J Mielcarek

Publications (16)22.33 Total impact

• Article: Ordered mesoporous silica material SBA-15: loading of new calcium channel blocker - lacidipine.

  A Kiwilsza, J Mielcarek, A Pajzderska, J Wąsicki
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  ABSTRACT: Mesoporous material SBA-15 of hexagonal structure was synthesised and its usefulness as a carrier for a poorly soluble drug - lacidipine (LA) - was tested. The source of silica was tetraethyl orthosilicate (TEOS) and the structure ordering agent was non-ionic surfactant Pluronic P123. SBA-15 with encapsulated LA was characterised by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetry (TG), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Adsorption of the therapeutically active substance was performed in anhydrous environment (chloroform). The content of the therapeutic substance in SBA-15 estimated from TG measurements reached 9%. The properties of the compound obtained were compared with those of a physical mixture of the components.
  Journal of Microencapsulation 06/2012; · 1.55 Impact Factor
• Article: Carbon nanotubes linked with pitavastatin: synthesis and characterisation.

  E Borowiak-Palen, P Skupin, M Kruszynska, L Sobotta, J Mielcarek
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  ABSTRACT: The paper presents a study on functionalisation of multi-walled carbon nanotubes in the area of lattice defects and an attempt to bind the nanotubes with pitavastatin. Carbon nanotubes were synthesised by alcohol-chemical vapour deposition in the presence of the catalyst Fe-Co/MgO. The nanotubes were purified and the product was subjected to chemical functionalisation. Functional groups were introduced in the reaction of the purified nanotubes with thionyl chloride to obtain acidic chlorides linked to pitavastatin. The properties and structure of the nanotubes were analysed by FT-IR and Raman spectroscopies, transmission electron microscopy and liquid chromatography coupled with mass spectrometry. Photochemical stability of pitavastatin linked with carbon nanotubes has been found to be increased.
  Journal of Materials Science Materials in Medicine 03/2011; 22(4):845-51. · 2.32 Impact Factor
• Article: 1H NMR study of rehydration/dehydration and water mobility in β-cyclodextrin.

  A Pajzderska, P Czarnecki, J Mielcarek, J Wąsicki
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  ABSTRACT: The processes of dehydration and rehydration of β-cyclodextrin were studied by analysis of the (1)H NMR (nuclear magnetic resonance) line shape. Dehydration was carried in an open ampoule as a function of temperature and above 400 K total dehydration of β-cyclodextrin was observed. This result was confirmed by the thermogravimetry (TG) measurements. Rehydration was studied as a function of time at room temperature. After 40 days, β-cyclodextrin was found to absorb eight water molecules. The analysis of temperature changes in the shape of the (1)H NMR line of β-cyclodextrin kept in a closed ampoule and its dielectric measurements provided information on the mobility of water molecules. The water molecules were found to perform complex molecular motions, that is, reorientational jumps below 200K and additionally, translational motion (diffusion) above 200K.
  Carbohydrate research 01/2011; 346(5):659-63. · 2.03 Impact Factor
• Article: Photochemical activity of glenvastatin, a HMG-CoA reductase inhibitor

  L Sobotta, P Kachlicki, L Marczak, M Kryjewski, J Mielcarek
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  ABSTRACT: Photochemical properties of glenvastatin (HR 780), a HMG-CoA reductase inhibitor, were studied. The drug was exposed to light in liquid state under aerobic conditions. The source of irradiation was an HBO-50 lamp. The lamp was equipped with a mercury burner and an appropriate set of glass filters. The conditions during photodegradation were the same as specified in the first version of the ICH Document. Photoproducts formed after illumination of a methanol solution of glenvastatin were identified by several analytical techniques, including: spectrophotometry, HPLC and HPLC–MS. Quantitative evaluation of photochemical degradation of glenvastatin was made on the basis of UV–Vis spectrophotometric and HPLC. The irradiation photodecomposition of glenvastatin led preferentially to two main photoproducts being stereoisomers. The photoproducts were isolated with the help of a semipreparative HPLC method and identified by mass spectrometry. As a result of glenvastatin exposure to irradiation, the heptene chain is oxidised and its cyclisation takes place with formation of two diastereoisomers containing three condensed rings.
  Journal of Photochemistry and Photobiology a-Chemistry. 01/2011; 224:1-7.
• Article: A hybrid method for estimation of molecular dynamics of diazepam-density functional theory combined with NMR and FT-IR spectroscopy.

