What is pharmacology

pharmacology

-science of drugs; their mechanisms of action

-how their effects can be measured

-their discovery, design and development

-their actions on the organism

-the actions of the organism on them

therapeutics

-main aim of pharmacology

-medicinal use of drugs to treat or relieve the symptoms of

disease

pharmacology

-branch of pharmacology that focusses on the harmful effects of chemicals, including drugs

pharmacy

-how drugs are formulated and dispensed for use as medicines

-Includes the law governing the medicinal use of drugs

drug definition

-chemical substance of known structure

-other than a nutrient or an essential dietary ingredient

-which, when administered to a living organism, produces a biological effect

is coffee a drug

no but caffeine is

how drugs are named

Drugs that are used therapeutically typically have at least three names

-chemical name

-common name

-proprietary (trade) name

how drugs are grouped

-therapeutic use

-mechanism of action

how drugs produce effect

-drugs are exogenous(outside organism) molecules that mimic or block the actions of endogenous(prod in organism) molecules

-drug wont work unless it is bound

-most drugs bind to molecular targets that are important proteins within body

target protein examples

-Receptors for neurotransmitters or hormones

-Enzymes

-Ion channels

-Carrier or transporter molecules

complementarity

for drug to bind to right target it needs right shape, therefor needs right chemical structure

ligand

small drug molecule that binds to large target proteins called ligands

how well a drug fits into its binding site depends on…

-steric factors: size and flexibility

how well the drug binds to its target protein is determined by…

nature of chemical bonds that form between drug molecule and its binding site

how do drugs bind

-reversibly to target protein

-through hydrophobic and hydrogen bonds

-some bind irreversibly through covalent interactions

-form ligand-protein complex; alters activity of protein

specificity

ability of a drug to bind in very precise way to protein target

what property does drug need to be useful therapeutically

-selective in its action

-no side effects

-eg if med lowers bp shouldnt also give gastrointestinal issues

how to achieve selectivity

-design drug that binds to only 1 molecular target and no others(specific)

-if same molecular target found in 2 systems then drug would not be selective

pharmacodynamics

-PD

-what drug does to body

-consequences of drugs actions at molecular level on physiology of organism

what is pharmacokinetics

-PK

-what the body does to the drug

-how drug is handled by organism

-how it gets to its site of action/metabolised/distributed to dif organs

-include side effects

elements of pharmacokinetics

-ADME

-absorption, distribution, metabolism, excretion

-each can be influenced by properties of drug or characteristics of person taking drug

absorption

-determines how much/quickly drug enters blood plasma

-influenced my chemical property of drug

-molecular size

-lipid solubility; influenced by ionization (in order to pass gut mem needs to be lipid soluble)

-chemical stability; some drugs can’t be taken orally as they cant survive acidic environment of stomach

distribution

-where drug goes after absorption

-usually drugs are distributed around body dissolved initially in blood plasma, then diffused thru tissues dissolved in extracellular fluid

-ability of drug to dissolve in plasma or ECF determined by its water solubility

what do u measure when studying drug action

-measure drugs concentration in blood plasma

-assume that conc in blood plasma is same as conc at site of action

what can interfere with how well drug is distributed

-if patient has adequate

-if drug bind to proteins in blood plasma: (drug bound to albumin is trapped in blood)

-if drug partitions into body fat store: drug dissolved in body fat is not active

-can drug gain access to organ it acts on 

blood brain barrier

-network of blood vessels and tissue that is made of closely spaced cells 

-helps keep harmful substances from reaching the brain

how to measure how well a drug is distributed within body

-measure parameter called Volume of Distribution(Vd)

-amount administered/conc in plasma(mg/l)

-apparent volume the drug would occupy if the total amount administered was dissolved in sol at same conc as that found in blood plasma

why would u want a low/high/med vd

-low: mostly stays in plasma: if u want in to act in blood

-med: extracellular fluid

-high: accumulates in tissues, explains long half lives

why wouldnt we want drugs to be distributed throughout body

-want drugs to stay in localised compartment of bod to minimise side effects

-local anaesthetics

-non-sedating

factors that determine how long the effects of a drug last

-metabolism & excretion

-drugs metabolized in liver, to metabolites then excreted by kidney

what to consider when giving drugs

-liver health

-liver enzyme effectiveness

-metabolite activity

-metabolite toxicity

what determines drugs half life

metabolism and excretion

drugs half life definition

time is takes for the plasma conc to fall by half

clearance

-volume of blood plasma cleared of the drug in unit time

-eg: ml of plasma per min