Identification of Radiodegradation Products of Acebutolol and Alprenolol by HPLC/MS/MS.

Two therapeutically active compounds from the group of ß-blockers, acebutolol (AC) and alprenolol (AL), in solid form were subjected to ionizing radiation emitted by a beam of high energy electrons from an accelerator with a standard sterilization dose of 25 kGy and in higher doses of 50-400 kGy. The effects of irradiation were detected by chromatographic methods (TLC, HPLC) and a hyphenated method (HPLC/MS/MS). No significant changes in the physicochemical properties of both compounds studied irradiated with 25 kGy were noted, but upon irradiation with the highest dose (400 kGy) the loss of AC and AL content determined by HPLC was 2.79 and 9.12%, respectively. The product of AC decomposition and the two products of AL decomposition were separated and identified by HPLC/MS/MS. It has been established that radiodegradation of AC and AL takes place by oxidation, leading to formation of the products of radiolysis, most probably alcohol derivatives of the ß-blockers studied. The additional product that appears on radiodegradation of AL is probably formed as a result of two simultaneous reactions: oxidation and CH2 group elimination.

Comparative analysis of selected beta-blockers.

The suitability and effectiveness of a few spectrophotometric and chromatographic methods (UV, FT-IR, MS, TLC) for differentiating analysis of 6 beta-blockers: acebutolol, alprenolol, atenolol, metoprolol, pindolol and propranolol have been tested.

The effect of ionizing radiation on metoprolol.

The influence of ionising radiation on physico-chemical properties of metoprolol tartrate (MT) in solid phase was studied. The compound was irradiated by radiation produced by a beam of high-energy electrons in an accelerator, in doses from 25 to 400 kGy, and the possible changes in the samples were detected by organoleptic analysis (colour, forms, clarity), chromatographic and spectrometric methods. Already at the standard sterilisation dose of 25 kGy, the presence of free radicals (0.3764 × 10(16) spin/g) and a decrease in the melting point by 1°C were noted. At higher doses of irradiation products of radiolysis appeared (100 kGy) and the colour was changed from white to pale cream (200 kGy). Our observation was that with increasing mass loss of MT after irradiation with 100, 200 and 400 kGy, the concentration of free radicals increased from 1.0330 to 1.6869 × 10(16) spin/g. The radiolytic yield of total radiolysis was 4.54 × 10(7) mol/J for 100 kGy, 7.42 × 10(7) mol/J for 200 kGy and 4.74 × 10(7) mol/J for 400 kGy. No significant changes were observed in the character of FT-IR spectra, but in UV an increase in intensity of the band at the analytical wavelength was noted. As follows from the results MT shows high radiochemical stability for the typical sterilisation doses 25-50 kGy, and will probably be able to be sterilised by radiation in the dose of 25 kGy.

Influence of e-beam irradiation on sulfamethoxazole in solid state.

The effects of ionizing radiation generated by a beam of electrons, in that doses varied from 25-800 kGy, on the physico-chemical properties of sulfamethoxazole (SMX) in solid state have been studied at room temperature and in the air atmosphere. The changes appearing after the irradiation were detected and evaluated by the spectroscopic methods (UV, IR, MS, EPR), chromatography (TLC and HPLC) and SEM, XRD and DSC. Already the lowest dose of 25 kGy was found to change the color of SMX from white to pale cream; such change became more intense with our increasing the irradiation dose. Products of radiodegradation and decreases in the drug content were detected by TLC and HPLC only after irradiation with 400 kGy. Since the SMX radiolysis products (sulfanilamide and sulfanilic acid) are colorless compounds, it is supposed that the color results from trapping of free radicals in the crystal lattice; the concentration of free radicals was 1.04 × 10(15) spin/g. Our results indicate that the radiolysis of SMX in the solid state caused by e-beams involves breaking of the S-N and N-C bonds. The mean radiolytic yield of this process is G((-SMX)) = 1.89 × 10(-7) mol/J, whereas the yield of formation of the two products of radiolysis is close and equal to 2.18 × 10(-8) mol/J (sulfanilamide) and 2.13 × 10(-8) mol/J (sulfanilic acid).

Has differentiated thyroid cancer (DTC) staging changed with in the last ten years in the Silesia region of Poland?

