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Drug Delivery Final
Terms in this set (105)
List two major reasons for failures during drug development.
-Lack of Efficacy
Briefly explain the different phases associated with drug pharmacokinetics.
Absorption: Need to get drug into patients body
Distribution: Where the drug goes once in the body
Metabolism: Used to convert drug into something that can be used or elimination
Excretion: Elimination of drug from body
The three advantages of drug delivery systems are:
Increased patient compliance
List three factors affecting adsorption of drugs
Route of administration
Molecular weight/ Solubility
Contents of GI tract
List one disadvantage of intravenous administration.
Overdose danger (cannot be easily reversed)
List one advantage of transdermal delivery.
Controlled and prolonged absorption
The Area Under the Curve of a drug in the blood represents --
Overall drug exposed
How does pH affect weak base drug's solubility?
As pH is increased solubility is decreased
Explain the difference between avidity and affinity
Avidity is multiple interactions b/w molecule and receptor
Affinity is a single interaction b/w molecule and receptor
Give one possible reason of the drug concentration profile into the brain over time after IV administration as shown in the figure
Drug passes through blood/brain barrier
Briefly explain what is the first pass metabolism.
The elimination that occurs when a drug passes through the liver making it hydrophilic
Hydrophilic drugs are excreted faster or slower than hydrophobic drugs?
Explain the concept of tissue permeability:
Usually tight junctions b/w endothelial cells (continuous) but in some cases the junctions break and the endothelium has holes (discontinuous)
What is the main function of cytochrome P450?
Changing the chemical makeup of drugs passed through phase 1
List 2 reactions accomplished by CYP450 to metabolize drugs
Describe the concept of "bioactivation" during metabolism.
Drug is modified from inactive to active form increases potency of drug
. QTc prolongation due to drug side effects refers to______________________
Heart Rate irregularity
Define "Therapeutic Index".
Max Toxic dose / Min Effective dose
(Larger number the wider the margin of safety is)
When the therapeutic index is a large number, the margin of safety is_____________.
List 3 different types of intellectual property
List one advantage of trade secrets over patents
Protection can apply for more than 20 years
When does a patent issued in 1993 expire?
17 years from date of file pre-1995
20 years from file date post 1995
. The Drug Price Competition Act requires generic manufacturers to demonstrate that the ----------------------------------is bioequivalent to an approved brand drug.
What are the three requirements to grant a patent?
What is the difference between first to file and first to invent for a patent?
First to file is by submitting a form whereas first to invent is the actual invention
What is the main outcome of the Hatch and Waxman Act?
generic companies can produce and market cheaper drugs
What is the mission of the Bayh-Dole Act?
To allow government funded researchers to pursue ownership of invention (biotech boom~ 4000 firms created)
What is the mission of the Food and Drug Administration?
To protect health and safety of patients (incl. medical devices and food)
What is the mission of Over The Counter review for drugs?
To ensure all over the counter drugs are safe and properly labeled
What is the mission of the Food, Drug, and Cosmetic Act?
Prove safety before marketing, regulate device misbranding
What is the mission of the Orphan Drug Act?
Encourage the development of drugs with small market (< 200,000 people)
What is the mission of the Prescription Drug User Fee Act?
Allowed FDA to collect fees from drug manufacturers to fund new approval process
List two outcomes (one positive and one negative) associated with Prescription Drug User Fee Act?
Helped fund the new drug approval process
Raised the prices of drugs
What is the mission of the Food and Drug Modernization Act?
Shorten the regulatory review phase --> increase speed to market new products
. Briefly explain the difference between Enzon and Kopecek's PEG-drug conjugate technologies.
Enzon is linear with no ability to attach side chains (kopecek's has linear polymer with side chains)
List three important components of drug delivery systems
Rate determining element
List three biodegradable polymers approved by the FDA for medical use
Poly- Lactic- co- glycolic acid
Describe the difference between "bulk" and "surface" erosion
Surface: Change in size (degrades from outside in)
Bulk: No change in size (degrades from inside out)
List three factors accelerating the polymer degradation and explain why.
