Mária Hajdú

In vitro efficiency of vancomycin containing experimental drug delivery systems.

Biofilm-forming Staphylococcus epidermidis strains are common cause of the periprosthetic infection. The treatment of the periprosthetic infection is very problematic, so the prevention of these infections by an antibiotic containing prothesis could be an option for prevention.The purpose of the present study was to examine the in vitro effects of drug delivery systems (DDSs), namely Wax 1 and Wax 2 with different vancomycin content: 0.5, 1, 2 and 4 mg. In order to control the antibacterial activity of DDSs killing curve study was performed and in order to determine the antibiotic release and the antibiotic peak concentration from the DDSs biological assay was carried out.The time kill curve studies showed, that both DDSs with all vancomycin concentration decreased significantly the bacterial counts, however, Wax 2 with 4 mg vancomycin significantly decreased the bacterial count than all the other groups.The vancomycin release was the best with the highest peak concentration from DDSs with 4 mg vancomycin contain; it was significantly better than in the other groups, however, no significant difference was observed between Wax 1 and Wax 2 in this respect.These findings suggest that Wax 2 with 4 mg vancomycin content could be a potential agent for clinical use.

Use of antibiotic-impregnated bone grafts in a rabbit osteomyelitis model

BACKGROUND Both osteomyelitis and prosthetic joint infection can be treated surgically with the use of antibiotic loaded bone grafts, as part of local antimicrobial therapy. OBJECTIVE The purpose of the study was to evaluate and to report on a novel, biodegradable, long-acting (4-6 weeks) antibiotic-impregnated bone graft (AIBG). A novel drug delivery system, containing vancomycin, was utilized in a rabbit osteomyelitis model in order to evaluate the antimicrobial efficacy of the antibiotic bone graft. METHODS Forty adult New Zealand rabbits were used. The animals were randomized into three Groups: healthy animals without osteomyelitis, where AIBG was used to fill a defect (Group I); osteomyelitis caused with a methicillin-resistant S.aureus strain (MRSA) treated with AIBG (Group II); osteomyelitis caused with MRSA and treated with bone grafts without local antibiotics (Group III). At six weeks post-operation, the animals were sacrificed and histological, laboratory and radiologic evaluations were performed. RESULTS Of the 24 operated rabbits, osteomyelitis was confirmed in 18 animals. In groups with osteomyelitis, only minor radiological changes were observed on day 21 post-op. Radiographs taken on day 42 post-op showed radiological signs of chronic osteomyelitis in Group III, whereas in Group II, bone healing was observed. Bacterial cultures taken on day 42 post-op revealed the original MRSA strain in Group III, whereas no bacteria were detected in Group II. Histological examinations showed the presence of macrophage cells which slowly break down the DDS matrix. The presence of DDS did not inhibit re-ossification. CONCLUSIONS The drug delivery system was effective against MRSA-induced osteomyelitis without negative effect on osteointegration. This biodegradable technology has the potential to be a powerful tool in fighting bone infections.

The influence of selected excipients on the rheological behaviour of chitosan based ocular pharmaceutical systems

Aims: Chitosan, a modified natural carbohydrate polymer, has received great attention in diverse scientific fields including pharmaceutical and biomedical research areas. Besides its low toxicity, mucoadhesiveness and biodegradability its special favourable rheological feature makes it a unique gelling agent for the design of ocular systems. Chitosan based (2.0 w/v %) ocular systems containing selected excipients were formulated in order to investigate the rheological influence of applied auxiliary materials. Rotational and oscillatory rheological properties of propylene glycol (1.0-20.0 w/v %), glycerin (1.0-5.0 w/v %) and castor oil (1.0-5.0 w/v %) containing chitosan gels were evaluated. The rheological behaviour of formulated ocular gels were compared before and after steam sterilization.Methods: Rotational and oscillatory rheological measurements were carried out with Kinexus Pro Rheometer. Comparison of flow curves and oscillatory frequency sweep measurements in the linear viscoelastic region made possible the evaluation of rheological effect of selected excipients.Results: In the applied concentration range the effect of propylene glycol among the selected excipients presents the most significant impact on rheology of chitosan formulations. Steam sterilization results in reduced viscosity in most of chitosan gels. However, the presence of polyols appears to prevent the degradation of chitosan after steam sterilization.