Macromolecular prodrugs: X. Kinetics of fenoprofen release from PHEA-fenoprofen conjugate.

The kinetics of fenoprofen release from poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)]-fenoprofen conjugate (PHEA-Fen) in aqueous buffer solutions (pH 10 and 1.1), simulated gastric (SGF) and intestinal fluids (SIF) was studied. In borate buffer pH 10, the following rate constants were obtained: k=0.2659 (t=60 degrees C) and k=0.0177 h(-1) (t=37 degrees C) and in glycine buffer solution pH 1.1 k=0.0036 h(-1). In SGF and SIF fenoprofen release did not occur in significant extend within 12 h. The hydrolysis of the ester bond between the polymeric carrier and fenoprofen followed the pseudo first-order kinetics, with activation energy indicative for the breakage of a sigma bond (E(a)=100.6 kJ mol(-1)). The concentration of the released fenoprofen was determined by high performance liquid chromatography (HPLC).

Macromolecular prodrugs. IX. Synthesis of polymer-fenoprofen conjugates.

Synthesis of several polymer-fenoprofen conjugates is described. Fenoprofen was first chemically modified into benzotriazolide 2 and amino acid amide derivatives: glycine fenoprofenamide (3a) and beta-alanine fenoprofenamide (3b) and their benzotriazolides 6a and 6b. Compounds 2 and 6 readily reacted with polyhydroxy aspartamide-type polymers, i.e. poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)] (PHEA) and poly[alpha,beta-(N-3-hydroxypropyl-DL-aspartamide)] (PHPA) forming conjugates 5, 8a,b and 9a,b, respectively. Conjugate 11 was obtained by partial aminolysis of poly-DL-(2,5-dioxo-1,3-pyrrolidinediyl) (PSI) with 2-aminoethyl fenoprofenamide (3c), followed by total aminolysis with 2-hydroxyethylamine. The synthesised polymer-drug conjugates differed in type of covalent bounding, type and/or length of spacer and drug-loading.

Gemfibrozil ester and amide derivatives--synthesis, spectroscopic characterisation and QSPR.

The synthesis and spectroscopic characterisation of various gemfibrozil esters 3 and amides 4 are described. In the first step gemfibrozil was reacted with N-1-benzotriazolecarboxylic acid chloride (1) yielding gemfibrozil benzotriazolide (2). Compound 2 readily reacted with alcohols and amines to form the corresponding esters 3 and amides 4, potential prodrugs of the well known hypolipaemic drug gemfibrozil. The quantitative structure property relationship (QSPR) was studied in the series of gemfibrozil esters and amides. The following topological descriptors and physicochemical parameters were used: Wiener number (W), connectivity index (l chi v), relative molecular mass (M(r)), van der Waals volume (Vw) and parameters of lipophilicity (log P and RM).

Macromolecular prodrugs. VIII. Synthesis of polymer-gemfibrozil conjugates.

Gemfibrozil is covalently linked to two similar polymers: poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)] and poly[alpha,beta-(N-3-hydroxypropyl-DL-aspartamide)]. The synthesised polymer drug conjugates differ in average molecular mass, type of covalent bonding, length of spacer, drug-loading and solubility.

The influence of different types of breakfast on the absorption of paracetamol among members of an ethnic group.

It is well known that food influences the absorption and therapeutic efficacy of many drugs. In this study, the influence of three different types of breakfast, on the absorption of paracetamol was studied in a South African ethnic population group (Tswanas). The results indicated that breakfasts with a high fat content delayed the absorption of paracetamol to the largest extent while breakfasts with a high carbohydrate content delayed the absorption of paracetamol to a lesser extent.