Lecture 8-Pharmacology Flashcards
Exam 1
Pharmacokinetics (PK)
- “movement” of drugs
- How the body acts on drugs
Pharmacodynamics (PD)
- “Power” of drugs
- How drugs act on the body
“PK” is described by ADME(T)
- Absorption
- Distribution
- Metabolism
- Elimination/Excretion
- Toxicity
All of these factors are influenced by body weight (dose and body fluid)
Common forms of administration
- Oral
- Inhalation
- Transdermal
- Intranasal
- Sublingual (via mucous membanes)
- Injection- intravenous, subcutaneous, Intramuscular, Intraperitoneally
- Lumbar puncture and epidural
- Rectal
- Devices (infusion pumps and IUDs)
Oral administration
- Drug must be soluble and stable in stomach fluid (not all drugs can handle stomach environment)
- Food in stomach will slow down “passing” which means delayed absorption and decreased maximum drug level achieved
- About 75% absorbed in 2-3 hours which is slow
Advantages of oral administration
- safest
- easiest to give measured, specific does bc of premade amounts
- slow absorption process
Disadvantages of Oral Administration
- slow absorption
- Occasional vomiting/stomach distress
- Unpredictable absorption rate (based on food in stomach)
- Some drugs are destroyed by stomach acid
caveat: crushing tablets- consider dangers and alternate routes
Inhalation
- Probably the 2nd most popular method
- faster than oral as the first organ blood leaving the lungs goes to is the brain
Transdermal (skin patches) how do they work?
- Works as patch has contact adhesive, drug reservior, and a drug releasing membrane
Advantages and disadvantages of transdermal administration
- alternative to oral (no gastro side-effects)
- increased penetration at sites with greater cutaneous blood flow
- Extended release
Disadvantages: skin is a strong barrier so the drug must be able to penetrate the skin
Sublingual administration
- Through mucous membranes (esp mouth bc lots of blood vessels and a mucuous membrane there)
- Is fast acting (efficient and quick absorption)
- Doesn’t irritate stomach or cause vomiting
Limitation: unpleasant tast of drugs- not used much (but good for people who can’t swallow)
Injection advantage and disadvantages
- Advantage: one of the fasted absorption rates depending on type
- Dis: “sterile” conditions necessary, danger of too much drug administration, painful
Subcutaneous vs Intravenous vs Intramuscular
- Subcutaneous: under the skin
- IV: into vein (directly into the bloodstream)
- IM: directly into muscle
Distribution
T/F: Once absorbed, a drug is distributed primarily to the site of its’ primary action
- FALSE
- Once absorbed, a drug is distributed ALL OVER the body by circulation of blood, not just at the site of action
Two concepts about absorption from the blood-brain
- Lipid solubility
- Drugs that are lipophilic (like lipids aka fat) take much longer to reach site of action
- Marijuana and alcohol are lipophilic which means the drug can linger and stay in fats, solvent that can adgere to fat and is why alcoholics get fatty liver
