The stimulatory effect of paracetamol and its derivatives on growth and the rat tibia test

Influence of position and size of substituents on the mechanism of partitioning: a thermodynamic study on acetaminophens, hydroxybenzoic acids, and parabens

The objective of the present investigation was to study the influence of size, nature, and topology of substituents on the thermodynamic characteristics of sublimation, fusion, solubility, solvation, and partitioning processes of some drug and druglike molecules. Thermodynamic functions of sublimation process 2-acetaminophen and 3-acetaminophen were obtained on the basis of temperature dependencies of vapor pressure by the transpiration method. Thermodynamic characteristics of solubility processes in water, n-octanol, and n-hexane were calculated from the temperature dependencies of solubility using the solubility saturation method. For evaluation of fusion parameters, differential scanning calorimetry was used. A new approach to distinguishing specific and nonspecific energetic terms in the crystal lattice was developed. Specific and nonspecific solvation terms were distinguished using the transfer from the "inert" n-hexane to the other solvents. For the acetaminophen compounds and for some related drug molecules, the correlation between melting points and a parameter describing the ratio between specific and nonspecific interaction in the crystal lattices was obtained. A diagram enabling analysis of the mechanism of the partitioning process was applied. It was found that for isomers of benzoic acids and for acetaminophens, the position of substituents affects the mechanism of the partitioning process but not the extent of partitioning (DeltaG(tr)(0) values). In contrast to this, an increased size of substituents (parabens) leads to essential changes in DeltaG(tr)(0) values, but the mechanism of the partitioning process stays the same.

Effects of aspirin and acetaminophen on fetal and placental growth in rats

Aqueous suspensions of aspirin or acetaminophen (125 and 250 mg/kg/day) were administered orally to pregnant Sprague-Dawley rats on Days 8-19 of gestation Day 20, each rat was sacrificed and the uterus was examined in situ. Each fetal-placental unit was resected and examined. Fetuses from rats given 125 or 250 mg/kg/day of aspirin were shorter and weighed less than those obtained from control rats. In animals receiving the higher dose of aspirin, the placentas were smaller and the number of fetal resorptions was increased. Acetaminophen (250 mg/kg/day) did not affect fetal length or weight or the incidence of resorption. Acetaminophen interfered less with the normal growth of the rat fetus and placenta than did aspirin.