Water sorption: Contact with water causes reaction that degrades polymer
Reduction of mechanical properties: Polymer gets cut into many pieces
Weight loss: When reduction in mass some smaller particles will diffuse out
High drug metabolism results in low or high drug bioavailability?
Briefly explain the difference between Nektar and Kopecek's PEG-drug conjugate technologies?
Nektar had branched PEG molecules while Kopecek's was a linear polymer with side chains able to be attached
Discontinuous endothelium increases or decreases drug adsorption.
List one type of diffusion controlled delivery system.
Osmotic pressure device
List one type of chemically controlled delivery system
Drug covalently attached to polymer
Explain the difference between sustained and controlled release
Sustained release: releases drug for short period of time (hours)
Controlled release: releases drug for a long period of time (days)
List one favorable situation for a burst release and one favorable situation for a lag time?
Favorable for burst release: Wound Treatment
Favorable for lag time: short half-life of drugs in vivo
Release of a dissolved drug in a matrix follows the _____ order kinetics.
Release of a drug through a polymeric membrane follows the _____ order kinetics
The Fick's Second Law model is used for dispersed or dissolved drugs?
Release from an osmotic pump is controlled by______________________.
Explain the diffusion of the drug from a swelling-controlled device and how it relates to the hydrodynamic radius of the drug
The faster the device swells the faster the drug is released, device will swell faster if the size of the network is large
List three advantages of oral drug delivery.
Reduce dosing frequency
Increase patient compliance
List three disadvantages of oral drug delivery
Possible dose dumping
Why could oral drug delivery systems be useful to deliver drugs with short half-lives?
What are 3 major components of the mucous barrier in the intestine?
Water, Proteins, Lipids, Glycoproteins
Why drug candidates for oral delivery needs to be very potent?
Describe three ways of action of enzyme inhibitors?
-Noncompetitive inhibitor: Binds to enzyme and changes structure of enzyme
-Competitive inhibitor: Binds to the same site of the drug on the enzyme substrate
-Complexing agent: Site will not recognize drug
Describe three mechanisms to allow drugs to cross the intestine barrier. Be specific about the MECHANISMS
-Between tight junctions
List three approaches to overcoming the physiological barrier of the intestine. Be specific about the formulation aspects that can increase drug adsorption
Capsules: Protect from degradation
Nanoparticles: Can cross membrane
Bioadhesives: Long half-life
What is the concept of wetting theory to explain the mechanisms of bioadhesives
Wetting theory is the spreading and intimate contact of polymer with mucus membrane
Why it could be critical to deliver insulin to the microvilli in the intestine?
Much higher chance of drug to get to blood stream
Why it could be critical to deliver a vaccine to the Peyer's Patch in the intestine?
To deliver drugs via lymph, spleen, systemic circuit
Describe three floating drug technologies for oral drug delivery
-Adhesion to stomach wall: Prevent drug from being flushed from stomach quickly
-Sedimentation pellet: DD system is heavy and stays at the bottom of the stomach
-Floating dosage form: Always floats in stomach so stays longer in stomach
What is the major limitation of osmotic pump drug delivery systems?
Toxicity: Gut wall irritation or gut wall perforation
What is the main difference between PPOP and CPOP systems and what could be the impact on the drug delivery?
PPOP has the addition of a "pull layer" so the drug cant completely diffuse out of the orifice
What is the main advantage of PSOP compared to OSMET capsule systems?
Multiple drug layers in PSOP compared to one drug reservoir in OSMET capsule
What is the main objective of bioadhesives for oral drug delivery?
Increase retention time of the drug in the intestines
What is the main limitation of the Poly-pill technology?
Medication dosages cant be adjusted as easy
What is the main advantage of the Assemblage Module Pill technology?
