Chapter 3 Flashcards
Once a drug is administered, what two phases occur?
Pharmacokinetic phase
Pharmacodynamic phase
What is a pharmacokinetic phase?
What the body does to the drug, describes movement of the drug through the body
What are the 4 steps in pharmacokinetic ?
Absorption
Distribution
Metabolism
Excretion
What does pharmacodynamic phase mean?
What the drug does to the body, involves receptor binding, postreceptor effects and chemical reactions
What does drug absorption mean?
The movement of the drug into the bloodstream after administration
What does dissolution mean?
Disintegrate the tablet or drug with a combination of liquid
What does excipients mean?
Items like honey, syrup that are used in a drug to help it dissolve more
There are some drugs like enteric coated that have resist disintegration in the gastric acid of the stomach
So instead, disintegration doesn’t happen until when?
It reaches a more alkaline environment like the small intestine
Most oral drugs enter the bloodstream after absorption across the mucosal lining of the small intestine.
What is this small intestine epithelial lining covered in? And what is its job?
Villi
Increased surface area for absorption
How does absorption occur in the muscosal lining of the small intestine? (3)
Passive transport
Active transport
Pinocytosis
passive transport happens in two processes name them and what they do?
Diffusion
- drugs move from high to low concentration
Facilitated diffusion
- carriers protein move from high to low
Does passive transport need energy?
No
What is active transport ?
Enzyme or protein move the drug against concentration gradient
Does active transport need energy for active absorption?
Yes
What is pinocytosis?
Process by which cells carry a drug across their membranes by engulfing the drug particles in a vesicle
What is first pass effect or first pass metabolism?
Where the liver metabolizes a drug into an inactive state and then are excreted out, reducing the effect
How is the absorption of oral drugs work?
Oral -> GI -> intestine -> liver
What is bioavailability mean?
Percentage of administered drug available for activity
What does distribution mean?
Movement of the drug from the circulation into the body tissue
What are some things drug distribution is influenced by?
Vascular permeability
Blood flow
PH
Cardiac output
Tissue perfusion
What does highly protein bound drugs mean?
Example?
Drugs that are more than 90% going to bind with a protein
Warfarin
What does weakly protein bound drugs mean?
Example?
Drugs less than 10% bound to a protein
Metformin
The portion of the drug that binds with the protein is inactive, meaning ?
It is not available to interact with tissue receptors, ultimately not being able to exert a pharmacologic effect
The portion of the drug that doesn’t bind with the protein is known as ?
Free drugs
Since free drugs are not bound to a protein, they do what?
Are able to exit the blood vessel, reach site of action and cause a pharmacologic response
What is a blood brain barrier ?
Blood vessels in the brain that are pressed together and protects the brain from forgein substances
What does metabolism mean?
Process by which the body chemically changes drugs into a form that can be excreted
What is the primary site of metabolism?
Liver
If it takes 5 mins for a drug to be absorbed how long should it take?
Really fast! 5mins probably !
What is the fastest and slowest form of drug to get in the body?
IV
Oral
We want to be careful with giving 2 protein bound together because?
They will compete for protein sites and potentially have too much active drug circulating ( toxic )
What can cross the blood brain barrier?
Lipid soluble drug
Is a placenta an absolute barrier to the passage of drugs?
No!!!
Why do we have to be careful with pregnant mothers with medications?
Because most can cause over to the baby and affect the baby And mom!
Which crosses the placenta and which doesn’t?
Lipid and protein?
Think of which gets into the brain?
Lipid do cross
Protein dont!
If the mother is an opioid/tobbacco addicted, what will happen to the baby?
The baby will be born drug dependent and we need weaned off of it
What is the system that helps metabolize the drug in the liver to help excrete it out?
P450 system
What is a prodrug?
Nothing happens until it is metabolized ( it works opposite ! )
What does half life mean for medication?
How much time does the body take to get rid of half of dose of medication
Why is half life important?
Give an example
24-36hours
Once a day
It determines how much and how often you give the medication
What does steady state mean?
When the amount of drug being administered is the same as the amount of drug being eliminated
Usually happens after the 4th round
However sometimes patients can’t wait for steady state of a drug, take an example of a seizure patient, they have to wait 22 hours?!?
Instead we are going to do a ______
Which is?
Loading dose
A larger dose than needed
A loading dose can help patients how?
To reach a steady state and still receive therapeutic effects
And when they do, they can go back to normal routine
What are some things that can decrease metabolism?
