Flashcards in Intravenous Drug Administration Deck (36)
List the 5 'rights' of medicine administration.
List reasons for IV administration.
When a patient can't swallow or can't take medicine via any other route
Greater percentage uptake
Medicine might not be available in another form
What are the disadvantages of IV administration?
Increased cost and time to administer
Trained staff required
Rapid onset can also be a disadvantage
Volume of fluid needed to dilute the medicine (e.g. in a severely hypertensive patient)
Health risk (e.g. infection)
There are 3 major types of intravenous device - can you name them?
Peripheral venous catheters
Central venous catheters (CVCs) (peripherally inserted or skin tunnelled CVCs)
What is a bolus injection and when is it used?
A method of administering unstable drugs intravenously or when a rapid response is required
What is the difference between continuous infusion and intermittent infusion?
- stable drugs
- short half life
- time dependant effects
- needs dedicated IV site
- unstable drugs
- long half life
- concentration dependant effects
- fewer compatibility concerns
Name some environmental factors that affect the stability of drugs.
What is bioavailability?
The fraction of unchanged drug that reaches the systemic circulation - IV is therefore 100%
What is the difference between infusion vs repeated injections?
Infusion - constant build up of blood plasma drug concentration to a peak (around day 4)
Repeat injections - peaks and troughs as administration of drug is carried out. Again, levels out at a plateau, around which the plasma concentration of drug fluctuates
What is clearance?
The volume of blood or plasma cleared of drug in a unit time, e.g. 10ml/min (think glitter bathtub)
What happens to the drug half life if clearance increases?
Decreases - inverse relationship
What does the steady state plasma concentration of drug depend on?
Rate of drug in and rate of drug clearance from the plasma
What are a few of the complications that can be associated with IV drug administrations?
What is thrombophlebitis?
Inflammation of a vein wall associated with thrombosis
What is red man syndrome and what chemical release causes its appearance?
Hypersensitivity reaction due to histamine release
List some symptoms of red man syndrome.
Erythematous rash of face, neck, and upper torso
What are red man symptoms in rare cases?
What is the drug used for both red man syndrome, but also MRSA?
If administered in the wrong way, vancomycin can cause hypertension...what is the correct administration procedure used to reduce this risk of hypertension?
Regulated concentrations of vancomycin, administered slowly.
Describe what the shape of a plasma drug concentration vs time graph would look like for intravenous drug continuous infusion.
Linear increase at the beginning, eventually plateauing as more drug is eliminated, until it reaches a point where infusion = elimination, hence a flat, horizontal line. After all the drug has been infused, the plasma concentration plunges and the line descends steeply, finally levelling out to become horizontal at a plasma drug concentration of 0
What does the time taken to reach the plasma steady state concentration depend on?
The drug's half life
What can be the result of incorrect vancomycin administration?
What dosage of vancomycin should be administered for a patient under 40kgs?
How much of what solution should vancomycin be mixed with for a patient under 40kgs?
What dosage (including solution) of vancomycin should be administered for a patient between 40 and 59kgs?
In 250ml solution
What dosage (including solution) of vancomycin should be administered for a patient between 60 and 90kgs?
In 500ml solution
What dosage (including solution) of vancomycin should be administered for a patient over 90kgs?
In 500ml solution
For how long should the vancomycin drug solution be infused in a patient over 90kgs?
For how long should the vancomycin drug solution be infused in a patient between 40 and 59kgs?
For how long should the vancomycin drug solution be infused in a patient under 40kgs?
For how long should the vancomycin drug solution be infused in a patient between 60 and 90kgs?
What is the 'steady state' and how is this represented on a graph?
Rate of drug input = rate of drug output (elimination)
Plateau on graph of plasma drug conc vs time
How does clearance differ from amount of drug eliminated per unit time?
Clarence is a constant - per unit volume rather than time
If clearance is at 10ml/min:
100ml --> 100ml --> 100ml --> 100ml
100mg -> 90mg --> 81mg ---> 72.9mg
0mins --> 1min ----> 2mins --> 3mins
10mg ---> 9mg ----> 8.1mg ---> 7.29mg (drug eliminated)
What is the relationship between IV bolus and IV infusion?
They are opposites of each other: IV bolus starts high, decreases rapidly, then plateaus out at 0; IV infusion starts low, increases rapidly, then plateaus out at 100
As clearance increases, drug half life decreases