Abstract
The mechanism of absorption inhibitory effect of polysorbate 80 was investigated. The following observations were demonstrated. 1) No significant difference in the uptake of drugs by the muscles either in the presence or absence of polysorbate 80 could be demonstrated. 2) Succinylcholine chloride was used as a muscle relaxant, but no detectable difference in the absorption of isonicotinamide in the presence or absence of polysorbate 80 could be observed. Therefore the effect of polysorbate 80 on the contractility of the muscles was excluded. 3) There was a marked inhibition in the distribution rate of isonicotinamide from blood to muscle, and the extracellular spaces were greatly decreased by pretreatment with polysorbate 80. 4) Permeation of drug through muscle slices and the connective tissue permeability were significantly lowered in the presence of polysorbate 80. Therefore it can be concluded that the mechanism of the absorption inhibitory effect of polysorbate 80 was mainly due to its influence on the extracellular space and the connective tissue permeability.
