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PubMed1975

[Characterization and determination of residual monomer content of implantation materials from polymethacrylic acid methylester].

Cold polymerizates "Kallocryl K" and "Palacos" were characterized by means of physico-chemical methods of examination. The residual monomer content of the polymerizates, which is of major toxicological interest, was also determined quantitatively. It was possible to show that the residual monomer content decreases exponentially as a function of the duration of polymerization. "Palacos" polymerizates had much higher residual monomer contents than "Kallocryl K" polymerizates when the same time of polymerization was used. Also discussed in this paper are possible methods of reducing the residual monomer content prior to implantation of the plastic materials.

Dental Implantation↗
PubMed2001

Direct compressible polymethacrylic acid-starch compositions for site-specific drug delivery.

The purpose of this study was to generate and characterize a direct compressible pH-sensitive excipient composition for controlled drug delivery. In acidic aqueous solutions, polymethacrylic acid (PMAA) forms complexes and precipitates with starch. As the extent of the interaction between PMAA and starch reaches a maximum at a weight ratio of 1:1.38 (PMAA/starch), this composition was used for the direct compression of tablets. These tablets (30 mg) showed no disintegration even after 2 days in a disintegration test apparatus according to the USP XXIII, in simulated gastric fluid at pH 1.2. In contrast, in 100 mM phosphate buffer pH 7.0 they disintegrated within 40.25+/-8.42 min (mean+/-S.D., n=3). Control tablets of starch disintegrated within the first minute at both pH values. Dissolution studies with the model peptide peroxidase demonstrated no release within 120 min at pH 1.2, whereas at pH 7.0, 100% of the peptide was released within 330 min. Similar release profiles were obtained with the model drugs amoxicillin and rifampicin. In addition, the use of a PMAA-starch composition as a carrier matrix for peroxidase and amoxicillin provided a protective effect towards pepsin and hydrolytic degradation at pH 1.2, respectively. According to these results, the PMAA-starch composition may be a useful tool to overcome the very harsh environment of the stomach for future delivery systems.

Amoxicillin↗
PubMed2006

Novel pH responsive polymethacrylic acid-chitosan-polyethylene glycol nanoparticles for oral peptide delivery.

In present study, novel pH sensitive polymethacrylic acid-chitosan-polyethylene glycol (PCP) nanoparticles were prepared under mild aqueous conditions via polyelectrolyte complexation. Free radical polymerization of methacrylic acid (MAA) was carried out in presence of chitosan (CS) and polyethylene glycol (PEG) using a water-soluble initiator and particles were obtained spontaneously during polymerization without using organic solvents or surfactants/steric stabilizers. Dried particles were analyzed by scanning electron microscopy (SEM) and particles dispersed in phosphate buffer (pH 7.0) were visualized under transmission electron microscope (TEM). SEM studies indicated that PCP particles have an aggregated and irregular morphology, however, TEM revealed that these aggregated particles were composed of smaller fragments with size less than 1 micron. Insulin and bovine serum albumin (BSA) as model proteins were incorporated into the nanoparticles by diffusion filling method and their in vitro release characteristics were evaluated at pH 1.2 and 7.4. PCP nanoparticles exhibited good protein encapsulation efficiency and pH responsive release profile was observed under in vitro conditions. Trypsin inhibitory effect of these PCP nanoparticles was studied using casein substrate and these particles displayed lesser inhibitory effect than reference polymer carbopol. Preliminary investigation suggests that these particles can serve as good candidate for oral peptide delivery.

Administration, Oral↗
PubMed2000

Electrosteric Stabilization of Al(2)O(3), ZrO(2), and 3Y-ZrO(2) Suspensions: Effect of Dissociation and Type of Polyelectrolyte.