  J Mielcarek, D M Nowak, A Pajzderska, B Peplińska, J Wąsicki
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  ABSTRACT: Reorientation of the molecule of diazepam was investigated by calorimetric methods, IR absorption and NMR. The investigation of dynamics was complemented by density functional study (DFT) of vibrational frequencies and infrared intensities, calculations of steric hindrances and Monte Carlo simulations. The results indicated the occurrence of reorientation jumps of the CH(3) group and conformational motion of the benzodiazepine ring. The activation parameters of the methyl group reorientation were determined and the activation barrier obtained was in good agreement with the theoretically estimated value. The FT-IR spectra were assigned using results of DFT calculations.
  International journal of pharmaceutics 11/2010; 404(1-2):19-26. · 2.96 Impact Factor
• Article: Photochemical properties of simvastatin and lovastatin induced by radiation

  J. Mielcarek, M. Naskrent, P. Grobelny
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  ABSTRACT: Cited By (since 1996): 1, Export Date: 19 July 2011, Source: Scopus
  Journal of Thermal Analysis and Calorimetry. 01/2009; 96:301-305.
• Article: The effect of ionizing radiation of 1,4-dihydropyridine derivatives in the solid state

  M. Naskrent, J. Mielcarek
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  ABSTRACT: Cited By (since 1996): 1, Export Date: 10 January 2012, Source: Scopus
  Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. 01/2007; 67:251-255.
• Article: The effect of beta-carotene on the photostability of nisoldipine.

  J Mielcarek, P Grobelny, O Szamburska
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  ABSTRACT: The effect of beta-carotene on the photostability of nisoldipine (NS) has been investigated. Light stability studies were carried out following the recommendations of the International Conference on Harmonization (ICH), version I, using a high-pressure mercury lamp, type HBO-50, equipped with the interference filter and Wood's filter to isolate 365 nm wavelength. The photodegradation process was assayed by means of UV spectrophotometry and the reversed phase High-Performance Liquid Chromatography (HPLC). The quantum yields of photodegradation of NS and NS in the presence of beta-carotene were determined using the Reinecke salt as a chemical actinometer. The methanol solutions of NS degraded following apparent first-order kinetics. The degradation rate constant decreased as beta-carotene concentration increased. To verify the photostabilising role of the dye, a Stern-Volmer plot was constructed. The results have proved that beta-carotene does not act as a photosensitiser.
  Methods and Findings in Experimental and Clinical Pharmacology 05/2005; 27(3):167-71. · 0.93 Impact Factor
• Article: Normal-phase TLC separation of enantiomers of 1.4-dihydropyridine derivatives.

  J Mielcarek
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  ABSTRACT: A new TLC-based method was proposed for the separation of enantiomers and mixtures of racemic DHP derivatives differing in the kind of substituent in the phenyl ring. The conditions for the effective determination of the substances involved and the mechanism of their sorption were also studied. For the separation of felodipine, nilvadipine, and isradipine enantiomers, thin-layer chromatography was used, with a chiral stationary phase of the ligand exchange type, and developing phases of a different concentration of methanol (phi) as an organic modifier. The retention coefficient values k' were used to make the plots log k' = f(log phi) and log k' = f(phi). The processes taking place in the chromatographic systems were shown to be described by the Snyder-Soczewiński equation.
  Drug Development and Industrial Pharmacy 03/2001; 27(2):175-9. · 1.49 Impact Factor
• Article: Identification of photodegradation products of nilvadipine using GC-MS.

