Purpose: This study aimed to evaluate the biological and mechanical properties of the poly(methyl methacrylate) (PMMA) denture base material as a vehicle incorporating novel hydroxyapatite nanoparticles (HA-NP) loaded with metronidazole (MZ) drug. Methods: HA-NP was prepared via wet-chemical-method, characterized by XRD, SEM/EDX, TEM, Fourier-transform infrared spectroscopy (FTIR), as well as the measurement of surface area and pore-size distribution. Four drug delivery formulas were prepared in the form of discs (10 x 2 mm) as follows: F1 (MZ/ HA-NP/PMMA), F2 (HA-NP/ PMMA), F3 (control-PMMA) and F4 (MZ/PMMA). Characterization of all formulas was performed using differential scanning calorimetry (DSC) and FTIR. MZ release rate, antimicrobial properties against three oral pathogens, cytotoxicity (MTT assay) and surface micro-hardness were also assessed. Statistical analysis of data was performed using one-way ANOVA test (P < 0.05). Results: DSC thermograms showed compatibility among MZ, HA-NP and PMMA along with physical stability over 6 months storage period at room temperature. FTIR spectroscopy proved the absence of any possible chemical interaction with MZ. MZ-HA-NP/PMMA formula showed relatively better drug release compared to MZ-PMMA. Both formulas showed statistically significant antimicrobial potentials against two microbial strains. MTT demonstrated reduction in cell cytotoxicity after 96 hours with the least value for HA-NP. Surface micro-hardness revealed non-significant reduction compared with the control PMMA. Conclusion: A novel biocompatible drug nanocarrier (HA-NP) was developed and incorporated in PMMA denture base material as a vehicle to allow prolonged sustained drug release to manage oral infections.

Objective: This study was proposed to evaluate and compare the in vitro dissolution profiles of six Metformin Hydrochloride (MH) market products.Methods: Different dissolution apparatuses (USP apparatus II, IV and beaker method) were used to evaluate the dissolution profiles (in phosphate buffer, pH 6.8) of two immediate release (IR) generic products of Metformin Hydrochloride (MH): Cidophage® 1000 mg (G1, Egyptian market) and Metformin arrow® 1000 mg (G2, French market) with respect to the reference products named Glucophage® 850 mg (R1, Egyptian market and R2, French market). In addition to a generic controlled-release (CR) product; Cidophage Retard® 850 mg (G3) versus the reference product; Glucophage XR® 1000 mg (R3) (both from Egyptian market). Dissolution efficiency (D. E.) and the similarity factor (f2) were calculated. Weight uniformity, hardness, tablet dimensions and MH content were measured. Results:Results of the three apparatuses showed that MH IR products studied (reference and generics) did not meet the 75% USP 30 specifications for MH dissolved at 30 min. For MH CR products, Glucophage XR® did not fulfill the USP release criteria, while Cidophage Retard® did. USP apparatus IV revealed the highest sensitivity and discriminative capability. Conclusion:Generally, MH IR generics (G1 and G2) might be interchangeable with the innovator product (Glucophage®). However, Cidophage Retard® might not be interchangeable with Glucophage XR®.

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Floating amoxicillin trihydrate (AmoxT) tablets, used for eradication of Helicobacter pylori (H. pylori), were prepared according to a gas-generating technique to extend the drug residence time in the stomach. The drug release rate from the floating tablets in acidic dissolution medium, in which AmoxT is known to be unstable, was studied using two dissolution techniques: openloop system of the flow-through cell (FTC) and the beaker method. Analysis of AmoxT in the dissolution medium was carried out by UV spectrophotometric and HPLC methods. The comparison indicates that the open-loop system of the FTC, which is based on non-cumulative (fresh) dissolution samples, is the preferred dissolution technique, and in this case, the drug could be analyzed by UV spectrophotometric and HPLC methods. However, in the case of a large number of QC samples, UV spectrophotometry is preferred to the HPLC method, which requires relatively longer time for analysis thereby increasing drug degradation. On the other hand, in the case of the beaker method, which is based on cumulative dissolution samples, the drug must be analyzed by HPLC. Generally, the beaker method is not recommended due to the problems associated with the accumulation of AmoxT degradation product in the dissolution medium. This study describes a simple dissolution method capable of discriminating between different AmoxT gastroretentive formulations without any additional experimental or calculational steps.

Floating amoxicillin trihydrate (AmoxT) tablets, used for eradication of Helicobacter pylori (H. pylori), were prepared according to a gas-generating technique to extend the drug residence time in the stomach. The drug release rate from the floating tablets in acidic dissolution medium, in which AmoxT is known to be unstable, was studied using two dissolution techniques: openloop system of the flow-through cell (FTC) and the beaker method. Analysis of AmoxT in the dissolution medium was carried out by UV spectrophotometric and HPLC methods. The comparison indicates that the open-loop system of the FTC, which is based on non-cumulative (fresh) dissolution samples, is the preferred dissolution technique, and in this case, the drug could be analyzed by UV spectrophotometric and HPLC methods. However, in the case of a large number of QC samples, UV spectrophotometry is preferred to the HPLC method, which requires relatively longer time for analysis thereby increasing drug degradation. On the other hand, in the case of the beaker method, which is based on cumulative dissolution samples, the drug must be analyzed by HPLC. Generally, the beaker method is not recommended due to the problems associated with the accumulation of AmoxT degradation product in the dissolution medium. This study describes a simple dissolution method capable of discriminating between different AmoxT gastroretentive formulations without any additional experimental or calculational steps.

The effect of different storage durations/temperatures on the stability of gliclazide (GLZ) in plasma was not studied before in the literature. A simple, reproducible ultra-high performance liquid chromatography coupled with ultraviolet detection (UHPLC/UV) was established for monitoring GLZ in rat plasma was established, with all stability parameters fully evaluated. The developed method provided simple solvent extraction for both GLZ and Glibenclamide as an internal standard (I.S.) with a short run time (≤ 7 minutes). A linear calibration curve (0.1-40 µg/ml), with good intra-and inter-day precision and accuracy, was established based on 40-ul plasma volume. Lower and upper limits of quantification allowed effective monitoring of the expected variations in GLZ absorption. The stock solution, freeze-thaw, short-term and bench stability results safeguard the rationale of the UHPLC/UV method. However, GLZ plasma samples were only stable for 1 week storage at −20°C or −80°C. The present study emphasized the importance of proper storage conditions, with recommendations for direct analysis of GLZ in plasma after sample collection or maximum storage for 1 week at −20°C or −80°C until analysis, to ensure accurate measurement of the drug in plasma. This method was effectively applied in a pharmacokinetic study of GLZ single oral dose from the market product Diamicron ® MR 30 mg administered in six rats.

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