Pharmacology Flashcards
what are local anaesthetics used for
to reduce awareness of pain
how do local anaesthetics work
by blocking ion channels, preventing propagation of AP
give examples of antibiotics used in dentistry
amoxycillin
give examples of anti-virals
aciclovir
give examples of anti fungals
topical - nystatin systemic - fluconazole
how do anti-inflammatories work
by inhibiting arachidonic acid binding to either COX 1 or 2, prevents prostaglandin production
what are common side effects with NSAID
increased risk of bleeding, increased gastric ulcer production, exacerbate asthma
what causes the side effects caused by NSAID
inhibiting COX 1 or 2 results in blocking thromboxane production, prevents platelet aggregation - more prone to bleeding
what drug interacts with aspirin and ibruprofen
warfarin
what is the difference between aspirin and ibruprofen
aspirin has much more severe side effects, aspirin blocks COX 1, ibruprofen blocks COX 2
what is diclofenac
an NSAID that can only be prescribed with prescription
what is a positive of using aspirin
if people have heart problems, blood is thinner
how do corticosteroids work
inhibits capillary permeability, bradykinin formation and white blood cell migration, suppresses inflammation but doesnt target the cause
give examples of corticosteroids
beclomethasone - inhaler, prednisolone - oral, hydrocortisone - topical
what are the side effects of corticosteroids
high blood pressure, diabetes, weight gain, adrenal suppression, gastric ulceration
what drugs are used in sedation
nitrous oxide and diazepan
how is nitrous oxide administered
inhaled as a gas but should be avoided in pregnancy - interacts with folic acid
name 3 ways in which a drug can exert its effect on the body
activating an ion channel, activating/inhibiting an enzyme, coupled to G-protein receptors
what is the result of activating a g protein
this activates an enzyme which results in production of a second messenger, acts within the cell to bring about change e.g. protein production
give an example of a drug altering ion channels
local anaesthetic blocks ion channels to prevent AP conduction
give an example of a drug that alters enzyme activity
aspirin, inhibits COX 1 preventing arachiodonic acid from binding
what effects a drugs efficacy
affinity and occupancy
when might a drugs affinity for a receptor be lowered
if the drug is only a partial agonist, doesnt fit as well into the binding site so wont work as well
what can be done to increase the efficacy of partial agonists
increase the concentration, increases occupancy, however, doesnt work for all drugs
name different types of antagonists and give explanations
reversible - unbinds to the receptor, leaving it unchanged
irreversible - permanent change to receptor
competitive and non-competitive - depends on whereabouts it exerts it’s effect
what are the phases of drug action
absorption, clinical effect, metabolism, excretion
what are the routes of administration for drugs
oral, subcutaneous, intravenous, intramuscular
what are the advantages of oral administration
socially acceptable
what are the disadvantages of oral administration
slow onset, variable absorption, unpredictable bioavailability, must have functioning GI tract and liver, drug must be lipophillic (unionised) to get through the membrane but then active part is ionised
describe first pass metabolism
oral drugs go through the GI tract and into hepatic portal vein into the liver before reaching the systemic circulation. therefore, before they reach the area they are targeting, a proportion of the drug is already lost. makes us unsure of how much drug is actually reaching the desired area and also a bigger dose is required
what routes of administration are unaffected by first pass metabolism
injection via muscle or vein, sublingual or rectal absorption
what organs must be working well for drugs to be given
liver and kidney
what is bioavailability
the proportion of drug exerting the clinical effect
what factors affect bioavailability
absorption, first pass metabolism, dosage, destruction in gut
how is the drug distributed amongst the body
lipid binding - accumulation and slow release
plasma protein binding
how does plasma protein binding work in drug distribution
drug bound to plasma protein is inactive, however, it frees up more space in the plasma to carry more drug. the drug in the plasma free is active and available. when this diffuses out to tissue, the drug unbinds from plasma protein and moves into plasma to be available.
give an example of drug interaction via plasma protein binding
aspirin and warfarin - one has a higher affinity to the plasma protein so this binds, making the other available
describe the 2 phases of drug metabolism
phase 1 - inactivation of drug via oxidation, hydrolysis, reduction
phase 2 - conjugation with a molecule being excreted
describe first order kinetics in terms of drug clearance
the amount of drug cleared is proportional to the concentration of drug. is a passive process, drug has a half life - for a given time half the concentration is cleared
describe zero order kinetics in terms of drug clearance
the amount of drug cleared in a given time is fixed. is an active process involving enzymes. when the enzyme is saturated, unable to clear any more drug, has to wait until space becomes available
how can plasma toxicity occur
if there is high levels of drug in the plasma and not enough being cleared, give more drug and building on plasma levels already there
how can drugs be excreted
through the kidney and liver then passed through GI tract, or through lungs with breathing or sweat
what is meant by a dosing schedule
knowing when and how much drug to give for the clinical effect to be seen but preventing plasma toxicity
