Lecture 1 Flashcards
Describe the 5 rights of pharmacology
- drug
- patient
- dose
- route
- time
Examples of correctly assessing and evaluating pharmacology in patient care:
- pre-administration assessment (is patient BP already too low to take more hypertensive meds?)
- Dosage and administration (does dosage/route make sense?)
- Evaluating and promoting therapeutic effects (see what BG to give the correct amount of insulin)
- Know what adverse effects are so you can minimize likelihood
- Know what drugs can interact to result in adverse effects
- Know how soon someone can get a medication
- Keep toxicity of drugs in mind
What are the three types of drug names?
Chemical name (paracetamol), Generic (Acetaminophen), Trader (Tylenol)
What are the four phases of drug activity?
- Absorption (from site of admin to blood/circulating fluids)
- Distribution (from the blood through the interstitial space and to the cell of action/target cell)
- Metabolism (what happens when the drug is altered, usually happen in the liver)
- Excretion (in urine or bile)
What are some factors that affect absorption of a drug?
- rate of dissolution (only available when dissolved)
- Absorbing surface (intestines need a large surface area so the microvilli can absorb)
- Blood flow (need good blood flow to get meds to places to absorb)
- Lipid solubility of drug (if lipids are available for lipid soluble medications)
- PH partitioning (specific ph is neccesary to properly absorb meds)
What is the difference between parenteral and enteral route of administration?
Enteral: Oral/PO
Parenteral: Everything other than oral/through GI tract. IV, IM, SQ
What are the pros/cons of IV meds?
Pros: No barrier to absorption, rapid onset, can give large amounts of fluid, dispersed and circulated quickly
Cons: Costly, inconvenient, not reversible, easily infected, risk of embolism, drugs HAVE to be water soluble
How quickly do IM medications take effect?
Absorption determined by blood flow and drug solubility. Usually within 10-30min.
How quickly do SQ medications take effect?
Blood flow isn’t as good as IM so it is absorbed slower
Describe the barriers to absorption of the enteral route
Has to move through the epithelial cells (move through cells) of the GI tract lining and then through the endothelial cells (move around cells) of capillary walls.
Medication needs to be soluble
GI PH needs to be right
Bowel movement has to take place
Food near the medication may affect dissolve, chem structure, absorption
Other drugs taken at the same time
Drug coatings/compounds make drug favorable for absorbing or not
What are disadvantages of enteral absorption
everyone has different absorption because their GI is different
Has potential to be inactivated by food, other drugs, gastric acidity
the drug goes though the liver before becoming systemic and is chemically changed so that it is no longer effective
Pt has to be awake to take PO
If patient voids quickly (vomiting, diarrhea) less/no change of absorption
What are some alternative route of med admin
Topical, inhaled, rectal/vaginal suppositories, direct injection (joints, heart, CNS)
What affects distribution of a drug
Blood flow, ability to enter/exit vascular system (most drugs exit at capillary cells but can be inhibited by barriers such as blood-brain or protein binding barriers), ability to enter cells
Describe the blood brain/protein binding barriers
Blood brain: Tight junctions at capillary cells in brain
Proteins binding: Med binds to a protein in the vascular system and can’t leave to do what it needs to do b/c too big
T/F: All drugs have to enter cells to be metabolized and excreted?
True. Some drugs have to enter the cell to act while others work attached to the outside of the cell
Define metabolism
Biotransformation /enzymatic alteration of drug
What is the P450 system?
The hepatic microsomal enzyme system. 11-12 different ENZYMES that help with changing the drug during metabolism
T/F: The metabolism of a drug can only mean the break down of a drug into usable forms?
False. Metabolism is where the drug turns into something else, not broken down
What are five things metabolism/biotransformation can do to a drug?
- Make a drug less lipid soluble and therefore more likely to be excreted by the kidneys
- Convert the drug into it’s inactive form
- Increase a drug’s therapeutic action(move from inactive to active form). For example, can turn codeine into morphine
- Activation of prodrugs through the liver
- Can increase or decrease the toxicity of a med
Define the fist pass effect
Liver rapidly inactivates certain oral drugs. Starts when PO med is absorbed through GI tract into capillary, move through venous system (Hepatic portal vein), and then to the liver. Ex: Nitroglycerin has to be given sublingually because it would make it through the first pass if swallowed into the GI tract
What factors may effect the metabolism of a drug?
Infants and elderly have undeveloped metabolisms and generally metabolize slower
Genetic polymorphisms occur in people in certain geographic locations as well as races.
Define excretion
Drug elimination (removal of drug from the body).
What are the three types of filtration?
Filtration: All drugs not attached to a protein are filtered our of blood in kidney and released into urine.
Reabsorption: Lipid soluble drugs move back into the blood, out of the urine. Polar and ionized drugs remain in the urine.
Secretion/Active transport: Blood removes PH into urine through tubular “pumps”
Other sites of excretion include the lungs, bile. breast milk, sweat, and saliva.
Factors that effect excretion
PH, active tubular transport, and age
Define the time course of a drug response
The time a drug action starts, peaks, and ends.
You can measure the amount of medication in blood plasma o determine if the drug is currently above the MINIMU EFFECTIVE CONCENTRATION (MEC) or a toxic concentration.
when does the duration/therapeutic range of a drug start/end?
Once the concentration of drug goes above the MEC level and goes below it
When would you use the term “this drug has a narrow therapeutic range”?
The concentration of MEC and toxic concentration is so close that the drug can easily become too concentrated/toxic
Define a drug half life
When the drug will be half gone after administration
Why is it important to know the half life of a drug?
It will help you understand the dosing schedule. If the half life is in a few minutes, the medication may need to be redosed daily whereas if its weeks, you may not need to redose for weeks.
How do you reach a half-life plateau?
Ex: Half life after 24 hours. Start w/ two grams dose, tomorrow when half life into one redose 2g so its 3 grams, continue until reach 4 plateau and plateau reach day 5.
Loading dose can help reach plateau faster
How are the effect drugs generally have on recepters?
Our body’s own receptors sites for hormones, neurotransmitters, ect are affected by drugs that attach to the receptor (lock/key style) by mimicking or blocking actions of the substance that normally interacts with the receptor. Drugs cannot give cells a new function.
Drugs can be an agonist (favor the action that receptor is responsible for) or an antagonist (block action receptor is responsible for.
What is ED50?
The dose required to produce a DEFINED therapeutic response in 50% of the population. Considered the standard dose because it is the dose that will most likely help an individual. Then see how pt reacts to see if pt is sensitive or not to drug to increase or decrease drug.
Define a therapeutic index
The measure of a drugs safety.
The highest dose to be effective should be lower than the lowest dose to be lethal.
