Exam With 100% Correct Answers 2024
what is bioavailability? - Correct Answer-The fraction of the drug that reaches systemic
circulation
what does bioavailability depend on? - Correct Answer-Depends on solubility, chemical
structure, size (large molecules have harder time), polarity/charge, presystemic
biotransformation (how it is metabolized)
Biotransformation (metabolism) and elimination of drugs contribute do bioavailability. -
Correct Answer-True
First order kinetics: - Correct Answer-means that a constant fraction of the drug (50%) is
removed during each time interval which is a half-life. Half-life is the amount of time it
takes for 50% of the drug to clear. Half-life is usually not dose dependent (doubling
dose will not double half-life) Steady state occurs after 4-5 half-lives. Pts with renal or
hepatic disease may have increased half-life.
Half life: - Correct Answer-amount of time it takes for 50% of the drug to clear-- r/t first
order kinetics
Is half life dose dependent? - Correct Answer-No (double dose will not double half life)
When does steady state occur? - Correct Answer-4-5 half lives
Zero-order kinetics means that: - Correct Answer-a drug molecule is eliminated as a
constant rate regardless of concentration. Happens when drug levels are high and
routes of metabolism or elimination are saturated (more drug molecules are available
than sites).
Example of zero-order kinetics: - Correct Answer-One such drug is ethyl alcohol. When
two or more drinks of alcohol are consumed in a relatively short period of time, alcohol
molecules saturate the enzyme-binding sites and metabolism occurs at its maximum
rate of approximately 10-15 ml/hr or 1 ounce of 100 proof per hour regardless of
concentration. Any consumption that occurs after saturation of enzyme will raise blood
levels dramatically and will produce intoxication. As levels drop and enzyme is no longer
saturated, biotransformation shifts to first order kinetics.
what are pharmacokinetics? - Correct Answer-what the body does to the drug
What are the 4 pieces of pharmacokinetics? - Correct Answer-absorption, distribution,
metabolism, excretion
, Distribution- - Correct Answer-after absorption, transport of a drug to site of action
Distribution: To what do drugs usually bind? - Correct Answer-protein (albumin usually)
Are highly bound drugs more or less available for action? - Correct Answer-less
distribution: binding sites: - Correct Answer-There are limited number of binding sites.
Drugs can compete for same site=reaction due to high serum levels of one of them.
distribution: what happens when patients have low albumin levels? - Correct Answer-
They will have fewer binding sites which will then lead to more free drugs leading to
toxicity
What are barriers to distribution? - Correct Answer-blood brain barrier and placenta
metabolism (biotransformation) - Correct Answer-process of chemically changing a drug
to a different compound called a metabolite.
what is the goal of metabolism/biotransformation? - Correct Answer-to make a drug
more water soluble so it can be excreted.
What is elimination? - Correct Answer-the excretion of drugs and their transport outside
of the body.
What are examples of ways that drugs can be eliminated from the body? - Correct
Answer-Kidney, bile, sweat, lungs, breastmilk, saliva.
Understand what is meant by "first pass" of a drug - Correct Answer-Occurs when
taking PO drug prior to reaching the circulatory system. During this time, a drug
concentration is reduced during the process of absorption in the liver and gut before
reaching the circulatory system. The drug is absorbed by the digestive system and
enters the hepatic portal system, to the portal vein and into the liver before it reaches
systemic circulation. The liver metabolized many drugs that ONLY A FRACTION IS
LEFT FOR CIRCULATION The first pass through the liver REDUCES
BIOAVAILABILITY of the drug. IV, IM and SL administration do not have a first pass.
Some drugs such as nitro have such a large first pass effect that they are useless as
PO, thus SL and paste.
Does first pass apply to IV, IM, and SL administration? - Correct Answer-NO
Some drugs have such a large first pass effect that they are useless as PO. Name an
example: - Correct Answer-Nitro- that is why it has to be given SL or as a paste
Toxic substances that trigger vomiting activate what area of the brain; understand the
concepts associated with this. - Correct Answer-The blood brain barrier is not complete.