DD Practice Questions JJB 2018 to Bb PDF

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Drug Delivery Practice Questions Dr. Jonny Blaker School of Materials

Lecture 1. (a) Explain the differences between temporal controlled and distribution controlled release systems using diagrams where appropriate. (b) Provide diagrams and brief explanations for FOUR drug delivery systems. Lecture 2. A membrane-controlled reservoir device has been implanted within a patient for controlled release of morpholine (a water-soluble pain killer). It consists of a membrane that has a volume fraction of porosity = 0.5, a thickness of 1 m and a tortuosity of 100. The total area of the membrane (which encapsulates the reservoir) is 1 cm 2. The partition coefficient for morpholine in the membrane is 0.56. The reservoir contains morpholine with a concentration of 10 wt.% The diffusion coefficient for the drug through the membrane is 10-10 m2s-1. (a) What is the morpholine flux expressed in the units of kgm -2s-1? You may assume that perfect sink conditions apply. The density of morpholine and reservoir medium are 1.0 gcm-3. (b) What is the release rate of morpholine expressed in units of mgh-1. (c) How much morpholine has been released in 24 h? (d) How could the release rate be halved? Which of these options could be achieved through modification of device design. Explain briefly. Lecture 3. (a) Briefly explain the processes that occur during a foreign body reaction. (b) Give a definition for a hydrogel. Briefly explain why hydrogels usually have very good biocompatibility. (c) What structural features would a polymer have if it were required to exhibit outstanding biocompatibility? Lecture 4. (a) Draw the structures of the repeat units for four biodegradable esters that are approved for use in medical devices by the FDA. How does the polymer structure affect the rate of degradation? (b) Give a chemical equation that describes the formation of polylactide from lactide. What are the limitations of its preparation from the viewpoint of constructing drug delivery vehicles? (c) Describe how a pulsatile release system can be constructed using biodegradable polymers for drug release. What advantages could this system provide?

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Lecture 5. (a) Explain the process used to prepare microspheres containing water-soluble therapeutic agents. (b) From your answer to (a) list three variables that can be altered during preparation and state what the effects each of these will have on drug delivery rates. (c) Explain the term “burst release”. From your answer to (a) explain how the process can be controlled to minimise burst release. (d) From your answer to (a) and assuming the agent is insoluble in the polymer matrix, (i) identify the general device type that the particles would resemble in the context of drug release rates and (ii) give the appropriate equation for mass of drug released as a function of time. (e) Microspheres used to deliver leuprorelin acetate over a 3 month period were prepared using PLA with a molar mass of 15,000 g mol -1. This contrasts to PLGA 12-14,000 g mol -1 which was used to prepare microspheres for releasing the drug over a 1 month period. Justify the choice of the material used for the 3-month release system. (f) Explain the leuprorelin acetate release vs. time profile for the 1-month depot formulation. Lecture 6. – The course work is based on this so no practice question given Lecture 7. (a) What is the optimum size range for drug carriers in order to passively target tumour tissue? Justify your answer. (b) Briefly explain the zipper effect in relation to binding of delivery systems onto cells. (c) Briefly describe a liposome. Use a sketch to illustrate your answer and describe how it can be used to target tumour cells. (d) Briefly explain the differences between passive and active targeting. Lectures 8 and 9. (a) The release of carmustine from Gliadel wafers is mainly diffusion controlled. Explain why this is the case and draw a diagram that depicts the %release as a function of time. (b) Compare and contrast the design of Lupron depot and Gliadel wafers in terms of (i) the nature of the matrix (ii) the rate of matrix degradation and (iii) the rate of active release. Lecture 10. (a) State FOUR types of stimulus that can be used to trigger a conformational change for polymers. (b) Describe the mechanisms for two of the stimuli given in (a)....