Pharmaceutical Practice Aulton Pdf 14 'LINK'
One of the world's best-known texts on pharmaceutics, Aulton's Pharmaceutics offers a complete course in one book for students in all years of undergraduate pharmacy and pharmaceutical sciences degrees.
Pharmaceutical Practice Aulton Pdf 14
Thoroughly revised, updated and extended by experts in their fields and edited by Professors Kevin Taylor and Michael Aulton, this new edition includes the science of formulation, pharmaceutical manufacturing and drug delivery.
Abstract:With the emergence of quality by design in the pharmaceutical industry, it becomes imperative to gain a deeper mechanistic understanding of factors impacting the flow of a formulation into tableting dies. Many flow characterization techniques are present, but so far only a few have shown to mimic the die filling process successfully. One of the challenges in mimicking the die filling process is the impact of rheological powder behavior as a result of differences in flow field in the feeding frame. In the current study, the rheological behavior was investigated for a wide range of excipients with a wide range of material properties. A new parameter for rheological behavior was introduced, which is a measure for the change in dynamic cohesive index upon changes in flow field. Particle size distribution was identified as a main contributing factor to the rheological behavior of powders. The presence of fines between larger particles turned out to reduce the rheological index, which the authors explain by improved particle separation at more dynamic flow fields. This study also revealed that obtained insights on rheological behavior can be used to optimize agitator settings in a tableting machine.Keywords: powder flow; die filling; powder rheology; dynamic cohesive index; excipients; tableting; continuous manufacturing; quality by design
Abdel Naser Zaid Pharmaceutical Chemistry and Technology, Pharmacy Department, Faculty of Medicine & Health Sciences, An-Najah National University, Nablus, West Bank, PalestineCorrespondence: Abdel Naser ZaidPharmaceutical Chemistry and Technology, Pharmacy Department, Faculty of Medicine & Health Sciences, An-Najah National University, PO. Box 7, Nablus, West Bank, PalestineTel +970 9 234 5113Email [email protected]Abstract: Pharmaceutical film coating is considered a key part in the production of solid pharmaceutical dosage forms since it gives superior organoleptic properties products. In addition, it can improve the physical and chemical stability of dosage forms, and modify the release characteristics of the drug. Several troubleshooting problems such as twinning mottling, chipping, etc., may arise during or after or even during the shelf life of the film coated dosage forms. These troubleshooting problems may be due to tablet core faults, coating formulation faults and/or coating process faults. These problems must be overcome to avoid unnecessary product problems. Film coating as well as other parts of the pharmaceutical technology is subjecting to continuous innovation. The innovation may be at different levels including pharmaceutical excipients, processes, software, guidelines and equipment. In fact, of particular note is the growing interest in process analytical technology, quality by design, continuous coating processing and the inclusion of new ready for use coating formulations. In this review, we tried to explore and discuss the status of pharmaceutical film coating, the challenges that face this manufacturing process and the latest technological advances in this important manufacturing process.Keywords: film coating, troubleshooting, advances, functional
Compression coating, also known as press coating or dry coating, has been developed to produce tablets containing incompatible drugs and to develop modified-release products. It involves the compaction of the dry coating excipients around tablet cores that have been produced on the same machine. It requires the use of special tableting machines which means further capital investment by the pharmaceutical industry. Therefore, it is considered a complex method and has not been commonly adopted as a method to coat tablets. Accordingly, it is usually exploited when the drug is heat and water sensitive since it eliminates the use of organic or aqueous solvents. Recently compression coating has been found useful to develop and produce novel drug-delivery applications such as controlled release DFs.5
Film coating (FC) is considered the most popular and versatile method. FC is a modern and widely spread process for coating oral solid DFs in the pharmaceutical and food industries. The process of FC involves the spraying of a thin, but uniform polymer-based formulations onto the surface of solid DFs including tablets, capsules, pellets or granules. It can be classified into two specific classes; nonfunctional FC which is used to change tablet appearance, organoleptic properties, swallowing properties, and to protect tablets from the negative effect of the environment such as humidity, oxidation, and light effects. On the other hand, functional FC can be used to modify or delay drug release as well as the aforementioned benefits in the non-functional coating. Microencapsulation is a modified form of FC. In fact, the only difference relay in the size of the particles to be coated and the methods by which the coating is achieved. This rapidly expanding process is based on either mechanical or physicochemical methods or techniques. The mechanical techniques include air-suspension, multi-orifice centrifugal, and modified spray-drying techniques, while the physicochemical methods involve coacervation-phase separation, which needs that the drug to be coated is dispersed in a suitable solution of the polymer6,7 (Figure 1).Figure 1 Different FC techniques and processes (A) Conventional FC pan, (B) Fluid bed FC, (C) Phases of FC, (D) Phases of microencapsulation.
