Drugs online research references
Aviat Space Environ Med. 1998 Feb;69(2):166-71.
Central effects of the H1-antihistamine, cetirizine.
Nicholson AN, Turner C.
Royal Air Force School of Aviation Medicine, Farnborough, Hampshire, United Kingdom.
BACKGROUND: Effects of the H1-antihistamine, cetirizine, were studied on daytime alertness and performance to establish whether the drug would be suitable for use by air personnel and others involved in skilled activity. METHODS: The investigation was carried out in six healthy volunteers, and the effects of the drug (5, 10, and 15 mg) were studied on sleep latency, subjective sleepiness, digit symbol substitution, tracking and vigilance from 0.5 h to 7.5 h after ingestion. The study was placebo-controlled and double-blind with a six-way cross-over design. Promethazine (10 mg) was used as an active control to establish the sensitivity of the experimental procedures. RESULTS: Promethazine (10 mg) decreased the mean level of vigilance over the day, increased objective and subjective sleepiness from 1.5 to 5.5 h, and impaired tracking 5.5 h after ingestion. Cetirizine (10 and 15 mg) led to shortened sleep latencies over the day, and at 7.5 h sleep latencies were shorter with 10 mg cetirizine than with placebo. Subjective sleepiness with cetirizine was increased compared with placebo after 5 mg at 1.5 h, 10 mg at 7.5 h, and 15 mg at 5.5 h and when meaned over the day. Tracking was impaired with 5 and 15 mg cetirizine 0.5 h after ingestion. CONCLUSION: The study failed to establish dose-response effects of cetirizine, but it is evident that cetirizine is not free of central activity over the therapeutic range, and so its use by air personnel is not recommended.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9491258&dopt=Abstract
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J Med Chem. 1998 Mar 12;41(6):853-63.
Molecular properties and pharmacokinetic behavior of cetirizine, a zwitterionic H1-receptor antagonist.
Pagliara A, Testa B, Carrupt PA, Jolliet P, Morin C, Morin D, Urien S, Tillement JP, Rihoux JP.
Institut de Chimie Therapeutique, Universite de Lausanne, Switzerland.
The ionization and lipophilicity behavior of the antihistamine (H1-receptor antagonist) cetirizine was investigated, showing the drug to exist almost exclusively as a zwitterion in the pH region 3.5-7.5. In this pH range, its octanol/water lipophilicity is constant and low compared to cationic antihistamines (log D = log PZ = 1.5), whereas its H-bonding capacity is relatively large (delta log PZ > or = 3.1). Conformational, electronic, and lipophilicity potential calculations revealed that zwitterionic cetirizine experiences partial intramolecular charge neutralization in folded conformers of lower polarity. Pharmacokinetic investigations have shown the drug to be highly bound to blood proteins, mainly serum albumin, and to have a low brain uptake, explaining its lack of sedative effects. As such, cetirizine does not differ from "second-generation" antihistamines. In contrast, its very low apparent volume of distribution in humans (0.4 L kg-1, smaller than that of exchangeable water) implies a low affinity for lean tissues such as the myocardium and is compatible with the absence of cardiotoxicity of the drug. The zwitterionic nature and modest lipophilicity of cetirizine may account for this pharmacokinetic behavior. The suggestion is offered that cetirizine and analogous zwitterions, whose physicochemical, pharmacokinetic, and pharmacodynamic properties differ from those of "first-" and "second-generation" drugs in this class, could be considered as "third-generation" antihistamines.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9526560&dopt=Abstract
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Clin Exp Allergy. 1998 Jan;28(1):101-9.
Cetirizine and hydrocortisone differentially regulate ICAM-1 expression and chemokine release in cultured human keratinocytes.
Albanesi C, Pastore S, Fanales-Belasio E, Girolomoni G.
Laboratory of Immunology, Istituto Dermopatico dell'Immacolata, IRCCS, Rome, Italy.
BACKGROUND: Cetirizine is a H1 histamine antagonist which possesses anti-inflammatory properties through inhibition of leucocyte recruitment and activation, and reduction of ICAM-1 expression on mucosal epithelial cells. No studies have addressed the potential anti-inflammatory activities of cetirizine on skin keratinocytes. OBJECTIVES: Cetirizine and hydrocortisone were compared in their capacity to counteract human keratinocytes activation by IFNgamma. In particular, expression of immuno-modulatory membrane molecules and chemokine release have been examined. METHODS: Keratinocyte cultures established from normal skin of healthy donors were activated by IFNgamma (100-500 U/mL) in the absence or presence of cetirizine (10(-3)-10(3) microM) or hydrocortisone (10(-3)-10(2) microM), and tested for expression of ICAM-1, HLA-DR, MHC class I and CD40 as well as for release of RANTES, IL-8, macrophage chemotactic protein-1 (MCP-1) and granulocyte macrophage-colony stimulating factor (GM-CSF). RESULTS: Cetirizine at high concentrations (10(2)-10(3) microM) markedly inhibited IFNgamma-induced expression of membrane ICAM-1, HLA-DR and up-regulation of MHC class I, but had no effect on CD40 expression. In contrast, hydrocortisone (10(2) microM) enhanced IFNgamma-induced membrane ICAM-1, reduced expression of HLA-DR and did not alter expression of MHC class I and CD40. Consistently, high doses of cetirizine decreased, whereas hydrocortisone increased, soluble ICAM-1 levels in the supernatants of IFNgamma-treated keratinocytes. The inhibiting and stimulating effects of cetirizine and hydrocortisone, respectively, on ICAM-1 expression were confirmed at the mRNA level by Northern blot analysis. Finally, cetirizine, but not hydrocortisone, inhibited the release of MCP-1 and RANTES from IFNgamma-stimulated keratinocytes. In contrast, hydrocortisone, but not cetirizine, reduced GM-CSF and IL-8 release. CONCLUSIONS: The results indicate that cetirizine has the capacity to block the IFNgamma-induced activation of keratinocytes, and thus can exert important regulatory effects on TH1 cell-mediated immune responses in the skin. The high doses required for evidencing these activities suggest the potential benefits of a topical use of cetirizine.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9537772&dopt=Abstract
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