INTRODUCTION: The aim of the study was to compare the advancement of thyroid cancer at diagnosis in Polish patients from the Silesian district in the years 1999 and 2008. MATERIAL AND METHODS: The analyzed group consisted of Silesian district patients with thyroid cancer, who were registered by the Department of Tumour Epidemiology of the Institute of Oncology in Gliwice in the years 1999 and 2008. From a group of 186 patients who entered on record in 1999, 167 were qualified for this analysis. Similarly, from 238 patients registered in 2008, finally 226 were added. We analyzed: sex, age at diagnosis, histotype of thyroid cancer, and DTC staging according to TNM (UICC 2002). In 1999 there were 137 females (82.04 %) and 30 males (17.93%) with thyroid cancer diagnosed at ages 5-81 years. In 2008 there were 183 females (80.97%) and 43 males (19.03%) diagnosed at ages 14-80 years. In both groups, in 1999 and 2008, the median age was the same (51 years). RESULTS: In the year 1999, 119 (71%) and in 2008, 197 (87%) patients were diagnosed with papillary thyroid cancer (p = 0.0003). Relations between age and sex were similar in these years. There was some increase in frequency of patients diagnosed with papillary microcancer (pT1a), which was on the border of statistical significance (p = 0.05). A statistically significant increase of pT1 (p = 0.02) and decrease of pT4 (p = 0.001) and of pTx (p = 0.002) was observed in the year 2008 in the whole cohort of DTC patients. CONCLUSIONS: 1. In 2008 the contribution of papillary histotype to all thyroid cancer patients (87%) was significantly higher than in 1999. 2. The percentage of DTC patients diagnosed with pT1 disease was significantly higher in 2008.

Effect of radiation sterilization on alprenolol in the solid state studied by high-performance thin-layer chromatography.

The possibility of radiation sterilization of alprenolol (AL) has been studied. Irradiation of AL in solid form with a 25 kGy beam of electrons caused only an insignificant change in color that became more intense with increasing irradiation dose. Moreover, with increasing dose a decrease in pH, the content of water, and the degree of crystallinity were observed. AL in solid form was radiated with a high-energy electron beam (9.96 MeV) at doses from 25-400 kGy and analyzed by HPTLC using the mobile phase methanol-ammonia 25% (99 + 1, v/v). Densitometric analysis was carried out directly from chromatograms at 270 nm. The applied method was validated and characterized by good precision (RSD = 3.95%); good accuracy (80% level 100.15%, 100% level 99.99%, and 120% level 104.44%); and low LOD (LOD = 0.52 microg/zone and LOQ = 1.55 microg/zone). Chromatograms recorded for samples irradiated at the doses of 25 kGy were unchanged, but at higher doses (100-400 kGy) additional peaks corresponding to the radiodegradation products appeared (Rf = 0.24 and Rf = 0.40). The decrease in the concentration of AL was proportional to the applied radiation dose, and for 400 kGy the concentration of AL was 90.23%. The calculated radiolytic yield of the radiodegradation process was G(-AL) = 7.12 x 10(-7) mol/J.

Radiostability of florfenicol in the solid state.

The effect of ionizing radiation on florfenicol (FF), an antibiotic with wide antibacterial properties was investigated to determine whether it can be sterilized using high-energy radiation. FF was irradiated by E-beam radiation to doses of 25-800 kGy, and then changes in the physico-chemical properties were examined using chromatographic methods (TLC and HPLC), spectroscopic methods (NMR and MS) and hyphenated methods (HPLC-MS). It was found that a standard sterilizing dose of 25 kGy led to the formation of two new products of radiolysis as well as lowering the content of FF by 0.95%. With higher doses of radiation, the content of FF further decreased (by 12.27% with a dose of 800 kGy), and new products of radiolysis appeared (up to five with a dose of 800 kGy). However, there were no differences between the NMR and MS spectra of irradiated and non-irradiated samples of FF. A linear dependence was found between the dose of radiation and the FF content (correlation coefficient of 0.9951) as well as between the melting point and the sum of products of radiolysis (correlation coefficient of 0.9975). It was found that a radiodegradation of FF took place by the breaking of an amide bond, leading to the formation of an aliphatic amine, which was subsequently oxidized to 4-methylsulfonylbenzoic acid. The radiolytic yield for the radiodegradation of FF was calculated to be 10.24 molecules/100 eV for a dose of 25 kGy. As a result of our investigation, we can conclude that FF shows a reasonably good radiostability in the range of doses used for sterilization, i.e. 25 kGy and below, and therefore it can be sterilized using high-energy radiation without changing its physicochemical, properties and hence its therapeutic efficacy.

Thermal stability of 1,4-dihydropyridine derivatives in solid state.

The effect of temperature and air humidity on the stability of 7 derivatives of 1,4-dihydropyridine (nifedipine, nisoldipine, nitrendipine, nimodipine, nicardipine, felodipine and amlodipine) in solid state has been studied by accelerated testing. Quantitative analysis of the compounds studied was made by UV spectrophotometry, identification of the thermodegradation products and reference to the standard were made by thin layer chromatography (TLC), UV spectra and the reaction with KMnO4. Thermodegradation of the derivatives studied was found not to occur in dry air, whereas at air humidity it occurred according to the first order reaction at a similar rate for all derivatives. The main product of thermodegradation of the derivatives with the nitro substituent was a nitrozoderivative formed as a result of dihydropyridine ring aromatisation accompanied by water molecule elimination.

