Chapter 3: Pharmacokinetics and Pharmacodynamics

Pharmacokinetics definition?

Drug movement throughout body and what the body does to the drug.

What are the 4 processes of pharmacokinetics?

Absorption, distribution, metabolism, excretion.

Pharmacodynamics definition?

What the drug does to the body as drug moves throughout the body.

What are the 3 phases of pharmacodynamics?

Receptor binding, post receptor effects, chemical reactions

What is the most common drug intake?

Orally

Disintegration definition?

-Breakdown of oral drug form into small particles

-adults have less gastric acidity

-enteric vs non enteric coated (ex.asprin)

Dissolution definition

-Combining small drug particles with liquid to form a solution

-needed if drugs irritate stomach mucosa

-reduced absorption if vili are damaged

3 drug absorption methods:

Passive transport

-diffusion

-facilitated diffusion

Active transport

-requires a carrier and energy to move drug against a concentration gradient

Pinocytosis

-cell carries drug across membrane by engulfing drug particles

Water soluble vs lipid soluble drugs:

Water soluble: need a carrier (ionized if small, non ionized if large)

Lipid soluble: (and non ionized) absorb faster than water

What are some factors affecting absorption?

Blood flow, pain, stress, pH, excerise, hunger, fasting, food texture, fat content, temperature, route of administration

First pass effect definition:

Drug metabolized to inactive form and excretion

Bioavailability definition:

% of drug availability for activity

Some factors affecting bioavailability:

-drug form

-route of administration

-gastric mucosa and motility

-administration with food and other drugs

-changes in liver metabolism

How are drugs distributed?

-movement of drug from circulation to body tissues

-influencing factors

-protein binding

-free drugs (

What are free drugs?

2 or more drugs compete for binding sites resulting in accumulation of drug and toxicity

where does the body process of chemically changing drug into a form to be excreted happen at?

Liver via cytochrome

What is the half life of a drug?

Time in takes for drug in body to be reduced by half

What is the steady state?

Plateau drug level or optimal therapeutic effect (amount of drug administered is equal to amount being eliminated)

What is the loading dose?

Initial large dose

Main route of drug excretion

Kidneys

Primary vs secondary effects?

Primary: desirable response of what drug is supposed to do

Secondary: desirable or undesirable, other effects caused by the drug

Drug response relationship:

Body’s physiologic response to changes in drug concentration at site of action

Potency

Amount of drug needed to elicit specific physiologic response

Maximal efficacy

Point which increasing a drugs dosage no longer increases therapeutic response

Therapeutic index

Relationship between therapeutic dose (effective dose) and toxic dose

Therapeutic range

Range that produced therapeutic responses without adverse effects

Onset of drugs is the

Time in takes for drug to reach minimum effective concentration (min amount of drug needed for effect)

Peak is the

Highest concentration in blood

Duration is the

Length of time drug exerts a therapeutic effect

Receptor theory

Drugs act by binding to receptors

What are the 4 receptors families?

-Cell membrane imbedded enzymes

-Ligand gated ion channels

-G protein coupled receptor systems

-transcription factors

Agonists

Activate receptors and produce a desired response

Partial agonists

Elicit only moderate activity when binding to receptors and prevent receptor activation by other drugs

Antagonists

Prevent receptor activation and block a response