Degradation Of Aspirin Research Articles

Mannitol-Coated Hydroxypropyl Methylcellulose as a Directly Compressible Controlled Release Excipient for Moisture-Sensitive Drugs: A Stability Perspective.

Hydroxypropyl methylcellulose (HPMC) is one of the most commonly used hydrophilic polymers in formulations of matrix tablets for controlled release applications. However, HPMC attracts moisture and poses issues with drug stability in formulations containing moisture-sensitive drugs. Herein, the moisture sorption behavior of excipients and drug stability using aspirin as the model drug in matrix tablets were evaluated, using HPMC and the newly developed mannitol-coated HPMC, under accelerated stability conditions (40 °C, 75% relative humidity) with open and closed dishes. Tablets prepared with mannitol-coated HPMC showed a slower drug degradation rate compared to tablets prepared with directly compressible HPMC. Initial moisture content and hygroscopicity were stronger predictors of drug stability compared to water activity when comparing samples without similar moisture content. In the early stage (day 0 to 30), the aspirin degradation rate was similar in both open and closed conditions, as moisture content is the main degradation contributor. In the later stage (day 30 to 90), aspirin degradation was faster under closed conditions than under open conditions, likely due to autocatalytic effects caused by the volatile acidic by-product entrapped in the closed environment. The findings from this study reinforced the importance of judicious excipient selection based on the understanding of excipient-moisture interactions to maximize the chemical stability of moisture-sensitive drugs. Mannitol-coated HPMC is a promising addition to the formulator's toolbox for the formulation of controlled release dosage forms by direct compression.

Sonoelectrochemical degradation of aspirin in aquatic medium using ozone and peroxymonosulfate activated with FeS2 nanoparticles

The catalytic performance of nano-FeS2 in the sonoelectrochemical activation of peroxymonosulfate (PMS) and ozone to remove aspirin (ASP) was studied for the first time. The crystal structure and Fe bonds in the catalyst were confirmed through XRD and FTIR analysis. Within 30 min, ASP (TOC) was removed by 99.2 % (81.6 %) and 98.6 % (77.4 %) in nano-FeS2/PMS and nano-FeS2/O3 sonoelectrochemical systems, respectively. Water anions, especiallyHCO3− (almost 50 %), had an inhibitory effect on ASP removal. The probes confirmed that SO4•−and HO• were the key to ASP degradation in nano-FeS2/PMS and nano-FeS2/O3 systems, respectively. The effective activation of oxidants due to the ideal distribution of Fe2+ by catalyst was the main mechanism of ASP removal, in which electric current (EC) and ultrasound (US) played a crucial role through the recycling of Fe ions, dissolution and cleaning of the catalyst. LC-MS analysis identified thirteen byproducts in the ASP degradation pathways. The energy consumption of the proposed sonoelectrochemical systems was lower than previous similar systems. This study presented economic and sustainable hybrid systems for pharmaceutical wastewater remediation.

RGB-algorithm whiteness appraisal approach for quantitative determination of clopidogrel and aspirin in presence of salicylic acid as a degradation product based on proton NMR technique

A rapid, precise, and selective spectroscopic method based on the quantitative proton nuclear magnetic resonance (1H-qNMR) was developed to estimate aspirin and clopidogrel in their pharmaceutical dosages for the first time. The evolved method was utilized to estimate both drugs in presence of the aspirin degradation product, salicylic acid. Moreover, aspirin and clopidogrel were subjected to various stress conditions such as acid hydrolysis, alkali hydrolysis, water hydrolysis, H2O2 oxidation, and photodecomposition for studying the stability of both compounds under these stress conditions. The 1H-qNMR analyses of the analytes of interest were conducted using the internal standard phloroglucinol and the solvent dimethyl sulfoxide-d6. The NMR spectra showed a quantitative doublet of doublets (dd) signal of aspirin at 7.945 ppm, a doublet signal of clopidogrel at 6.875 ppm, and a dd signal of salicylic acid at 7.810 ppm. The internal standard phloroglucinol exhibited a singlet signal at 5.690 ppm. The results demonstrated the linearity (r2 > 0.999), accuracy, precision (RSD < 2.0 %), stability, selectivity, and specificity of the evolved method. Linearity was confirmed in the ranges of 0.05–3.0 mg/mL for aspirin, 0.15–10.0 mg/mL for clopidogrel, and 0.1–5.0 mg/mL for salicylic acid. The evolved method was efficiently applied to analyse aspirin and clopidogrel in their dosages with high %recovery. Moreover, The RGB algorithm technique was used to evaluate the whiteness profile of the suggested method; the findings confirmed the sustainability of the evolved method, which employed an ecological solvent, followed a simple and straightforward procedure, and avoided any pretreatment or labelling stages for the samples. All the aforementioned advantages gave the technique the privilege.

