Pharmacokinetics Flashcards
Pharmacodynamics
The effects of drugs and their mechanisms of action
“the effect of the drug on the body”
Pharmacokinetics
The movement of drugs through the body
“the effect of the body on the drug”
Pharmacotherapeutics
The clinical (therapeutic) uses of drugs
“using drugs to treat disease”
Therapeutic Index (ratio)
The amount of drug that brings about the therapeutic effect compared to the amount that causes toxicity or death
“effective dose vs. harmful dose”
3 ways that drugs cross membranes
Via Channels and Pores
Via Transport Systems (P-Glycoprotein)
*Via Direct Penetration of the Membrane
ADME
Absorption
Distribution
Metabolism
Excretion
Drug Absorption
The movement of a drug from the site of administration into the blood
Drug Distribution
Once in the blood, the movement of drugs throughout the body
Drug Metabolism
Also known as biotransformation, it is the enzymatic alteration of drug structure (done, by in large, by the liver.)
Drug Excretion
The removal of drugs from the body, done either by excretion into bile or urine
Lipid Solubility
A measure of the ability of a drug to dissolve in water vs. lipid
- Effects membrane diffusion, ADME
Ionization (Pka)
When ionized drugs are charged. Acidic drugs are ionized in basic solutions and basic drugs are ionized in acidic solutions.
- Effects rate and location of drug absorption.
Protein Binding
The extent to which a drug binds to plasma proteins.
- Effects Distribution, Metabolism, and Excretion
Bioavailability
The fractional extent to which a dose of drug reaches the blood stream and its site of action.
Depends greatly on several factors: physiochemical properties of the drug, route of Administration, metabolic or excretory capacity by the liver or intestines for the drug.
first-pass effect
when a large percentage of the drug is metabolized by the liver, so that the concentration of a drug is greatly reduced before it reaches the systemic circulation
oral administration (key points on absorption; advantages and disadvantages)
Absorption: Can is variable and depend on many factors
Pros: Most convenient and economical, often also most safe
Cons: Requires patient compliance, bioavailability can be erratic and incomplete
Intravenous administration (key points on absorption; advantages and disadvantages)
Bypasses absorption,
Potential immediate effects, suitable for large volumes and irritating substances.
Pros: Valuable for emergency use, permits titration
Cons: Increased risk of adverse side effects
Subcutaneous administration (key points on absorption; advantages and disadvantages)
Can be prompt or slow depending on drug preparation, can be affected by changes in blood flow to tissue
Pros: Suitable for self-administration
Cons: Not suitable for large volumes, possible pain or necrosis at site
Intramuscular administration (key points on absorption; advantages and disadvantages)
Can be prompt or slow depending on drug preparation, can be affected by changes in blood flow to tissue
Pros: Suitable for self-administration
Cons: Contraindicated with anticoagulants
Sublingual administration
absorbed via oral mucosa, bypasses the liver
Transdermal administration
absorbed through intact skin, drugs are usually highly lipid soluble, compromised skin integrity can greatly affect absorption
Rectal administration
50% of drugs absorbed via the rectum will bypass the liver, absorption however can be irregular and incomplete and some drugs may irritate the rectal mucosa
Intra-arterial administration
administration requires great care, can help localize drug effects, bypasses liver
Intrathecal administration
drugs administered into CSF (into spinal subarachnoid space, or into brain intraventricular space) , bypasses BBB
