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.
[Show abstract][Hide abstract] 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
[Show abstract][Hide abstract] 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
[Show abstract][Hide abstract] ABSTRACT: The effect of ionizing radiation on the physicochemical properties of chloramphenicol in solid state has been studied. The compound was e-beam irradiated with doses from the range 25-400 kGy and the possible changes were detected in the organoleptic methods (colour form odour solubility and clarity) by SEM observations X-ray chromatography (TLC) spectrophotometry (UV IR EPR) and thermal (DSC) methods. No significant changes relative to the unirradiated sample were observed as a result of irradiation with the dose of 25 kGy - a standard dose for radiation sterilization besides free radicals generation. Higher doses were found to produce a change in colour increase in absorbance (UV) changes in the XRD spectra and appearance of products of radiolysis. The presence of the radiolysis products was confirmed by the TLC method indirectly by DSC showing a decrease in the melting point from 0.2 to 4.5°C and enthalpy from 3.8 to 23.3 J g-1 respectively. A linear relationship was obtained between the irradiation dose (25-400 kGy) and the melting point of chloramphenicol characterised by the correlation coefficient r=0.9968. The EPR signal intensity increased with increasing dose of irradiation and the lifetime of the free radicals was longer than 6 months. No changes were detected in SEM and IR spectra. As follows from our results the DSC method is most suitable for a fast monitoring of the drugs subjected to sterilization by irradiation as it permits detection of changes occurring even on irradiation with low doses and their quantitative description.
Journal of Thermal Analysis and Calorimetry 05/2006; 84(3):741-746. DOI:10.1007/s10973-005-7545-3 · 2.04 Impact Factor
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