[The effect of fluorine substituent on radiochemical stability of some steroid and azole derivatives]. / Wplyw podstawnika fluorowego na trwalosc radiochemiczna niektórych leków pochodnych steroidów i azoli.

Radiochemical stability of three fluorine containing therapeutic substances: dexamethasone, fludrocortisone acetate (steroid derivatives) and fluconazole (azole derivative) has been studied. The compounds in the solid phase were exposed to ionising radiation in the form of electron beam using doses of 20-400 kGy. The inital and irradiated compounds were subjected to comparative analyses by organoleptic, spectrophotometric (UV and IR) and chromatographic (TLC and HPLC) methods. For all compounds studied the irradiation was found to lead to a decrease in the active substance content (HPLC), appearance of radiolysis products (TLC), changes in the physical and chemical properties such as colour (fluconazole), formation of agglomerates (dexamethasone), decrease (dexamethasone, fludrocortisone acetate) or increase in UV absorption (fluconazole). The two steroid derivatives were found resistant to ionising radiation at doses of 25-50 kGy and can be sterilised by radiation, whereas fluconazole was too sensitive to electron beam irradiation and should be sterilised by other methods. The results were compared with those of earlier studies on radiation sterilisation of other steroid derivatives. An interesting conclusion is that the presence of the fluorine atom in the molecule of fludrocortisone acetate has no significant effect on its radiochemical stability when compared with that of hydrocortisone acetate--the analogue without fluorine.

Photo- and radiostability of some 1,4-dihydropyridine derivatives in the solid state.

The effect of UV (254 nm) and beta-irradiation at doses 10-100 kGy on physical and chemical properties of four 1,4-dihydropyridyne derivatives in the solid state (nifedipine, nitrendipine, felodipine and nimodipine) has been studied. It has been established that the irradiation causes the appearance of free radicals (EPR) and decomposition products (TLC, GC), a decrease in the melting point (DSC) and the content (GLC, IR) and an increase in microbiological purity. The changes appear faster under the effect of UV than by beta-irradiation and their intensity and character depend on the derivative and dose. The most sensitive to UV irradiation is nifedipine (about 300 times more sensitive than the most resistant nimodipine), while the most sensitive to beta-irradiation is felodipine (about twice as sensitive as the most resistant nitrendipine). The results of our study indicate that 1,4-dihydropyridyne derivatives in solid state can be safely subjected to sterilization by beta-irradiation at doses < 20 kGy.

Effect of gamma-irradiation on cladribine and cladribine-containing biodegradable copolymers.

The aims of this study were to assess the effects of sterilization with gamma-irradiation on (i). bulk cladribine and (ii). cladribine-containing biodegradable copolymers. The stability of cladribine upon irradiation was confirmed by TLC, HPLC, UV, IR, DSC, rentgenography and electron microscopy. The stability of copolymers containing cladribine upon irradiation was assessed by IR, DSC and EPR. In vitro kinetics of nucleoside release from the copolymers before and after irradiation were compared, and only slight changes were found. Results of our study indicate that gamma-irradiation can be safely applied for the sterilization of cladribine or cladribine-containing copolymers for medical purposes.

In vitro release of cytotoxic nucleoside analogs from lactide-caprolactone and lactide-glycolide copolymers.

The aims of our study were to assess the release of cytotoxic nucleoside analogs 5-fluorouracil and 2-chloro-2'-deoxyadenosine from different lactide-glycolide or lactide-caprolactone biodegradable copolymers and the effects of sterilization on this release. The polymers were sterilized either with ethylene oxide at 37 degrees C, or with gamma radiation (15 kGy, 20 kGy, or 25 kGy). The kinetics of nucleoside release from the copolymers were measured over 50 days. Four copolymers exhibited relatively constant release of nucleosides in micromolar concentrations during the entire observation period. Sterilization with either ethylene oxide or gamma radiation only slightly influenced nucleoside release. Further development of these copolymers as an intracerebral nucleoside delivery system for local treatment of brain tumors is indicated.

Sterility and antibacterial activity of some antibiotics sterilized by irradiation.

Sterility and antibacterial activity of several antibiotics (including some penicillins and their salts, gramicidin and neomycin) subjected to sterilization by irradiation has been studied. The compounds in solid phase have been exposed to gamma irradiation in air atmosphere at room temperature, with a dose of 25 kGy, and afterwards they have been subjected to tests recommended by FP V (volume I, 1990) checking their sterility and activity. The results have shown that the majority of initial compounds have been to a slight degree contaminated by bacteria from the genera Bacillus and Micrococcus, the number of bacteria did not exceed 10(2) CFU, and fungi up to 10 CFU in 1 g of the compound. All compounds subjected to sterilization with a dose of 25 kGy were sterile and preserved the activity required by FP V. The decrease in activity observed for some compounds was always within the limits of FP specification. The results have proved that the penicillins analysed, gramicidin and neomycin can be sterilized by irradiation with a dose of 25 kGy, without any detrimental effect on their properties and antibacterial activity.