Facial thermography is a sensitive tool to determine antihistaminic activity: comparison of levocetirizine and fexofenadine

Abstract

Aims: To assess the antihistaminic activity of levocetirizine and fexofenadine 2 h and 24 h after drug administration using facial thermography and to compare the results with those using well-established parameters of antihistaminic activity in the nose and skin.

Methods: This was a randomized, double-blind, three-treatment, three-period, single-dose, cross-over study in healthy males taking levocetirizine 5 mg, fexofenadine 120 mg or placebo. The primary endpoint was nasal skin temperature after nasal histamine challenge recorded for 20 min at 2 and 24 h after drug intake. The secondary endpoints were nasal symptoms and a histamine skin prick test.

Results: Thirty subjects were randomized. At 2 h after drug intake the inhibition of the nasal temperature increase from baseline was not significantly different between levocetirizine and fexofenadine. At 24 h it was significantly more pronounced after levocetirizine than fexofenadine (difference: least-squares mean: -0.13 degrees C; P < or = 0.024, 95% CI -0.24, -0.02). Both drugs significantly reduced (P < or = 0.001) the mean temperature increase from baseline compared with placebo at 2 and 24 h (least-squares mean increase and (95% CI): levocetirizine, -0.28 degrees C (-0.42, -0.14) and -0.32 degrees C (-0.43, -0.21); fexofenadine -0.35 degrees C (-0.49, -0.21) and -0.19 degrees C (-0.30, -0.08), respectively). Results of nasal symptom score and wheal and flare were consistent with the thermography results.

Conclusions: Facial thermography is an objective, non-invasive and sensitive method to study antihistaminic activity at the nose level. Levocetirizine and fexofenadine demonstrate the same activity at 2 h after drug intake, but levocetirizine has a more sustained activity at 24 h.

Figure 1

Study procedure of each treatment period. IR, infrared; NHP, nasal histamine provocation; T4SS, nasal symptom score; SPT, skin prick test

Figure 2

Nasal region before and after nasal histamine provocation. Differences in nasal skin temperature were measured with infrared thermography. The temperature is colour coded. A change from black to yellow indicates an increase in temperature

Figure 3

Mean temperature change (°C) after nasal histamine provocation at 2 h (A) and 24 h (B) after drug intake (n = 30)

Figure 4

Inhibition in wheal (A + B) and flare (C + D) after nasal histamine provocation at 2 h and 24 h after drug intake (mean ± 95% CI)