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  1. Article ; Online: Accelerated reactive dissolution model of drug release from long-acting injectable formulations.

    Sonntag, Erik / Kolář, Jiří / Djukaj, Suada / Lehocký, Róbert / Štěpánek, František

    European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V

    2023  Volume 189, Page(s) 122–132

    Abstract: Long-acting injectable formulations represent a rapidly emerging category of drug delivery systems that offer several advantages compared to orally administered medicines. Rather than having to frequently swallow tablets, the medication is administered ... ...

    Abstract Long-acting injectable formulations represent a rapidly emerging category of drug delivery systems that offer several advantages compared to orally administered medicines. Rather than having to frequently swallow tablets, the medication is administered to the patient by intramuscular or subcutaneous injection of a nanoparticle suspension that forms a local depot from which the drug is steadily released over a period of several weeks or months. The benefits of this approach include improved medication compliance, reduced fluctuations of drug plasma level, or the suppression of gastrointestinal tract irritation. The mechanism of drug release from injectable depot systems is complex, and there is a lack of models that would enable quantitative parametrisation of the process. In this work, an experimental and computational study of drug release from a long-acting injectable depot system is reported. A population balance model of prodrug dissolution from asuspension with specific particle size distribution has been coupled with the kinetics of prodrug hydrolysis to its parent drug and validated using in vitro experimental data obtained from an accelerated reactive dissolution test. Using the developed model, it is possible to predict the sensitivity of drug release profiles to the initial concentration and particle size distribution of the prodrug suspension, and subsequently simulate various drug dosing scenarios. Parametric analysis of the system has identified the boundaries of reaction- and dissolution-limited drug release regimes, and the conditions for the existence of a quasi-steady state. This knowledge is crucial for the rational design of drug formulations in terms of particle size distribution, concentration and intended duration of drug release.
    MeSH term(s) Humans ; Antipsychotic Agents ; Prodrugs ; Drug Liberation ; Solubility ; Injections, Intramuscular ; Suspensions ; Delayed-Action Preparations
    Chemical Substances Antipsychotic Agents ; Prodrugs ; Suspensions ; Delayed-Action Preparations
    Language English
    Publishing date 2023-06-14
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1065368-5
    ISSN 1873-3441 ; 0939-6411
    ISSN (online) 1873-3441
    ISSN 0939-6411
    DOI 10.1016/j.ejpb.2023.06.003
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Design of particle size distribution for custom dissolution profiles by solving the inverse problem

    Djukaj, Suada / Kolář, Jiří / Lehocký, Róbert / Zadražil, Aleš / Štěpánek, František

    Powder technology. 2022 Jan., v. 395

    2022  

    Abstract: Dissolution testing is widely used to measure the rate of drug release and predict its in-vivo behavior. The release rate can be controlled by adjusting the particle size distribution (PSD). However, experimental investigation of various particle sizes ... ...

    Abstract Dissolution testing is widely used to measure the rate of drug release and predict its in-vivo behavior. The release rate can be controlled by adjusting the particle size distribution (PSD). However, experimental investigation of various particle sizes requires many time-consuming experiments. To reduce the need for them, we propose an optimization framework to solve the inverse problem, i.e., design a PSD that results in a prescribed dissolution profile. The framework's computational core predicts a dissolution profile using a population balance model coupled with a mass balance equation, while the optimization algorithm obtains the inverse solution. The model was validated using mono- and multimodal particle populations of a reference compound (KCl). The validation resulted in a good agreement between the simulated and experimental data. This suggests that the usage of the framework can provide a fast determination of the required PSD, reducing the number of experiments needed.
    Keywords algorithms ; drugs ; equations ; models ; particle size distribution ; technology
    Language English
    Dates of publication 2022-01
    Size p. 743-757.
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 0032-5910
    DOI 10.1016/j.powtec.2021.10.023
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Occurrence and prevention of Pickering foams in pharmaceutical nano-milling.

    Lehocký, Róbert / Pěček, Daniel / Saloň, Ivan / Štěpánek, František

    European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V

    2019  Volume 143, Page(s) 91–97

    Abstract: Particle size reduction to sub-micrometer dimensions in stirred media mills is an increasingly common formulation strategy used for improving the bioavailability of poorly aqueous soluble active pharmaceutical ingredients (APIs). Due to their hydrophobic ...

    Abstract Particle size reduction to sub-micrometer dimensions in stirred media mills is an increasingly common formulation strategy used for improving the bioavailability of poorly aqueous soluble active pharmaceutical ingredients (APIs). Due to their hydrophobic character, the API particles need to be stabilised by a surfactant in order to form a stable nano-suspension. This work is concerned with the understanding of an undesired phenomenon often encountered during the development and scale-up of wet nano-milling processes for hydrophobic APIs - the formation of foams. We investigate the microstructure, rheology and stability of these foams, and find them to be Pickering foams stabilised by solid particles at the gas-liquid interface rather than by a surfactant. By exploring the effect of surfactant concentration on the on-set of foaming in conjunction with the milling kinetics, we find a relationship between the specific surface area of the nano-suspension, the quantity of surfactant present in the formulation and the occurrence of foaming. We propose a mechanistic explanation of foam formation, and find that in order to prevent foaming, a large surfactant excess of approx. 100x above the critical micelle concentration has to be present in the solution in order to ensure a sufficiently rapid coverage of freshly exposed hydrophobic surfaces formed during the wet nano-milling process.
    MeSH term(s) Biological Availability ; Hydrophobic and Hydrophilic Interactions ; Nanoparticles/chemistry ; Particle Size ; Solutions/chemistry ; Surface-Active Agents/chemistry ; Suspensions/chemistry ; Technology, Pharmaceutical/methods
    Chemical Substances Solutions ; Surface-Active Agents ; Suspensions
    Language English
    Publishing date 2019-08-22
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1065368-5
    ISSN 1873-3441 ; 0939-6411
    ISSN (online) 1873-3441
    ISSN 0939-6411
    DOI 10.1016/j.ejpb.2019.08.016
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Scale-up from batch to flow-through wet milling process for injectable depot formulation.

