Pharmacology Flashcards
Pharmacology
Study of substances that interact with living systems
Toxicology
Deals with the undesirable effects of chemicals on living systems
Pharmacotherapeutics
Study of the therapeutic uses and effects of drugs
Pharmacokinetics (PK)
ADME: A-Absorption D-Distrubition M-Metabolism (biotransformation) E-Elimination of drugs
Pharmacodynamics (PD)
Study of the relationship between the concentration of a drug and the response obtained in a patient
What is the only drug that can affect on the body?
Free drug
Bioavailability
- Fraction (F) of the administered dose that reaches the systemic circulation
- Defined as 100% for intravenous administration
After administration by other routes (less than 100%) bioavailability is generally reduced by what?
- Incomplete absorption- And in the intestine, expulsion of drug by intestinal transporters)
- First-pass metabolism, and any distribution into other tissues that occurs before the drug enters the systemic circulation
How is medication absorbed via buccal/sublingual route?
- Directly into the systemic venous circulation
- Bypasses the hepatic circuit and first-pass metabolism
How is medication absorbed via inhalation route?
- Delivery closest to respiratory tissues
- Very rapid absorption
How is medication absorbed via topical route?
Application to the skin or to mucous membrane of:
- EENT
- Vagina
What effect does topical route of administered meds have?
Local effect
How is medication absorbed via Transdermal route?
- Application to the skin
- Absorption is very slow due to thickness of skin
What effect does transdermal route of administered meds have?
Systemic effect
What is the gastric pH @ birth?
6-8
What does the gastric pH decrease to in newborns?
1 to 3 w/in 24 hrs
Why is skin absorption increased in newborns?
- Underdeveloped stratum corneum
2. Increased skin hydration
How are most drugs absorbed?
Via Passive Diffusion
How are nutrients absorbed/
Active Transport
What nutrients have impaired absorption in older adults?
- Vitamin B12
- Iron
- Calcium
- Magnesium
- Leucine
Why is there an increased bioavailability and higher plasma concentration of drugs in geriatric patients?
Decreased first-pass effect on hepatic or gut wall metabolism
Define First-Pass Effect
- Concentration of a drug is greatly reduced before it reaches the systemic circulation
- Fraction of lost drug during the process of absorption which is generally related to the liver and gut wall
Examples of passive transport
- Paracellular transport
2. Diffusion
Examples of Active Transport
- Facilitated diffusion
2. Drug transporters
Define volume of distribution (vd)
- Relates to the amount of drug in the body to the serum concentration
- Determined by:
1. Physiologic volume of blood and tissues
2. How the drug binds in blood and tissues
How many half lives does it take to reach steady state?
4 to 5
Define receptors
Specific molecules in a biologic system with which drugs interact to produce changes in the function of the system.
Define Agonist
Drugs bind to and activate the receptor in some fashion, which directly or indirectly brings about the effect
Define Partial Agonist
Binds to its receptor but produces a smaller effect at full dosage than a full agonist
Define Antagonist
Drugs, by binding to a receptor, compete with and prevent binding by other molecules
Define Allosteric
Drugs bind to the same receptor molecule but do not prevent binding of the agonist
- -> Maybe enhance or inhibit the action the agonist molecule
- ->Not overcome by increasing the dose of agonist
Define Irreversible antagonist
An antagonist that cannot be overcome by increasing the agonist
What is the most important organ for drug metabolism?
Liver
what group of enzymes are responsible for most drug metabolism oxidation reactions?
Cytochrome P450
Define substrate
Drug which is metabolized by one of the CYP450 enzyme
Define inducer
Drug which can increase the activity of a CYP450 enzyme
Define inhibitor
Drug which can decrease the activity of a CYP450 enzyme
