EPR studies of free radicals decay and survival in gamma irradiated aminoglycoside antibiotics: sisomicin, tobramycin and paromomycin.

Science.gov (United States)

Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

2012-02-14

Radiation sterilization technology is more actively used now that any time because of its many advantages. Gamma radiation has high penetrating power, relatively low chemical reactivity and causes small temperature rise. But on the other hand radiosterilization can lead to radiolytic products appearing, in example free radicals. Free radicals in radiative sterilized sisomicin, tobramycin and paromomycin were studied by electron paramagnetic resonance (EPR) spectroscopy. Dose of gamma irradiation of 25kGy was used. Concentrations and properties of free radicals in irradiated antibiotics were studied. EPR spectra were recorded for samples stored in air and argon. For gamma irradiated antibiotics strong EPR lines were recorded. One- and two-exponential functions were fitted to experimental points during testing and researching of time influence of the antibiotics storage to studied parameters of EPR lines. Our study of free radicals in radiosterilized antibiotics indicates the need for characterization of medicinal substances prior to sterilization process using EPR values. We propose the concentration of free radicals and other spectroscopic parameters as useful factors to select the optimal type of sterilization for the individual drug. The important parameters are i.a. the τ time constants and K constants of exponential functions. Time constants τ give us information about the speed of free radicals concentration decrease in radiated medicinal substances. The constant K(0) shows the free radicals concentration in irradiated medicament after long time of storage. Copyright © 2011 Elsevier B.V. All rights reserved.

125I-radioimmunoassay of amikacin and comparison with a microbioassay

International Nuclear Information System (INIS)

Stevens, P.; Young, L.S.; Hewitt, W.L.

1976-01-01

A radioimmunoassay (RIA) has been developed using 125 I-amikacin. Amikacin was iodinated by a modified Bolton and Hunter method. Dextran-charcoal was used to separate bound from free drug. The standard curve was linear on a logit-log plot in the range of 0.5 ng to 4 ng amikacin per tube. There was no cross-reactivity of amikacin antisera to the aminoglycosides gentamicin, tobramycin, netilmicin, and sisomicin but a 70% cross-reaction was observed with kanamycin, the compound from which amikacin is synthetically derived. Correlation of the RIA with a microbioassay for the determination of serum amikacin levels in 18 patient samples was excellent (r=0.94). This new RIA technique is more sensitive, rapid, versatile, and less costly than the RIA using 3 H-amikacin, and is far more sensitive and faster than microbioassay. (auth.)