Pharmacological Principles Flashcards
Are ionized or nonionized drugs more readily absorbed?
Nonionized
Why does oral absorption of drugs have the first pass effect,but not the sublingual absorption?
Because the veins of the stomach and small intestine drain directly into the portal system.
The veins of the esophagus and mouth drain into the SVC so drugs absorbed here go into the systemic system first.
What layer of the skin is an effective barrier to small, lipid-soluble drugs (clonidine, nitroglycerin,scopolamine, fentanyl)?
Stratum corneum
What does plasma protein levels affect?
The solubility of the drug in blood, but not the rate of equilibration
What increases the rate of onset of a drug?
High levels of binding in the blood compared to in the tissue because fewer molecules need to transfer into the tissue to reach an effective free drug concentration
What kind of PH does albumin usually bind?
Acidic drugs
What binds basic drugs?
Alpha 1 glycoproteins
What happens to drug solubility if albumin or AAG is decreased in the blood?
The solubility decreases
What conditions increase AAG levels?
Trauma, surgery, infection, MI, chronic pain
What condition decreases AAG levels?
Pregnancy
What drug is administered with its own binding molecules?
Propofol
What is the blood brain barrier made up of?
Pericapillary glial cells and endothelial cell tight junction
What kind of drugs readily pass the blood brain barrier?
Lipophiloc drugs (hypnotics and opioids)
What is redistribution?
The process by which the drug re-equilibration from the tissue to the plasma as drug concentration falls in the plasma.
- delays emergence following prolonged infusions
What is context sensitive half time?
The time required for a 50% decrease in plasma drug concentrations following an infusion
What is the context referring to in context sensitive half time?
Duration of the infusion
What is context sensitive decrement time?
Refers to any clinically relevant decreased concentration in any tissue
What is volume of distribution equation?
Bolus dose/plasma concentration (time)
What is Vdss?
The volume of distribution of 3 compartments
2 peripheral compartments: rapid equilibration (organ and muscle) and slow (fat and skin)
1 central compartment (blood and lung)
What does a small Vdss imply?
High aqueous solubility, stays in the blood (pancuronium)
What does Vdss reflect
.
The volume into which the drug would have to distribute to account for the observed plasma concentration given the dose that was administered
What is phase 1 reaction?
Converts parent compounds into polar molecules through redox reactions or hydrolysis