Pharmacokinetic and Dynamics Flashcards
Study of the drugs actions on the body
Pharmacokinetics
The movement of a drug from the site of application to the specific target
Absorption
The process whereby a drug is transported from the site of absorption to the site of action
Distribution
How a drug is metabolized or broken down into different chemicals
Biotransformation
Movement of a drug out of the body
Elimination
Factors that Affect Drug Absorption
- Drug solubility
- Drug concentration
- Drug pH
- Site of absorption
- Absorbing surface area
- Circulatory status- force and volume of blood flow
- Bioavailability
Amount of medication in systemic circulation
Bioavailability
The tendency of a drug to dissolve
Solubility
Note for Drug Concentration
Drugs given in high concentrations are more quickly absorbed than those in low concentration
Drug pH Notes
- Acidic drugs more rapidly absorbed in acidic environments (stomach)
- Basic drugs more rapidly absorbed in alkaline environments (kidneys)
Factors Affecting Distribution
- Cardiovascular function
- Regional Blood flow
- Drug storage reservoirs
- Physiological barriers
Prevents most drugs from passing directly into brain
Blood-Brain Barrier
What does the Blood Brain Barrier Consist of?
Network of capillary endothelial cells, surrounded by glial connective tissue
What can pass through the Blood Brain Barrier?
- Fats, fatty acids
- O2 and CO2
- Fat soluble molecules (anesthetics, nicotine, entonox, alcohol)
Acts as a barrier to some substances passing from mother into fetal circulation
Placental Barrier
Everything taken PO is metabolized in the liver before reaching systemic circulation
Hepatic “First Pass” Metabolism
Cumulative drug effects may occur
Decreased Biotransformation
Dosing rates may need to be increased to maintain effective plasma concentrations
Increased Biotransformation
Time required for the total amount of a drug in the body to decrease by half
Drug Half-Life
What drugs will do to the body
Pharmacodynamics
Anticipated response beyond the desired effect
Predictable Responses
Factors Affecting Drug Responses
- Age
- Weight
- Gender
- Environment
- Time of administration
- Condition of patient
- Genetic factors
Minimum drug amount necessary for an ideal or desired response in the body
- Excess drug amount may be toxic or fatal
- Dosage is determined by reaching ideal effects
Therapeutic Index
An adverse condition inadvertently induced in a patient by the treatment given
Iatrogenic Responses
Decreased response to the same amount of medication
Tolerance
Concentration needed to become effective
Minimum Concentration
- Prolonged administration may lead to this
- Significant symptoms of they stop using the medication
Drug Dependency
Increases effort of a drug given in several successive effects
Cumulative Effect
Majority of drugs act by binding to the protein molecules on the surfaces of cells
Receptor Theory
Minimum concentration necessary for a drug to produce its desired effect
Therapeutic Threshold
