MN 552 Midterm Exam Study __., __., __., __., __.,
Guide with complete solutions.
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What is a Liposome? __., Microvesicle consisting of a bilayer of
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amphipathic lipids surrounding an aqueous core __., __., __., __., __.,
- Liposomes are good carriers of drug molecules
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- hydrophilic and hydrophobic drugs can be incorporated into liposomes
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> Hydrophilic drugs can be encapsulated within the aqueous core, whereas
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hydrophobic drugs can be associated with the bilayer
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As drug carriers they can provide sustained and targeted release of the
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associated drug __.,
Phospholipid __.,__., - one FA chain forms a micelle
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- two FA chain form bilayers and with a high enough concentration, you
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can get liposome
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- spontaneously forms structure
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- Name = # carbons : # unsaturated bonds in chain
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- the more unsaturated it is, the less interaction with the hydrophobic
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tails because they tend to kink
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Transition Between the Solid and Fluid State
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results in a Change in Bilayer Dimensions
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- measure stability through melting temperature
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,- less kinked forms a good liposome because better interactions
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- liposome melts when chain gets disorganized (reduces interactions)
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- cholesterol can make liposome more stable by increasing interactions
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- n = length of FA tail
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- longer FA tails are harder to melt (interacting better)
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- including an unsaturated bond, the transition temperature is greatly
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reduced (stability is reduced) __., __., __.,
What is Modified Release?
__., The term modified-
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release is used to describe dosage forms that alter the timing and/or the
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rate of release of a conventional drug product/dosage form
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- FDA does define this
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Some Modified Release Systems
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1. Delayed release
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2. Repeated Release or Repeat Action
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4. Extended, Sustained, Long-Acting, Prolonged, Controlled Release
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5. Targeted Release
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Delayed-release - __.,__., __.,
dosage forms release the drug at a later time than an immediate dose
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system
- Delayed-release can include enteric-
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coated tablets, where timed release is achieved by a barrier coating
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takes more time to release drug; doesn't start dissolving until a certain
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point of time __., __.,
,Repeat-release - __.,__., __.,
multiple doses of immediate release drug units with intermittent dosing
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- Such as repeat-action tablets and capsules
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Extended, Sustained, Long-Acting, Prolonged, Controlled Release
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Extended, Sustained-
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release systems slowly release the drug over an extended period of time
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- Rate and duration are not always designed to a particular profile
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__.,If the system can maintain predictable levels of drug in the target tissue
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_., or cells, it is considered controlled- release. (Examples: XL,SR,CR)
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- Controlled release systems are also called extended or sustained
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(prolonged) release __.,
- dissolves and continues dissolving for a longer time
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Targeted Release - Site- __., __.,__., __., __.,
specific or targeting refers to concentrated drug release at a certain site
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such as a tissue, organ, receptor, or cell
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- A form of controlled release
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- very difficult to achieve
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- trying to control distribution of drug to target area
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What is Controlled Release?
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Controlled Drug Delivery attempts to deliver the precise amount of a the
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rapeutic agent (drug), to a specific site (site of action), for a specific time
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(duraterm-5tion of treatment)
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, - OR Achieve both spatial (targeted) and/or temporal "control" of the drug
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- a lot of prediction involved, very precise, and targeted
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- The Drug Delivery System attempts to control the drug concentration
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at the target tissue
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Disadvantages of Conventional Delivery - __., __., __., __.,__., __.,
Inconvenient because pt can forget to take dose
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- Difficult to monitor
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- Overdosing possible
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__., Large amounts of drug can be "lost" when it does not get to the target
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__., organ because has to distribute to the whole body
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- Drug goes to non-target cells and can cause damage
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- Expensive (using more drug than necessary)
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The Goal of Modified Drug Delivery
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- Absorption
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- Distribution - includes Cellular Uptake
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- Metabolism (reduce it so more drug available)
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- Elimination (reduce how fast eliminated to prolong effect of drug)
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- Toxicity (reduce it)
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What is Sustained Drug Action?
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- pt only has to take one time rather than multiple times
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