Pharmacology Flashcards
what is meant by drug absorption
the process by which a drug enters the body from its site of administration
what is meant by drug distribution
the process by which a drug leaves the site of administration, enters the blood and subsequently the tissues perfused by the blood.
what is meant by drug metabolism
the process by which tissue enzymes (principally in the liver – hepatic metabolism) catalyze the chemical conversion of a frequently lipid soluble drug to an often less active and more polar form that is more readily excreted from the body
what is meant by drug excretion
the processes that remove the drug, or its metabolites, from the body (principally the kidneys – renal excretion)
what is meant by drug elimination
The linked processes of metabolism and excretion
what factors affect drug absorption
solubility
chemical stability
lipid to water partition coefficient
what is acids relationship with protons
donates protons
what is base’s relationship with protons
accepts protons
what does the degree of ionisation depend on in drugs
pKa of the drug
local pH
what can calculate Proportions of ionised and unionised drugs
the Henderson-Hasselbalch equation
what is the Henderson-Hasselbalch equation
pKa - pH = log(AH/A-)
for acid
pKa - pH = log(BH+/B)
for base
what facilities the absorption of weak acids
pH of the stomach lumen
where are bases readily absorbed
small intestines
what is oral availability
the fraction of drug that reaches the systemic circulation after oral ingestion
what is systemic availability
fraction that reaches the systemic circulation after absorption
