Week 1 Flashcards
Agonist
Activates receptor(s)
produces same as bod’s internal response – meds that bind to or mimic receptor activity that endogenous compounds imitate (morphine)
What is a drug?
Any chemical that can affect a living process
What is pharmacology?
the study of drugs and their interactions with living systems
What is pharmacokinetics?
- Effect body has on drugs
2. How the body MOVES the drug around
Mechanisms of absorption
- passive diffusion
- facilitated diffusion
- active transport
- pinocytoses/phagocytoses
Where does most of absorption happen?
In the intestines and stomach
What is the most popular method of absorption?
80% PO, SL, and PR
What is absorption?
How the drug gets into the body
movement of a drug from site of administration into the blood (generally mouth –> stomach –> GI tract)
What is distribution?
where the drug goes to in the body
What is metabolism?
how the body chemically modifies the drug
What is excretion?
how the body gets rid of the drug
What are the main types of administration of drugs?
Enteral (PO, SL, PR)
Parenteral (IV, IM, SQ)
Other methods of drug administration?
Transdermal Topical Inhaled/nasal Optic/otic Vaginal Rectal
What are factors that affect drug absorption?
- stability of medication
- solubility of medication
- GI pH
- emptying time of stomach
- if food in stomach/intestines (food-drug interaction)
- if on concurrent meds (drug-drug interaction)
- different formulations of oral meds (enteric coated vs liquid)
What is facilitated diffusion?
diffusion of a non-lipid soluble molecule
carrier molecule
If a drug was high protein bound, what would that mean for the dose?
Drugs that are high protein bound require a higher dose as much of the drug will bind with protein and not be available in the blood.
What three factors influence distribution?
- protein-binding
- blood flow
- body tissue affinity
- -> pharmacologic effect
What happens in the metabolism phase?
The liver (mainly) changes the meds to a less active or inactive form by action of enzymes (also kidneys, lungs, intestines, and blood)
How can we skip the first pass effect?
inhalation or IV
Why does grapefruit interfere with metabolism?
Cytochrome p450 in grapefruit juice can cause a person to break down a drug faster
Already have an amount of cytochrome p450 in body, but can’t easily measure that amount
why do we adjust the dosage of meds for older people?
hepatic function tends to decline with age. This can cause a drug to accumulate in the body if the hepatic process is slowed.
What are individual variances in drug responses?
- infants have a limited med metabolism capacity
- age (varies with individual)
- hepatic metabolism tends to decline with age (accumulation of drugs –> smaller doses)
- first pass effect - can bypass through SL or IV or IM
- If taking drug with same metabolic pathway (could enhance or inhibit each other)
- Nutritional status (malnourish - deficient in factors needed to produce certain enzymes required for metabolism - affects metabolism and could lead to build up of drug in system)
How can we bypass the first pass effect?
Parenteral administration (IV, IM, SQ) - go immediately to blood then liver - bypassing first pass effect
What is bioavailability?
How much of the drug is available after the first-pass effect?
Parenteral administration types?
IV
IM
SQ
When does biotransformation occur?
When the structure of a drug is chemically altered during metabolism.
creates metabolites (by-product of metabolism)
Why is bioavailability significant?
indicates onset time
the fraction of administered dose that reaches systemic circulation
IV = 100%; non-IV = 0-100%
What is the pathway of drug?
dose –> gut –> not absorbed –> destroyed by gut wall –> destroyed by liver –> systemic circulation –> receptor site –> action –> excretion
How does kidney dysfunction influence pharmacokinetics?
Kidney dysfunction could lead to an increase in duration and intensity of med response - important to monitor creatinine
What are pharmacodynamics?
What drug does to body
What is the dose response?
relationship between size of a dose and intensity of response produced
How does the peak differ from the peak action of a drug?
peak is when a drug is at its highest conc in serum levels
peak action is how high a drug concentration can be without toxic effects
Maximal efficacy
largest effect that a drug can produce
What are the categories of drug actions
- stimulation (opiate) or depression (receptor site narcan)
- replacement (electrolytes, hormones)
- inhibition or killing of organisms (antibiotics)
- Irritants (GI irritant to help put NG tube in place)
Antagonist
block usual receptor activity that endogenous compounds regulate or blocking other meds
Partial agonist
produces a weaker or less effective response than the internal response – limited affinity to receptor site (agonist on some receptor sites and antagonist in others)
Therapeutic range/level
- Serum conc needed to achieve desired therapeutic effects
- Between MEC and toxic conc. – not causing organ damage and have therapeutic effects
- Therapeutic level (blood)
Steady state
- Administration rate = rate of clearance
- Staying steady – goal of all drugs – then we stop taking meds and body breaks it down
- Dependent on half-life
Peak level
- Drug level following administration of a set number of doses
- Typically pertains to IV drugs
Random level
- Drug level not related to administration time
2. Reflects steady state concentration
Trough level
- Drug level taken 30 minutes before next drug administration due
- Should be at lowest concentration
