Pharmacokinetics & Pharmacodynamics Flashcards
Pharmacokinetics definition
The study of how a drug moves throughout the body and how the body impacts the availability of drugs.
(i.e. How the body affects the drug)
Pharmacodynamics definition
The study of how the drug affects the body.
(i.e. What is the drug doing to the body)
Components of pharmacokinetics
Absorption
Distribution
Metabolism
Excretion
Components of pharmacodynamics
Drug onset, peak, and duration
Includes receptors, enzymes and hormones
Absorption
Movement of drug from site of admistration into blood.
Impacted by cell membranes, blood flow, drug solubilty, pH, drug concentration, and method of adminstration.
Bioavailability
How much drug reaches systemic circulation.
Impacted by absorption rate and first pass effect.
Distribution
Movement of drug throughout body to the target tissue. Requires blood supply.
Areas of high blood flow: heart, liver, kidney, brain
Lower blood flow: bone, fat, skin
Types of drugs that can cross blood brain barrier
Lipid soluble
First Pass Effect
Drug is absorbed in GI system and metabolized in portal circulation therefore lowering bioavailability.
Metabolism
The chemical inactivation of a drug through conversion to a more soluable compound which can be excreted.
Inhibitor
Compoud that slow metabolism of a drug.
Increases the overall drug effect.
Common Inhibitors
GPACMAN
- Grapefruit
- Protease inhibitors
- Azole antifungals
- Cimetidine
- Macrolides (except azithromycin)
- Amiodarone
- Non-DHP Calcium Channel Blockers
Inducer
Increases rate of metabolism.
Decreases overall drug effect.
Common Inducers
PCRABS
- Phenytoin
- Carbamazepine
- Rifampin
- Alcohol
- Barbituates
- St. John’s Wort
Excretion
Elimination of drug from the body
Therapeutic Range
Maximum toxic concentration - minimum effective concentration
