Edward Tidswell | Merck - Academia.edu (original) (raw)

Papers by Edward Tidswell

PDA journal of pharmaceutical science and technology, 2010

Let's read! We will often find out this sentence everywhere. When still being a kid, mom used... more Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd microbiology and sterility assurance in pharmaceuticals and medical devices to read.

Pharmaceutical manufacturing processes are vulnerable to varying degrees of microbial challenge (... more Pharmaceutical manufacturing processes are vulnerable to varying degrees of microbial challenge (hazard) quantifiable as microbial ingress, and microbial retention risks affecting raw materials and inputs to the final product. Control over these risks is exacted by both purposefully designed and incidental (or fortuitous) properties of the manufacturing processes. Within the manufacturing environment, equipment cleaning and hold processes are uniquely prone to microbial challenge yet paradoxically demonstrate the greatest potential for mitigation of these risks. Cognition of those components and contributing factors associated with microbial challenge are necessary to facilitate scientifically sound risk assessments. In the context of equipment cleaning and hold processes, risk assessments are necessary to identify and contrive conditions, which are truly worst case for the validation of the control of microbial challenge. A number of components contribute to the risk of microbial r...

Risk management and formal risk assessment represents an efficient vehicle for achieving enhanced... more Risk management and formal risk assessment represents an efficient vehicle for achieving enhanced quality assurance and regulatory compliance. One area of pharmaceutical manufacture which benefits especially from risk-based strategy is validation. Moreover, expedient validation of the control of risks posed by extrinsic microbial hazards to pharmaceutical manufacture may be achieved through formal risk assessment. For decades, the food industry has recognized that the attendant uncertainty and variability associated with microbial hazards is adequately accounted for in such risk assessments. Within routine pharmaceutical manufacturing operations, the processes of equipment cleaning and hold (pre-clean and post-clean) are chronically vulnerable to challenge from microbial hazards. Yet simultaneously they demonstrate great potential for the incidental mitigation of risks realized from these hazards. Validation of the control of microbial hazards during equipment cleaning and hold proc...

PDA journal of pharmaceutical science and technology, 2006

Expedient risk assessment of aseptic manufacturing processes offers unique opportunities for impr... more Expedient risk assessment of aseptic manufacturing processes offers unique opportunities for improved and sustained assurance of product quality. Contemporary risk assessments applied to aseptic manufacturing processes, however, are commonly handicapped by assumptions and subjectivity, leading to inexactitude. Quantitative risk modeling augmented with Monte Carlo simulations represents a novel, innovative, and more efficient means of risk assessment. This technique relies upon fewer assumptions and removes subjectivity to more swiftly generate an improved, more realistic, quantitative estimate of risk. The fundamental steps and requirements for an assessment of the risk of bioburden ingress into aseptically manufactured products are described. A case study exemplifies how quantitative risk modeling and Monte Carlo simulations achieve a more rapid and improved determination of the risk of bioburden ingress during the aseptic filling of a parenteral product. Although application of qu...

PDA Journal of Pharmaceutical Science and Technology

PDA journal of pharmaceutical science and technology, Jan 27, 2018

The terminal sterilization of drugs and devices is the most appropriate means of assuring patient... more The terminal sterilization of drugs and devices is the most appropriate means of assuring patient safety in terms of prevention of infection. Adoption of terminal sterilization processes requires a supporting and thorough program for control and monitoring of bioburden; especially if a parametric release program of sterilization is desired. Such a control program must necessarily assess and evaluate the resistance of associated bioburden (primarily spores) which may resist inactivation and challenge the sterilization cycle. Evaluation of the resistance of the bioburden can be achieved by several means and procedures (e.g., using the boil test), however these must be designed and implemented with consideration of the nature of the spore and spore recovery. This short review also describes the application of moist heat resistance determination in the terminal sterilization of drugs.

PDA journal of pharmaceutical science and technology, Jan 12, 2017

Marketed drugs and devices possess specifications including critical microbiological quality attr... more Marketed drugs and devices possess specifications including critical microbiological quality attributes purposed to assure efficacy and patient safety. These attributes are legislated requirements intended to protect the recipient patient. Sampling, microbiological testing, interpretation of data for final products, raw materials and intermediates all contribute to a cohesive assessment in the assurance of finished product quality. Traditional culture-based microbiological methods possess inherent and unavoidable variability, recognized by the compendia and which might lead to erroneous conclusion pertaining to product quality. Such variability has been associated and intrinsically linked with data integrity issues; manufacturers have subsequently been encouraged by regulatory authorities to introduce multiple microbiologists or checks to prevent such issues. Understanding microbiological variability is essential such that genuine data integrity issues are identified. Furthermore, a...

