Aulton's Pharmaceutics: The Science of Dosage Form Design Here is the link. Get this from a library! Pharmaceutics: the science of dosage form design. [ Michael E Aulton;] -- A comprehensive textbook covering the design of dosage forms. PHARMACEUTICS: THE SCIENCE OF DOSAGE FORM DESIGN, LONDON: CHURCHILL LIVINGSTONE, GB,. PAGE(S) - , ISBN: .
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1 The design of dosage forms Peter York CHAPTER CONTENTS Principles of dosage form design 1 Biopharmaceutical aspects of dosage. Pharmaceutics: the science of dosage form design subject in the pharmacy curriculum, encompassing design of drugs, their manufacture, and Format: PDF. Aulton__PharmaceuticsThe Science of Dosage Form Design 2 Ed - Free ebook download as PDF File .pdf), Text File .txt) or read book online for free. hhhhh.
The Pharmaceutical Journal Vol No p September 16, The Conference Science presentations Pharmaceutics: solid dosage form design, biomaterials and particulate technology Pharmaceutics was well represented in both oral and poster formats. A wide range of disciplines was evident including solid dosage form technology, pharmaceutical materials science, rheological analysis of pharmaceutical systems, particulate technologies and unit operations. This review provides an overview of selected abstracts that were presented at the Conference either as posters or in a podium session on materials science chaired by Dr Peter Timmins Bristol Myers Squibb. Solid dosage form technology This category encompassed a wide range of topics, including tablet-coating technology, the formulation of controlled-release systems, compaction properties of powders and granulation. The interest from industry in this category was evident as many abstracts were either authored or co-authored by workers from pharmaceutical companies.
Williams University of Nottingham. The immiscibility of the two components, and the preferential surface expression of MPC-co-LMA were identified using atomic force microscopy. In the light of the ultimate role of the adhesion of these molecules to the bioincompatibility of medical devices, this study has identified a material with promise as a medical device coating.
On a similar topic, M. Santin, A. Motta, M. Migliaresi, A. Lloyd and S.
Denyer University of Brighton concluded that the interaction of fibrin ogen with fibroin, a biocompatible polymer, occurred in a calcium-independent manner. Interestingly, the authors speculated that the biocompatibility of fibroin could be modified by alterations in the processing procedures. This route may therefore offer a practical method to enhance the use of silk fibroin as a medical device biomaterial.
Examples of pharmaceutical dosage forms that were characterised in this fashion included liquid crystalline semi-solids, polymer gel networks, nasal sprays and transdermal matrices. Of particular interest to the rheological fraternity was the application of capillary rheometry for the analysis of the extensional deformation of nasal sprays by G.
Eccleston and N. Hudson University of Strathclyde. Capillary rheometry is a technique that is commonly employed for the characterisation of the extensional deformation of polymer melts and has an obvious role in the understanding of polymer flow for processes such as injection moulding and polymer extrusion.
Using this technique, the authors highlighted the importance of extensional viscosity both on the flow of nasal solutions through the orifice of the container and also on the size of the atomised droplets. Rheological methods were also employed to identify the instability of hydroxyethylcellulose HEC gels in the presence of redox agents by B.
Muldoon, D. Jones and A. Woolfson Queen's University of Belfast. The authors reported that the textural and flow properties, as determined using texture profile analysis and flow rheometry, of HEC gels were compromised by the presence of a model redox agent ironoxide following storage at different temperatures 0 and 37C for one month. These observations were attributed to oxidative depolymerisation of HEC and, considering the redox potential of many drugs and excipients, the use of HEC as a gel matrix for such formulation components may be limited.
Continuing the theme of topical pharmaceutical systems, the mechanical properties of bioadhesive amethocaine films for percutaneous local anaesthesia were examined by A. Woolfson, D. McCafferty and G. Moss Queen's University of Belfast using tensile analysis. In particular, these authors reported that the polymer concentration, pH of the casting gel and concentration of glycerol significantly affected the mechanical properties of these hydrophilic films.
Interestingly, this study highlighted the plasticiser properties of amethocaine base and suggested that a clinically acceptable film may be manufactured without the addition of a specific plasticiser. On a related issue, M. Reason, G. Smith, P. Teesdale-Spittle, R. Latham, G. Dawson and P. Porteous De Montfort University described the novel use of the thickness shear mode TSM sensor to simultaneously characterise the viscoelastic and mucoadhesive properties of low crystallinity cellulose LCC films.
In this, LCC was deposited on to the surface of the TSM sensor and, from the resultant impedance spectra, the viscoelastic properties of this material were characterised. Exposure of the deposited LCC film to mucin solutions over a range of pH values increased both the mass and viscosity of the films in a pH-dependent fashion, these changes being attributed to interaction between the two polymeric species.
