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

Pectin, beta-cyclodextrin, chitosan and albumin based gastroprotective systems for piroxicam maleate: Synthesis, characterization and biological evaluation

In order to optimize drug action, new drug formulations have been developed based upon the prodrug approach. This study was inspired by the increasing interest in the field of macromolecular prodrugs and Piroxicam maleate was used as a model drug. A total of five prodrugs were synthesized using beta cyclodextrin, chitosan, pectin, egg albumin, bovine serum albumin. The synthesized conjugates were characterized on the basis of UV, IR and NMR techniques. In-vitro hydrolysis studies were carried out at pH 1.2, pH 7.4, pH 9.0 and in 80% human plasma followed by in-vivo evaluation of analgesic, anti-inflammatory and anti-ulcerogenic potential. The extent of hydrolysis was found to be proportional to increase in pH. Beta cyclodextrin conjugate was found to possess significant analgesic activity whereas chitosan conjugate was found to be the best anti-inflammatory. Pectin conjugate provided maximum protection against ulcers.

Synthesis, characterization, and in vitro evaluation of new Ibuprofen polymeric prodrugs based on 2-hydroxypropyl methacrylate

The present research work describes the synthesis and evaluation of new acrylic-type polymeric systems having degradable ester bonds linked to ibuprofen as materials for drug delivery. Ibuprofen was linked to 2-hydroxy-propyl methacrylate by an activated ester methodology in a one-pot procedure with a high yield. The resulting material was copolymerized with either 2-hydroxyethyl methacrylate or methyl methacrylate (in 1:3 mole ratios) by the free radical polymerization method, utilizing azoisobutyronitrile at 65-70 °C. The characterization of the resulting products by FTIR, (1)H NMR, (13)C NMR, DSC, and elemental analysis confirmed their synthesis successfully. Ibuprofen release from the obtained polymers was preliminarily evaluated at different buffered solutions (pH 1, 7.4, and 10) into dialysis bags to show the capacity of prodrugs to release the drug under hydrolytic conditions. Detection of hydrolysis by UV spectroscopy at selected intervals showed that the drug can be released by selective hydrolysis of the ester bond at the side of the drug moiety. The release profiles indicated that the hydrolytic behavior of polymers is strongly based on the polymer hydrophilicity and the pH value of the hydrolysis solution. The results suggest that these polymers could be useful in controlled release systems.

Controllable synthesis of polymerizable ester and amide prodrugs of acyclovir by enzyme in organic solvent

A facile control of the acylation position at the primary hydroxyl and amino of acyclovir, respectively, was achieved and five polymerizable acyclovir prodrugs were synthesized. Various reaction conditions were studied in detail. Thus, lipase acrylic resin from Candida antarctica (CAL-B) in pyridine or acetone showed high chemo-selectivity toward the primary hydroxyl of acyclovir. However, lipase PS 'Amano' (PS) in DMSO selectively acylated the amino group. The selectivity of PS could be adjusted by changing reaction solvents. The acyclovir vinyl derivatives obtained would be important monomers used for the preparation of macromolecular nucleoside drugs.

Macromolecular prodrugs XI. Synthesis and characterization of polymer-estradiol conjugate

Estradiol-3-benzoate (EB), an ester derivative of the main oestrogen hormone estradiol, was chemically modified and bound to poly(alpha,beta-(N-2-hydroxyethyl-DL-aspartamide))-poly(alpha,beta-(N-2-aminoethyl-DL-aspartamide)) copolymer (PAHA). EB was first converted to estradiol-3-benzoate-17-(benzotriazole-1-carboxylate), which readily reacted with amino groups in PAHA affording the polymer-drug conjugate PAHA-EB. In PAHA-EB estradiol moiety was covalently bound to the polymeric carrier by carbamate linkage, through non-toxic ethylenediamine spacer. The synthesized compound is a potential hydrosoluble estradiol prodrug.

Synthesis and characterization of thiomers of polyaspartamide type

Synthesis of poly[alpha,beta-(N-2-hydroxyethyl-DL-aspartamide)]-thioglycolic acid (PHEA-TGA) conjugate as a new polyaspartamide thiomer is described. The parent polymer PHEA is chemically modified by introducing sulphydryl-bearing compound thioglycolic acid. By varying the reaction conditions several batches of PHEA-TGA conjugates were prepared and analyzed. Tensile studies revealed that total work of adhesion of PHEA-TGA increased more than twice compared to the unmodified polymer. Microparticles prepared from the thiolated polymer preserved its bioadhesive properties.