Multiple drugs can be delivered and the release order can be controlled
Describe the expected release kinetics (Mt/Minf. vs time) of one drug encapsulated into the active core for both Geomatrix (2-layers system) and Geomatrix (3-layers system). The layers are biodegradable membranes and not swelling membranes
2 layer system follows first order release kinetics
3 layer generally follows 0 order kinetics
List three safety considerations associated with nasal delivery of drugs
List two advantages of nasal drug delivery
Avoid first pass metabolism
Explain the mechanism to increase drug adsorption into the skin when using iontophoresis
Repealing of the drug from the active electrode
Describe the drug delivery approaches of transdermal microneedle systems as shown in the figure below
-More needles has more surface are so more drug can be administered
-Injection above pain receptors increases patient compliance
Sedimentation of particles into the lungs increases with ________ diameter
List two advantages of large and porous particles in the context of pulmonary drug delivery.
Decrease of phagocytosis
More efficient aerosolization
Of the three mechanisms for the accumulation of particles into the lungs, which is not directly related (inversely related) to d2?
Explain what is the main benefit of using a spacer for a p Metered Dose Inhaler (pMDI)
Changes flow dynamics and allows drugs to go into lungs instead of staying in the mouth
Name 4 methods of drug release using microchips?
Polymer membrane controlled
Describe the drug used and delivery method of the Cypher drug eluting stent
Drug is sirolimus, sandwiched between coating and polymer layer
Describe the concept of micropump microchip technology
micropump uses shape memory to push drug out
Describe the concept of the rapid delivery microchips
System allows for pulsatile or continuous release of multiple independent doses
Explain the need of a cell reservoir chamber for cell drug delivery systems
cells stored in micro reservoir with release controlled by properties/responsiveness of a membrane
Describe the drug loading difference between the Taxus and the Achieve drug eluting stent technology
Achieve stent has drug directly deposited on the stent
Taxus stent has drug in the adhesive layer
Describe the drug loading difference between the Janus CarboStent technology and the Taxus drug eluting stent technology.
Taxus: Drug is polymer matrix on top of the stent
Janus: Drug is in polymer matrix that fills the grooves
Describe the DNA loading method on the BiodivYsio stent.
Delivers DNA to the cell wall to promote growth of endothelial cells to prevent clotting around the stent
List one advantage of multilayer compared to one layer biodegradable stent.
Can be used to control release rate of drug
List three growth factors used in tissue engineering and one function of each.
Vascular endothelial growth factor (VEGF) - Wound Repair
Fibroblast growth factor (FGF) - Wound Repair
Nerve growth factor (NGF)- neural tissue regeneration
List three polymers used for drug delivery in tissue engineering?
Name three main applications of drug delivery systems in tissue engineering
Name two drugs that could be used for wound repair
Vascular Endothelial Growth Factor (VEGF)
Fibroblast growth factor (FGF)
Name 3 routes of administration used to deliver drugs in front of the eye
Describe the mechanism of action of Vysudin
Drug is delivered via IV for 10 minutes Drug collects at the back of the eye, patient wears a special lens and a "cool" laser is focused thorugh the lens on the back of the eye for 83 seconds at a specific wavelength activating the drug
List 3 criteria required for developing a successful ocular drug delivery system.
What is the main advantage of using iontophoresis for ocular drug delivery?
Name 3 disadvantages of OCUSERT
Can fall out
Describe the concept of topical delivery using nanoparticle drug delivery systems on the surface of the lens.
Positively charged particles to allow them to adhere better and not be removed by a simple blink
List three advantages of buccal drug delivery
Used if patients are unable to swallow pills
List one limitation of buccal drug delivery
Device May be swallowed accidentally
Describe how keratinized oral mucosa can affect drug delivery efficacy compared to non-keratized oral mucosa
Keratinized oral mucosa is tougher because it contains keratin making drug delivery more difficult
List two barriers associated with buccal drug delivery
pH, Salivary activity
List three important properties associated with bioadhesives to enhance their surface interactions with the tissue.
Describe the benefit of high molecular weight polymers for enhancing bioadhesive properties.
They provide more available bonding sites
Explain the mechanism of electrothermal delivery of drugs in the context of microchips.
Change in temperature/ Electrical properties elicits release of drug from microchip
Explain the mechanism of drug delivery from the polymeric microchip technology
Drug is in reservoir on top of sealant layer and below a degradable membrane
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