Fabrication of rare earth (Tb+3) and alkaline earth metal (Mg+2) Co-doped CdAl2O4@MXene composite: A unique approach to tune bandgap energy through quantum confinement effect for photocatalytic applications

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl2O4 via dopant assimilation to enhance the bandgap energy (Eg) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl2O4 (CA), Mg–CdAl2O4 (MCA), and Tb-doped Mg–CdAl2O4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl2O4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in Eg of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl2O4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants.

Tungsten-doped BiVO4 and its composite with g-C3N4 for enhanced photocatalytic applications

In this study, BiVO4, W–BiVO4, and W–BiVO4@g-C3N4 composite were successfully synthesized by hydrothermal and ultra-sonication approach respectively. The physiochemical characterizations of BiVO4, W–BiVO4, and W–BiVO4@g-C3N4 were performed by XRD and FTIR techniques. Band gap values of BiVO4 and W–BiVO4 were found to be 2.42 eV and 2.50 eV, respectively. The photocatalytic degradation of pendimethalin (PM) and Aspirin was done in the presence of BiVO4, W–BiVO4, and W–BiVO4@g-C3N4 under visible light irradiation. When used for photocatalytic application, W–BiVO4@g-C3N4 composite showed ∼86% removal of aspirin while W–BiVO4 and pure BiVO4 showed 78% and 63% degradation of aspirin respectively. Furthermore, the nanocomposite (W–BiVO4@g-C3N4) exhibited remarkable degradation activity of ∼91% against PM as compared to BiVO4 (60%) and W–BiVO4 (66%). The higher degradation activity of W–BiVO4@g-C3N4 composite for both aspirin and PM as compared to pure and doped BiVO4 is accredited to its large surface area provided by gCN sheets, and effective separation of photo reactive species because of its Z scheme electron transfer mechanism.

Degradation of Aspirin in a Microbial Fuel Cell Powered Electro-Fenton System Using an Etched Graphite Felt Cathode

Degradation of Aspirin in a Microbial Fuel Cell Powered Electro-Fenton System Using an Etched Graphite Felt Cathode

Iron and vanadium co-doped WO3 nanomaterial and their composites for waste water applications

Tungsten oxide (WO3), Iron and vanadium co-doped tungsten oxide (FeVWO3), and the composite of iron and vanadium co-doped tungsten oxide with graphitic carbon nitride (FeVWO3@g-C3N4) were prepared for the photocatalytic study. WO3 and FeVWO3 were synthesized by co-precipitation, and the composite FeVWO3@g-C3N4 was synthesized by an ultra-sonication approach. All the prepared materials were analyzed by different techniques. Structural study was done by XRD, functional group analysis by FTIR, and SEM was used for the morphological study of the nanoparticles. EIS measurements were done to investigate the electrical properties of fabricated materials. Photocatalysis was performed for the band gap analysis. Pendimethalin (PM) a herbicide and aspirin (pharmaceutical product) were used in photocatalysis and degraded by the prepared photocatalysts (WO3, FeVWO3, and FeVWO3@g-C3N4). WO3 and FeVWO3 have 2.62 eV and 2.34 eV Eg values of band gap, respectively. FeVWO3 has a lower Eg value than WO3. The decrease is due to the doping, and generation of further energy levels in the band gap of the pure sample, and these energy levels cause changes in the electronic structure of the sample. The composite shows a high degradation efficiency. The percentage degradation of pendimethalin and aspirin by FeVWO3@g-C3N4 was 82.26 % and 92.84 %. It is because of the presence of g-C3N4 which provides greater surface area for better degradation efficiency.