While further clarification of the limitations of this technique is required, the TSM mode biosensor would appear to offer great potential for the characterisation of the interaction between mucin and pharmaceutical excipients. Particle and crystal technologies A recurring theme in the pharmaceutics section of this year's Conference was the design and characterisation of particulate dosage forms and crystal structure. Many topics were described in this category including freeze-drying, the crystalline, polymorphic and amorphous states, and supercritical fluid SEDS technologies for particle engineering.
In particular, three presentations from the University of Bradford described the importance of SEDS for the production of particles of salbutamol sulphate D.
Gilbert, S. Palakodaty and P. York and terbutaline sulphate M.
Rehmen, B. Shekunov, P. York and P. Colthorpe and for the production of pure anhydrous polymorphs of carbamazepine A. Edwards, B. Shekunov, R. Forbes and P. The authors illustrated the versatility of the technique for the production of particles of defined size and shape that were suitable for respiratory drug delivery.
Furthermore, the ability of the technique to produce defined drug polymorphs carbamazepine was confirmed by X-ray powder diffraction. The last study has confirmed the significance of SEDS for the generation of defined forms of a single drug substance, a problem that has plagued the pharmaceutical industry for many years. Several presentations described the applications of freeze-drying to the production of pharmaceutical materials and dosage forms and factors by which this process may be controlled.
Frequently, sugars, such as trehalose, are employed as lyoprotectants during the freeze-drying and subsequent storage of dosage forms like liposomes and peptides. Due to the importance of the amorphous state in this lyoprotectant behaviour, the transition from amorphous to crystalline states of trehalose was examined by O. McGarvey and D. Craig Queen's University of Belfast using differential scanning calorimetry.
The authors reported that amorphous trehalose recrystallised above the glass transition temperature and that the temperature range over which this occured was dependent on the moisture content. This has obvious implications for freeze-drying using trehalose as an excipient. In a related presentation, C. Martin, V. Bramwell and H. Alpar Aston university described the effects of freezing rate and the addition of sucrose, another lyoprotectant, at different time points during liposome preparation on resultant liposomal size and the entrapment of carboxyfluorescein.
Similarly, the effect of storage of a freeze-dried formulation containing lactate dehydrogenase on the subsequent activity was described by V. Kett and D. Craig Queen's University of Belfast with D. Deutsch Glaxo Wellcome, Ware. Following freeze drying, samples were stored over a range of temperatures, following which the glass transition was measured by differential scanning calorimetry and the lactate dehydrogenase activity assayed.
Interestingly, the stability of this protein under examination was not enhanced following storage at temperatures below its glass transition. This has important consequences in the storage of protein-based freeze-dried formulations.
Further advances in particulate technology have involved the design and characterisation of systems for the delivery of macromolecules, and this was the focus of several presentations at the conference. In an interesting study, K. Controlled release delivery is available for many routes of administration and offers many advantages over immediate release delivery. Controlled Drug Release Technology of Drugs In order to achieve efficient disease management, the concentration of released drugs from polymeric matrices should be within the therapeutic window with minimal fluctuation in blood levels over prolonged periods of time at the intended site of action [ 1 — 3 ].
The release of drug can be controlled by diffusion, erosion, osmotic-mediated events or combinations of these mechanisms [ 4 , 5 ]. Typically, a triphasic release pattern is observed, consisting of an initial burst [ 4 ], primarily attributed to drug precipitates at the particle surface and surface pores in the polymer, and the osmotic forces in highly water-soluble peptide formulations [ 6 ], a lag period depending on the molecular weight and polymer end-capping [ 5 ] and finally erosion-accelerated release [ 6 ].
Considering release rate control as a key parameter, a decrease in particle size i. Also, higher porosity of the particles inducing a larger inner surface can increase the influx of the release medium into the particles and, thereby, facilitate the drug diffusion rate [ 7 ].
In addition, the specific properties of the polymer matrix e. Therefore, switching to a different molecular weight or an end group capped polymer, and the use of block copolymers will alter the diffusion and drug release rate [ 10 , 11 ]. To achieve zero-order release kinetics indicative of uniform release with respect to time, which is desired for most applications, a combination of fast- and slow-releasing particles or the use of copolymers are possible alternative advanced methods [ 12 , 13 ].
A one-time only dose can be achieved by co-injection of a bolus of soluble drug as a loading dose and zero-order releasing microspheres as a maintenance dose. Types and Classes of Biodegradable and Biocompatible Pharmaceutical Polymers Biodegradability and biocompatibility of a polymer are among the most important properties for pharmaceutical applications.
Biodegradation is generally described by two steps, namely: 1. Biocompatibility refers to specific properties of a material not having toxic or injurious effects on biological systems.