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31 Cards in this Set
- Front
- Back
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Advanced Drug Delivery: A therapeutic Systems approach to optimize the timing (temporal control) and location (spatial control) of drug delivery.
(Statement, not a question) |
Statement, not a question
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Rationale and Incentives for ADR, what are the three?
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1) Benefits to the patient
2) Convenience 3) Compliance |
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Rationale and Incentives for ADR: What are the benifits to the patient?
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1) Safety and Efficacy
2) Convenience 3) Compliance |
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Temporal control of drug delivery. What is it?
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Optimizing the TIMING of drug delivery.
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In reference to Temporal Control of Drug Delivery, what ar the three objectives?
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1) To achieve constant blood levels. I.E. to minimize peaks and troughs in the blood.
2) To accommodate Periodic Changes in the Body--where drug delivery is timed to maximize effects or minimize side effects. 3) To Achieve Bioresponsive Drug Delivery. Where the drug is delivered automatically in response to a biological need. |
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What is Chronotherapeutics?
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Therapeutics based on biological rhythms.
There are several types of rhythms that operate in bodily processes. |
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Give some examples of bodily processes that are periodic in nature?
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1) Endocrine Function
2) Cardiovascular Function 3) Immune Function 4) Cytokinetics |
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Self-Regulated Systems (Glucose-responsive insulin delivery) is best used in the "To achieve bioresponsive drug delivery"
(statement, not a question) |
Statement, not a question.
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What is Targeting?
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Where the goal of the therapeutic system is to deliver the drug only to where it is needed.
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What are some potential target sites?
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1) Tissue Site
2) The Cell 3) Intracellular |
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Descirbe the Ideal Drug Delivery System.
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1) Gives proper timing of drug delivery over the period of treatment.
2) Delivers the drug only to the site of action |
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Descirbe the Available and Experimental Theraperutic Systems.
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1) Polymeric and Mechanical Devices: Intravenous, Oral, Transdermal, Subdermal, Intrauterine, Ophthalmic.
2) Carriers: A) Particles (Liposomes and microspheres) and B) Soluble Macromolecules (antibodies and other proteins). |
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Why are polymers for therapeutic systems important?
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They are critical for most of advanced drug delivery:
1) They control the rate of drug release from the system (drug travels through pores in the polymer) 2) They are currently used in most routes of administration |
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Mass Transfer Across Polymers. Describe the rate of passage (flux) of the drug through a polymer.
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Flux = (area/length) x (permeability) x (concentration deifference)
Permeability = (partition coefficient) x (diffusivity) |
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Flux = rate of transport through the polymer
Area = area in contact with the environment Length = polymer thickness Permeability = a function of drug/polymer interaction Concentration difference = concentration gradient across the polymer Partition Coefficient = solubility in external medium/solubility in polymer Diffusivity = how well the drug can diffuse through the polymer (this is not a question) |
(not a question)
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What are the three main mathematical models that apply to drug release from polymer systems?
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1) Zero-Order Release
2) First-Order Release 3) Square-root-of-time release |
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Descirbe Zero-Order Release.
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Release rate remains constant until the device is exhausted of active agent.
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Describe First-Order Release.
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Release rate is proportional to the mass of active agent contained within the device. Generally not important for controlled release.
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Describe Square-root-of-time release.
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Release rate is linear with the square roote of time and remains finite as the system approached exhaustion. Very important for controlled release.
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Know the equations and the graph, page 3-4 of the notes.
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Know the equations and the graph, page 3-4 of the notes.
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Which plot depict steady, prolonged drug release rates?
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t^1/2 (square-root-of-time)
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What is a diffusion device?
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Diffusion through polymer determines release.
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Diffusion Device: Describe the resevoir.
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Where diffusion from a saturated resevoir is controlled by polymer membrane.
A) Initial high release from membrane B) Constant release when depot concentration is constant C) Release rapidly decline as device rapidly approaches exhaustion |
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Diffusion Device: Describe the Matrix.
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Unifromly dispersed drug diffuses thorugh a polymer matrix.
Fluid enters and dissolves the drug in the outer areas. The dissovled drug leaves, creating a ghost (empty) matrix, which continously expands (i.e. path length increases) over time. Square root of time release. |
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Describe solvent-controlled osmotic release.
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Osmotic pressure governs the release.
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What type of osmotic release device are focusing on?
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Ones with Flexible Compartment.
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Describe the mechanics of the Flexible Compartment.
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Water is drawn in by osmosis, because an osmotic agent (NaCl) is inside.
Drug is forced through a laser-drilled hole and is released in a precisely controlled fashion. Note: dry release is nearly zeri-order. |
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Note: the "flexible membrane" may look totally different from the above picture
(not a question) |
Statement, not a question.
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Describe the Solvent-controlled Swelling type of release.
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The drug is uniformly dispersed in a polymer matrix. Release is governed by the swelling of the matrix in biological fluids.
As matrix swells, pore size increase, as does flux. |
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Describe the Solvent-controlled chemical controlled release.
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Bioerodible polymers. The drug is uniformly dispersed in a polymer matrix. The matrix degrades in biological fluids, usually by hydrolysis of the polymer.
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Different factors can control the drug release. Such as...?
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Boerodible: drug can be released as matrix degrades AND by diffusion through intact matrix.
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