23 - principles of toxicology Flashcards
types of adverse reaction
type A (pharmacological)
or
type B (idiosyncratic)
what are type A reactions
- represent an exaggeration of the normal pharmacological reaction of drug
- dose dependant
- predictable
example of type a
a px with a respiratory dysfuntion, for glaucoma medications, beta blockers are contraindicative as there are beta receptors in the lungs, which can cause bronchocontristion
what are type B reactions
uncommon and unrelated to the known action of the drug
what are the determinsnt of ADR
- patient variables
- pharmacological variables
what are patient variables
- age
- gender
- renal and hepatic function
- history of drug allergy
- general health
what are pharmacological variables
- dose
- therpeautic index
- formualation
- route of delivery
- duration
- multiple drug therapy
what is digoxin
a cardiac glycoside used in the treatment of cardiac arrhythmias and heart failure
formula for therapeutic index
Minimum toxic dose
Minimum effective dose
what does digoxin inhibit
Na + K+ ATPase
do ocular ADR occur in patients taking cardiac glycosides
yes. 11-25%
most common ocular ADRs for cardiac glycosides
- disturbances of colour vision
- various entopic phenomena
types of ocular ADR
lids/conjunctiva
- blepharoconjunctivitis
cornea + lens
- deposits/opacity
- refractive changes
uvea
- uveitis
- IOP changes
- cycloplegia
retina
- retinopathy
- colour vision disturbances
- reduced VA
- scotoma
optic nerve
- optic neuritis
- field changes
what should be reported
- change in acuity, IOP or ocular structures
- reports all adverse reactions to new therapeutic agents
- all adverse reactions in children
amiodarone - used for what
treatment of cardiac arrythmias
what is the most comon OAR when amiodarone is used
corneal epithelial deposits
- bilateral
- reversible: takes 3 months
- VA not affected
What do patients on amidarone experience
most asyptomatic but 1-12% experience
- haloes around lights
- blurred vision
- glare effects
chloroquine
- treatment of rhumatoid arthiritis if other drugs have failed
hydroxychloroquine
used in malaria prophylaxis
how do anti-malarials and chloroquine and hydroxychloroquine work
- binds to melanin
- can lead to irreversible visionloss
chlorpromazine
schizonphrenia
- pigmentory depostion in eyelids, conjunctiva, retina and lens
- corneal and lenticula changes are dose dependant
- lenticular changes initially observed as fine deposits under anterior capsule
- px may report glare, haloes around lights and hazy vision
corticosteroids
allergic/rheumatic/inflammatory disease
steroids most important therapeutic drug - for inducing significant adverse effects
