Abstract
Summary
Rats and guinea pigs injected with propylene glycol, 4 ml/kg, with or without p-chloroacetanilide, showed a uniform increase in hematocrit to 51% as compared with a normal value of 42-45%. Animals receiving no propylene glycol showed no increase in hematocrit above the normal value. p-Chloroacetanilide, 100 mg/kg, dissolved in propylene glycol, 4 ml/kg, produced methemoglobinemia in both species; to a greater extent in the rat than in the guinea pig: 8.1% and 4.2% of the total blood pigment, respectively. Propylene glycol alone, 4 ml/kg, produced no increase in methemoglobin above normal range: 1.5% for rats, and 2.2% for guinea pigs. p-Chloroacetanilide, 100 mg/kg, in aqueous suspension increased the methemoglobinemia in both species; the increase more pronounced in the rat than in the guinea pig: 40.8% and 6.9% of the total blood pigment, respectively. These results indicate a decrease in production of the methemoglobin-producing metabolite of p-chloroacetanilide in the presence of propylene glycol. It is suggested that results attributed to a compound administered in propylene glycol solution should be carefully interpreted since the propylene glycol may make a marked contribution to the physiological activity of the mixture.
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