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What are the disadvantages of Concentration time plots?
- Limited utility
- Do not describe the actual drug movement
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What are the methods for determining Area Under the Curve?
- Calculus integration
- Cut and way paper
- Trapezoid method
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What is the equation for the area of a trapezoid?
1/2(base1 + base2) x height
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How do you use the trapezoid method for determining the area under the curve?
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Approximate the linear function and then use teh equation:
1/2(base1 + base2) x height
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What are the units for an AUC of a concentration time curve?
(mg)(hr)/L
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What does the area under the curve for a concentration time plot mean?
The total drug exposure
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What is the Area under the curve affected by?
All drug processes and movements
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What can the AUC be used for?
Comparing drug products and dosage forms
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How is Bioavailability usually reported?
As a percentage of the total drug given
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Is Bioavailability a measure of drug action and effects?
- Is somewhat interpreted that way, assumed to be related
- Though, is not really
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What is the Equation for Bioavailability?
F = AUCa/AUCb
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What is the critical determining factor for Bioavailability?
The denominator
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What is the denominator of Bioavailability?
The Reference material
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What is Relative Bioavailability?
A comparison between two dosage forms, where one form becomes the denominator
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What is the absolute Bioavailability?
A comparison of the amount of drug that reaches circulation to the amount that was given
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What is the reference/denominator for Absolute Bioavailability?
The AUC following IV administration
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What are the assumptions of Bioavailability?
- Patient sample is representative
- Absorption is the universal and unchanging
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What is Pharmaceutical Equivalence?
 - Contains the same active ingredient(s)
- Same dosage form/Route of administration
- Identical in strength or concentration
- May differ in shape, scoring configuration, release mechanisms, packaging, excipients, expiration time
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What is Pharmaceutical Alternatives?
- Contain the same therapeutic moiety
- Different salts, esters, or complexes of that moiety, or are different dosage forms or strengths
- Different dosage forms and strengths and extended-release products within a product line by a single manufacturer are pharmaceutical alternatives
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What is Therapeutic Equivalent?
- They are pharmaceutical equivalents and can be expected to have the same clinical effect and safety profile
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Who conducts Bioequivalence studies?
Generic drug manufacturers
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What are FDA pivotal parameters for Bioequivalence?
- AUC
- Cmax
- tmax (subjective)
- All should be 80-120% of the reference product
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What are the limits on AUC, Cmax and tmax of a generic drug compared to a reference drug?
- Need to be within 80-120% of the reference drug
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What are bioavailability studies used for usually?
To compare different routes of administration
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What are Bioequivalence studies used for usually?
Compare new drugs to a known drug product
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What are the units for Salt factor?
Unit less
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What are the units of Bioavailability?
Unit less
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What is the salt factor?
The fraction of the dose that is bioavailable and is active
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What is the Amount available of a drug?
The dose times the bioavailability times the percent that is in an active form (the salt factor)
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How do you calculate Bioequivalence?
SxFxD = SxFxD
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What drugs are concerning to give bioequivalents of?
- Drugs that:
- have a small therapeutic range
- require high doses
- are not well absorbed
- studies show different products have different effects
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What is Bioavailability?
The rate and extent to which the AI is absorbed and available at the site of action
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What is a Bioequivalent drug product?
- Pharmaceutical equivalent or alternative products with comparable bioavailability
- May sometimes be demonstrated using an in vitro bioequivalence standard, especially when such an in vitro test has been correlated with human in vivo bioavailability data.
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