Pharm Flashcards
What are the sources of drugs or where do they come from?
Plants, Animals, Minerals, Synthetic Chemicals, Genetically engineered chemicals
How does the movement of drugs occur? (like what are the 3 main ways drugs pass thru the membrane)
Drugs must cross membranes in order to move thru the body
- Between molecules in a membrane
- Transport systems : passive & active
- Direct membrane penetration:
…. - drug must be lipophilic (EASIEST to cross the membrane)
… - MOST common method
Out of the three 3 ways the drugs move to cross the membranes, how does lipophilic/lipid soluble drugs move??
Any drugs that are LIPID SOLUBLE will always move across the membrane by Direct membrane PENETRATION!!!
What is absorption affected by?
- Route of administration:
- SLOWEST absorption: oral/ by mouth (bc it has to be taken by mouth, has to go thru the stomach & be broken down before it starts to be absorbs)
- QUICKER: parental routes or break in the skin- subQ and IM shots
- FASTEST or “instant” : IV push
- Surface area
- the larger the surface area, the faster absorption
- Blood flow
- higher blood flow means faster absorption
- Lipid solubility
- if it is fat soluble, it’s going to absorb faster and moves faster
- Drugs that are Lipid soluble are FASTER than water soluble
- pH differences/Ionization
- If you’re taking Antacids, that’s going to lower ur stomach’s pH and affects absorption since ur decreasing the acidity that helps break it down. IF UR TAKING ANTACIDS, take it SEPARATE from other drugs bc it can impact absorption either making it absorbs quicker or making it longer to absorbs.
- Very older & younger ppl have LESS acidic stomach so their absorption is slower
- Drugs that are NON Ionized are absorbed FASTER than drugs that do carry a charge
- Physiological condition
- Ppl that have issues w their guts or have inflammatory bowel disease, it’ll take longer time for things to move thru the gut bc the motility is slower. There are ppl whose motility’s really fast (like ppl who just constantly get diarrhea) so they have no time to absorbs those medications.
- Decreased or Increased motility change the speed of medications being absorbed
List the route of administration from slowest to fastest absorption
Slowest
PO (by mouth)
SubQ
IM
IV
Fastest
So if a drug is lipid soluble and non-ionized, how does that help with absorption?
If drugs are lipid soluble and non-ionized (not holding any charge), that’s going to FASTEN absorption
The distribution of drugs can be Affected by what 6 things?
- Blood flow to the tissues
- Cardiovascular disease (and others that have issues with circulation) can take longer for medications to go to that tissues
- Things that don’t get good blood supply: adipose tissues, tumors, scars tissues. Medications are harder to get to there because the blood supply is not as good
- Drug’s ability to leave the blood
- Drug’s ability to enter the cells
- Protein Binding
- Drugs likes to form bonds with Protein/Albumin
- Some drugs are highly protein bound
- Some drugs with little attraction to protein.
- Drugs likes to form bonds with Protein/Albumin
- The Blood-Brain Barrier
(protects the brain against harmful things that may enter)- Cells tightly packed:
- To keep out toxins/poisons
- Can prevent treatment - Only some drugs can penetrate
- Lipophilic drugs
- Transport system (sometimes they might use this to carry them across) - Barrier not fully developed @ birth
.. - thus, implications: Increases vulnerability to infant’s CNS or brain
- Cells tightly packed:
- The placental membrane
- Any drugs can go to the baby IF:
1. Lipophilic
2. Not protein bound
3. Not ionized
- Any drugs can go to the baby IF:
Can drugs that bind with Albumin/protein pass thru the capillary walls/membrane?
NOPE. When drugs bind with protein, they become INACTIVE and won’t be able to pass thru the capillary walls.
What are active drugs? What does it mean?
FREE DRUGS. If the drugs don’t bind with protein/albumin, then they are free drugs which mean they are ACTIVE and works!
They are able to pass the capillary walls and give us the pharmacological effect response
What are examples where patients have lower-than-expected protein levels
Malnutrition, Liver failures, and burns
What happens to patients with lower-than-expected protein levels?
Since they don’t have much protein and drugs aren’t able to bind to proteins, there’s going to be EXTRA free drugs hanging around and TOO much of it can cause TOXICITY!
What happens to patients with lower-than-expected protein levels?
Since they don’t have much protein and drugs aren’t able to bind to proteins, there’s going to be EXTRA free drugs hanging around and TOO much of it can cause TOXICITY!
What happens if you give 2 drugs that are highly-protein bound to patients?
What to do if this happens/alternations?
Those 2 drugs are going to be competing for protein to bind to. This means there’s going to be more FREE drugs hanging around and can cause toxicity.
What should you do?
Dosing and timing needs to be altered!
What type of drugs can penetrate blood-brain barrier?
Lipophilic drugs (fat soluble drugs)
Where does Metabolism PRIMARILY occur?
In some degree, where does it happen?
How does metabolism achieved?
PRIMARILY in liver!
Some degree in small intestine, lungs, kidney, brain, nasal mucosa, skin
- Achieved by liver enzymes (transform it, breaks it down to get rid of it
What is the Biotransformation that happens to drugs in the Metabolism process?
Drugs are going to be transformed from Lipophilic to Hydrophilic (water soluble)
What happens to drugs during the Metabolism process?
A) Happens primarily in Liver & achieved by enzymes
B) Biotransformation: drugs are transformed from Lipophilic to Hydrophilic
C) Metabolites formed:
1. ACTIVE: drug go thru metabolism, turn into an active form of metabolite & is secreted out
2. INACTIVE: go thru metabolism & turn into an inactive metabolite & don’t work @ all
3. PRO-DRUGS: you take it, it doesn’t do anything until it goes thru the process of metabolism & then it’s able to start to work
D) First Pass Effect
- means that a drug gets metabolized at a specific location in the body that results in a reduced concentration of the active drug before it even reaches its site of action.
- Drug is taken orally, drug enters GI tract, Active drug is absorbed from stomach & small intestines, high blood concentration of drug is in hepatic portal vein, then low levels of drugs after passing thru the liver
- If you have a drug that is HIGH First Pass Effect, don’t take it by mouth! INSTEAD give it by IV, IM or Subq to avoid the first pass effect.
E) Rates of Metabolism
- There’s different rates for different drugs (some drugs are metabolized v quickly some take longer)
- There’s a percentage of the drug that is metabolized (broken down) each time it passes thru the lives and the circulation
If someone has a liver disease, it might take longer to break down the drugs. What would you need to do r/t his medications?
Lower the dose; by doing so, you make sure that there aren’t many free drugs hanging around & it doesn’t become toxic
Medications are given by which way that will bypass the First Pass Effect? What routes of administration should you assess instead to avoid the First Pass Effect?
by Mouth!
To avoid, give it thru IV, IM, and SubQ instead!
Highly metabolized drug is gonna loose its effect if its given by what?
If its given orally/by mouth; bc it’s going to pass the First Pass Effect
You are caring for a patient with a cerebral abscess. How might the blood brain barrier influence the ability to treat this infections?
Stops the drugs from reaching the brain
You are caring for a patient with liver failure. How might this influence their ability to metabolize medications? What could be the consequences of this alternation? What should you do?
- It decreases the ability to metabolize medicines.
- The consequences are that it will increase pharmacological effect and increase toxicity.
- Should lower the dose
