Abstract:Schistosomiasis is one of the major public health problems worldwide. Even though this is a common illness among preschool children in poor countries, treatment is carried out mainly through the administration of praziquantel tablets, which has some disadvantages, such as the strong bitter taste. As an alternative to overcome this problem, the development of new encapsulated praziquantel formulations is demanded. For this reason, suspension polymerizations are carried out for the in situ encapsulation of prazi… Show more
“…This behavior is probably due to the increase of the viscosity of the organic phase when PZQ is added, which affects the rates of breakage and coalescence of the particles. Similar behavior was reported by Paiva et al and Oliveira et al, when PZQ and doxorubicin were incorporated into microparticles through suspension polymerizations of MMA and suspension copolymerizations of vinyl acetate and MMA, respectively.…”
Section: Resultssupporting
confidence: 85%
“…Figure 3 and Table 2 present the particle size distributions and mean diameters, respectively, of the produced microparticles. As it can be observed, all particles presented the characteristic micrometric size, as expected for particles produced through suspension polymerizations, indicating that addition of the cationic comonomers to the suspended organic mixture did not prevent the successful formation of the polymer microparticles, as also reported previously for reactions performed in the presence of lower comonomer contents . Besides, one can note the shifting of particle size distributions toward larger particle sizes with the increase of the comonomer contents, due tvo increase of rates of particle coalescence, as shown in the next paragraphs.…”
Section: Resultssupporting
confidence: 80%
“…First of all, it is important to mention that praziquantel presents excellent thermal stability, showing maximum rate of thermal degradation near 300 °C, which guarantees its safe manipulation and stability in the suspension polymerization trials, performed at 80 °C …”
Section: Resultsmentioning
confidence: 99%
“…In order to verify the pH‐sensitive response, dissolution tests were conducted at two different media: in intestinal environment (phosphate buffer pH 6.8) and in the gastric environment (HCl 0.1 m pH 1.2). The tests were performed using the same methodology described previously by Paiva et al and recommended by distinct Pharmacopeias.…”
Section: Methodsmentioning
confidence: 99%
“…Particularly, a previous work showed that it is possible to produce smart microparticles, loaded with PZQ and presenting suitable properties for biomedical applications, through suspension polymerization reactions in the presence of low cationic comonomer contents (below 10 wt%). For this reason, the present work investigates the manufacture of pH‐sensitive smart microparticles through copolymerization of methyl methacrylate (MMA) and the cationic comonomers diethylaminoethyl methacrylate (DEAEMA) or dimethylaminoethyl methacrylate (DMAEMA) in broader ranges of comonomer feed compositions (0 to 40 wt%).The obtained results indicate that microparticles with sizes in the range of 10–1100 µm can be produced successfully, allowing high PZQ encapsulation efficiencies (>80%).…”
Schistosomiasis is a parasitic disease that affects millions of people, especially low‐income people, and is considered a major public health problem in underdeveloped countries. The drug used most often for the treatment of the disease is praziquantel (PZQ), which has a strong and characteristic bitter taste that makes treatment of children inconvenient. For this reason, the present work investigates the development of smart pH‐sensitive polymer microparticles produced through suspension polymerizations to be used as vehicles for the controlled release of praziquantel in the body. The microparticles are produced through copolymerization of methyl methacrylate and the cationic comonomers diethylaminoethyl methacrylate or dimethylaminoethyl methacrylate. The obtained results indicate that microparticles with sizes in the range of 10–1100 µm can be formed successfully, allowing high PZQ encapsulation efficiencies (>80%). Zeta potential analyses and drug release assays confirm the pH‐sensitive responses of the cationic copolymers, leading to effective release of PZQ (around 80% in pH 1.2) in acidic media that simulate the organic fluids present in the stomach.
