Aleš Obreza

Aleš Obreza


Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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11 January 2008 in Molecules
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Journal Article
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Rok FrlanRok Frlan
Rok Frlan
AKAndreja Kovač
Andreja Kovač
DBDidier Blanot
Didier Blanot
SGStanislav Gobec
Stanislav Gobec
SPSlavko Pečar
Slavko Pečar
Aleš ObrezaAleš Obreza
Aleš Obreza
A series of novel N-benzylidenesulfonohydrazide compounds were designedand synthesized as inhibitors of UDP-N-acetylmuramic acid:L-alanine ligase (MurC) andUDP-N-acetylmuramoyl-L-alanine:D-glutamate ligase (MurD) from E. coli, involved inthe biosynthesis of bacterial cell-walls. Some compounds possessed inhibitory activityagainst both enzymes with IC50 values as low as 30 μM. In addition, a new, one-potsynthesis of amidobenzaldehydes is reported.

13 February 2020 in Molecules
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Journal Article
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TTTim Tome
Tim Tome
ZCZdenko Casar
Zdenko Casar
Aleš ObrezaAleš Obreza
Aleš Obreza
This article presents the development of a reversed-phase (RP) high-performance liquid chromatographic (HPLC) method for determination of process-related impurities in a celecoxib drug substance following Analytical Quality by Design (AQbD) principles. The method from European Pharmacopeia (EP) for celecoxib drug substance does not sufficiently separate celecoxib from its EP impurity B because the system suitability criterion is not achieved (resolution NLT 1.8). The same issue was observed with the proposed method from United States Pharmacopeia (USP) for celecoxib capsules, where EP impurity A elutes under the main peak. A new HPLC method was developed that eliminates the disadvantages of the two pharmacopeial methods and is capable of efficiently separating and determining all seven impurities listed in EP and the proposed USP monographs. The development of a new HPLC method started with method scouting, in which various C18 and phenyl stationary phases were tested. Improved selectivity was obtained only with a chiral stationary phase. An immobilized Chiralpak IA-3 column used in RP mode turned out to be the most appropriate for method optimization. The ratio of acetonitrile in the mobile phase, flow rate, and column temperature were recognized as critical method parameters (CMPs) and were further investigated using a central composite face response-surface design. A multiple linear regression (MLR) method was applied to fit the mathematical models on the experimental data to determine factor–response relationships. The models created show adequate fit and good prediction abilities. The Monte Carlo simulation method was used to establish the design space. The method developed was verified in terms of precision, sensitivity, accuracy, and linearity, and the results showed that the new method is suitable for determination of seven process-related impurities of celecoxib.

1 December 2012 in Acta Pharmaceutica
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TVTanja Vehovec
Tanja Vehovec
AGAndrej Gartner
Andrej Gartner
OPOdon Planinšek
Odon Planinšek
Aleš ObrezaAleš Obreza
Aleš Obreza
Influence of some commercially available types of microcrystalline cellulose (MCC) on the stability of certain active pharmaceutical ingredients (APIs), when in contact, has been investigated. Two structurally similar APIs, perindopril erbumine (PER) and enalapril maleate (EM), both well-known angiotensin-converting enzyme inhibitors were used. The main properties of an MCC that could determine the stability for each API were measured and correlated to the stability of these two APIs in binary mixtures. The stability of these APIs differed when in contact with different types of MCC. The dominant properties of MCC from one manufacturer were surface features that influenced the stability of PER and acidity that influenced the stability of EM. In the case of MCC from other manufacturers, unbound water was stability determining for both substances.

10 June 2020 in Molecules
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TTTim Tome
Tim Tome
Aleš ObrezaAleš Obreza
Aleš Obreza
ZCZdenko Casar
Zdenko Casar
This article presents the development of a reversed-phase ultra-high-performance liquid chromatographic method for determining process-related impurities in ropinirole hydrochloride drug substance applying the analytical quality by design approach. The current pharmacopeial method suffers from selectivity issues due to two coelutions of two pairs of impurities. The development of a new method began with preliminary experiments, based on which the Acquity UPLC BEH C8 was selected as the most appropriate column. The effects of six different critical method parameters (CMPs) were then investigated using a fractional factorial screening design. Column temperature, the ratio of methanol in mobile phase B, and gradient slope turned out to be highly significant CMPs in achieving critical resolutions, and they were further evaluated using a central composite face-centered response-surface design. Mathematical models were created by applying a multiple linear regression method. Based on the elution order of an unknown degradation impurity and impurity C, two design spaces were established, and for each design space an optimal combination of CMPs was determined. The method developed was validated for precision, accuracy, linearity, and sensitivity, and it was proven suitable for determining nine process-related impurities of ropinirole.

2 May 2017 in Pharmacy
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TGTanja Gmeiner
Tanja Gmeiner
NHNejc Horvat
Nejc Horvat
MKMitja Kos
Mitja Kos
Aleš ObrezaAleš Obreza
Aleš Obreza
TVTomaž Vovk
Tomaž Vovk
Borut BožičBorut Božič
Borut Božič
This article presents the results of mapping the Slovenian pharmacy curriculum to evaluate the adequacy of the recently developed and validated European Pharmacy Competences Framework (EPCF). The mapping was carried out and evaluated progressively by seven members of the teaching staff at the University of Ljubljana’s Faculty of Pharmacy. Consensus was achieved by using a two-round modified Delphi technique to evaluate the coverage of competences in the current curriculum. The preliminary results of the curriculum mapping showed that all of the competences as defined by the EPCF are covered in Ljubljana’s academic program. However, because most EPCF competences cover healthcare-oriented pharmacy practice, a lack of competences was observed for the drug development and production perspectives. Both of these perspectives are important because a pharmacist is (or should be) responsible for the entire process, from the development and production of medicines to pharmaceutical care in contact with patients. Nevertheless, Ljubljana’s graduates are employed in both of these pharmaceutical professions in comparable proportions. The Delphi study revealed that the majority of differences in scoring arise from different perspectives on the pharmacy profession (e.g., community, hospital, industrial, etc.). Nevertheless, it can be concluded that curriculum mapping using the EPCF is very useful for evaluating and recognizing weak and strong points of the curriculum. However, the competences of the framework should address various fields of the pharmacist’s profession in a more balanced way.

15 December 2017 in Acta Chimica Slovenica
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MJMarko Jukič
Marko Jukič
KGKatarina Grabrijan
Katarina Grabrijan
SKSelmir Kadić
Selmir Kadić
FGFernando Juan de Lera Garrido
Fernando Juan de Lera Garrido
ISIzidor Sosic
Izidor Sosic
Aleš ObrezaAleš Obreza
Aleš Obreza
Chlorocarbonylsulfenyl chloride cyclizations towards piperidin-3-yl-oxathiazol-2-ones as potential covalent inhibitors of threonine proteases