Cetirizine pharmacokinetics

A single 240-mg dose of intravenous theophylline was given to 6 healthy subjects after they had taken cetirizine 10 mg twice daily for 3.5 days. There was no change in theophylline pharmacokinetics, but the half-life of cetirizine was decreased by 19%. This change in cetirizine pharmacokinetics was not considered to be clinically relevant. ... 

Pagliara, A., Testa, B., Carrupt, P.A., Jolliet, P., Morin, C., Morin, D., Urien, S., Tillement, J.P. and Rihoux, J.P. (1998) Molecular properties and pharmacokinetic behavior of cetirizine, a zwitterionic Hl-receptor antagonist. Journal of Medicinal Chemistry, 41, 853-863. 

In term of pharmacokinetics, cetirizine (4) is rapidly absorbed, reaching a peak plasma concentration of 257 pg/L within 1 h of administration at a dose of 10 mg in healthy volunteers. The AUC is 2.87 mg/L with this dose. 

Example Diphenhydramine HC1 (Benadryl), astemizole (Hismanal), cetirizine (Zyrtec) chlorpheniramine maleate (Chlor-Trimeton, Kolomnin, Phenetron, Techlor, Teldrin) loratadine (Claritin) Route PO, IM, IV Pregnancy category B Pharmacokinetic Absorbed from GI tract. Metabolized by the liver and excreted in urine. 

M., and Stockis, A. Retrospective population pharmacokinetic analysis of cetirizine in children aged 6 months to 12 years. British Journal of Clinical Pharmacology 2004 57 402-411. 

Active metabolites may have superior pharmacological, pharmacokinetic, and safety profiles compared to their respective parent molecules (Fura, 2006 Fura et al., 2004). As a result, a number of active metabolites have been developed and marketed as drugs with improved profiles relative to their parent molecules. Examples of active metabolites of marketed drugs that have been developed as drugs include acetaminophen, oxyphenbutazone, oxazepam, cetirizine (Zyrtec), fexofenadine (Allegra), and desloratadine (Clarinex). Each of these drugs provides a spedlic benefit over the parent molecule and is superior in one or more of the categories described above. 

Cetirizine 10 mg was given to 8 patients with chronic urticaria before and after they took cimetidine 600 mg every 12 hours for 10 days. The pharmacokinetics of cetirizine were statistically unaltered and its effects remained unchanged. ... 

Fexofenadine levels are raised by both azithromycin and erythromycin but because this does not result in adverse cardiac effects concurrent use is considered safe. Azelastine, cetirizine (and therefore probably its isomer levocetirizine) desloratadine and levocabastine seem to be free from clinically significant pharmacokinetic interactions, and have no cardiac effects, and so may therefore provide suitable alternatives if a non-sedating antihistamine is needed in a patient taking macrolides. 

In a study in 16 healthy subjects the concurrent use of cetirizine 10 mg daily and ritonavir 600 mg twice daily for 4 days (after reaching steady-state ritonavir levels), increased the AUC of cetirizine by 42% with a slight 9% increase in maximum plasma levels. It was suggested that ritonavir may have decreased the renal excretion of cetirizine. The increase in cetirizine levels was not considered to be clinically relevant. Ritonavir pharmacokinetics were minimally affected by cetirizine. ... 

Peytavin G, Gautran C, Otoul C, Cremieux AC, Moulaert B, Delatour F, Melac M, Strolin-Benedetti isi Farinotti R. Evaluation of pharmacokinetic interaction between cetirizine and ritonavir, an HIV-1 protease inhibitor, in healthy male volunteers. Eur J Clin Pharmacol (2005)61,267-73. 

Azelastine, cetirizine, ketotifen, mequitazine, mizolastine, pemirolast, repirinasit, and terfenadine do not appear to alter the pharmacokinetics of theophylline. 

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