Intro to Pharmacology

- branch of medicine concerned with the uses, effects + modes of action of drugs

-study of the changes in ther structure, function + chemical properties of the body brought on by drugs

Chemical Name- eg Actaminophen

Brand name- Calpol

Generic name- paracetamol (name under license)

Presciption only- antibiotics

Pharmacy- co-codamol

General Sales List- paracetamol

British National Formulary

-main guide to drugsz + prescribing

-published twice a year (Sept & March)

-provides information on side effects, contraindcations + cautions 

-what a drug does to the body

-signalling molecules 

-Neurotransmitters (dopamine + acetylcholine)

-Hormones (insulin, testosterone)

-Growth factors (inflammatory mediators)

-most drugs bind to proteins found in cells + on the membrane of cells

-membrane controls what enters + leaves cell

-cell have a smasll voltage which is contaned across the membrane

RICE

receptors

-found on the membranes of cells

-receives messages from the body in the form of hormones + neurotransmitters

Ion Channels

-allow movement of ions (Na+ & K+) across cell membrane

Carrier Proteins

-found on cell membranes

-allow molecules to pass across the membrane

Enzymes

-Proteins n cells + on cell surface that catalyse biochemical reactions

DNA

-contains building blocks whch can be targeted by drugs

-molecule that binds to another (usually larger) molecule naturally occuring n the body (endogenous)

-many drugs mimic or inhibit the acton of endogenous chemical messengers

-Hormones

-Neurotransmitters

-Mediators

Angonist

-bind to receptors + produce the same effect as naturally occuring (endogenous) ligand

Antagonist

-bind to receptors + block them from the effects of the naturally occuring ligand

Specificity

-how well the receptor + ligand interact together

-how specific is the effect produced

Efficacy

-How good/effective the ligand is at producing a response in the cell

-What the body does to the drug

-ADME

Enteral- into GI tract

Parental- Not into GI tract (injectons)

Topical- onto surface of skin (creams)

Inhalation- inhaled 

movement of molecules acorss cell membrane

Lipophillc- best drugs

-drugs that are lipid soluble

-diffuse through membrane easily absrobed from gut

Hydrophillc

-water souble molecules

-need help across membrane by carrier proteins

-vomiting

-stomach pH

-gastric emptying time

-gut motility (fast or slow)

-bowel length

-Jejunal feeding tubes

-gut microbiome

-splenic blood flow

-plasma protein binding (albumin)

-disassociate from plasma proteins + move into tissues to exert an effect 

-only free drugs can exert effect

-drugs are distrbuted in 4 flud compartments

-intravascular

-intracellular

-extracellular

-interstitial

-dependent on:

-molecular size of drug

-polarity(hydrophillic/lipophillc)

-pH of drug

-blood supply to tissues

-affinity of the drug for plasma protein

-blood brain barrier

-young children have a high volume of water so may need higher dose

-Hypovolaema

-gastroententis

-blood loss

-changes in protein levels (neonates, illness kdney function)

-drugs carried in systemic circulation are subject to metabolism in the liver each tme they pass

-most drugs are metabolised by HEPATIC BIOTRANSFORMATION

-converted by liver enzymes (cytochrome p450) into molecules that kidneys can excrete

-converts lipophilic drugs to hydrophilic molecules

-conjugation with glucose

-pro drugs= drugs that dont become active until metabolised (aspirne, predinisolone)

- substrate (drug --------enzyme------------> metabolite

-liver function

-drug interactions

-neonates + young children may lack metabolic enzymes

-enterally administered drugs

-drugs shuted to liver via hepatic portal vein

-drug is metabolised

-as a result in some cases only a small proporation of the active drug reaches systemic circulation + its intended target

BIOAVAILABILITY

-proporation of drug that has reached systemic circulation

-proportaion of drug available for distribution

-may take several cycles of systemic circulaton for all drug to be excreted

DRUG CLEARANCE= removal of drug from body

HALF LIFE= time taken for body to clear half rthe plasms drug concentraton

THERAPEUTC WINDOW

-dosage range between a minimum effective therapeutic concetraion and the minmum toxic concentration

- tippng the balance too far

-hitting an unintended target

-auto immune reactons

-toxic drugs (chemo)

-polypharmacy

-cytochrome p450 cascades (increase or decrease activity effects bioavailability of other drugs)

-competitive inhbiton (drugs competing for same target)

-Additive effect (drugs wth same effecrt)