  J Mielcarek, M Stobiecki, R Frański
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  ABSTRACT: Nilvadipine (NV) photodegradation products have been analysed with gas chromatography-mass spectrometry (GC-MS). The photodegradation was carried out in the conditions recommended in the first version of the document issued by the International Conference on Harmonization (ICH), currently in force in the studies of photochemical stability of drugs and therapeutic substances. Methanol solutions of NV were irradiated with a high-pressure UV lamp - type HBO 200. The maximum intensity at the wavelength lambda = 365 nm was achieved by applying the interference filter and Wood's filter. Using the Reinecke salt as a chemical actinometer, apparent quantum yields of photodegradation were obtained, which after extrapolation to the zero time of irradiation gave the actual quantum yield ((phi = 7.58 x 10(-5). The structure of three nilvadipine photodegradation products was established, after mass spectra analysis of compounds registered during GC-MS carried out of irradiated nilvadipine solutions. The quantitative results of GC-MS analyses enabled to determination of the kinetic parameters of NV photodegradation, calculated from the dependence In c =f(t). Quantitatively the process was described with the calculated rate constant of decomposition (k), decomposition time of 50% of the compound (t0.5) and decomposition time of 10% of the compound (t0.1). The exposure of nilvadipine to UV light was found to lead to aromatization of the DHP ring and elimination of the HCN molecule.
  Journal of Pharmaceutical and Biomedical Analysis 01/2001; 24(1):71-9. · 2.97 Impact Factor
• Article: Photodegradation of inclusion complexes of isradipine with methyl-beta-cyclodextrin.

  J Mielcarek, E Daczkowska
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  ABSTRACT: The paper presents results of the studies on photochemical decomposition of isradipine (IS) and its liquid inclusion complexes with methyl-beta-cyclodextrin (M-betaCD). The process of photodegradation was assessed by the methods of UV spectrophotometry, HPLC (reverse-phase) and HPTLC (normal phase) chromatographic methods. The process of photodegradation of IS was analysed in the conditions of version I of the document of International Chemical Harmonization (ICH)-HBO-200 lamp. Quantitative evaluation of the photochemical decomposition was performed on the basis of the calculated photodegradation rate constant (k), half-life period (t0.5) and time of degradation of 10% of the compound (t0.1). Formation of inclusion complexes of IS with M-betaCD was proved to increase twice the photostability of the drug. The analytical methods used were subjected to a validation procedure in which the limits of detectability and determinability as well as specificity, precision and sensitivity of the method were determined.
  Journal of Pharmaceutical and Biomedical Analysis 12/1999; 21(2):393-8. · 2.97 Impact Factor
• Article: Analytical study of photodegradation of inclusion complexes of nimodipine with alpha-, gamma-cyclodextrin, methyl-beta-cyclodextrin, and hydroxypropyl-beta-Cyclodextrin.

  J Mielcarek
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  ABSTRACT: The inclusion behavior of alpha-cyclodextrin (alpha-CD), gamma-cyclodextrin (gamma-CD), hydroxypropyl-beta-cyclodextrin (HP-betaCD), and methyl-beta-cyclodextrin (M-betaCD) with nimodipine (NM) in solution and in the solid state was investigated. Inclusion complexes of nimodipine with cyclodextrins (at a molar ratio of 1:1) in the solid state were obtained by the kneading method. Photochemical stability of NM in the solid inclusion complexes was assessed by IR spectrometry. The modified derivatives of beta-CD and alpha-CD were found to slow the photodegradation rate, whereas in the presence of gamma-CD the photodegradation of NM was a bit faster than in the corresponding physical mixture. Photochemical degradation of NM in liquid inclusion complexes was monitored by UV spectroscopy. According to the slowing effect on photodegradation of NM in the inclusion complexes, the studied cyclodextrins can be ordered as gamma-CD < alpha-CD < HP-betaCD < M-betaCD.
  Drug Development and Industrial Pharmacy 03/1998; 24(2):197-200. · 1.49 Impact Factor
• Article: Photochemical stability of the inclusion complexes formed by modified 1,4-dihydropyridine derivatives with beta-cyclodextrin.

