Effects of diphenhydramine, naphazoline and m-amino-alpha(1-aminoethyl)benzyl alcohol dihydrochloride on the nasal mucosa determined by impedance method: a simple method for evaluation of nasal decongestant.

A simple, new method was devised for evaluating nasal decongestants. In anesthetized dogs, two needle electrodes were inserted bilaterally into the superficial mucosa of the nasal wings. An impedance plethysmorgraphy provided with a DC output was used to measure impedance between the two electrodes. When 1% histamine solution was sprayed into a nostril focusing on the inside mucosa of a nasal wing, impedance decreased markedly and thereafter recovered to a control level within 1-1.5 h. Comparable responses were obtained when the same solution was sprayed into the opposite nostril. The drugs to be tested were administered intravenously or topically between these two histamine application. Intravenous administrations of diphenhydramine (0.5 mg/kg) and m-amino-alpha)1-aminoethyl) benzyl alcohol dihydrochloride (0.1 mg/kg) inhibited the histamine effect completely. Pretreatment with naphazoline administered topically also inhibited impedance changes cause by histamine application. Local appliations of acetycholine (10%) and bradykinin (0.1%) did not change nasal impedance significantly in any instances.