J Chem Technol Biotechnol, 2007

Enzyme and Microbial Technology, Aug 1, 1997

Prominent among several factors that have been reported to affect the enantioselectivity of keton... more Prominent among several factors that have been reported to affect the enantioselectivity of ketone reduction by washed suspensions of microorganisms are (i) the phase of batch culture at which the organisms are harvested, and (ii) the concentration at which the ketone is supplied. S&atone (6-methylhept-5-en-2-one) is only poorl) soluble in aqueous media, but in the present study a novel microbe friendly organic solvent mixture was employed to present this ketone in a range of concentrations to cell suspensions offour bacteria that were then incubated in an atmosphere of hydrogen for 6 h at 30°C. The bacteria employed were Clostridium pasteurianum, Clostridium tyrobutyricum fr~o strains), and Lactobacillus brevis that had been harvested at various times from unaerobically growing batch cultures. L. brevis formed R(-)-sulcatol in high enantiomeric excess irrespective of its period of pregrowth in batch culture and the substrate sulcatone concentration (over the range 0.02-1.5 mM); however, in the case of all three clostridia, the enantiomeric selectivit?, of sulcatone reduction was substantially aflected by both of these factors. It is likely that this reflects the possession by these clostridia of multiple ketone reductases differing in their K, values for sulcatone and present in the organisms in di$fering proportions during the course ?f their batch culture growsth.

Appl Microbiol Biotechnol, 1991

Growth of Clostridium tyrobutyricum on mannitol was possible only when an ancillary oxidant was a... more Growth of Clostridium tyrobutyricum on mannitol was possible only when an ancillary oxidant was additionally supplied. Hexacyanoferrate(III) in the presence of methylviologen could fulfil this role, which is normally better accomplished by acetate (and some other organic electron acceptors including acetoin, crotonate and 3-hydroxybutyrate). Several ketones, including pentan-2-one, although slowly reducible by the organism were unable to support its batch culture growth on mannitol. However, when a chemostat culture supplied with excess mannitol but limiting acetate was supplemented with pentan-2-one, a spontaneous mutant strain was selected that was much improved in its specific rate of reduction of this and other ketones, and which was capable of batch growth on mannitol plus pentan-2-one. This procedure may more generally be employed to select strains of anaerobic bacteria improved in their bioreductive abilities.

Pda Journal of Pharmaceutical Science and Technology Pda, 2010

Vascular access of patients by peripheral and central venous catheters for the delivery of steril... more Vascular access of patients by peripheral and central venous catheters for the delivery of sterile or aseptically manufactured parenterals is commonly regarded as one of the major causes of blood stream infections. Rigorous evaluation and management of the risks of microbial infection originating from the administration of aseptically manufactured therapies remain imperative to reduce patient infection risks. Healthcare clinicians are continually faced with choosing intravenous (IV) parenteral administration strategies to minimize patient blood stream infection risk. Data facilitating such decisions are often difficult to obtain. Analysis and interpretation of the available, reported hospital infection rate data to evaluate medical device- and therapy-associated infection rates are constrained by the variability and uncertainty associated with each individual administration scenario. Moreover, clinical trials quantifying infection risk are constrained by their practicality, cost, and the control of the exacting requisite trial criteria. Furthermore, it is ethically inappropriate to systematically conduct clinical evaluations incorporating conditions that do not favor the best possible patient outcomes. Quantitative risk modeling (QRM) is a unique tool offering an alternative and affective means of assessing design and clinical use in the context of the clinical environment on medical device and combinatorial therapy infection rates. Here, we report the generation of QRMs and the evaluation of manual admixing IV bags for use in IV administration sets upon patient infection rates. The manual admixing of IV bags was assessed for the opportunity and risk of microbial ingress accessing across the sterile barrier during clinical preparation and contaminating the IV solution. The risk of microbial contamination was evaluated under (a) ISO 5 compounding conditions adopting ideal aseptic technique (in compliance with USP 〈797〉) and (b) realistic worst-case point-of-care conditions (typically found in hospital wards). These choices of conditions encompass the complete spectrum of clinical environments encountered in the hospital. The evaluation estimated contamination rates ranged from &amp;lt;2.2 ppm (2.2 contaminated units in every million uses) to 2.9% (29 contaminated units in every 1000 uses), contingent upon the clinical environment. QRM permits the swift probabilistic evaluation of contamination rates providing the healthcare professional with data to make an informed choice of medical devices and a preparation strategy in their precise clinical context, reducing hospital acquired infections for optimal clinical patient outcomes.

PDA journal of pharmaceutical science and technology / PDA

Mollah/Risk Management Applications in Pharmaceutical and Biopharmaceutical Manufacturing, 2013