Hydrolysis of fatty acid esters of acetaminophen in buffered pancreatic lipase systmes I

Solubility prediction in supercritical CO(2) using minimum number of experiments

The correlation ability and solubility prediction in supercritical carbon dioxide of a proposed equation were studied. The work involved the solubilities of nicotinic acid and p-acetoxyacetanilide in supercritical carbon dioxide using a dynamic flow solubility system at 35-75 degrees C and 100-200 bar. The generated experimental solubility data together with 21 data sets collected from the literature were used to evaluate the correlation ability of available empirical equations. The average absolute relative deviations (AARD) for the empirical equations are 12.6-24.8%. The prediction capability of the modified empirical relationship was studied with six experimental data points as a training set. Then, solubility at other temperatures and pressures were predicted. The AARD between predicted solubilities and observed values is 17%.

Synthesis and in vitro degradation of testosterone-lipid conjugates

Testosterone-lipid conjugates were obtained by covalent binding of the drug to 1,3-dipalmitoylglycerol via succinic acid to 4-(1,3-dipalmitoyl-2-glyceryl)butyric acid and to 3-palmitoyloxy-2-palmitoyloxmethylpropionic acid. In contrast to the corresponding bis-deacyl derivatives, the lipids were not significantly hydrolyzed in aqueous buffers and in plasma. Incubation with pancreatic lipase yielded primarily the bis-deacyl compounds, which are comparable to monoglycerides, and subsequently slowly liberated testosterone. It is concluded that the lipid conjugates are substrates for pancreatic lipase. However, the drug was released very slowly due to steric hindrance.

Phenytoin-lipid conjugates: chemical, plasma esterase-mediated, and pancreatic lipase-mediated hydrolysis in vitro

Phenytoin-lipid conjugates obtained by covalent binding of hydroxymethylphenytoin to diacylglycerides and to 3-acyloxy-2-acyl-oxymethylpropionic acids formed dispersions with a particle size of 10-200 microns when briefly sonicated in a sodium taurodeoxycholate-containing ethanol-water mixture. In contrast to the corresponding bis-deacyl derivatives, the lipids were not significantly hydrolyzed in aqueous buffers and in plasma. Incubation with pancreatic lipase yielded primarily the bis-deacyl compounds, which are comparable to monoglycerides, and subsequently liberated phenytoin. The glyceride-derived prodrugs were better substrates for the enzyme than the 3-acyloxy-2-acyloxymethyl-propionic acid derivatives. It is concluded that the phenytoin lipid conjugates are hydrolyzed by pancreatic lipase in a similar manner as natural triglycerides.

Pancreatic lipase-catalyzed hydrolysis of esters of hydroxymethyl phenytoin dissolved in various metabolizable vehicles, dispersed in micellar systems, and in aqueous suspensions

Lipase-catalyzed hydrolysis of fatty acid esters of 3-hydroxymethyl phenytoin was studied in various triglyceride and ethyl oleate emulsions, dispersed in micellar solutions, and suspended in an aqueous buffered solution. Phenytoin release from ethyl oleate emulsions of the prodrugs show apparent first-order kinetics with the pentanoate to nonanoate derivatives and sigmoidal kinetics with the long-chain fatty acid derivatives (stearate and oleate). A transition in the kinetic behavior, between the short- and the long-chain acyl prodrugs, was observed with the decanoate derivative. These observations are accounted for by a proposed kinetic model. Phenytoin release from the solid prodrugs follows zero-order kinetics and is independent of the total amounts of suspended material but directly proportional to the lipase concentration. Lipolysis of the solid suspended prodrugs was dependent on the length of the acyl side chain of the prodrug, with maxima for the pentanoate and the octanoate derivatives. The short-chain derivatives, acetate and propionate, as well as the long-chain prodrug, stearate, showed the slowest lipolysis rate when present as solid dispersions. The zero-order rate is qualitatively correlated with the melting point of the prodrugs. This result might be expected if the melting point is taken as a measure of the cohesivity or packing of the molecules at the surface of a crystal.

Synthesis and bioevaluation of a series of fatty acid esters of p-[N,N-bis(2-chloroethyl)amino]phenol

A series of even numbered fatty acid esters (C2-C18) of p-[N,N-bis(2-chloroethyl)amino]phenol were synthesized and evaluated as to acute toxicity as well as effectiveness against L-1210 mouse leukemia. The acetate through the decanoate derivatives demonstrated toxicity between 2 and 3 times that of phenol mustard in HA/ICR mice. The less soluble laurate, myristate, palmitate, and stearate derivatives were less toxic. Significant survival times in the leukemia studies (T/C% greater than or equal to 125) were observed for all compounds except the acetate and hexanoate derivatives. The myristate derivative produced the greatest significant increase in survival time, 162%. The palmitate and stearate derivatives produced significant survival at five and four dosage levels, respectively. The butyrate and laurate derivatives produced significant survival at three dosage levels and the octanoate, decanoate, and myristate at two dosage levels.

Blood concentration profiles of acetaminophen following oral administration of fatty acid esters of acetaminophen with pancreatic lipase to dogs

Fatty acid esters of acetaminophen were administered orally to dogs, and blood concentrations of acetaminophen were determined at various time intervals. Blood concentrations of acetaminophen following oral administration of a short chain ester, p-acetamidophenyl acetate, were not significantly different from those found using acetaminophen. Blood concentrations of acetaminophen following oral administration of intermediate hydrocarbon chain-length compounds were less than those of the control at 1 and 3 hr postdosing. There appears to be a direct relationship between the in vitro hydrolysis rates and the blood concentration in vivo. Concomitant oral administration of acetaminophen derivatives, pancreatic lipase, and calcium salts resulted in an increase in the blood levels of acetaminophen as compared to administration of the esters alone. Calcium carbonate was included as a source of calcium ion to activate the lipase involved in the hydrolysis of the fatty acid esters. A combination of p-acetamidophenyl acetate, p-acetamidophenyl dodecanoate, pancreatic lipase, and calcium carbonate was shown to achieve a prolonged release of acetaminophen. p-Acetamidopheny acetate was thought to provide the initial release of acetaminophen; p-acetamidophenyl dodecanoate, being hydrolyzed more slowly, provided the prolonged release, which maintained therapeutic blood concentrations for 13 hr following a single dose of the combination in dogs.