Pharm Week 1 Flashcards
Describe pharmacodynamics.
What does the drug do to the body?
Describe pharmacokinetics.
What does the body do to the drug?
Define absorption.
Movement of the drug from the site administration to the bloodstream.
Define distribution.
Movement of the drug from bloodstream to fluids and tissues of the body.
What is metabolism?
The breakdown of the parent drug to the metabolites.
Describe excretion.
The process by which the drug is eliminated by the body.
What are routes of administration?
IV, oral, buccal, transdermal, sublingual, rectal, inhalation, nasal, topical, ophthalmic, IM, Intradermal, intrathecal
Describe parenteral.
Any route other than oral. Primarily IV
How can a membrane affect absorption?
Channels/ Pores
transport systems
direct penetration - lipid soluble (fastest)
Describe bioavailability.
Amount of drug available in the bloodstream after absorption.
How is absorption affected by pH?
pH can affect the ionization of a drug, changing its ability to cross membranes. (uncharged compounds cross membranes more easily)
What 3 routes give 100% bioavailability?
IV, IM, SubQ
What factors affect bioavailability?
Route. Food. Age - skin Environment - heat Bowel resection Certain medical conditions - GI issues (diarrhea, constipation, Chrone's)
What is the clinical relevance of bioavailability?
It explains why some drugs given orally must be higher doses than those given IV.
What is volume of distribution?
The percent of drug in the tissues compared to drug in the bloodstream.
How does blood brain barrier influence distribution?
Must be lipid soluble to cross the barrier
How does the placental barrier affect distribution?
Drugs must be lipid soluble to cross the placenta
How does breast milk affect distribution?
Drugs can easily get into breast milk. Be careful!
How do blood proteins affect distribution?
The binding of drugs to proteins (such as albumin) will reduce their bioavailability.
How does fluid composition affect distribution?
Neonates and small children have higher fluid composition than older people, and hydrophilic drugs stay in that water longer (higher volume of distribution, needing a larger dose)
Describe half life.
The time it takes for a drug to be reduced by 50% in the blood. Not dose dependent.
What variables affect clearance?
Age - metabolism differences.
Gender - metabolism such as women and alcohol
Interacting Meds - competition
Ethnicity/Genetics/Heredity - difference in enzymes and metabolism
Health - liver diseases, renal diseases, CHF
How many half lives does it take to clear a drug?
3-5
Define therapeutic window/index?
The concentration range at which the drug is safe and effective, while not reaching toxic levels.
Describe minimal effective concentration.
The minimal amount of drug in the serum to elicit the desired effects.
Describe the maximal safe concentration.
The maximum level of drug serum concentration before toxicity occurs.
Describe toxicity.
Serious or unexpected adverse drug reactions that typically happen above the maximum safe concentration.
Describe duration of action.
The length of time that a drug will have a pharmalogical affect.
Describe steady state.
The point at which drug input equals drug output.
How many half lives does it take to reach steady state?
5
Describe onset of action.
The point at which blood levels reach the therapeutic range.
Describe adverse drug reactions (ADRs).
An umbrella term to describe a variety of effects not desirable from the drug.
Describe an adverse effect, or side effect.
An undesired effect from a drug, usually dose dependent and depends on the mechanism of action. Related to how the drug works.
Describe an exaggerated effect.
When a drugs effects exceed what is desired. Example: BP meds bottoming out your blood pressure.
Describe an allergic reaction.
An immune response, antibodies are produced, includes drug class.
Describe anaphylactic shock.
Life threatening allergic reaction.
Describe a pseudo-allergic drug response.
These resemble an allergic response, but no antibodies are released. Histamines are released.
Describe an intollerance.
An ADR that bothers the patient enough that the drugs usefulness is not desired.
Describe linear kinetics.
Changes in dosage will result in proportional serum levels. True for most drugs.
Describe Michaelis-Menten kinetics.
Dosage passes saturation and no longer proportionally affects serum levels. Very hard to deal with, but is less common.
What are examples of high risk drugs?
Drugs with narrow therapeutic windows
Lots of side effects
Lots of allergic reactions
Who might be a high risk patient?
Neonates
Elderly
Malnourished
Diseases: Uncontrolled Diabetes, Epilepsy, Liver disease, heart disease, arrhythmias, co-morbidity
Describe a high risk patient.
A patient who would be least likely to tolerate an ADR or loss of efficacy.
What is the receptor theory?
The idea that a drug produces an effect by combining with a molecular constituent.
What is an agonist?
A drug that mimics a natural compound by binding with a receptor and stimulating a cellular response.
What is an antagonist?
A drug that binds with a receptor, blocking it and preventing cellular stimulation.
Describe affinity.
It is the strength of attraction between a drug and a receptor, measuring the tightness of its bond. A higher affinity would more likely result in a response.
Describe selectivity.
Refers to the degree to which a drug acts on a site as opposed to all other possible sites. Usually, the more selective, the less adverse responses.
