Loratadine-d₅is intended for use as an internal standard for the quantification of loratadine by GC- or LC-MS. Loratadine is a non-sedating antihistamine that acts as a selective inverse agonist of peripheral histamine H₁receptors (K_i= 35 nM).^1,2,3It has been shown to inhibit the release of leukotriene C₄(IC₅₀= 8 µM) and histamine (IC₅₀= 11 µM) from rodent mast cells and to inhibit allergic bronchospasm in guinea pigs with an ED₅₀value of 0.40 mg/kg.⁴Formulations containing loratadine have been used in the treatment of allergic rhinitis and chronic idiopathic urticaria.

1.Ahn, H.S., and Barnett, A.Selective displacement of [3H]mepyramine from peripheral vs. central nervous system receptors by loratadine, a non-sedating antihistamineEur. J. Pharmacol.127(1-2)153-155(1986) 2.Kay, G.G., and Harris, A.G.Loratadine: A non-sedating antihistamine. Review of its effects on cognition, psychomotor performance, mood and sedationClin. Exp. Allergy29(Suppl 3)147-150(1999) 3.Barnett, A., Iorio, L.C., Kreutner, W., et al.Evaluation of the CNS properties of SCH 29851, a potential non-sedating antihistamineAgents Actions43(3-4)149-156(1994) 4.Kreutner, W., Chapman, R.W., Gulbenkian, A., et al.Antiallergic activity of loratadine, a non-sedating antihistamineAllergy42(1)57-63(1987)