Study Guide 1 Flashcards
scope of practice for APRN prescribing
2 components
- right to prescribe independently
- right to prescribe w/o limitation
med adherence
extent to which pts take their meds as prescribed by LIP and agreed to by pt
medication hx and factors to consider when prescribing
- cost
- disease guidelines
- interactions (drugs and polypharmacy)
- s/e
- allergies
- liver and renal fx
- need for monitoring
- special populations
teratogen
substance which will cause permanent abnormalitiy, growth retardation, or death if fetus exposed
renal function when prescribing
look at creatinine clearnace
e- prescribing
trend bc less likely to have errors
cannot e-prescribe scheduled meds or narcs
pharmacokinetics
study of drug movement throughout the body
first pass effect
o Refers to the rapid heaptic inactivation of certain PO drugs. when drugs are absorbed from the GI tract, they are carried direcly to the liver through the hepatic portal vein before they enter the systemic circulation. If the capacity of the liver to metabolize a drug is extremely high, that drug can be completely inacticated on its first pass through the liver. As a result, no therapeutic effects can occur. To circumvent the first pass effect, a drug that undergoes rapid hepatic metabolism is often administered parenterally.
steady level aka plateau
Administering repeated doses will cause a drug to build up in the body until a plateau (steady level) has been achieved.
time to plateau
approximately 4 half lives with constant dose
decline from plateau
When drug administration id dc’ed, most (94%) of drug in the body will be eliminated over an interval equal to about 4 half lives.
excretion
removal of drugs from the body
most common organ for drug excretion
renal
absorption
movement of drug from site of admin into systemic circulation
factors affecting drug absorption
Rate of dissolution Surface area Blood flow Lipid solubility Ph partitioning
half life
time required for the amount of drug in the body to decrease by 50%
passage of drugs across membranes
ADME
3 ways to cross cell membrane
- passage through channels or pores
- passage with aid of transport system
- direct penetration of membrane
polar molecules
molecules that have no net charge and uneven distribution of electrical charge
ions
molecules that have net electrical charge- positive or negative
unable to cross membranes
ion trapping/og oartutuibubg
• Bc of ionization of drugs is Ph depdendent, when the ph of the fluid on 1 side of a membrane differs from the ph of the fluid on the other side, drug molecules tend to accumulate on the side where the ph most favors their ionization. Accordingly, bc acidic drugs tend to ionize in basic meida, and bc basic drugs tend to ionie in acidic media, when there is a ph gradient between 2 sides of a membrane, the following occurs
o Acidc drugs accumulate on the alkaline side
o Basic drugs accumulate on the acidic side
• The process whereby a drug accumulates on 1 side of a membrane where the ph most favors its ionization is referred to as ion trapping or ph partitioning
metabolism
aka biotransformation
enzymatic alteration of drug structure
takes place in liver
p450 system
o Metabolism that takes place in the liver is perfroemd by hepatic microsomal enzyme system, known as P450 system. The term P450 refers to cytochrome P450, a key component of this enzyme system.
therapeutic consequences of drug metabolism
Accelaterated renal excretion of drugs Drug inactivation Increased therapeutic action Activation of prodrugs Increased toxicity Decreased toxicity