EFFECT OF AMILORIDE AND SALINE ON NASAL MUCOCILIARY CLEARANCE AND POTENTIAL DIFFERENCE IN CYSTIC-FIBROSIS AND NORMAL SUBJECTS

Background-Mucociliary clearance is an important component of pulmonar y defence. Maximum clearance is thought to depend on an optimal depth of the sol layer, allowing the most efficient interaction between the cilia and the overlying mucus layer. Sodium absorption, the major ion transport in human airways, is thought to be important in the regulati on of the depth of the sol layer. In the airways of patients with cyst ic fibrosis sodium absorption is increased and mucociliary clearance d ecreased. Amiloride, a sodium channel blocker, has been shown to impro ve pulmonary mucociliary clearance in patients with cystic fibrosis. H owever, its effects on nasal mucociliary clearance in either normal su bjects or those with cystic fibrosis are unknown. A study was therefor e performed to investigate whether nebulised amiloride improves nasal mucociliary clearance in normal or cystic fibrosis subjects. Methods-N asal mucociliary clearance was measured by the saccharin clearance tec hnique in 12 normal subjects and 12 with cystic fibrosis. For the cont rol study measurements were made on two consecutive days and the mean time for each subject averaged. For the drug study measurements were a lso made on two consecutive days, after administration of nasally nebu lised amiloride or placebo (saline) in a double blind manner. Nasal po tential difference was measured in eight patients with cystic fibrosis after the administration of amiloride or placebo to assess the effica cy of deposition and duration of action. Results-Baseline values of mu cociliary clearance were significantly faster in the normal subjects t han in those with cystic fibrosis. In both groups mucociliary clearanc e was increased after both saline and amiloride, with no significant d ifference between either treatment. As previously reported, baseline n asal potential difference was significantly more negative in the subje cts with cystic fibrosis. Amiloride significantly reduced the potentia l difference for at least 60 minutes in these subjects. Conclusions-Ne bulised saline significantly improves nasal mucociliary clearance in b oth normal subjects and those with cystic fibrosis. Amiloride did not appear to exert any additional effects in either group of subjects, de spite evidence of its efficacy of deposition.