A magnetite catalysed heterogeneous solar photo electro-Fenton system enhanced with lanthanum doped bismuth ferrite photoanode for the degradation of aspirin in water

The effect of photoanode on a solar photo electro-Fenton system (SPEF) consisting of a magnetite nanoparticle catalyst impregnated carbon felt cathode is studied by coupling the SPEF system to a lanthanum-doped bismuth ferrite (La-BFO) photoanode. The resulting system, referred to as La-BFO /SPEF, was used in the degradation of acetyl salicylic acid in wastewater. The synthesised La-doped/undoped BFO photoanodes and magnetite nanoparticles were characterised with SEM, XRD and FTIR. The heterogeneous electro-Fenton system was prepared by attaching the magnetite nanoparticle to a carbon felt electrode through magnetisation. The effects of La dopant concentration in the photoanode material (doped and undoped BFO on a fluorine doped tin oxide substrate), pH values, current density and anodic oxidation contribution to the SPEF system were explored through parameters such as total organic carbon (TOC) measurements and mineralization current efficiency. A TOC removal of 68 % and 54 % was recorded for the La-doped photoanode (La-BFO/SPEF) and undoped system (BFO/SPEF) respectively, thus reflecting the contribution from the band gap tuning of the photoanode material. The predominant species in the degradation of acetyl salicylic acid were deduced by radical scavenging experiments. The coupling approach and the irradiation with visible light, enhanced the overall performance of the degradation system.

Crystalline boron significantly accelerates Fe(III)/PMS reaction as an electron donor: Iron recycling, reactive species generation, and acute toxicity evaluation

Crystalline boron (C-boron) could provide redox active sites in Fenton-like reactions due to the surface B-B bonds and interfacial suboxide boron in the surface structure of B12 icosahedra. However, related research on boron chemistry is limited. We demonstrate here that addition of C-boron to the Fe(III)/peroxymonosulfate(PMS) system effectively improves the degradation of flunixin meglumine, aspirin, nitrobenzene, and benzoic acid at pH 4.0–10.0 (without buffer). Compared with the Fe(III)/PMS system, the kobs of the C-boron/Fe(III)/PMS system for degradation of these four contaminants at pH 7.0 was approximately 8.7–65.1 times higher. C-boron enhanced the homogeneous Fe(II) concentration in the Fe(III)/PMS system from 5.4 to 16.2 mg/L in a 20-min reaction, whereas Fe(IV) was generated from the Fe(II) produced in the system.Electron paramagnetic resonance and quenching experiments revealed the presence of ·OH, 1O2, and O2·− in the reaction, and the corresponding contributions of ·OH to oxidizing flunixin meglumine and aspirin were 16.7 % and 28.1 % at pH 7.0. The C-boron/Fe(III)/PMS solution significantly inhibited Microcystis aeruginosa growth, with the rate increasing in the first 24 h and then decreasing from 48 to 96 h. This toxicity was resulted by the inhibition of the chlorophyll a and chlorophyll b in the photosynthetic system. Overall, this work reported the feasibility of C-boron enhancement for pollutants degradation in Fe(III)/PMS system for the first time.

Alginate ester: New moisture-scavenging excipients for direct compressible pharmaceutical tableting

The objective of this work is to evaluate methyl ester alginates and alginic acid (AA) as moisture-scavenging excipients for the formulation of aspirin tablets obtained by direct compression. The tablets were stored at accelerated conditions (40 °C/75 % RH) and assessed for changes in tensile strength, mass, thickness and disintegration time. While moisture caused a reduction in the hardness of MCC and AA tablets, hardness of the tablets made from methylated materials was virtually unaffected. The physical stability of alginate ester tablets was found to be related to their increased plastic deformation leading to extended interparticle contact with less impact on tablet porosity. Finally, the combination of higher moisture affinity and lower water dissociation exhibited by alginates esters resulted in tablets with the lowest aspirin degradation. These findings suggest that excipients with high water retention can act as moisture-scavengers without losing their functional properties and reducing the degradation of moisture-sensitive drugs.

Improved Magnetite Nanoparticle Immobilization on a Carbon Felt Cathode in the Heterogeneous Electro-Fenton Degradation of Aspirin in Wastewater.

