study on the enantiomer separation of cetirizine dihydrochloride using proteinate- and amylose-based chiral stationary phase]

[Article in Chinese]

Zhang ZF, Yang GL, Liang GJ, Zhou Y, Chen Y.

College of Chemistry and Environmental Science, Hebei University, Baoding 071002, China.

AIM: To study the chromatographic behavior of cetirizine dihydrochloride on the proteinate- and amylose- based chiral stationary phases so as to optimizate the chromatographic condition of its enantiomers separation. METHODS: When using amylose-based, alpha1-acid glycoprotein and ovomucoid protein chiral stationary phase, the mobile phase was hexane-isopropyl alcohol-alcohol-trifluoroacetic acid (430:45:25:1), acetonitrile-10 mmol x L(-1) phosphate buffer solution (adjusted to pH 7.0 with sodium hydroxide) (4:96) and acetonitrile-20 mmol x L(-1) KH, PO4 solution (adjusted to pH 7.0 with triethylamine) (12.7:87.3), respectively. The temperature of proteinate column was 25 degrees C. The detective wavelength was 230 nm. RESULTS: The two enantiomers could be separated on the two kinds of chiral stationary phases without derivatization and the resolution was above 2.0. The methods developed on the two kinds of chiral stationary phases are accurate, sensitive and specific. CONCLUSION: Both the proteinate- and amylose-based chiral stationary phases can be used to separate the enantiomers of cetirizine.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15171656&dopt=Abstract cetirizine Zyrtec



Zyrtec
Treatment of canine atopic dermatitis with cetirizine, a second generation antihistamine: a single-blinded, placebo-controlled study.

Cook CP, Scott DW, Miller WH Jr, Kirker JE, Cobb SM.

Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.

Cetirizine and placebo were administered orally as individual agents to 23 dogs with atopic dermatitis. The pruritus was satisfactorily reduced in 4/22 (18%) dogs that completed the trial with cetirizine. Two dogs vomited after administration of the active drug.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15206590&dopt=Abstract cetirizine Zyrtec