Chapter 1 Flashcards
What are the four basic processes of pharmacokinetics?
- Absorption
- Distribution
- Metabolism
- Elimination
What determines the bioavailibility of a drug?
ADME (Absorption, Distribution, Metabolism, Elimination)
What is bioavailibility?
how much of the drug that is administered actually reaches its target
what does the kinetics part of ‘pharmacokinetics’ refer to?
movement and time
What are the three ranges that drug concentrations in blood can be?
- ineffective range
- therapeutic range
- toxic range
What does drug absorption refer to?
Processes and mechanisms by which drugs pass from the external world into the bloodstream
What are the two categories of ways that drugs can be administered?
- Enteral routes (administration involving the GI tract)
2. Parenteral (routes of administration that do NOT involve the GI tract)
List the 2 enteral routes
- Orally
2. Rectally
List the 4 parenteral routes
- Injected
- Inhaled
- Absorbed through the skin
- Absorbed through mucous membranes
What is insufflation
“snorting,” or sniffing, the drug, with the drug depositing on the oral or nasal mucosa (note to review this because I feel like it might be more broad)
Drugs administered orally in liquid form absorb faster than tablet (true or false)
true
by which process are drug molecules absorbed across the intestinal mucosa?
passive diffusion: they pass from an area of high concentration to one of lower concentration
In order to be absorbed through the intestinal mucosa a drug must be
lipid soluble (at least to a small degree)
What is pharmacokinetics?
What is pharmacodynamics?
What is pharmacokinetics = how drugs move through the body.
What is pharmacodynamics = ow drugs exert their effects in the body (mechanisms of action)
What is first pass metabolism?
Class explanation: A majority of the blood supply leaving the area of the stomach and upper intestines goes directly to the liver (enterohepatic circulation) where many drug molecules (up to 60% of those absorbed) are metabolized before they can be distributed to the body and the brain (hepatic first pass).
Textbook explanation: The process by which nutrients (and drugs) from the intestines are absorbed into veins, which collect into the hapatic vein, which transports them to the liver as a first stop before going to other organs
Why should caution be taken when having grapefruit juice with a drug taken orally?
Because over 85 drugs have an interaction with a component of grapefruit juice (furanocoumarin), which inhibits an enzyme that metabolizes the drug
What are some of the disadvantages of oral administration?
- Can lead to vomiting/stomach distress
- difficult to predict how much drug will be absorbed because of (1) differences across people (2) differences in manufacturing
- some drugs cannot be administered this way because they are destroyed by stomach acid
What are some of the disadvantages to rectal administration?
Absorption, is irregular, unpredictable, and incomplete
can irritate the membranes that line the rectum
Why is inhalation a popular route of administration for recreational drugs?
- Large surface area of lungs with lots of blood flow mean rapid absorbtion
- The blood flow from the lungs goes almost directly to (left side of heart then into aorta and arteries carring blood to the brain) the brain, which makes onset even faster than intravenous administration
- This rapid effect on the brain is highly reinforcing
What is a benefit of transdermal administration?
It allows for slow, continuous absorption over many hours (or days), which may limit side effects associated with rapid rise and fall of drug concentrations in blood plasma
What are the 4 types of administration by injection?
- Intravenous (vein)
- Intramuscular (muscle)
- Subcutaneous (just under skin)
- Spinally
What features are shared by all injection methods?
more rapid repsonse than oral, easier to control dosage than oral
What are the advantages and disadvantges of Intravenous
Advantages:
- Valuable for emergency use
- Permits titration of dosage (start low and increase)
- Can administer large volumes and irritating substances when diluted
Disadvantages:
- Increased risk of adverse effects
- Must inject solutions slowly as a rule
- Not suitable for oily solutions or insoluble substances (could result in embolism)
What are the advantages and disadvantges of Intramuscular
Advatanges:
1. Suitable for moderate volumes, oily vehicles, and some irritating substances
Disadvantages:
- Precluded during anticoagulant medication
- May interfere with interpretation of certain diagnostic tests (for example, creatine phosphokinase)