    Lehocký, Róbert / Pěček, Daniel / Štěpánek, František

    European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences

    2016  Volume 95, Page(s) 122–129

    Abstract: Injectable depot formulations are aimed at providing long-term sustained release of a drug into systemic circulation, thus reducing plasma level fluctuations and improving patient compliance. The particle size distribution of the formulation in the form ... ...

    Abstract Injectable depot formulations are aimed at providing long-term sustained release of a drug into systemic circulation, thus reducing plasma level fluctuations and improving patient compliance. The particle size distribution of the formulation in the form of suspension is a key parameter that controls the release rate. In this work, the process of wet stirred media milling (ball milling) of a poorly water-soluble substance has been investigated with two main aims: (i) to determine the parametric sensitivity of milling kinetics; and (ii) to develop scale-up methodology for process transfer from batch to flow-through arrangement. Ball milling experiments were performed in two types of ball mills, a batch mill with a 30ml maximum working volume, and a flow-through mill with a 250ml maximum working volume. Milling parameters were investigated in detail by methodologies of QbD to map the parametric space. Specifically, the effects of ball size, ball fill level, and rpm on the particle breakage kinetics were systematically investigated at both mills, with an additional parameter (flow-rate) in the case of the flow-through mill. The breakage rate was found to follow power-law kinetics with respect to dimensionless time, with an asymptotic d
    MeSH term(s) Chemistry, Pharmaceutical/methods ; Delayed-Action Preparations/administration & dosage ; Delayed-Action Preparations/chemical synthesis ; Injections ; Nanoparticles/chemistry ; Particle Size ; Solubility ; Suspensions
    Chemical Substances Delayed-Action Preparations ; Suspensions
    Language English
    Publishing date 2016-12-01
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1154366-8
    ISSN 1879-0720 ; 0928-0987
    ISSN (online) 1879-0720
    ISSN 0928-0987
    DOI 10.1016/j.ejps.2016.08.043
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Preparation of feed premix for veterinary purposes.

    Franc, Aleš / Lehocký, Róbert / Muselík, Jan / Vetchý, David / Dobšíková, Radka / Modrá, Helena

    Ceska a Slovenska farmacie : casopis Ceske farmaceuticke spolecnosti a Slovenske farmaceuticke spolecnosti

    2014  Volume 63, Issue 5, Page(s) 213–216

    Abstract: This experimental study describes the preparation of a veterinary medicated premix containing tetracycline hydrochloride for oral administration to aquatic animals. For the manufacture of the premix, commercially produced animal feed is used, which is ... ...

    Abstract This experimental study describes the preparation of a veterinary medicated premix containing tetracycline hydrochloride for oral administration to aquatic animals. For the manufacture of the premix, commercially produced animal feed is used, which is intended for consumption in the form of pellets that were coated with a mixture of chlortetracycline hydrochloride and other excipients. Feed pellets were combined with a mixture of an active substance and excipients with a large specific surface (colloidal silica - Aerosil® 200) allowing an easy adhesion to the surface of the pellets, and a solid polymer with a low glass transition point (Eudragit® E) which ensures the formation of a hard coat. A mixture of these substances has been applied to the surface of the pellets either A) in the solid state simply by dry adhesion; B) by coating the pellets with the mixture and additional impregnation with ethanol; or C) the polymer was subsequently applied in solution. In the final stage, the pellets were heated in order to achieve the glass transition point of the polymer to create a solid and mechanically resistant coating. Coated pellets prepared by three methods described above are almost identical in their physical properties. With this technology it is possible to produce a feed mixture with a very low content of the active substance in situ without the need for a complex technological equipment.
    MeSH term(s) Administration, Oral ; Animals ; Chlortetracycline/administration & dosage ; Excipients/chemistry ; Polymers/chemistry ; Polymethacrylic Acids/chemistry
    Chemical Substances Excipients ; Polymers ; Polymethacrylic Acids ; methylmethacrylate-methacrylic acid copolymer (25086-15-1) ; Chlortetracycline (WCK1KIQ23Q)
    Language English
    Publishing date 2014-10
    Publishing country Czech Republic
    Document type Journal Article
    ZDB-ID 1187133-7
    ISSN 1210-7816 ; 0009-0530
    ISSN 1210-7816 ; 0009-0530
    Database MEDical Literature Analysis and Retrieval System OnLINE

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