Flashcards in Lecture 3: Pharmacokinetics Part 1 Deck (66)
-What the body does to drugs
-The quantitative study and characterization of the time course of drug concentrations in the body
What is the ultimate goal of pharmacologic therapeutics?
To achieve a desired beneficial effect with minimal adverse effects
Differences in ____ play a major role in a patient's response to drugs
The majority of variability seen in patient populations with respect to their drug response are ___________ in nature
Define drug absorption
The movement of drugs from the site of administration to the site that we measure the drug concentration in the body; we typically measure drug concentrations in the blood
Define drug distribution
The reversible movement of drugs from the blood to tissues and other extravascular tissues in the body. This process is reversible. Drugs must be able to distribute to their intended target site.
Define drug elimination
The removal of the drug from the blood through drug metabolism and drug excretion. Drug elimination has the greatest variation between individuals and is the major deciding factor in the difference between pharmacokinetics in individuals
4 factors of pharmacokinetics
Routes for drug administration
Systemic: Enteral or parenteral
Enteral route of drug administration properties
-The desired effect is systemic (non-local)
-The substance is given via the digestive tract
The most common and convenient route for enteral drug administration is:
The first pass effect
-A major downfall of oral drug administration
-The drugs are required to "first pass" through your small intestine and liver, which both produce enzymes capable of breaking the drug down, prior to getting into the circulation.
-The metabolism by enzymes reduces the amount of the drug that gets into the systemic circulation; the enzymes limit bioavailability.
The enteral oral route is not suitable for drugs that (3):
-Are rapidly metabolized
-Drugs that are acid labile (would be broken down in the highly acidic environment of the stomach)
-Drugs that cause irritation of the gastrointestinal tract
3 examples of enteral routes
-Gastric feeding tube
Parenteral route of drug administration properties
-Desired effect is systemic (non-local)
-Drug is given via a route other than the digestive tract
The most common rout for parenteral drug administration is
Injection is most commonly administered (3 ways):
Intravenous, intramuscular, subcutaneous (just under the skin)
______ injection is the most rapid means for delivery of drugs to systemic circulation
Why does intravenous injection allow for 100% bioavailability?
Intravenous injection bypasses the first-pass effect. If you inject 100mg, then 100mg will go directly into the blood and be metabolized from there.
Acid labile drugs are best administered via
Injection, as they would be metabolized if given via the enteral route.
Downfalls of drug administration via injection (3)
-May require professional administration
-Costs associated with injection materials and disposal
-Requires sterile preparation
Parenteral routes of drug administration (2 categories)
Transdermal (e.g. nicotine patches and Transmucosal
Three types of transmucousal drug administration
-Buccal (nitroglycerine tablets; under tongue or on cheek)
-Insufflation (cocaine; nasal membranes)
-Inhalational (general anesthetics; inhaled to lungs)
Where are topical drugs administered and where is the drug action desired?
Topical drugs have a local effect and thus are applied directly where the action is desired
Ways to apply topical drugs (6)
-Epicutaneous (application on skin)
The most common drug absorption method is
Oral drug absorption
Define oral drug absorption
The process of a drug moving from the site of administration (GI tract) to the site of measurement (the blood).
In order to be absorbed into the body, drugs have to pass through _____ cells in the intestinal wall. If it isnt absorbed, it will be ______.
-excreted in the feces
Most oral drug absorption occurs by _____ across membranes