Zyrtec
Participation of chemical mediators in the development of experimental allergic conjunctivitis in rats.

Minami K, Fujii Y, Kamei C.

Department of Pharmacology, Faculty of Pharmaceutical Sciences, Okayama University, Tushima-naka 1-1-1, Okayama 700-8530, Japan.

In the present study, we investigated the participation of chemical mediators in the development of experimental allergic conjunctivitis in rats. Cetirizine (a histamine H1 receptor antagonist), ramatroban (a thromboxane A2 (TXA2) receptor antagonist) and zafirlukast (a cysteinyl leukotrienes (cys-LTs) receptor antagonist) were orally administered from day 14 to day 42 during repeated topical antigen challenge. An increase in reactivity to antigen- and histamine-induced eye scratching behavior was observed by topical sensitization in sensitized rats. Although increased reactivity to antigen was not influenced by cetirizine, ramatoroban and zafirlukast, increased reactivity to histamine was significantly inhibited by ramatroban. The development of conjunctival edema was also observed for topical sensitization. Cetirizine caused no inhibition of the development of conjunctival edema, but ramatroban and zafirlukast inhibited the development of conjunctival edema. In addition, the number of eosinophils in the conjunctiva was increased by topical sensitization. Cetirizine had no significant effect on the increase in the number of eosinophils. However, ramatroban and zafirlukast were effective in inhibiting an increase in the number of eosinophils induced by topical sensitization. These results indicate that TXA2 is involved in increased histamine reactivity, and TXA2 and cys-LTs are associated with not only the conjunctival edema but also eosinophil infiltration during the development of experimental allergic conjunctivitis in rats.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15351322&dopt=Abstract cetirizine Zyrtec



Zyrtec
Failure of Cetirizine to Prevent Nevirapine-Associated Rash: A Double-Blind Placebo-Controlled Trial for the GESIDA 26/01 Study.

The Grupo Estudio Syndrome Immunodeficiencies Adquirida 26/02 Study Group .

OBJECTIVES: Rash is the most frequent adverse event associated with nevirapine. The use of antihistamines remains unclear in this setting. A double-blind placebo-controlled study was performed to evaluate the efficacy of cetirizine in the prevention of nevirapine rash. METHODS: A multicenter, randomized, double-blind, placebo-controlled clinical trial with cetirizine (10 mg/d x 30 days) was conducted. Inclusion criteria were HIV-1 infection and nevirapine therapy started with any CD4 cell count or plasma viral load and without simultaneous use of abacavir, cotrimoxazole, or rifampin. Clinical follow-up was performed at 15, 30, and 90 days. RESULTS: Two hundred seventeen evaluable patients were enrolled (107 patients receiving cetirizine and 110 patients receiving placebo), 32.3% of whom were women. The median baseline CD4 cell count and plasma viral load were 341 cells/mm and 11,000 copies/mL, respectively. Overall, 29 rashes (13.4%) were detected: 16 (15.0%) in the cetirizine group and 13 (11.8%) in the placebo group (odds ratio [OR] = 1.31, 95% confidence interval [CI]: 0.60-2.88; P = 0.50). The incidence of moderate to severe rashes leading to nevirapine withdrawal was 10.3% (11 of 107 patients) in the cetirizine group and 7.3% (8 of 110 patients) in the placebo group (OR = 1.46, 95% CI: 0.52-4.18; P = 0.43). Adverse events leading to withdrawal of therapy appeared in 14 patients (13.1%) from the cetirizine group and 10 (9.1%) from the placebo group (P = 0.34). CONCLUSION: Cetirizine does not prevent the incidence or affect the severity of nevirapine-associated rash.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15385735&dopt=Abstract cetirizine Zyrtec



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

Elzainy AA, Gu X, Simons FE, Simons KJ.

Faculty of Pharmacy, University of Manitoba, Winnipeg, Canada.

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. Copyright (c) 2004 John Wiley & Sons, Ltd.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15490489&dopt=Abstract cetirizine Zyrtec



Zyrtec
H1 histamine receptor mediates inflammatory responses in human keratinocytes.

Giustizieri ML, Albanesi C, Fluhr J, Gisondi P, Norgauer J, Girolomoni G.

Istituto Dermopatica dell'Immacolata, Istituto di Ricovero e Cura a Carattere Scientifico, via dei Monti de Creta 104, 00167 Rome, Italy.

BACKGROUND: Keratinocytes participate in initiation and amplification of T-cell-mediated skin diseases. During these disorders, histamine can be released from both residents skin cells and immigrating leukocytes, and can affect the functions of dendritic cells, monocytes, and lymphocytes. Little information is available on the effects of histamine on keratinocytes. OBJECTIVE: To examine the presence of functional H1 receptors on human keratinocytes and the capacity of histamine to modulate the expression of inflammatory molecules in these cells. METHODS: Primary cultures of resting and cytokine-activated keratinocytes from healthy subjects were analyzed for histamine H1 receptor expression and the production of inflammatory mediators after exposure to histamine receptor agonists and antagonists. RESULTS: Cultured keratinocytes constitutively expressed the H1 receptor mRNA and protein, which was not influenced by IFN-gamma, TNF-alpha, or IL-4. H1 but not H2 agonists induced calcium fluxes in keratinocytes. Treatment of keratinocytes with histamine (10 -7 to 10 -4 mol/L) or beta-histine increased the IFN-gamma-induced expression of membrane intercellular adhesion molecule 1 and MHC class I but not MHC class II molecules. Moreover, H1 stimulation promoted basal CC chemokine ligand (CCL)-5/RANTES and GM-CSF secretion and augmented IFN-gamma-induced release of the chemokines CCL2/monocyte chemoattractant protein 1, CCL5/RANTES, CCL20/macrophage inflammatory protein 3alpha, and CXC chemokine ligand 10/IFN-induced protein of 10 kd, as well as GM-CSF. Administration of the H1 antihistamine levocetirizine, but not of the H2 antihistamine cimetidine, abolished histamine-dependent expression of all of the investigated proinflammatory molecules in a dose-dependent manner (0.01-10 mumol/L). Levocetirizine at higher doses also reduced intercellular adhesion molecule 1, CCL5/RANTES, and GM-CSF release induced solely by IFN-gamma. CONCLUSION: Histamine exerts proinflammatory effects on keratinocytes via the H1 receptor, and these effects are efficiently inhibited by levocetirizine.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15536428&dopt=Abstract cetirizine Zyrtec



