Impact of alternative solid state forms and specific surface area of high-dose, hydrophilic active pharmaceutical ingredients on tabletability

YesIn order to investigate the effect of using different solid state forms and specific surface area (TBET) of active pharmaceutical ingredients on tabletability and dissolution performance, the mono- and dihydrated crystalline forms of chlorothiazide sodium and chlorothiazide potassium (CTZK) salts were compared to alternative anhydrous and amorphous forms, as well as to amorphous microparticles of chlorothiazide sodium and potassium which were produced by spray drying and had a large specific surface area. The tablet hardness and tensile strength, porosity, and specific surface area of single-component, convex tablets prepared at different compression pressures were characterized. Results confirmed the complexity of the compressibility mechanisms. In general it may be concluded that factors such as solid-state form (crystalline vs amorphous), type of hydration (presence of interstitial molecules of water, dehydrates), or specific surface area of the material have a direct impact on the tabletability of the powder. It was observed that, for powders of the same solid state form, those with a larger specific surface area compacted well, and better than powders of a lower surface area, even at relatively low compression pressures. Compacts prepared at lower compression pressures from high surface area porous microparticles presented the shortest times to dissolve, when compared with compacts made of equivalent materials, which had to be compressed at higher compression pressures in order to obtain satisfactory compacts. Therefore, materials composed of nanoparticulate microparticles (NPMPs) may be considered as suitable for direct compaction and possibly for inclusion in tablet formulations as bulking agents, APIs, carriers, or binders due to their good compactibility performanceSolid State Pharmaceutical Cluster (SSPC), supported by Science Foundation Ireland under Grant No. 07/SRC/B1158

Computer-Aided Quality (CAQ) for powder technology

Quality is considered to be the most important factor in the world market competition. Increasing quality, however, increases the cost. Thus, the main objective of the industry achieving higher quality with less cost is essential and extremely difficult to obtain. One of the effective techniques used to overcome this difficulty is the acceptance sampling plan. Therefore, a complete review of all sampling plans including single, double, sequential, chain and continuous sampling is made here. Also, computer programs are constructed for all of these plans and incorporated in one package, coded in Visual Basic Language. The package contains guidelines to assist the user to select the proper sampling plan according to his/her objectives, and probabilities of Risk I and Risk II types. Unequal subgroups are also included, in order to help the user to construct the standardisation control charts. The package is friendly, flexible and interactive in nature. It showed excellent performance and displayed similar results to those found in the literature. Finally, typical illustrative examples and results are given, including some applications from the powder technology.King Saud Universit

Fatigue behaviour of AA 7075-T6 plates repaired at different crack lengths

Bonded Composite Repair Technology (BCRT) is widely used to reinforce weakened cracked components and damaged metallic structures in various aerospace applications. In this work, the fatigue crack behaviour of V- notched aluminium 7075-T6 plates, of 2 mm thickness, bonded with "single side" carbon composite patch configuration was experimentally investigated. The repair efficiency and fatigue life of cracked specimens repaired at different initial crack lengths of (a0 = 3 mm, 6 mm and 9 mm) and different stress ratios of (R = 0 and R = 0.1) were investigated. The results obtained showed that the bonded patch increases the fatigue life of all repaired samples ranging from 2.2 folds for 9 mm to 4.3 folds for 3 mm initial crack lengths. Repair can be treated at any level of crack initiation but preferably should be conducted as soon as it is detected. Stress ratio and initial crack lengths affect the repair efficiency. This is clearly manifested in the extended life and load carrying capacity of adhesively bonded specimen

Fatigue life enhancement of cracked aerospace grade aluminium repaired with bonded composite patch: experimental study

Bonded composite patch repair of cracked components and weakened aircraft structures has gained high acceptance and demand. In the present study, fatigue crack behavior of 2 mm thick V-notched aluminum 2024-T3 plates, repaired with composite patch was experimentally investigated. This includes assessment of repair efficiency and fatigue life of cracked samples repaired at different levels of crack length. The experimental results showed that the reinforcement of patch increases the fatigue life about 4.5 times. However, the repair efficiency decreases with initial crack length. Consequently, cracks must be repaired as soon as detected. The SEM images clearly demonstrate that the fracture mode of 2024-T3 is predominantly trans-granular with small sized dimples

Comparison between double and single sided bonded composite repair with circular shape

In this study, a new approach is applied to compare the performances of single sided and double-sided symmetric composite patch with circular shape for repairing cracked aircraft structures. This is an approach that consists to evaluate the mass gain eventually obtained by the use of double symmetric composite patch if the two patch configurations give the same stress intensity factor at the crack tip. The three-dimensional finite elements method is used to compute the stress intensity factor. The obtained results show that the use of the double patch technique leads to a significant reduction of the stress intensity at the crack tip. The mass gain eventually given by the double patch technique can be very significant and this gain depends on the patch shape and the adhesive properties.King Saud Universit

Numerical analysis of the effect of thermal residual stresses on the performances of bonded composite repairs in aircraft structures

In this study the finite element method is used to analyse the effect of the thermal residual stresses resulting from adhesive curing on the performances of the bonded composite repair in aircraft structures. The stress-intensity factor at the crack tip is chosen as fracture criterion in order to estimate the repair performances. The obtained results show that the presence of the thermal residual stresses reduces considerably the repair performances and consequently decreases the fatigue life of cracked structures. The effects of the curing temperature, the adhesive properties and the adhesive thickness on the stress-intensity factor (SIF) variation with thermal stresses are also analysed.King Saud Universit