Pharm Quiz 2 Flashcards
pharmacokinetics word breakdown
pharmakon- drug or poison
kinesis- motion
what quesitons should come to mind with pharmacokinetics?
- how does te drug get into the body & where does it go?
- what does the body do to/with the drug?
- how does the body get rid of the drug?
process of pharmacokinetics through the body
- absorption
- distribution
- metabolism
- excretion
how do drugs get to their desired location?
through the blood/ blood flow
where does the majority of drug metabolism occur?
in the liver
can also occur in the kidney or GI tract
where does the majority of drug metabolism occur?
in the liver
can also occur in the kidney or GI tract
which organ does excretion mostly occur in?
kidneys
absorption
movement of a drug from its site of administration into the blood
ex: tylenol is absorbed by GI > blood
absorption
movement of a drug from its site of administration into the blood
ex: tylenol is absorbed by GI > blood
rate
determines how soon effects will take place
how soon
amount
determines how intense the effects will be
how intense
factors that affect the process of absorption
- rate of dissolution
- surface area
- blood flow
- lipid solubility
- pH partitioning
- route of administration
how does rate of dissolution affect absorption?
the quicker it dissolves, the quicker the effect
* dissolvable = quicker
* extended relsease medication (dissolves slower over time) (ER)
how does surface area of dissolution affect absorption?
larger surface area where the drug is aborbed affects the rate/amount
* small intestine
drop vs. a lot of eczema cream
how does blood flow of dissolution affect absorption?
certain ages/areas of high blood flow would dissolve/take effect sooner
how does lipid solubility of dissolution affect absorption?
drugs need to be lipid soluble to enter the blood stream
2 groups of routes of administration
- enteral (GI tract)
- parenteral (outside GI tract)
enteral (GI tract) medications
oral (PO)
parenteral (ouside the GI tract) medications
- intravenous (IV)
- subcutaneous (subQ)
- intramuscular (IM)
injection
absorption pattern & barriers to absorption for oral (PO) medications
- absorption pattern: slow & variable
- barriers: epithelial lining of GI tract, capillary wall
advantages & distadvantages of oral (PO) medication
ADVANTAGES:
* safer than injection routes (slower absorption, more time to react to abnormalities, generally not monitored)
* ideal for self administration
* easy, convenienet, inexpensive
DISADVANTAGES:
* can cause GI irritation
* requires cooperative patient (age, mental status)
* inactivation (caused by other drugs, food)
* variability
PO
latin
*per os
by way of mouth
PO
latin
*per os
by way of mouth
absorption pattern & barriers to absorption for intravenous (IV) medications
- absorption pattern: instantaneous & complete
- barriers: none (absorption is how drugs get to the blood, it is already there)
advantages & disadvantages for intravenous (IV) medications
ADVANTAGES:
* rapid onset
* control (administrating meds at specific rates)
* permits use of large fluid volumes
* permits use of irritant drugs
DISADVANTAGES:
* high cost, difficulty, inconvenience
* irreversibilkity
* infection
* high risk
which types of medication admin routes have no barriers?
IV, IM, subQ
no barriers to get to the blood
which types of medication admin routes have no barriers?
IV, IM, subQ
no barriers to get to the blood
absorption pattern & barriers to absorption for intramuscular (IM) & subcutaneous (subQ) medications
- absorption pattern: variable (water solubility, blood flow)
- barriers: none (little through muscle, skin)
advantages & disadvantages for intramuscular (IM) & subcutaneous (subQ) medications
ADVANTAGES:
* used for** poorly soluble drugs**
* used for depot preparations (1 injection that lasts weeks/months (BC, mental health meds))
DISADVANTAGES:
* discomfort
* inconvenience
* cause** muscle & nerve injury** with improper technique
* bleeding risk
what medican route are depot preparations usually administered?
IM or subQ
when would parenteral (injection) admin be preferred?
- emergencies
- situations requiring tight control
- GI incompatibility (destruction of drugs by GI/ cause GI injury)
- tx with drugs that cannot cross membranes
- better treated with** long acting preparation (depot)**
- pt who cannot/will not take PO meds
distribution
the movement of drugs throughout the body
distribution process
- blood flow to tissues
- drug’s ability to exit the vascular system
- drug’s ability to enter cells
drug metabolism
the enzymatic alteration of drug structure to a more water-soluble form that can be excreted
where is the majority of drug metabolism done?
liver
special factors/considerations in drug metabolism
- age- young & old have decreased metabolism
- first-pass effect- some meds are completely metabolized by the liver the first time passing through (nitroglycerin, administered topically)
- nutritional status
- competition between drugs
excretion
removal of drugs from the body
how can drugs & their metabolites exit the body?
- bile
- urine/feces
- sweat/saliva
- breast milk
- expired air
how can you monitor drug responses through plasma drug levels?
correlation b/w response to drug & level in plasma
what two levels can you use to monitor drug response?
- minimun effective concentration (MEC)
- toxic concentration
therapeutic range
determines whether the drug can be safely given
drug half-life
determines dosing interval
repeated dosing
determines rate & extent of accumulation
* may use a loading dose as well as maintenance
pharmacodynamics
pharmakon (drug or poison) + dynamikos (force or power)
dose-response relationship
relationhsip between the size of an administered dose and the intensity of the response produced
what does the dose-response relationship determine?
- relative potency- minimum amount of drug needed to elict a response
- maximum efficacy- maximum response a drug can elicit
therapeutic index chart
3 possible outcomes of drug-drug interations
- potentiate- intensifies the effects
- inhibit- reduce the effects
- new response- effect not seen with single drug alone
how can food interact with drug effects?
- absorption
- drug metabolism
- drug toxicity
- drug action
- timing