Cardiovascular dysfunction
Renal insufficiency
Starvation
Obstructive jaundice
Slow acetylator
Ketoconazole therapy
( fungal infection )
What are 4 things that help increase factors of metabolism?
Fast acetylator
Barbiturate yherapy
Rifampin therapy
Phenytoin therapy ( seizure )
Where does the drug excrete from?(6)
Kidney
Liver
Lungs
Saliva
Sweat
Breast
Why is it important to know where and if our patient has some disease like kidney disease the drug is being excreted?
Then there kidneys aren’t filtering there substances
Meaning that won’t be able to excrete it, it can be toxic
Cause kidney can’t filter it out
Just because it is okay to give medication to someone is pregnant ( like a pregnant medication ) does it mean it’s okay to give it to them when breast feeding after baby is born?
NO!!! It passes to the baby and harms them
What does pharmacodynamics mean?
Study of the way drugs affect the body
What is the primary effect of pharmacodynamics?
What is the secondary effect of pharmacodynamics?
Desirable response
Desirable or undesirable ( side effect )
It’s important to note that the reason why sometimes we may give a medication may not be for the primary effect ( desirable response ) but instead for?
The secondary effect
( that’s why on many medications there are other indications as well )
What does dose response relationship mean?
The body physiologic response to changes in drug concentration at the site of action
What is potency?
An example?
Amount of drug needed to elicit a specific response to a drug
Fentanyl has high potency so we give very low dose
What does maximal efficacy mean?
Where we max out the drug usage or dose that it doesn’t provide any more therapeutic benefits
What does therapeutic index mean?
Therapeutic dose and therapeutic toxic that helps a therapeutic effect
Give me an example In where we would use the therapeutic index? And why?
Warfarin
Because it can suppress toxic and kill patient so we want to keep them safe
For a therupetic index to be safe and administered to a patient, we must make sure of what?
And explain it more
Therapeutic range
( Where plasma drug levels are in that range and won’t cause adverse effects )
What does onset mean?
How long the drug is taking to work
What does peak mean?
The time it takes for a drug to reach its maximum therapeutic response
What does duration mean?
The time a drug concentration is sufficient to elicit to a therapeutic response ( how long it works )
Sometimes we have to monitor a patients therupetic ranges because it can either be good or toxic
In which we do a what?
Peak & trough
What is a peak & trough?
Peak is highest plasma concentration of drug at a time
(30-60minsIV after infusion ends)
Trough is the lowest plasma concentration of drug
(Drawn just before the next dose)
What is a receptor theory?
To what? (3)
Drugs act by binding to receptors
Activate, produce response, inactive a receptor
What is agonists?
To produce what?
Medications that activate receptors to produce desired response
What is partial agonists?
To prevent what?
Medications that elicit only moderate actively when binding to receptors
Prevent receptor activation by other drugs
What is antagonist ?
Block what?
Prevent receptor activation
Block response
( turn it off )
What is a nonspecific drug effect?
It affects multiple receptors sites
( affects the same type of receptors )
What is a nonselected drug effect?
Affect multiple receptors
( affects multiple body systems )
Notes
Mechanism of drug action
Stimulation
Depression
Irritation
Replacement
Cytotoxic action
Antimicrobial action
Modification of immune status
What does side effect means?
Things we didn’t intend to do
( may be a yeast infection, but it’s unpleasant !! )
What is an adverse reaction mean?
Allergy
We didn’t expect it and it’s undesirable effect
What does drug toxicity mesn?
Too much drug
What does tolerance mean?
Getting use to a medication overtime
You have ro give a higher dose to achieve same therapeutic effect
What is tachyphylaxis?
Acute
Rapid decrease in response to a drug
It works but then stops
( change medication most of the time )
What is placebo effect?
Sugar pill
It’s fake
Why do we have to be careful of medication?
Because of drug interactions
( positive or negative ! Be careful )
What does additive drug effect mean?
Two drugs work together
( but they work fine alone )
What does synergistic drug mean?
Two drugs together work so much better than them being by themselves
What is antagonistic drug effect?
One drug reduced or blocks the other drug
( narcan antagonistic to opioid )
What is drug nutrient interactions?
Food increase, decreases or delay drug response
What is drug laboratory interactions?
Drug may cause misinterpretation of test results
( think of like iron meds making poop black, then when you want a poop exam, it changes the test results )
What is drug induced photosensitivity ?
Drug induced skin reaction cause by sunlight exposure
