Levocetirizine: the allergist’s arsenal grows larger

The crystal structure of N-((3,5-di-tert-butyl-4-hydroxyphenyl)(phenyl)methyl)-4-methylbenzenesulfonamide, C28H35N3S

C28H35NO3S, triclinic, P1̄ (no. 2), a = 10.3965(4) Å, b = 10.7525(5) Å, c = 12.2772(6) Å, α = 86.651(4)°, β = 86.653(4)°, γ = 75.323(4)°, V = 1324.05(11) Å3, Z = 2, R gt(F) = 0.0472, wR ref(F 2) = 0.1298, T = 291 K.

Palladium-Catalyzed Enantioselective Three-Component Synthesis of α-Substituted Amines

The first general palladium-catalyzed, enantioselective three-component synthesis of α-arylamines starting from sulfonamides, aldehydes, and arylboronic acids has been developed. These reactions generate a wide array of α-arylamines with high yields and enantioselectivities. Notably, this process is tolerant to air and moisture, providing an operationally simple approach for the synthesis of chiral α-arylamines.

Inhibition of allergen-induced wheal and flare reactions by levocetirizine and desloratadine

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

The reproducible and standardized histamine-induced wheal and flare model helps identify the objective effectiveness of antihistamines in humans, as well as their differences in onset and duration of action. Some of the newest antihistamines have already been compared in a head-to-head setting using this model. However, their objective action at inhibiting the allergen-induced wheal and flare response has not been reported yet.

WHAT THIS STUDY ADDS

The time-response study presented here shows the objective activity of two of the newest generation of antihistamines, levocetirizine and desloratadine, at inhibiting the allergen-induced wheal and flare response in a randomized, cross over, placebo-controlled trial. This model is interesting to the clinical setting since allergic subjects are recruited, and the response to allergen involves mast cell degranulation and release of numerous vasoactive and pro-inflammatory mediators additionally to histamine. In addition, this study reports receptor occupancy for both antihistamines at therapeutic dosage, leading to analysis of potential differences in activity. This study clearly shows the potential anti-inflammatory properties of desloratadine and levocetirizine in their skin activity when allergen is the challenging agent as occurs in the clinical situation.

AIMS

To evaluate the inhibitory activity of the new-generation antihistamines levocetirizine and desloratadine at their therapeutic doses on the allergen-induced wheal and flare reaction at 1.5 h, 4 h, 7 h, 12 h and 24 h postdose, and to measure their plasma and skin concentrations.

METHODS

A double-blind, randomized, cross-over, placebo-controlled study in 18 allergic subjects was carried out. The time-response of the wheal and flare reaction areas under the curve (AUC) were compared by anova.

RESULTS

Both antihistamines significantly (P < 0.001) inhibited the allergen-induced wheal and flare reactions compared with placebo. Levocetirizine was significantly more potent than desloratadine. Mean +/- SEM wheal AUC(0-24 h) was 506.4 +/- 81.0 with levocetirizine and 995.5 +/- 81.0 mm(2) h with desloratadine as compared with placebo (1318.5 +/- 361.0 mm(2) h). Flare AUC(0-24 h) was 5927.3 +/- 1686.5 and 15838.2 +/- 1686.5 mm(2) h, respectively [P < 0.001 for both compared with placebo (22508.2 +/- 7437.1 mm(2) h)]. Levocetirizine showed significant inhibition of wheal and flare already at 1.5 h postdose compared with placebo (P <or= 0.001); desloratadine achieved a significant effect only after 4 h. The mean total plasma concentration at 12 h and 24 h after intake was higher for levocetirizine (58.1 +/- 13.4 and 20.0 +/- 8.1 ng ml(-1), respectively) as compared with desloratadine (0.82 +/- 0.24 and 0.45 +/- 0.16 ng ml(-1)). Similarly, higher mean unbound skin concentrations were observed for levocetirizine 24 h after intake (1.80 ng g(-1)) than for desloratadine (0.07 ng g(-1)). This was associated with greater receptor occupancy for levocetirizine (54%) than desloratadine (34%) at 24 h.

