Drug Absorption and Distribution Flashcards
What is bioequivalent?
two drugs that produce the same rates/extents of bioavailability
What are the requirements for pharmaceutical equivalents?
same active ingredients, identical strength/concentration, dosage form and route of adminstration
What is bioavailability?
fraction of an administered dose that reaches systematic circulation
What is IV bioavailability?
100%
Where are most of oral drugs absorbed?
by small intestine due to large surface area
although the stomach absorbs some drugs, especially acid drugs
Where is most ibuprofen absorbed?
although it’s acidic, most is absorbed in small intestine because of the large surface area and longer time spent in small intestine
What factors affect bioavailability of drugs taken orally?
- direct interaction with digestive enzymes or gastric pH
- first pass metabolism
- inhibition of transport processes/metabolic enzymes
What is first pass metabolism and what enzymes are responsible?
metabolism of drugs in gut and liver before reaching systematic circulation
enzymes like CYP3A4 are present in gut and liver
What is the function of ferranocumins?
found in grapefruit juice, inhibits CYP3A4 and p-glycoprotein decreasing drug metabolism and increasing bioavailability
What organs have first phase distribution (rapid distribution)?
liver, heart, brain
What does affinity of drugs for tissues depend on?
lipid solubility and non-ionized
What is Vd?
volume of distribution: hypothetical volume needed to contain total amount of administered drug at same concentration as plasma
What leads to higher Vd?
accumulation of drugs in tissues and high first pass metabolism
What is the equation for Vd?
Vd = (total amount of drug adminstered)/(plasma conc)
What plasma proteins do drugs bind to?
albumin and a acid glycoprotein
