Test 1 - Topical Anesthetics (General) Flashcards
What is FALSE about local anesthetics?
A) Amine group is hydrophilic and ionizable
B) Amides are more likely to cause allergic hypersensitivity
C) Esters are metabolized by pesudocholinesterase in the plasma
D) Lidocaine (Xylocaine) is lease likely to cause an allergic hypersensitivity
E) Proparacaine is a ester of meta-amino benzoic acid
B) Amides are more likely to cause allergic hypersensitivity
Amides are least likely to cause allergic hypersensitivity
What is the linkage group of the following anesthetics? (Is it para-amino benzoic acid or meta-amino benzoic acid?)
1) Benoxinate
2) Tetraincaine
3) Proparacaine
4) Lidocaine
Where is ester and amides metabolized?
1) Benoxinate - ester linkage, para-amino benzoic acid
2) Tetraincaine - ester linkage, para-amino benzoic acid
3) Proparacaine - ester linkage, meta-amino benzoic acid
4) Lidocaine - amide linkage
Esters metabolized by pseudochinesterase
Amides metabolized in liver
What is FALSE about the MOA of topical anesthetics?
A) blocks Na+ influx to prevent depolarization
B) Blocks Na+ channel from inside by binding to receptor inside the cell
C) Needs to be biphasic
D) increased velocity of nerve conduction
D) increased velocity of nerve conduction
- decreased velocity of nerve conduction
What is FALSE about the differential sensitivity of neurons? What is the order of loss of sensation? (motor, touch, pain, temperature, pressure)
A) Smaller, unmyelinated neurons are more sensitive and anesthetize more easily
B) Motor sensation is lost last among sensation neurons
C) Temperatures sensation is lost first among sensation neurons
D) Large, myelinated nuerons recover first
C) Temperatures sensation is lost first among sensation neurons
- Pain sensation is lost first.
Order: Pain, Temperature, Touch, Pressure, Motor
What is TRUE when considering Local anesthetics?
A) LA become more effective in acidic media
B) Increased blood flow may decrease effectiveness of LA
C) Combining two LA will increase their effective beyond additive
D) Epinephrine prolongs duration for topical and injectable LA
E) The maximum effective concentration for Tetracaine 1% and Cocaine 20% are frequently used.
B) Increased blood flow may decrease effectiveness of LA
- LA become less effective in acidic media
- Combining two LA’s does not have an further effect than additive
- Epinephrine only prolongs topical LA
- Tetracaine stings at 1% and cocaine 20% is toxic for corneal epithelium
Which is NOT a common ocular toxicity with LA?
A) Epithelial staining and edema B) Conjunctival hyperemia C) decreased TBUT and secretion D) increased blink reflex E) Burning and stinging
D) increased blink reflex
decreaased blink reflex
What is NOT a more serious toxicity of LA?
A) Reduced epithelial regeneration B) Block mitosis C) Prevent normal healing D) Ulceration E) Conjunctival hyperemia
E) Conjunctival hyperemia
Is a toxicity but is more common
What is FALSE about Epithelial Toxicity?
A) Rapid epithelial damage can occur in minutes
B) Blurry vision can be caused by desquamation, edema, folds in Descemet’s
C) Can also lead to lacrimation and photophobia
D) Use systemic analgesics, artificial tears and cold compresses in ALL cases
D) Use systemic analgesics, artificial tears and cold compresses in ALL cases
Only use in severe cases. In mild cases, epithelium can start to heal spontaneously
What is FALSE about Allergies related to LA?
A) Delayed allergic hypersensitivity seen after 6-12 hours
B) Patients can complain of swollen, injected conjunctiva, burning and itching
C) If this occurs, switch to another LA that has less cross sensitivity
D) Systemic allergic reactions can occur after topical use
E) May see peeling and cracking on finger tips from occupational hazard
D) Systemic allergic reactions can occur after topical use
No systemic allergies after topical use
What is FALSE about systemic toxicities related to LA?
A) None seen with reasonable use of topical LA
B) See a linear increase in toxicity with more concentrated solutions
C) Expect to see early CNS excitation (anxiety, nervousness) followed by general CNS depression
D) Expect to see early Hypertension, tachycardia followed by hypotension and bradycardia
B) See a linear increase in toxicity with more concentrated solutions
- will see a geometric increase in toxicity with increased concentrations
What is the most serious contraindication for LA?
A) Myasthenia Gravis B) Glaucoma C) Allergic hypersensitivity to other LA D) Hyperemic Conjuntivitis E) Self Administration
E) Self Administration
All others are cautions, but Self-Administration is a major contraindication (can melt cornea)