“…This behavior is probably due to the increase of the viscosity of the organic phase when PZQ is added, which affects the rates of breakage and coalescence of the particles. Similar behavior was reported by Paiva et al and Oliveira et al, when PZQ and doxorubicin were incorporated into microparticles through suspension polymerizations of MMA and suspension copolymerizations of vinyl acetate and MMA, respectively.…”
Section: Resultssupporting
confidence: 85%
“…Figure 3 and Table 2 present the particle size distributions and mean diameters, respectively, of the produced microparticles. As it can be observed, all particles presented the characteristic micrometric size, as expected for particles produced through suspension polymerizations, indicating that addition of the cationic comonomers to the suspended organic mixture did not prevent the successful formation of the polymer microparticles, as also reported previously for reactions performed in the presence of lower comonomer contents . Besides, one can note the shifting of particle size distributions toward larger particle sizes with the increase of the comonomer contents, due tvo increase of rates of particle coalescence, as shown in the next paragraphs.…”
Section: Resultssupporting
confidence: 80%
“…First of all, it is important to mention that praziquantel presents excellent thermal stability, showing maximum rate of thermal degradation near 300 °C, which guarantees its safe manipulation and stability in the suspension polymerization trials, performed at 80 °C …”
Section: Resultsmentioning
confidence: 99%
“…In order to verify the pH‐sensitive response, dissolution tests were conducted at two different media: in intestinal environment (phosphate buffer pH 6.8) and in the gastric environment (HCl 0.1 m pH 1.2). The tests were performed using the same methodology described previously by Paiva et al and recommended by distinct Pharmacopeias.…”
Section: Methodsmentioning
confidence: 99%
“…Particularly, a previous work showed that it is possible to produce smart microparticles, loaded with PZQ and presenting suitable properties for biomedical applications, through suspension polymerization reactions in the presence of low cationic comonomer contents (below 10 wt%). For this reason, the present work investigates the manufacture of pH‐sensitive smart microparticles through copolymerization of methyl methacrylate (MMA) and the cationic comonomers diethylaminoethyl methacrylate (DEAEMA) or dimethylaminoethyl methacrylate (DMAEMA) in broader ranges of comonomer feed compositions (0 to 40 wt%).The obtained results indicate that microparticles with sizes in the range of 10–1100 µm can be produced successfully, allowing high PZQ encapsulation efficiencies (>80%).…”
Schistosomiasis is a parasitic disease that affects millions of people, especially low‐income people, and is considered a major public health problem in underdeveloped countries. The drug used most often for the treatment of the disease is praziquantel (PZQ), which has a strong and characteristic bitter taste that makes treatment of children inconvenient. For this reason, the present work investigates the development of smart pH‐sensitive polymer microparticles produced through suspension polymerizations to be used as vehicles for the controlled release of praziquantel in the body. The microparticles are produced through copolymerization of methyl methacrylate and the cationic comonomers diethylaminoethyl methacrylate or dimethylaminoethyl methacrylate. The obtained results indicate that microparticles with sizes in the range of 10–1100 µm can be formed successfully, allowing high PZQ encapsulation efficiencies (>80%). Zeta potential analyses and drug release assays confirm the pH‐sensitive responses of the cationic copolymers, leading to effective release of PZQ (around 80% in pH 1.2) in acidic media that simulate the organic fluids present in the stomach.
Praziquantel (PZQ) composes a regular medicine available in a tablet form to fight schistosomiasis and just half of its mass is composed by the active principle (L‐PZQ), the other half, D‐PZQ, is frequently associated to a strong bitter taste. Moreover, optically pure L‐PZQ derivatives could be used in studies about adult and juvenile worms' resistance. Nowadays, these studies use racemic PZQ (rac‐PZQ) as starting point. The D‐PZQ, which would be discarded, could be racemized, coming back as feed concentration in the process. The present work aims to get L‐PZQ and D‐PZQ with high optical purities (more than 97%) and productivity (more than 253 g kgads−1 day−1) towards semipreparative scale for researches involving L‐PZQ, L‐PZQ derivatives, and D‐PZQ racemization. In order to achieve this goal, a built‐in‐house simulated moving bed chromatographic unit with the cellulose tris (3‐chloro‐4‐methylphenylcarbamate) (Chiralcel OZ) as chiral stationary phase (CSP) was used to investigate different scenarios of separation according to a well‐known design method called triangle theory. In all scenarios investigated, at least one of the outlet streams presented high optically purity for one of the enantiomers. Comparison with literature showed superior performance of our unit even at racemic mixture concentrations that were 10 times lower than the racemic concentrations found in literature.
The present work evaluated the effects of different ionic and nonionic stabilizers and respective concentrations on methyl methacrylate (MMA) miniemulsion polymerizations. The stabilities of the prepared miniemulsions are characterized through sedimentation and phase separation analyses and afterwards polymerizations are performed at the most stable conditions for each analyzed stabilizer. Monomer conversion profiles and final product properties are determined for comparative purposes. Obtained results indicated that the performances of the stabilizers during the polymerizations are not necessarily related to the stabilizing performances observed during preparation of the miniemulsions and that polymer latexes produced with the nonionic surfactant Tween80 presented the most suitable properties for applications in the biomedical field, as this stabilizer presented good stabilizing performances both during miniemulsion preparation and miniemulsion polymerization.
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