final Flashcards
What are the assumptions made when using a 1 compartment model?
Body is a single uniform compartment
Instantaneous administration of entire dose
Rapid distribution throughout the body
Drug elimination starts immediately upon administration
Well stirred model
What is clearance?
Volume of plasma fluid cleared of drug per unit of time
What are the units for Clearance?
L/h
mL/min
What is k?
Elimination rate constant
Proportion of drug elimination and the amount of drug in the body
Hepatic or renal
What is t1/2?
Half life
Time it takes for a drug concentration to decrease by 50%
What is volume of distribution?
Volume of the single compartment that the dose was administered into but is not an actual volume just theorhetical
What are the units for AUC?
mg*h
How do you get Co?
Dose/Vd
How do you get k in one compartment model?
slope/2.3
How do you get clearance in one compartment model?
Vdk
How do you get t1/2 in one compartment model?
0.693/k
How do you get AUC in one compartment model?
A(n-1)-A(n)/2 *(tn-tn-1)
What are teh units of k?
1/h
What are the units of clearance?
L/h
How do you get concentration in one compartment model?
Coe^-kt
What is k independent of?
Concentration or amount of drug at any given time
What is Cl not dependent of?
The amount or concentration of the drug
What is delayed release?
A dosage form that releases a small amount of drug at a time other than immediate release after administration
An initial portion may be released after administration
What is delayed release?
A dosage form that releases a small amount of drug at a time other than immediate release after administration
An initial portion may be released after administration
What is the common form of pill for delayed release?
Enteric coated tablets
What is extended release?
Dosage form that allows at least twofold reduction in dosage frequency as compared to that drug presented as immediate release dosage form
What does extended release dosage form prevent?
Prevents very rapid absorption of drug
Where do extended release dosage forms release at?
At a predetermined rate at a specific site
What are microcrystalline cellulose spheres used for?
Increase durability of the slow release coverings
What is the multitablet system?
Many tiny tablets in a capsule
Each tablet can have different release characteristics
What are teh 5 advandages of ER formulation?
Less fluctuation in drug blood levels
Decrease in frequency of dosing
Enhance convenience and compliance
Reduction in adverse effects
Reduction in overall health care costs
What are the 3 disadvantages of ER formulations?
Dose dumping
Less flexible in dose adjustments
Less possiblity for high dose
How do ER formulations cause less fluctuations in drug plasma levels?
Eliminates the peaks and valleys in concentrations
How do ER formulations decrease the frequency in dosing?
Deliver more than a single dose
How do ER formulations enhance convenience and compliance?
Less frequency
Increased day and night time dosing
How do ER formulations decrease side effects?
Fewer peak blood levels so less toxicity
How do ER formulations decrease health care costs overall?
Enhanced therapeutic benefit
Fewer side effects
Decrease time to dispense and administor and monitor patient
What is dose dumping?
When the release of more than intended fraction of the drug may increase toxicity
The ER formulations cannot be crushed or chewed due to this
How would you get ER formulations out of the body?
Bowel evacuation and gastric lavage
very intrusive
Why cant you have high dosed ER formulations?
They would be too big to swallow
What is contained in gum type matrix systems?
Methylcellulose
Veegum
Alginic acid
Tragacanth
Are gum type matrices biodegradable?
Yes
What do gum type matrices do?
alter degredation based on hydration control, pH dependency, thickness, and viscosity
What kind of drugs can be in polymeric matrix?
biodegradable or non
Hydrophobic or philic
What is cautioned when using non biodegradable polymeric matrices?
GI decreased motility
What are polymeric matrices used for?
Implants
What does ionic exchange resin do?
Upon exposure in the GI tract, cations in the gut, such as K and Na, will displace drug from resin and release the drug
What does the osmotic pump do?
Push pull system
Water from GI tract enters the tablet to increase pressure in osmotic layer and pushes against the active drug layer and releases drug from laser filled orifice
How do you alter or affect release rate of drug in osmotic pumps?
Alter the size of the orifice
How is the drug delivery for osmotic pumps?
Usually constant drug delivery as long as the osmotic gradient stays constant
What are the clinical considerations for ER formulations?
Advise of frequency and dose
Not use interchably with IR
Advise that modified released drugs cannot be crushed or chewed
Empty shells can be in poop for osmotic devices
What are the 5 factors affecting percutaneous absorption?
Drug concentration per unit Surface area
Large the area and the longer the contact time the more drug absorbed
400kDa-100kDa is best for adequate liquid and aqueous solubiltiy
Patch applied to the skin
Hydration of skin
What are the 7 advantages of transdermal route?
- Bypass the GI absorption and 1st pass metabolism
- Substitute for oral when unsuitable
- Non invasive
- Extended therapy increases compliance
- Short half life drugs are extended through resovior
- Therapy is terminated when removed
- Easily identified during emergencies