Toward the improvement of the application of heterogeneous electro-Fenton in water treatment, we report a new strategy of enhancing the immobilization of a magnetite nanoparticle catalyst on a carbon felt cathode. Exploiting the intrinsic ferrimagnetic properties of magnetite nanoparticles, magnet bars were used to attach the magnetite into the void spaces of the porous carbon felt (CF) cathode. The magnetite nanoparticles were prepared by coprecipitation with variations in the molar ratios of Fe2+/Fe3+. The magnetite was characterized, attached onto the CF electrode with magnetic bars, and used in the heterogeneous electro-Fenton (EF) degradation of aspirin. The effects of the following on the degradation were studied: Fe2+/Fe3+, pH, catalyst loading concentration, and voltage. The heterogeneous EF degradation of aspirin in wastewater improved by 23% when magnetic bars were used to enhance the immobilization of the magnetite catalysts. The 1:4 Fe2+/Fe3+ ratio resulted in the highest hetero-EF catalytic degradation of aspirin with complete degradation (100%) achieved after 140 min. For a mixture of pharmaceuticals, degradation percentages of 94.3% (aspirin), 88% (ciprofloxacin), and 80% (paracetamol) in 3 h were obtained. The magnetized magnetite on the cathode was reusable for 10 cycles. Thus, the use of magnets shows a promising strategy to avoid the leaching of ferrimagnetic nanoparticle catalysts embedded in the cathode for heterogeneous EF processes.

Simple synthesis of WO3 based activated carbon co-doped CuS composites for photocatalytic applications

This research work reports the simple synthesis of pure tungsten trioxide (WO3), its doping series with activated carbon (AC) in addition to pure copper sulfide (CuS). Then, WO3 based AC was co-doped with CuS composites, prepared through the facile hydrothermal method. The photocatalytic activity for the degradation of Aspirin is reported here. The percentage of CuS was varied as 10% and 15% in the 2% AC doped WO3 sample. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transforms infrared (FTIR) spectroscopy, photoluminescence spectroscopy and ultraviolet–visible (UV–vis) spectroscopy techniques have been used to characterized the prepared samples. Photocatalytic performance was investigated for the time period of 150 min for degradation of the Aspirin drug. Here in this research, Aspirin has been used as a as a model organic pollutant. The photocatalytic study revealed that WO3 based AC co-doped 15% CuS have the highest degradation efficiency (97%) following by first-order pseudo reaction rate. It is observed that the same sample is photo-stable, anti-photo corrosive and has been proved to be environmental friendly. This is also reusable after many cycles of activity. These results suggested that 15% CuS composite can be utilized as a photo-catalyst for the degradation of pharmaceutical pollutants without causing any other secondary pollutant.

Forced Degradation Study for Simultaneous Quantification of Aspirin and Omeprazole in Pharmaceutical Dosage form by RP-HPLC

Aims: To study force degradation of aspirin and omeprazole simultaneously by RP-HPLC method&#x0D; Study design: RP-HPLC method was used to measure % degradation.&#x0D; Place and Duration of Study: Study was carried out at center of excellence, G.I.D.C., vapi-396195, Gujarat, India between June 2019 to march 2020.&#x0D; Methodology: A force degradation study of aspirin and omeprazole was carried out simultaneously. The drugs were subjected to various degradation conditions like hydrolysis by acid and base, Oxidative degradation, and thermal degradation study.&#x0D; Results: For acidic condition, the degradation was found to be 32.63 % for aspirin and 61.64 % for omeprazole. For basic condition, the degradation was found to be 10.17 % for aspirin and 4.29 % for omeprazole. By oxidative hydrolysis, the aspirin was degraded by 15.48 % and omeprazole was degraded by 26.38 %. By thermal degradation, 0.37 % degradation was observed for aspirin and 4.32 % degradation for omeprazole.&#x0D; Conclusion: In this proposed method the retention time for drug is less than 8 min, which is less then available method. For omeprazole, strong degradation was observed in acidic conditions and mild in basic hydrolysis conditions. For aspirin, more degradation was observed in basic conditions than acidic hydrolysis. Both drugs were degraded in oxidative conditions using 3% H2O2. Omeprazole degraded more than aspirin by dry heat degradation. The method was successfully applied for the quantitative determination of both Active Pharmaceutical Ingredients.

