Pharmacology 2

what are the 4 compartments of the body?
plasma, interstitial fluid, intracellular fluid, transcellular water

How does drug exist in the 4 compartments of the body?
in free solution and bound form

How do drugs that are WA and WB exist in the 4 compartments?
equilibrium of charged to uncharged forms

What does the equilibrium pattern of WA and WB depend on?
permeability of drug through tissue barriers, drug binding within compartments, pH partition, fat:water partition

WA drugs exist more in
urine (basic)

WB drugs exist more in
stomach (acidic)

What is ion trapping?
altering pH of urine to increase renal excretion of drugs

What is used to increase urinary pH?
sodium bicarbonate

How is ion trapping used in an aspirin overdose?
Urinary pH increased, aspirin becomes ionized, making it less lipid soluble, reducing reabsorption from renal tubule, increasing excretion.

What is the henderson-hasselbalch equation for WA?
pH= pka + log (ionised/unionised)

What is the pka?
pH at which drug is 50% ionised, 50% unionised

What is the pka of aspirin?

Use the henderson hasselbalch eq to explain ion trapping…
pH= pka + log (ionised/unionised). If pH of urine is increased, ratio of ionised/unionised increases, therefore most of drug ionised, aspirin is trapped and excreted.

What is the BBB?
continuous layer of endothelial cells, joined by tight junctions

What is the volume of distribution?
volume of fluid needed to contain the total amount of drug in the body, Q, at the same conc as that in plasma, Cp

Q (drug in body)/ Cp (conc in plasma)

Lipid soluble drugs are _____ distributed in the body…
well, may accumulate in fat. High vol of distribution drugs

Lipid insoluble drugs are ____ distributed in the body…
not well, stay in plasma. Low vol of distribution drugs

Vd< 5L=
drug is retained in vascular compartment

drug is restricted to extracellular fluid

distribution throughout body water or concentration in specific tissues

How do most drugs travel in plasma?
bound to proteins, free drug fraction as small as 1%

What is the most important plasma protein for drug binding?

What does albumin bind?
acidic drugs

What happens when the binding of albumin saturates?
non-linear relationship between dose and active drug conc

What does plasma protein binding do to drug elimination?

Describe the model for lipid soluble drugs?
initial steep decrease in plasma levels which is due to redistribution (alpha phase) from plasma into the body tissues followed by a slower decrease in plasma conc (beta phase) which is due to elimination.

Where is half life calculated from?
terminal phase (beta)

How much of THC in blood is distributed in plasma?
90%, 10% within RBC

How much THC in plasma is bound to plasma proteins?

What type of plasma protein is THC most bound to?
lipoproteins and then albumin

What is the initial Vd like for lipophilic drugs?
small, due to high degree of protein binding

How is THC distributed?
rapidly to body tissues especially fat, elimination slowed down b/c trapped in fat

Does THC cross the placenta?

Do THC metabolites cross the placenta?

Make sure you know the learning objectives. Describe the pharmacokinetic parameters: clearance, apparent volume of distribution, bioavailability, and half-life. Explain how plasma drug concentration is dependent on the route and schedule of drug administration. Explain how plasma drug concentration in …

What is the equation for volume of distribution? Vd = Dose/Co Vd = volume of distribution Co = Conc. of drug in plasma at time zero. What is the equation for half-life of a drug? t1/2 = 0.7 x Vd/Cl …

Passive Diffusion High conc. -> low majority of drugs work this way does not involve carrier, is not saturable, and shows a low structural specificity Facilitated Diffusion involves carrier proteins High conc -> low no energy required, an be saturated, …

What marked the beginning of modern pharmacology? During the 1800s chemists were able to isolate the pure chemicals from plants. When did mass production of medicine begin? In the World War II era (1939-1945) WE WILL WRITE A CUSTOM ESSAY …

Pharmacology The study of substances that interact with living systems through chemical processes, especially by binding to regulatory molecules and activating or inhibiting normal processes Pharmacokinetics “the body’s effects on the drug” Changes in plasma drug concentration over time WE …

aka Biodisposition; The effects of biologic systems on drugs. It deals w/ the Absorption, Distribution, & Elimination of Drugs. Loading & Maintenance Doses can be calculated. What is Pharmacokinetics? What processes are involved? What can be calculated in Pharmacokinetics? The …

David from Healtheappointments:

Hi there, would you like to get such a paper? How about receiving a customized one? Check it out