DSC study of radiostability of 1,4-dihydropyridine derivatives
Faculty of Physics, Adam Mickiewicz University, Posen, Greater Poland Voivodeship, Poland Journal of Thermal Analysis and Calorimetry
(Impact Factor: 2.04).
01/2004; 77(2):581-596. DOI: 10.1023/B:JTAN.0000038996.14324.34
The effect of sterilisation by irradiation has been studied for the seven most often used in medicine derivatives of 1,4-dihydropyridine
(nifedipine, nisoldipine, nicardipine, nitrendipine, nimodipine, felodipine and amlodipine). The sterilisation was performed
for the compounds in the solid phase with an electron beam of the energy 10 MeV, at room temperature, using the irradiation
doses from 20 to 400 kGy. The effects of the irradiation were studied by the methods SEM, DSC, XRD and TLC. The sterilisation
with doses 20-100 kGy was found to cause no changes in the physico-chemical properties of the compounds, while the irradiation
with higher doses (200-400 kGy) was found to induce changes in the colour, DSC spectrum and TLC picture. As follows from the
TLC results, the main product of radiolysis of the compounds studied was a pyridine nitrozoderivative, which indicates the
same mechanism of decomposition as in the process of photodegradation. The results prove that the 1,4-dihydropyridine derivatives
being highly sensitive to visible and UV radiation are generally resistant to ionising radiation and thus can be subjected
to sterilisation by irradiation.
Available from: Ştefan Perişanu
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ABSTRACT: Non-irradiated and gamma irradiated monohydrated (l Asn·H2O) and anhydrous (l Asn) asparagines, in solid state, were studied by means of DSC. The samples were irradiated at room temperature with gamma radiations using a 137Cs source. The exposure doses ranged between 1 and 10 kGy. All samples were scanned in sealed pans, from room temperature to a temperature beyond the melting point. The DSC scans of l Asn·H2O samples in sealed crucibles revealed the presence of two dehydration processes and one of decomposition and only decomposition in the case of l Asn. The influence of gamma irradiation consisted in decreasing the enthalpy of dehydration and of decomposition. A decomposition mechanism is proposed.
Journal of Radioanalytical and Nuclear Chemistry 01/2012; 295(1). DOI:10.1007/s10967-012-2157-4 · 1.03 Impact Factor
Available from: Maciej Stawny
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ABSTRACT: The study has been undertaken to check the effect of ionising radiation on the physical and chemical properties of florfenicol, an antibiotic of a wide range of antibacterial activity. The solid-state samples were subjected to an electron beam generated by accelerator corresponding to the doses of 25, 100 and 400 kGy, and the effect of the exposure was analysed by the methods not requiring changes in the state (with no preliminary treatment), such as SEM, DSC, FTIR, XRD, EPR and HPLC.
Florfenicol irradiated with a dose of 25 kGy has not changed the form or colour, however, a small increase in intensity of some absorption bands in the FTIR spectrum and of some peaks in the XRD pattern, a decrease in the melting point by 0.6°C, the appearance of free radicals and a loss in the FF content within the error of the method (0.91%) have been observed. After irradiation with greater doses (100 and 400 kGy) the changes have intensified, yellow discolouration appeared and the loss of FF content has increased to 6.39%. As follows from the results, the compound studied in solid-state undergoes radiolysis after e-beam irradiation in the doses ≥25 kGy, but lower doses (15–20 kGy) can be applied for its decontamination or sterilization with no adverse effect on its physico-chemical properties.
Journal of Thermal Analysis and Calorimetry 09/2008; 93(3). DOI:10.1007/s10973-008-9137-5 · 2.04 Impact Factor
Analytical Chemistry 06/2005; 77(12):3755-3769. DOI:10.1021/ac050580o · 5.64 Impact Factor
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