Zyrtec
Retrospective population pharmacokinetics of levocetirizine in atopic children receiving cetirizine: the ETAC study.

Hussein Z, Pitsiu M, Majid O, Aarons L, de Longueville M, Stockis A; ETAC Study Group.

Medeval Ltd, Skelton House, Manchester Science Park, Lloyd Street North, Manchester M15 6SH, UK. zhussein medeval.com

AIMS: To evaluate the population pharmacokinetics of levocetirizine in young children receiving long-term treatment with cetirizine. METHODS: Data were available from a randomized, double-blind, parallel group and placebo-controlled study of cetirizine in 343 young children between 12 and 24 months of age at entry, who were at high risk of developing asthma, but were not yet affected (ETAC study). Infants received oral drops of cetirizine at 0.25 mg kg(-1) twice daily for 18 months. Plasma concentration of the active enantiomer levocetirizine was determined in blood samples collected at months 3, 12 and 18 (1-3 samples per child). A one-compartment open model was fitted to the data using nonlinear mixed effects modelling (NONMEM). The influence of weight, age, gender, BSA and other covariates on CL/F and V/F was evaluated. RESULTS: CL/F increased linearly with weight by 0.044 l h(-1) kg(-1) over an intercept of 0.244 l h(-1), and V/F increased linearly with weight by 0.639 l kg(-1). Population estimates in children with weights of 8 and 20 kg were 0.60 and 1.13 l h(-1) for CL/F, and 5.1 and 12.8 l for V/F, respectively, with interpatient variabilities of 24.4% and 14.7%. Weight-normalized estimates of CL/F and V/F were higher than in adults. The estimated relative bioavailability was 0.28 in 12% of instances of suspected noncompliance. Levocetirizine pharmacokinetics were not influenced by severe allergy or aeroallergen sensitization. Results on the effects of concomitant medications or diseases were inconclusive due to limited positive cases. AUC(ss), calculated in compliant subjects using posterior estimates of the final model, was 1952 (1227-3319) microg l(-1) h (mean, min-max), a value similar to that in adults after intake of 5 mg oral solution (2036 (1414-2827) microg l(-1) h. CONCLUSIONS: The model suggests that administration of levocetirizine 0.125 mg kg(-1) twice daily in children 12-48 months of age or weighing 8-20 kg yields the same exposure as in adults taking the recommended dose of 5 mg once daily.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15606437&dopt=Abstract cetirizine Zyrtec



Zyrtec
Automated 96-well solid phase extraction and hydrophilic interaction liquid chromatography-tandem mass spectrometric method for the analysis of cetirizine (ZYRTEC) in human plasma--with emphasis on method ruggedness.

Song Q, Junga H, Tang Y, Li AC, Addison T, McCort-Tipton M, Beato B, Naidong W.

Covance Bioanalytical Services, LLC, 8211 SciCor Drive, Suite B, Indianapolis, IN 46214, USA. qi.song covance.com

A high-throughput bioanalytical method based on automated sample transfer, automated solid phase extraction, and hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) analysis, has been developed for the determination of cetirizine, a selective H(1)-receptor antagonist. Deuterated cetirizine (cetirizine-d(8)) was synthesized as described and was used as the internal standard. Samples were transferred into 96-well plates using an automated sample handling system. Automated solid phase extraction was carried out using a 96-channel programmable liquid-handling workstation. Solid phase extraction 96-well plate on polymer sorbent (Strata X) was used to extract the analyte. The extracted samples were injected onto a Betasil silica column (50 x 3, 5 microm) using a mobile phase of acetonitrile-water-acetic acid-trifluroacetic acid (93:7:1:0.025, v/v/v/v) at a flow rate of 0.5 ml/min. The chromatographic run time is 2.0 min per injection, with retention time of cetirizine and cetirizine-d(8) both at 1.1 min. The system consisted of a Shimadzu HPLC system and a PE Sciex API 3000 or API 4000 tandem mass spectrometer with (+) ESI. The method has been validated over the concentration range of 1.00-1000 ng/ml cetirizine in human plasma, based on a 0.10-ml sample size. The inter-day precision and accuracy of the quality control (QC) samples demonstrated <3.0% relative standard deviation (R.S.D.) and <6.0% relative error (RE). Stability of cetirizine in stock solution, in plasma, and in reconstitution solution was established. The absolute extraction recovery was 85.8%, 84.5%, and 88.0% at 3, 40, and 800 ng/ml, respectively. The recovery for the internal standard was 84.1%. No adverse matrix effects were noticed for this assay. The automation of the sample preparation steps not only increased the analysis throughput, but also increased method ruggedness. The use of a stable isotope-labeled internal standard further improved the method ruggedness. Practical issues of analyzing incurred samples were discussed. This HILIC-MS/MS method for analysis of citirizine in human plasma was successfully used to support clinical studies.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15607714&dopt=Abstract cetirizine Zyrtec