The effect of bromhexine hydrochloride on the viscoelastic properties of mucus from the mini-pig.

Mucus was collected daily from open-ended pouches established surgically in three mini-pigs. After a five day control period bromhexine hydrochloride (BHCl) was administered to each pig at dose levels of 0.5, 1.0 and 2.0 mg.kg-1 twice daily for five days. Each study period was followed by a five day washout period, when mucus was collected but no drug given. The viscoelastic properties of each mucus sample were determined using creep compliance analysis. BHCl was shown to reduce the residual shear viscosity (p less than 0.05) and increase the instantaneous shear compliance at all dose levels (p less than 0.005), despite the large inherent intra- and inter-animal variation in the rheological properties of the daily samples. No change was found in the wet weight of the mucus samples throughout any of the study periods. This experimental model would appear to provide a valuable in vivo method of assessing the mucoregulatory potential of administered compounds.