Pharmacokinetic Principles Flashcards
Pharmacokinetics
the study of the action of the body on drugs
Pharmacodynamics
the study of the action of drugs on the body
Therapeutic Range
the concentration of drug in the blood above which the risk of side effects or complications outweigh the benefits and below which therapeutic benefits are not seen
Bioavailability
the fraction or percentage of the drug that reaches the systemic circulation
First Pass Effect
blood from GI tract passes through the liver before systemic circulation; some drugs are significantly metabolized by the liver before reaching systemic circulation
A drugs with a high first pass rate has a _____ bioavailability and should not be given _______.
Lower; PO
Passive DIffusion
High concentration to low concentration
Active transport and saturable kinetics
Specific carrier proteins carry drugs across bilayer; saturable kinetics explains that there are only so many proteins to carry the drug
Factors that influence drug absorption
ionization state, molecular weight, solubility, formulation
Drugs that permeate the plasma membrane most readily
Small, non-ionized, lipid-soluble drugs
Patient associated factors
Presence of food in GI tract, stomach acidity, blood flow to the GI tract, gastric emptying time
Advantages of PO
Patient convenience and storage
Disadvantages of PO
Non-emergent use, Must pass through GI tract, First pass effect
Advantages of SL
Avoids first pass effect Rapidly absorbed
Disadvantages of SL
Limited by volume and sublingual absorption
Advantages of PR
Unconscious or vomiting patients
Children
1° treat local conditions
Disadvantages of PR
Comfort
Unreliable absorption
Advantages of IV
Rapid onset
F = 100%
Emergency
NPO
Disadvantages of IV
Must be soluble in water
Increased risk
Advantages of IM
Quick onset
Avoids stomach
Disadvantages of IM
Erratic absorption
Increased risk; pain
Advantages of SC
Less painful than IV or IM
Disadvantages of SC
Slower, sometimes erratic absorption
Limited volume
Advantages of Inhalation
Rapid onset
Local effect
Disadvantages of Inhalation
Technique
Potential alveolar irritation
Advantages of Intranasal
Local effect
Disadvantages of Intranasal
Comfort