Is ionizing radiation effective in removing pharmaceuticals from wastewater?

Wastewater and effluent discharges are the main causes of receiving water body pollution and important challenges in water quality management. Among the emerging contaminants, pharmaceuticals have increasingly drawn attention due to their incomplete removal during conventional biological treatment, inducing potential and actual risks to living organisms following residue discharges in river effluent. Electron beam irradiation (EBI) is a clean process technology for organic compound degradation and mineralization, as well as persistent pollutant detoxification. This study aimed to evaluate EBI effects on the degradation and toxicity removal of anti-inflammatory aspirin (ASA) in a single solution and in a fluoxetine (FLX) mixture. Results indicate that 98% of the single aspirin was degraded at 5.0kGy. Aspirin toxicity to Daphnia similis, however, increased with increasing absorbed dose (1.0 to 5.0kGy), possibly as a result of the presence of H2O2 and other byproducts formed during the oxidation process. Regarding the irradiated mixture, complete degradation was achieved for both pharmaceuticals. Toxicity removals for the mixture were of 56.2 ± 0.9% and 58.8 ± 5.4% for 1.0 and 2.5kGy, respectively. These findings demonstrate that EBI can be an interesting alternative process to be applied as a pre-treatment followed by biological treatment.

Development and Validation of HPTLC Method for Studying Stress Degradation of Aspirin in Fulvic Acid Inclusion Complex

A new, precise high performance thin layer chromatographic (HPTLC) method for the analysis aspirin (ASP) in inclusion complexes with HPβCD and fulvic acid (FA) was developed and validated as per ICH guidelines. A precoated silica gel aluminium plate 60F-254 and a mixture of solvents, toluene: ethylacetate: formic acid (5:4:1 v/v) were used as stationary and mobile phase, respectively. This developed method was found to give an excellent defined sharp peak at a retention factor (RF) value of 0.52 ± 0.001. The LOQ and LOD values were found 35.29 and 123.54 ng / spot, respectively. The spray dried inclusion complexes of ASP/HPβCD and ASP/FA in the molar ratio 1:1, were subjected for forced degradation under stress conditions, and a significant reduction of ASP degradation were noted in complexed ASP as compared to ASP alone.

Do Aspirin and Flavonoids Prevent Cancer through a Common Mechanism Involving Hydroxybenzoic Acids?-The Metabolite Hypothesis.

Despite decades of research to elucidate the cancer preventive mechanisms of aspirin and flavonoids, a consensus has not been reached on their specific modes of action. This inability to accurately pinpoint the mechanism involved is due to the failure to differentiate the primary targets from its associated downstream responses. This review is written in the context of the recent findings on the potential pathways involved in the prevention of colorectal cancers (CRC) by aspirin and flavonoids. Recent reports have demonstrated that the aspirin metabolites 2,3-dihydroxybenzoic acid (2,3-DHBA), 2,5-dihydroxybenzoic acid (2,5-DHBA) and the flavonoid metabolites 2,4,6-trihydroxybenzoic acid (2,4,6-THBA), 3,4-dihydroxybenzoic acid (3,4-DHBA) and 3,4,5-trihydroxybenzoic acid (3,4,5-THBA) were effective in inhibiting cancer cell growth in vitro. Limited in vivo studies also provide evidence that some of these hydroxybenzoic acids (HBAs) inhibit tumor growth in animal models. This raises the possibility that a common pathway involving HBAs may be responsible for the observed cancer preventive actions of aspirin and flavonoids. Since substantial amounts of aspirin and flavonoids are left unabsorbed in the intestinal lumen upon oral consumption, they may be subjected to degradation by the host and bacterial enzymes, generating simpler phenolic acids contributing to the prevention of CRC. Interestingly, these HBAs are also abundantly present in fruits and vegetables. Therefore, we suggest that the HBAs produced through microbial degradation of aspirin and flavonoids or those consumed through the diet may be common mediators of CRC prevention.

Insights on the role of excipients and tablet matrix porosity on aspirin stability.

