Pharm (Pharmacokinetics)

What is pharmacokinetics?

physiological movement of drugs

What is Passive Diffusion?

moving from high to low concentration without the use of energy

What are some requirements for passive diffusion to work?

the cell membrane must be porous, and the drug must be small enough to fit through the pores

How long will passive diffusion take place?

until equilibrium is reached

What is Facilitated Diffusion?

has a little help from a carrier molecule that helps move the drug across the cell membrane

What are some requirements for facilitated diffusion to work?

requires a little energy, drug needs to be small enough to fit through the pores

What is Active Transport?

uses carrier molecule to move against the gradient (Low to high)

What does active transport allow?

more concentrated drugs

Pino

cell drinking

pinocytosis

the act of a cell drinking/sucking in a drug

What is pinocytosis/phagocytosis done by?

larger molecules

What are the steps for movement of drugs?

Absorption, distribution, biotransformation/metabolism, excretion/elimination

Absorption

absorption from site to the fluid part of the body, any drug not IV

What are drug factors of absorption?

pH, molecular size, solubility

what are patient factors of absorption?

age, health status, genetic factors, sex, species

What is bioavailability?

% of the drug administered that goes into circulation

Distribution

bioavailability

what are factors of distribution?

membrane pores, tissue perfusion, protein binding, volume of distribution

what are things to consider with tissue perfusion?

amnt of blood/fluid in the area

what are things to consider with protein binding?

some drugs bind to proteins, proteins are large

What are things to consider with volume of distribution?

concentration of drugs in the body, more fluid= not as good distribution

Biotransformation/Metabolism primary sites and secondary sites

liver (primary), kidney, skin, SI, brain (secondary)

Drug elimination/excretion sites

Kidney (most important), liver, milk, sweat, saliva, lungs

How does the kidney eliminate drugs?

filtration, changes in BP according to drugs

How does the liver eliminate drugs?

drugs will go through bile ducts and be excreted into the duodenum

Withdrawal time

period of time from when the drug is administered to when it takes for a drug to get out of the body

Half-life

time req for the drug to be reduced in half

Steady state

point at which the drugs accumulation and elimination are balanced