Pharmacology Flashcards
What is the therapeutic window?
The area between the MEC for adverse responses and the MEC for therapeutic response (desired response)
What factors affect pharmacokinetics?
Age, liver/renal function, BMI
How do most drugs interact with the plasmalemma?
Via surface receptors since they’re polar and cannot diffuse across
What are most drugs conceptualized as, as far as their interactions with the cell?
Ligands for surface receptors
Which kinds of drugs are lipid soluble? Water soluble?
Uncharged (hydrophobic)
Charged (hydrophilic)
What is ion trapping and how does it work?
Ion trapping is the use of a drug’s pKa to change its charge to transport it to the desired location (like into the blood stream from the GI tract)
When pKa is greater than its environment, the charge is hydrated and it becomes nonpolar. THEN it can be transported across lipid bilayers.
(TLDR: pKa=4.4 in stomach, uncharged. Transported to blood. In blood, regains charge)
What is a prerequisite for CNS active drugs?
Must be hydrophobic (due to BBB)
What are the main uptakes for drugs from slowest to fastest?
Oral, Transdermal, IM, IV and intrathecal
What is the reason oral intake is slow?
Has to go through first-pass metabolism (via portal circulation)
How is bioavailability calculated?
F=
Quant of drug reaching system circulation
OVER
Quant of drug administered
What route of intake has the highest bioavailability? Lowest?
Intravenous; oral
What is the issue with inhalation as a route of intake?
Patient education and patient technique
Where is a drug located if the Vd is 4L (equal to blood plasma volume)?
ALL OF IT is in the blood
Where is a drug most likely located if the Vd is 250?
Extravascular spaces (muscle, tissues, adipose, etc)
Where is a drug mostly located if the Vd is low?
Blood plasma (vascular compartment)
What is the Vd of drugs that are most likely to need a loading dose?
High Vd may need loading dose to increase plasma levels to the therapeutic range
Describe first order kinetics in regards to elimination of a drug?
drug concentration determines how much drug is eliminated (like a constant 16% elimination per half life. The plot’s slope gets smaller as more drug is eliminated)
What are zero-order kinetics in relation to drug elimination?
A constant amount of drug is eliminated regardless of concentration (very linear elimination line)
What is steady state?
Rate of elimination= rate of administration (takes 4-5 half lives)
maintains concentration in the blood plasma through multiple maintenance doses
What is the formula for clearance?
Clearance= metabolism plus excretion, divided by the concentration of drug in plasma
How does drug binding to proteins affect its activity?
Protein bound drugs (like bound to albumin in the blood) are INACTIVE
What is protein binding’s effect on Vd?
More protein binding= lower Vd
Less protein binding= higher Vd
How can disease-state modifications of proteins affect drug action?
Less protein= greater risk of toxicity due to incr free drug in plasma
More protein= higher conc needed for therapeutic range (not as important)
What drugs are most susceptible to dangerous effects when protein is low?
Those with a low therapeutic index
