Drug Toxicology - Priyesh Flashcards
What is a toxic effect?
When you get an unwanted effect of the drug when using its NORMAL concentration
*Normal is important because this will disregard overdose.
What is an example of a Type A reaction - Beta Blockers in glaucoma
Bronchoconstriction - beta receptors in the lungs.
(DO not use on px with asthma or obstructive airways disease)
There is two types of Adverse drug reaction… What is type A?
- Exaggeration of the normal pharmacological reaction of the drug. The higher the dosage the more likely this will happen
Why can we predict Type A reactions?
We know how the drug mechanisms
What is a type B reaction?
This is idiopathic aka fuck knows why these happen. They are rare.
Uncommon and unrelated to the known action of these drugs
What Px variables are involved in an adverse side effect?
- Drug allergy history ; if they are allergic to one drug, there is a possibility they will be allergic to another drug
- Age
- Gender
- Renal/hepatic function (kidney / liver)
- GH
What Pharmacological variables are involved with an adverse side effect?
- Dosage
- Therapeutic Index ; min toxic / min effective
- Formulation ; impact on the gut
route of delivery ; does it go through the liver or not? - Duration
- Multiple drug intervention : like Hypertension drugs
What is digoxin?
Originating from foxglove plant and found in the leaves. It is used to treat heart failure and cardiac arrythmias
- 11-25% will have an OAR
Digoxin mode of action?
It works by inhibiting NA/K ATPase which is found in the heart and in cornea
Side effects of Digoxin?
- Death.
2.Slow pulse
3.Cold sweats
4.Fainting
5.Sickness
6.Confused vision (xanthopsia- they see yellow or green tinge to objects)
What are the black triangles on drugs?
This is showing it is a new drug and needs to be monitored when the px has this as intervention
What is the the yellow card scheme 1964?
- The MHRA (Medicines and Healthcare Products Regulatory Agency) and commissions human medicines monitor this closely.
- It is a database of drugs with voluntary reporting’s of side effects of drugs. Px and clinician report
what does the yellow card cover?
- Adverse effects of P,POM and GS drugs
- Medical devices- Cl products
- Suspecting fake medicines
- E-cigs
What is Vigabatrin?
Drug for epilepsy
Why was Vigabatrin problematic?
It took 10 years to realise the VF loss ; 33% had Peripheral VF loss
What is our role as optometrists detecting ADR?
- Most of them are revisable, early we detect the better.
- Be aware of what drugs can cause ADR, from other clinicians
Types of ADR:
- Blepharoconjunctivitis
- Deposits and opacity in cornea and lens
3.Refractive changes in the lens
4.Uveitis, IOP change and cycloplegia - Retinopathy
- CV disturbances
- Reduced VA
- Scotomas - field changes
- Optic nerve , optic neuritis
When do we detect an ADR?
- Make connection via an unexpected clinical sign when taking a drug.
- Number of reports will help determine the risks of AR
What are the guidelines for recording drug reactions?
- In general population we only interested with life threatening reactions
- However, in children we want to record everything
Where to find information on a drug (reminder)?
BNF, Optometry Formulary
What is chloroquine?
It is used for anti-malaria and rheumatoid arthritis
What adverse effect can chloroquine initiate?
Binds to melanin so it will express as the following:
1.Pigmentary retinopathy
2.Maculopathy - Bullseye pattern
3. VF affected - idiopathic
What is hydrochloroquine?
More modern drug of chloroquine, malaria prophylaxis + rheumatoid arthritis
What is the problem with Hydrochloroquine?
You do not get any pigmentary changes ; it does not bind to melanin like Chloroquine
However, using the OCT we can see there is still adverse reactions.
Chloroquine and hydrochloroquine as still issued, so what are the rules for them?
NEED TO REVIEW ANSWER
Anyone with these drugs of 5 years they need a ophthalmic exam, they will take a OCT + fundus photos as baseline and then do a full VF 10-2 (lots of points in the central 10 degrees)
- Then repeat periodically during the 5 years.
Then repeat these rests periodically for how long this px is taking these drugs
what is chlorpromazine?
This is a tranquilizer, used for schizophrenia.
What are adverse effects of chlorpromazine?
It can deposit into the:
1.Cornea
2.Lens
3.Retina
4.Eyelids (pigmentary changes)
How can chlorpromazine deposit?
- Lens ; originating from the AH
- Cornea ; originating from AH or surrounding blood vessels in the periphery
What can cortiocosteroids cause?
- High IOP
- PSC - 4% chance
- Weaker cornea - this is the reason as SUPER infection can manifest
List of corticosteroids
1.Prednisolone
2.Betamethasone
3.Dexamethasone
4.Hydrocortisone
5.Fluromethalone
5.Loteprednol
What are the chances of a px getting PsC from corticosteroid usage?
Depends on the dosage and how long they have been using it ; normally usage over a year will increase the risk
SIDE : Px has been using prednisolone for a long time and a high %. They get glare, photophobia and reduced VA. What do they have?
Posterior Subcapsular Cataract
What is a steroid responder?
This is a px who get a higher IOP whilst they take corticosteroids - indefinitely
Some px are some are not - due to genetic variation
Px has anterior uveitis, what corticosteroid do we administer and why?
Dexamethasone- this has the penetrating strength to get the job done
Px has Surface inflammation what do we give?
- Loteprednol
- Fluromethalone
These are non - penetrating corticosteroids
Px is a steroid responder, they have anterior uveitis. What are we going to do and how are we as a team going to help alleviate this?
REFER - emergency
Ophthalmologist knows from past records they are a Steroid Responder : they most likely will give them dexamethasone (penetrating) and during this endurance they will be in a HOS bed receiving IOP lowering drugs .
What is tamoxifen?
This is a drug for Breast cancer. It is an anti-oestrogen drug - 20mg
What can tamoxifen cause with the retina?
- Deposits in the retina, pigmentary changes and hemorrhages.
- Macular oedema and yellow refractile opacities
What can tamoxifen cause moving more outside of the eye?
- Dry eye
- Keratopathy
When giving out tamoxifen what should we do?
- Give a baseline screening : VAs and Fields.
- Then we do annual monitoring when given the drug out.
Can the Contraceptive pill give any adverse reactions?
This has low prevalence of causing a reaction but the possible OAR are:
- Decreased CL tolerance due to change in tear film
- Potential risk of thrombosis in the retinal vascular abnormalities
What is the therapeutic index?
Minimum toxic dose/ minimum effective dose
Where can the black triangle drugs be obtained from?
The MHRA website
What is amiodarone used for?
Treatment of cardiac arrhythmias
What ocular issue is associated with taking amiodarone?
Bilateral corneal epithelial deposits- starts as horizontal line in the lower of cornea (reversible)
How many grades are there grade bilateral corneal deposits from taking aminodarone?
3
What OARs can occur with digoxin?
Colour vision effected
