Pharmacology Flashcards
What is a drug?
A chemical (artificial or inartificial) that is introduced to the body, to produce a desired effect often to combat a disease
Can work on our own cells or other cells
Rights of drugs
Right drug
Right patient
Right time
Right strength
Right route
Right documentation
Right technique
General use of activated charcoal
acute oral poisoning or oral drug overdose within 1 hour
General use of adrenaline
Anaphylaxis and life threatening asthma
General use of chlorphenamine
Allergic reaction falling short of anaphylaxis but causing distress
General use of Entonox
Moderate to severe pain
General use of Glucagon
hypoglycaemia where when oral glucose administration is ineffective and IV access is not possible for 10% glucose.
General use of Glucose Gel
Hypoglycaemia in a conscious patient
General use of GTN
Chest pain due to angina or MI
Cocaine toxicity
General use of Hydrocortisone
severe asthma, exacerbation of COPD, adrenal crisis
General use of ipratropium bromide
Acute, severe or life-threatening asthma, unresponsive to salbutamol, exacerbation of COPD, expiratory wheeze
General use of naloxone
Reversal of acute opioid or opiate toxicity
respiratory arrest or respiratory depression
Cardiac arrest arrest where opioid toxicity is likely the cause
General use of oxygen
significant injury or illness
critical illness
COPD
General use of salbutamol
Acute asthma attack, expiratory wheeze, exacerbation of COPD
General use of paracetamol
Mild to moderate pain
High temperature
Enteral route
absorbed along GI tract
Parental route
any route that isn’t the alimentary canal
skin/mucous membrane
Topical route
absorbed through the skin, through a mucous membrane or pulmonary route.
What does pharmacokinetics mean
what the body does to drugs
Factors effecting pharmacokinetics
route, form, molecular size, blood flow, patient condition, food, gastric emptying time, age and environment
Why is IM not recommended for patients with hypothermia
because the drug is likely to just sit in muscle due to vasoconstriction
Absorption of topical drugs
applied directly to the site of action
Absorption of enteral drugs
through GI tract
need to be able to survive the conditions of the stomach and intestines
less invasive, less risk of infection, more comfortable
Absorption of parenteral
IV/IM/IO/SC/BUC/SL
do not survive the digestive process - such as those that are protein based
barriers to the distribution of drugs
cardiovascular function - heart not pumping effectively = not enough pressure to get drugs out of capillaries
blood flow
drug storage reservoirs
physiological barriers - blood/brain barrier
Bioavailability
the amount of the drug that is available to the body to produce a therapeutic effect
Why can bioavailability only be ensured with IV?
because every other route means the drug goes through the liver and experiences the first pass effect
If the bioavailability is high, is the dose highered or lowered?
lowered
Main functions of metabolism
conversion of food into energy
conversion of food into useful molecules such as amino acids
elimination of metabolic waste
Biotransformation
process of changing a drug so that it can be excreted
Explain the first pass effect (enteral route)
the drug is absorbed through the digestive tract so the drug enters the liver via the hepatic portal vein and then enters systemic circulation via the inferior vena cava. The liver deactivates some of the drug so decreases the bioavailability
What enzymes impact drugs and why
P450 enzymes
so that it is easier for the kidneys to remove the drugs
Pro drugs & example
drugs that are activated by the first pass effect - such as aspirin
What is “half life” and why’s it useful
the time taken fir the concentration of a drug by half
useful for calculating interval doses
opiate/naloxone interaction
opiates can cause respiratory depression/arrest
we give naloxone as a reversal but it has a much shorter half life than opiates
so it wears of quicker, therefore we give repeated doses or use multiple routes
What does pharmacodynamics mean
What the drugs do to the body
What do drugs need to work?
A target that is accessible and specific
Why do we give salbutamol to people with respiratory issues instead of adrenaline even when adrenaline results in bronchodilation?
Because adrenaline targets B2 receptors which aren’t just present in the lungs, so adrenaline affects all of the body whereas salbutamol only targets the lungs
Types of protein target: receptors
bind to one specific molecules/substrate on the outside of the cell causing a cascade of reactions inside the cell
can be inside of the cell too
Types of protein target: ion channels
Gateway for charged molecules
What do channel blocking drugs do to ion channels? & example
block them completely
Tetracaine: blocks sodium channels in neurons to prevent pain.
What do modulator drugs do to ion channels? & example
enhance or inhibit channel activity
Diazepam: enhances the opening of chloride channels in neurons creating a regulatory effect for the uncontrolled firing of neurons
Types of protein target: Enzymes
& examples
speed up chemical reactions
drugs block the active site of enzymes to prevent further reactions
Simvastatin/Atorvastatin/Pravastatin - block enzymes in the liver to stop the production of cholesterol
Types of protein target: Carrier proteins
& example
facilitate the diffusion of molecules across the cell membrane via active transport
Furosemide: inhibits a carrier protein in the loop of Henle in the nephron & prevents water reabsorption
Lock and key model: agonists
bind to receptors to initiate/enhance a response
natural molecule has a similar shape
Lock and key model: antagonists
binds to receptors and does not produce an effect/ prevents the natural physiological process
Why is it important to know if someone is on beta blockers?
They bind to A2 receptors to block adrenaline = reduction in rate
= reduced cardiac output = SOB, dizziness and chest pain
Therapeutic effect & what can effect it
the desired effect of the drug
dose, bioavailability, first-pass effect, interactions with other drugs
age, diet, genetics
How to side effects occur?
doses: some people can’t tolerate normal doses
wrong target: binding to similar shaped active sites
intrinsically hazardous: some drugs are designed to attack cells - such as chemotherapy
