Pharm lecture #3

What are the four steps of pharmacokinetics?

ADME:

-Absorption

-Distribution

-Metabolism

-Elimination

Absorption

movement of a drug from the site of administration to the systemic circulation

Bioavailability

Quantity of what is administered that actually enters systemic circulation (gets absorbed)

What are the two ways drugs get absorbed into cells in the body?

Passive transport (no energy required) OR active transport (energy required)

How does ionization status and pH of environment impact absorption?

Depending on whether a drug is hydrophilic or lipophilic determines where it can be absorbed.

The pH changes how lipophilic/hydrophilic a drug is therefore changing how easily it is absorbed

What is needed to move drug molecules across the cell membrane?

Proteins!!

What happens if the liver can't metabolize and eliminate the drug?

It stays in the body and causes toxicity

How can interactions with other medications and foods affect drug absorption?

Certain foods and meds can decrease or prevent absorption of drugs

How does a drug get distributed through the body?

Drug moves from site of absorption, into the bloodstream, and then to cells in the tissue

What dog breed have defective blood brain barriers?

Collies

Biotransformation

when the body alters the chemical structure of a drug to produce a form that is able to be eliminated by the body AKA metabolism

Where does most drug metabolism occur?

The liver

What does the liver have the greatest effect on?

The biotransformation of most drugs

What role do enzymes play in biotransformation?

They break down a drug into particles called metabolites that can be more readily eliminated

Three other sites of less effective biotransformation besides the liver

-Kidney

-Lungs

-Nervous system

What should NEVER be given to cats?

Acetaminophin (Tylenol)

What is the antidote for Tylenol toxicity in cats?

Acetylcysteine (Mucomyst)

Why can't neonates metabolize drugs as fast as adults?

Because they don't have a fully functional liver, therefore not as many proteins

What do neonates have a decreased ability to do?

They have a decreased ability to biotransform drugs

Why do neonates need a lower amount of drug?

Because they have a reduced clearance - higher body water content, not as many proteins

In what organ does most drug excretion occur?

The kidney

Drug residue

The quantity of a drug remaining in animal products

Withdrawal times

length of time an animal must be kept off medications prior to slaughter or for consumption of milk/eggs to be used for human consumption

What drug should NEVER be given to food animals?

Chloramphenicol