INHIBITORY EFFECTS OF ORALLY OR SUBLINGUALLY ADMINISTERED CETIRIZINE ON HISTAMINE-INDUCED WEALS AND FLARES AND THEIR CORRELATION WITH CETIRIZINE PLASMA-CONCENTRATIONS

In an open, randomized crossover study, the inhibition of histamine-induced weals and flares after one dose of 10 mg cetirizine administered orally or sublingually to seven healthy volunteers was compared. Formation of both weals and flares was significantly inhibited by cetirizine administered by either route; weals were inhibited as early as 20 min after oral intake but not clearly inhibited until 90 min after sublingual intake. There was no clinically relevant difference between the effects of the two routes of administration on flare area. Cetirizine was not well tolerated when given sublingually: two patients reported a burning sensation in the tongue and one reported a local anaesthetic effect. Plasma cetirizine concentrations showed no clear difference between the two routes of administration.