Product stability is considered one of the most important goals in pharmaceutical developments. Accordingly, a scrutinized effort should be carried out to achieve stable products for the longest time. This includes using suitable pack design, desiccants, and specialized moisture protective FC polymers (Table 1).19
Modifying drug release is a common practice in DF design which can be accomplished using FC. Two types of modified release DFs are described by the USP, those that are enteric-coated and those that are extended-release. Delayed-release products which often designed to prevent drug release in the upper part of the GIT. FDs is designed to produce this type of DF are commonly named enteric coatings.30 On the other hand, FCs that are designed to prolong drug release over a long period or to reduce the drug regimen are commonly named sustained- or extended-release FCs.31
Continuous innovation in pharmaceutical processes and equipment allows for continuous innovation in pharmaceutical technology including pharmaceutical coating. The industry now requires technology for coating not only core tablets and pellets, but also other delivery systems such as catheters, ingestible imaging instruments, stents, joint plates etc. Accordingly, with the appearance of such technologies, FC will continue to flourish hand-in-hand. However, such technologies require complicated coating techniques to keep patient safety at the vanguard. In fact, drugs are required to be released at very specific intervals and at very specific sites in the GIT. Accordingly, these requirements push the FC industry toward advanced and novel innovations. This implies pharmaceutical industries to continuously be engaged in process and product improvement and does not limit only to sugar and FC but have also varied into other excipients. Unfortunately, an internal conservatism shown by many pharmaceutical industries towards accepting significant changes in excipients, equipment and processing technologies. Therefore, the intended trend looks to be evolutionary rather that revolutionary. In fact, of particular note is the growing interest in process analytical technology (PAT) which tends to bring several analytical procedures out of the laboratory and closer to the production process with which they may be linked. Therefore, introducing, an in-line control function, specific analytical techniques that can be used to enhance the quality of the final coated products is considered an important innovatory step in this field. For example, near infra-red techniques which can be used to analyse coated product in a manner that, the in process quality tests such as; moisture contents, drug contents, amounts of the applied film coating, and even, to some extent, drug release profile can be predicted before the end of the coating process and before the product is being discharged from the coating pan. This would greatly positively impact the quality and the final cost of the produced coated brand.61,62
Recently, Zhu et al have developed a novel method of applying powder coatings using electrostatic charges.70 This process involves sequential spraying of a liquid plasticizer to the tablets being coated. After that, the powder of the remaining coating materials is applied and then completing the formation of the coating using a heat-curing phase. Another work about electrostatic dry powder FC technique was reported by Qiao et al Two immediate release coating liquids were successfully applied using this process. A liquid plasticizer was sprayed onto the surface of the tablet cores to improve the conductivity of these cores. In fact, this would result in enhancement of the deposition of the sprayed particles, reduction of the electrical resistivity, and reduction of the glass transition temperature of the coating polymer in the coating pan. After that, the liquid plasticizer was successfully applied. Then, spraying charged coating particles using an electrostatic charging gun to enhance the uniform deposition on the tablet surface was carried out. This enhanced the coalescence of the coating particles into a thin film by processing it at an acceptable curing temperature. The authors claimed that that the optimized dry powder coating process produced FC tablets with good coating uniformity, smooth surface, and release profiles that are comparable to that of the tablet cores. The data also suggest that this novel electrostatic dry powder FC technique may be used as an alternative approach to aqueous- or solvent-based FC process for solid DFs.71 In addition, this technique showed successful results among a range of existing pharmaceutical coating materials, and has been applied for both immediate-release and modified-release FC. Recently 3D printing is gaining important interest in pharmaceutical technology since it addressed several novel challenges including combinations of several APIs in one DF, on request production at the point of need, personalization of drug release patterns as well as patient-specific solutions. Accordingly, 3D printing may become a novel and promising road to develop and produce drug products, capable to support specific therapies, and improve patient compliance, safety, and efficacy. In 2020, Elini et al, tried to partially coat tablets with a glyceride, namely Precirol ATO 5 using a semi-solids 3D printer as an approach for tuning the release of two APIs, a hydrophilic and lipophilic drug, Melevodopa and Acyclovir respectively. The percentage of the tablet surface coated, the number of coating layers the coated sides of the tablet as well as other manufacturing parameters where adjusted to achieve the desired release profile for both APIs.72 Vacuum film coating follows a novel procedure since it offers explicitly designed pans and offers some aspects of the fluid-bed coating. Precisely, a water jacket is used to keep a constant temperature. In addition, it could be sealed to achieve the desired vacuum level. The core tablets are placed in the sealed pan and nitrogen is used to displace the air in the pan before attaining the desired vacuum state. The heated pan is used to dry and vacuum is used to remove the evaporated liquids. The absence of high-velocity heated air causes an improvement in the efficiency of the process. In addition, there is an energy-saving when compared with the conventional pharmaceutical FC process.73