12. Pharm- Exam 3 Flashcards
Pharmacokinetics=
What the body does to the drug
Pharmacodynamics=
How a drug interacts with the body to produce its effects
First order kinetics=
elimination of a drug occurs at a constant fraction of drug remaining in the body per unit of time
Zero order kinetics=
when drug administration exceeds the body’s ability to clear it, leading to drug accumulation
what should be done To prevent drug accumulation
drug infusion rates should be adjusted according to patient response
what 4 things does hemodiltion cause
- Reduction in circulating protein concentration
- Reduction in RBC concentration
- Reduction in concentration of free drug (unless your pump prime matches exactly)
- Alterations in organ blood flow, affecting distribution and clearance
What happens if you add drugs to your prime BEFORE RAP or AFTER RAP??
lose drugs that are in that given prime that is removed
what 4 things does hypothermia cause
- Fluid shifts from intravascular to interstitial space= Altered volume of distribution & Increased 3rd spacing
- Vasoconstriction= Changes in organ perfusion
- Reductions in enzyme-mediated biotransformation
- Increased solubility of volatile anesthetics
Lungs being excluded from circulation effects what 3 drugs
Valium, propofol, opioids
Altered hepatic blood flow effects what 2 drugs
Fentanyl, propofol
Sequestration: Drugs may be taken up by various components of the CPB circuit. give 3 examples
- Coated tubing= lipophilic drugs stick to the circuit
- Oxygenators= takes the drug up invitro
- Hemofilters= sieving coefficient and protein binding
when Administering medications, what do you ensure
- you have a physician’s order or standing protocol authorizing you to administer the medication
- the patient is NOT allergic to the medication
- you have the correct medication, the correct concentration and the correct dosage
when Administering medications, what do you inspect
expiration date, precipitates, and sterility
What is in your drug box? (8)
- Heparin
- Neo-Synephrine
- NaHCO3
- Lidocaine
- MgSO4
- Calcium
- Potassium
- Mannitol
Heparin Sodium is derived from what?
bovine lung tissue or porcine mucosa standardized for anticoagulant activity
Heparin Sodium’s potency is determined by what
a biological assay using a USP reference standard based on units of heparin activity per milligram
100 units Heparin Sodium= ____mg
5000 units= _____mg
1 mg
50mg
Heparin Sodium action
stops coagulation by potentiating antithrombin III and inhibiting the action of activated Factors IX and XI
Heparin Pharmacokinetics=
•Eliminated by kidneys
•Half life at CPB doses is 2 or more hours
–Prolonged by hypothermia and renal blood flow alterations
Heparin Side Effects=
- Activation of t-PA and platelets
- Boluses decrease SVR by 10 to 20%
- Anaphylaxis rarely occurs
- HIT and HITT
Heparin Loading Dosing
300 to 450 units/kg
Rarely need to exceed 35,000 to 40,000 units
how does Heparin distribute
Distributes primarily in plasma, so increasing dose with increasing body weight is only relevant to a certain point
the Heparin priming solutions should contain heparin at approximately what level
Priming solution should contain heparin at approximately the same concentration of the patient’s blood stream
target ACT is ? this is prolonged by what?
Target ACT controversial (300 to 480 seconds)
ACT is prolonged by hypothermia and hemodilution
most Heparin vials come in what increments
Most vials you will see for adult CPB will be 1000 units/mL
a loading dose of 30000 units is how many ml
30 ml
Neo-Synephrine action
Synthetic selective α1-adranergic agonist that causes vasoconstriction in arterioles
Neo-Synephrine duration
less than 5 minutes
•Titrated to effect
•Start with a test dose
Neo-Synephrine Dosing: IV bolus
- 100 micrograms/mL
- 200 micrograms/mL
- 400 micrograms/mL
Neo-Synephrine Dosing: IV infusion
•10 or 15 mg in 250 mL IV fluid (40 to 60 micrograms/mL)
starting with 10 mg Phenylephrine in 1 mL vial– Add 49 mL Normosol and you get:
50 mL containing 10,000 mcg = 200 mcg/ML
Sodium Bicarbonate=
- A sterile, nonpyrogenic, hypertonic solution of sodium bicarbonate (NaHCO3) in water for injection for administration by the intravenous route as an electrolyte replenisher and system alkalizer
- Also used to treat hyperkalemia
Sodium Bicarbonate dosing equation
Dose (mEq) = 0.3 x Weight (kg) x BD (mEq/L)
*Or just “1 amp” (50 mEq)
Sodium Bicarbonate dosing for hyperkalemia
Adults: 50 mEq
•Peds: 1-2 mEq/kg