Excipient-moisture interaction can be a critical attribute in determination of product stability. This study aimed to investigate influence of integrating excipients having different moisture interaction into moisture sensitive drug formulations. Aspirin was formulated with maize starch (MS), microcrystalline cellulose (MCC) and calcium hydrogen phosphate dihydrate (DCP). The excipients were evaluated for their inherent moisture content and water activity. Tablets fabricated at different compression pressures were exposed to 40°C, 75% relative humidity for a stipulated period before analyzing for aspirin degradation. The results revealed that while MS had higher moisture content, the water activity was relatively low. Consequently, MS tablets had lower aspirin degradation than MCC and DCP tablets. In contrast, high water activity of DCP resulted in greater aspirin degradation. This was despite the low moisture content of DCP. Influence of tablet porosity on aspirin degradation was minimal. This illustrated the fugacity of moisture, possessing high thermodynamic activity and physical spatial delimitation would not suppress its distribution. The findings suggested that excipients possessing high water retentive capacity could potentially be useful as internal tablet desiccants by acting as a moisture scavenger. This study also highlights the importance of water activity in preformulation studies related to the choice of excipients.

Stability-indicating HPLC method for simultaneous quantification of 14 impurities in excedrin tablet formulations and identification of new impurity by LC-MS in accelerated stability studies.

We developed novel stability-indicating HPLC method for simultaneous estimation of 14 impurities in excedrin tablet, a formulation with a combination of acetaminophen, aspirin, and caffeine. In addition, a new impurity that was generated through degradation of aspirin at high temperatures during the accelerated stability conditions was positively identified and confirmed, using liquid chromatography-mass spectrometry technique. The HPLC method was optimized using the Inertsustain C18 , 250 × 4.6 mm, 5.0 μm column, employing simple gradient method. Forced degradation studies were performed under acidic, basic, oxidative and thermal conditions to prove the scope and stability-indicating the nature of the method. The optimized method was validated as per the International Conference on Harmonization guidelines. The HPLC method showed linearity from LOQ concentration to 21 μg mL-1 . Precision and intermediate precision values were <5% RSD. The validated HPLC method is currently applied for the routine testing of excedrin tablet formulations in quality control laboratories.

Mathematical modeling of drug release from biodegradable polymeric microneedles

Transdermal drug delivery systems have overcome many limitations of other drug administration routes, such as injection pain and first-pass metabolism following oral route, although transdermal drug delivery systems are limited to drugs with low molecular weight. Hence, new emerging technology allowing high molecular weight drug delivery across the skin—known as ‘microneedles’—has been developed, which creates microchannels that facilitate drug delivery. In this report, drug-loaded degradable conic microneedles are modeled to characterize the degradation rate and drug release profile. Since a lot of data are available for polylactic acid-co-glycolic acid (PLGA) degradation in the literature, PLGA of various molecular weights—as a biodegradable polymer in the polyester family—is used for modeling and verification of the drug delivery in the microneedles. The main reaction occurring during polyester degradation is hydrolysis of steric bonds, leading to molecular weight reduction. The acid produced in the degradation has a catalytic effect on the reaction. Changes in water, acid and steric bond concentrations over time and for different radii of microneedles are investigated. To solve the partial and ordinary differential equations simultaneously, finite difference and Runge–Kutta methods are employed, respectively, with the aid of MATLAB. Correlation of the polymer degradation rate with its molecular weight and molecular weight changes versus time are illustrated. Also, drug diffusivity is related to matrix molecular weight. The molecular weight reduction and accumulative drug release within the system are predicted. In order to validate and assess the proposed model, data series of the hydrolytic degradation of aspirin (180.16 Da)- and albumin (66,000 Da)-loaded PLGA (1:1 molar ratio) are used for comparison. The proposed model is in good agreement with experimental data from the literature. Considering diffusion as the main phenomena and autocatalytic effects in the reaction, the drug release profile is predicted. Based on our results for a microneedle containing drug, we are able to estimate drug release rates before fabrication.

Photocatalytic degradation of aspirin from aqueous solutions using the UV/ZnO process: modelling, analysis and optimization by response surface methodology (RSM)

Photocatalytic degradation of aspirin from aqueous solutions using the UV/ZnO process: modelling, analysis and optimization by response surface methodology (RSM)