  J Mielcarek
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  ABSTRACT: The results of studies of photochemical stability of the derivatives of 1,4-dihydropyridine (NR) are reported. The NR with various substituents (-NO2, -Cl, -F, CF3) at different positions in the phenyl ring were identified by UV spectrophotometry. Photodegradation of NR in the inclusion complexes with beta-cyclodextrin (beta-CD) was studied in the liquid phase. The rate of photodegradation of NR derivatives was dependent on the position of -NO2 group in the phenyl ring; for the ortho isomer it is ten times higher than for the meta one. The rate of photodegradation of 2-NO2-NR (ortho isomer) in inclusion complex with beta-CD was 200 times slower than that for this compound in the crystal phase. In the case of halogeno- and cyanoderivatives, the presence of beta-CD caused a 4-fold increase in the photodegradation rate.
  Journal of Pharmaceutical and Biomedical Analysis 04/1997; 15(6):681-6. · 2.97 Impact Factor
• Article: Inclusion complexes of nifedipine and other 1.4-dihydropyridine derivatives with cyclodextrins. IV. The UV study on photochemical stability of the inclusion complexes of nisoldipine, nimodipine, nitrendipine and nicardipine with beta-cyclodextrin in the solution.

  J Mielcarek
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  ABSTRACT: The results of measurements of photochemical stability of the inclusion complexes formed by nimodipine (NM), nisoldipine (NS), nitrendipine (NR) and nicardipine (NC) with beta-cyclodextrin (beta-CD) are reported. The inclusion complexes were obtained in solution. The formation of inclusion complexes in the liquid phase was estimated from a phase solubility diagram. The analysis of solubility curves in the phase diagram permitted calculation of stability constants of the inclusion complexes formed. Photochemical stability of 1.4-dihydropyridine derivatives obeyed the 1 order kinetic equation. The photodegradation of NM, NR and NC was found to be a single stage reaction. The photodegradation of NS occurred in two stages. In the inclusion complexes the photosensitivity of all studied DHP derivatives decreases. The complexation with beta-CD improved their photostability by 5-10 times. The greatest decrease in the photodegradation rate was observed for the most photosensitive compound NS whose photostability increased 100 times when in inclusion complex with beta-CD.
  Acta poloniae pharmaceutica 52(6):459-63. · 0.66 Impact Factor
• Article: The effect of ionizing radiation of 1,4-dihydropyridine derivatives in the solid state

  M. Naskrent, J. Mielcarek
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  ABSTRACT: Cited By (since 1996): 1, Export Date: 24 March 2012, Source: Scopus, References: Gopal, N.G.S., Patel, K.M., Sharma, G., Bhalla, H.L., Wills, P.A., Hilmy, N., (1988) Radiat. Phys. Chem., 32, p. 619;
  Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. 67(1):251-255.
• Article: The effect of ionizing radiation of 1,4-dihydropyridine derivatives in the solid state

  M. Naskrent, J. Mielcarek
  [show abstract] [hide abstract]
  ABSTRACT: Cited By (since 1996): 1, Export Date: 24 March 2012, Source: Scopus, CODEN: SAMCA, doi: 10.1016/j.saa.2006.07.009, PubMed ID: 16987696, Language of Original Document: English, Correspondence Address: Naskrent, M.; Department of Medical Physics, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland; email: marekn@amu.edu.pl, Chemicals/CAS: 1,4 dihydropyridine, 3337-17-5; felodipine, 72509-76-3; nifedipine, 21829-25-4; nimodipine, 66085-59-4; 1,4-dihydropyridine, 3337-17-5; Calcium Channel Blockers; Dihydropyridines; Felodipine, 72509-76-3; Nifedipine, 21829-25-4; Nimodipine, 66085-59-4, References: Gopal, N.G.S., Patel, K.M., Sharma, G., Bhalla, H.L., Wills, P.A., Hilmy, N., (1988) Radiat. Phys. Chem., 32, p. 619;
  Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. 67(1):251-255.