Anaesthetics Flashcards
Are topical anaesthetics POM?
Yes
What are the indications of use of anaesthetics?
- Contact tonometry
- CLs fitting
- FB removal
- Gonioscopy
- Lacrimal procedures
What are three advantages of anaesthetics?
1) Allows for certain procedures to be carried out
2) More comfortable px
3) Make procedures easier for practitioner
What are some disadvantages of anaesthetics?
1) Sting
2) Delayed healing
3) Eye more susceptible to damage
4) Repeated instillations may be required
In terms mode of action, how do anaesthetics work?
Reversibly block sodium channels so an action potential cannot be created as depolarisation cannot occur.
What properties of anaesthetics allow it to diffuse rapidly through the lipid membrane?
It is both lipophillic and hyrdophobic, and charged and uncharged
Name three ester link anaesthetics and their durations
1) Oxybuprocaine (Benoxinate) - 15 mins
2) Tetracaine (Amethocaine) - 20 mins
3) Proparacaine (Proxymetacaine)- 15 mins
These are HYDROLYSED by choloinesterase
What is the issue with ester link anaesthetics?
They break more easily than amide bonds (shorter duration) and are common with allergic reactions
What is an example of an amide link anaesthetic?
Lignocaine (Lidocaine) -30 mins
This is RESISTANT to hydrolisation and has a longer duration.
What is Amethocaine (Tetracaine HCl) good for?
FB removal due to deep anaesthesia
What % does Amethocaine (Tetracaine HCl) come in and how should it be stored?
0.5% ad 1.0% minims, it should be stored below 25 degrees
What is the most widely used anaesthetic?
Oxybuprocaine HCl (Benoxinate)
What are some contraindications of Oxybuprocaine HCl (Benoxinate)?
- Due to bactericidal properties, careful when administrating it in hospital if you have just taken a culture
- Known allergy
- Premature babies
- Pregnancy/ breast feeding
What % does Oxybuprocaine HCl (Benoxinate) come in and how should it be stored?
0.4% minims and stored below 25 degrees
Which drops sting the least?
Proxymetacaine Hydrochloride
What are some pros of Proxymetacaine Hydrochloride ?
Minimal punctate corneal staining and least antibacterial properties
What % does Proxymetacaine Hydrochloridecome in and how should it be stored?
0.5% minims and stored between 2-8 degrees in a refrigerator
What % does Lidocaine Hydrochloridecome in and how should it be stored?
4% combined with 0.25% fluorescein minims and store below 25 degrees
Name six side effects of anaesthetics.
1) Transient stinging
2) Transient blurring
3) Conjunctival hypermia
4) Mild superficial damage
5) Punctate keratitis
6) Hypersensitivity reactions (mild conjunctival)
What are some precautions that should be mentioned when using anaesthetics?
1) Enhances effects of other drugs as permeability of epithelium cells increased
2) Px must be informed to not rub their eye
3) Healing delayed
4) Open to abuse
5) Young children
