Drug Movement

What is a dose?

Amount of drug administered

What is dosage?

Amount of drug and the frequency it's given

What are the different routes of administration?

Intravenous

Orally

Per rectum

Oral transmucosal

Subcutaneous

Intramuscular

What does IV stand for?

Intravenous

What does PO stand for?

Per os (orally)

What does PR stand for?

Per rectum

What does OTM stand for?

Oral transmucosal

What does SC stand for?

Subcutaneous

What is another acronym for subcutaneous besides SC?

SQ

What does IM stand for?

Intramuscular

What does CRI stand for?

Constant rate infusion

What is the measurement for CRI?

mg of drug administered per kg of body weight per unit of time (mg/kg/hr)

How is CRI most commonly administered?

Intravenously

What does QD stand for?

Every day, once every 24 hours

What is another acronym for once a day, besides QD?

SID

What does BID stand for?

Every twelve hours

What does TID stand for?

Every 8 hours

What does QID stand for?

Every 6 hours

What are reasons a dose might change?

Pharmacokinetics and pharmacodynamics

What are the categories in pharmacokinetics?

Absorption

Distribution

Metabolism

Elimination

What are the categories of pharmacodynamics?

Absorption

Distribution

Metabolism

Effects

What is absorption in pharmacokinetics/dynamics?

How the drug gets from the site of administration into the vasculature

What is distribution in pharmacokinetics/dynamics?

How the drug moves within the body

What is metabolism in pharmacokinetics/dynamics?

How drugs are chemically changed in the body, if at all

What is elimination in pharamacokinetics?

How the drug leaves the body

What is effects in pharmacodynamics?

What the drug causes, such as clinical effects or dose-responses

How are effects in pharmacodynamics measured?

Drug concentration at a receptor/target for a period of time

Why is drug metabolism important?

It enables elimination of the drug, affecting half life and drug effects

What are the factors that affect drug delivery/distribution?

Plasma protein binding

Anatomic barriers

Drug lipophilicity

Blood flow

Drug transporters

Drug ionization

How does plasma protein binding affect drug distribution?

Drugs bound to a plasma protein can not enter into tissue

What can a drug be bound to that prevents tissue entry?

Plasma proteins

How to anatomic barriers affect drug distribution?

Extra layers decrease/restrict drug movement

What does drug lipophilicity impact?

Its ability to diffuse across lipid membranes

In drug distribution, what is more important than total blood flow?

Blood flow to tissue mass ratio

How does the the blood flow to tissue mass ratio affect drug distribution?

A higher ratio results in more drug delivery

A lower ratio results in less drug delivery

How does drug ionization affect drug distribution?

Charged drugs have more trouble diffusing through lipid membranes

Why can't drugs bound to plasma proteins move into tissues?

Plasma proteins create the oncotic pressure needed to retain fluid in the capillaries, meaning they can't leave or else interstitial fluid would build up

How does lipophilicity affect drug distribution?

If a drug isn't lipophilic, it can't get through lipid membranes

If a drug is too lipophilic, it can get stuck inside lipid membranes

How do anatomic barrier affect drug distribution?

By creating a physical barrier that drugs have to cross

What are physiologic barriers?

Active transporters that move drugs into or out of the vasculature

How can some drugs over lipophilicity?

Through use of ion channels, pores, and/or transporters

What kind of drugs can go through pores in the membranes?

Aqueous drugs

Diffusion always moves drugs from a _______ concentration to a _______ concentration

higher, lower

What properties of tissues can affect drug diffusion?

Tight junctions, membrane thickness, surface area, active transporters

What physiochemical properties affect drug diffusion?

Protein binding

Lipophilicity

Molecular weight (size)

Ionization

What does a drug have to be to use a transporter?

A substrate for the transporter

Affinity for transporter/substrates is what?

Highly specific

What way do transporters move drugs?

Into or out of a region

What influences what way a transporter moves a drug?

Orientation of the transporter

What are characteristics of facilitated diffusion?

No energy expended

Protein carrier

Saturable

Specific

What determines which way a drug moves in facilitated diffusion?

Concentration, always moves from high to low

What are characteristics of active transport?

Energy needed

Saturable

Specific

Can be inactivated or up-regulated

What determines which way a drug moves in active transport?

Orientation of the transporter, can go with or against concentration gradient

What can inactivate or up-regulate transporters?

Genetic mutations

What are examples of tissues with low blood flow:tissue mass?

Adipose tissue

Bone

What are examples of tissues with intermediate blood flow:tissue mass?

Muscle

Skin

GI tract

What are examples of tissues with high blood flow:tissue mass?

Lungs

Brain

Heart

Kidneys

Liver

Endocrine glands

What type of blood flow to tissue mass ratio will have the highest drug exposure?

High ratio tissues