CONCLUSIONS

Levocetirizine suppressed the cutaneous allergic reactions with a higher potency than desloratadine, which correlated with its high receptor occupancy. Receptor occupancy rather than drug affinity or plasma half-life is more representative of antihistamine potency.

A new antihistamine levocetirizine inhibits eosinophil adhesion to vascular cell adhesion molecule-1 under flow conditions

BACKGROUND

We previously demonstrated that low concentrations of a new antihistamine levocetirizine inhibited eosinophil transmigration through human microvascular endothelial cells.

OBJECTIVE

Here, the inhibitory effect of levocetirizine on eosinophil adhesion to recombinant human vascular cell adhesion molecule-1 (rhVCAM)-1 was examined under conditions of shear stress using an in vitro model of the post-capillary venules.

METHODS

Eosinophils isolated from normal subjects were pre-incubated with a concentration range of levocetirizine (10(-6)-10(-10) m) or negative dilution control. Resting or granulocyte macrophage-colony stimulating factor (GM-CSF)-stimulated cells were pumped through rhVCAM-1 (10 microg/mL) coated capillary tubes using a microfluidic syringe pump at a precise and constant flow rate (1 dyn/cm(2)). Images of rolling and firmly adherent eosinophils were captured using real-time video microscopy.

RESULTS

Levocetirizine significantly inhibited resting eosinophil adhesion to rhVCAM-1 with maximal effect at 10(-8) M with an EC(50) of 10(-9) m. Levocetirizine almost abolished resting eosinophil adhesion by the 15 min time-point. GM-CSF significantly enhanced eosinophil adhesion and their ability to flatten on rhVCAM-1. Both phenomena were inhibited by levocetirizine in a dose-dependent manner, at both 5 and 15 min (optimal concentration of 10(-8) m with an EC(50) of 10(-9) m). Real-time imaging revealed that the effect of levocetirizine on post-adhesion behaviour (detachment, flatness) contributed to its inhibitory action on eosinophil adhesion to rhVCAM-1. In contrast, very late antigen (VLA)-4 mAb inhibited eosinophil adhesion to rhVCAM-1 from the earliest time-points.

CONCLUSION

Physiologically relevant concentrations of levocetirizine inhibit resting and GM-CSF-stimulated firm eosinophil adhesion to rhVCAM-1 under flow conditions.

A treatment for allergic rhinitis: a view on the role of levocetirizine

BACKGROUND

Allergic rhinitis is a significant public health concern in many developed countries. However, despite evidence for a significant impact on patients' quality of life (QoL) including sleep disruption and reduced daytime performance, allergic rhinitis remains under-managed and hence poorly controlled. This is largely owing to lack of knowledge about, and poor adherence to, established treatment guidelines.

SCOPE

The panel considered available evidence and focused on four published studies on the second-generation antihistamine, levocetirizine. Three of these studies explored the clinical impact of levocetirizine in a broad range of different clinical settings.

FINDINGS

Levocetirizine demonstrated an increased benefit over other antihistamines in terms of a more durable antihistamine response: levocetirizine provided improved symptom relief at 24 hours compared to desloratadine or fexofenadine, two frequently prescribed second-generation antihistamines. Levocetirizine also maintained relief of the key symptoms of allergic rhinitis and improved patients' QoL over a treatment period of 6 months, in a real-life setting. The variable efficacy and durability of response of different antihistamines arise from differing modulatory effects on the H(1)-receptor. The speed of relief of symptoms with levocetirizine is supported by the pharmacokinetic data, which shows that steady state plasma concentrations are achieved in a shorter period of time than other second-generation histamines (additionally levocetirizine T(max) is reached in 0.9 h).

CONCLUSION

These findings support both the short-term and long-term use of levocetirizine in the clinical management of allergic rhinitis. The World Health Organization (WHO) ARIA Guidelines (Allergic Rhinitis and its Impact on Asthma), recommend using a combination of a non-sedating antihistamine with a decongestant, or glucocorticosteroids for treating allergic rhinitis - with the order and combination of treatment depending on severity and duration of symptoms.