ADME Flashcards
What kinds of drugs can pass through the cell membrane readily?
Non-ionized, they are lipid soluble
Where do weak acids get readily absorbed?
Stomach
Where do weak bases get readily absorbed?
Small intestines
What are the two kinds of transport proteins that influence absorption of drugs?
- Uptake
2. Efflux
What is the main difference between the two kinds of proteins that influence absorption of drugs?
Uptake - promotes absorption
Efflux - limits absorption
What is the CYP enzyme that is relevant in the GI tract?
CYP3A4/5
How does the CYP enzyme affect absorption?
Can limit absorption of certain CYP3A4 substrate medications, like simvastatin
How do you calculate Systemic drug exposure?
AUC = ng*hr/mL
How do you calculate bioavailability?
AUC (po) x Dose (iv) / ( AUC (iv) x Dose (po) )
What affects drug distribution?
- Lipid solubility
- Uptake / Efflux proteins
- Plasma protein binding
- Molecular size
- Organ blood flow
(T / F) Half of the drugs are usually protein bound
False, 10-99% are protein bound
What kind of plasma protein binding drugs can enter cell membranes easily?
Free unbound ones
What kind of plasma protein binding drugs CANT enter cell membranes easily?
Highly protein bound
What are the reactions involved in phase I metabolism?
Oxidation, hydrolysis, reduction
What is the main purpose of metabolism?
To make drugs more water soluble and thus more easily renally excreted
What kinds of reactions are involved in phase II metabolism?
Conjugation
What is the first step in drug secretion?
Glomerular filtration
How does reabsorption affect the drugs in the urinary system?
- Movement of drug from tubules back into blood stream
- Dependent on drug’s lipid solubility
- Non-ionized drug can be reabsorbed
How does secretion affect the drugs in the urinary system?
Unbound drug is secreted
from blood into renal tubule
then urine
Excreted conjugated drugs can sometimes be hydrolyzed back to their active parent compound by…
Intestinal bacteria
What is the rate limiting step in oral absorption?
Disintegration / dissolution of dosage form
What does albumin typically bind to?
Acidic drugs
What do alpha1-acid glycoproteins typically bind to?
Basic drugs
What is the most common conjugation reaction?
Glucuronide