The mechanisms of eight anionic polyelectrolytes stabilizing colloidal sized alpha-Al(2)O(3), pure ZrO(2), and Y(2)O(3)-doped ZrO(2) particles in aqueous solution are discussed. The polyelectrolytes studied were the Na(+) and NH(4)(+) salts of polyacrylic acid and polymethacrylic acid having different molecular weights. The particle-dispersant interactions were studied by measuring adsorption isotherms, particle size, thickness of adsorbed layer, and zeta potentials by elektrokinetic sonic analysis at different powder volume fractions (straight phi=0.01-0.3), pH, and electrolyte (KCl) content. The dissociation of the polyelectrolytes was studied by potentiometric titrations. The dissociation constant of the polymethacrylates was found to be 0.6 pH unit higher than that for the polyacrylates. High-affinity adsorption isotherms were observed over the pH range when the polyelectrolytes were fully ionized. The results show good correlation between adsorption isotherms and zeta potential data in systems of dispersed, dilute alumina particles. When particles and polymers were of equal charge (the same sign of charge) the polymer shell was thicker. At higher volume fractions (straight phi=0.3), and when alumina particles/added ammonium polyelectrolyte were of equal charge, a maximum in the absolute value of zeta potential resulted. Due to adsorption all the anionic polyelectrolytes studied provided electrosteric stabilization of the alpha-Al(2)O(3), and Y(2)O(3)-doped ZrO(2) suspensions by enhancing the zeta potential to 40 mV or over and by shifting the isoelectric point to lower pH, the low-molecular-weight polyelectrolytes decreasing the isoelectric point more than the polyelectrolytes having higher molecular weight. The polyelectrolytes studied failed to stabilize pure monoclinic ZrO(2) particles. Due to the shortness of the chain of polyelectrolytes studied, no bridging was observed between oppositely charged polyelectrolyte/alumina particles. Copyright 2000 Academic Press.

Journal Article↗
PubMed1972

Effect of antiviral agents in equine abortion virus-infected hamsters.

Equine abortion virus, a member of the herpesvirus group, produces a lethal infection in hamsters. With this system, the protective effect of certain inhibitors of deoxyribonucleic acid viruses, inducers of interferon and exogenous interferon, was evaluated. Of the various agents studied, 9-beta-d-arabinofuranosyladenine markedly suppressed mortality, and 5-iodo-2'-deoxyuridine, distamycin A, and N-ethylisatin beta-thiosemicarbazone were inactive. Of the inducers tested, statolon, ultraviolet-irradiated Newcastle disease virus, and polyriboinosinic:polyribocytidylic acid (poly I:C) were protective, and endotoxin, polyacrylic acid, and polymethacrylic acid did not protect. Administration of exogenous interferon did not afford protection. Statolon and ultraviolet-irradiated Newcastle disease virus induced circulating interferon in hamsters, whereas poly I:C, endotoxin, and polyacrylic acid did not produce interferon. Because of the severity of the disease produced in hamsters by equine abortion virus, lack of protective activity by an agent in this system should not preclude possible efficacy against other members of the herpesvirus group.

Animals↗
PubMed2005

Interferon: ten stories in one. A short review of some of the highlights in the history of an almost quinquagenarian.

This short review article on some pertinent observations in the unfolding story of interferon is dedicated to Professor Ilona Béládi on the occasion of her 80th birthday. This by no means covers the whole story on interferon. It just highlights some of the more striking findings made with interferon (or its inducers) over a time span of almost 50 years since its original discovery (in 1957) by Isaacs and Lindenmann. These observations concern (i) the induction of interferon by synthetic polyanions such as polyacrylic acid and polymethacrylic acid; (ii) the prolonged antiviral activity shown by polyacrylic acid in vivo; (iii) the interferon-inducing ability of double-stranded RNAs such as poly(I) x poly(C) and (iv) mismatched derivatives thereof (i.e. ampligen); (v) the cloning and expression of interferon-beta, and (vi) its usefulness in the treatment of multiple sclerosis; (vii) the potential of (pegylated) interferon-alpha in the treatment of hepatitis C and (viii) the therapy/prophylaxis of SARS; (ix) the efficacy of interferon (inducers) in the experimental treatment of flavivirus encephalitis and enterovirus myocarditis; and, finally, (x) the role of interferon in the activity shown by S-adenosylhomocysteine inhibitors such as 3-deazaneplanocin A against experimental Ebola virus infections in mice.

Animals↗