Local anesthetics (LA) 2

Question 1

Pharmacological (systemic) actions of LAs on CVS?

Answer 1

1. LAs are myocardial depressants (↓ Heart rate, Conduction and Contraction).
2. LAs Cause arteriolar dilatation due to direct effect and ganglion blocking activity leading to
   hypotension
3. Cocaine causes vasoconstriction and hypertension as cocaine inhibit neuronal uptake of NE
   (Indirect sympathomimetic activity)
4. Lidocaine has anti-arrhythmic properties => in treatment of ventricular arrhythmia as 1st choice
   (IV ONLY).

Question 2

Mention the drug:
drug of choice in treatment of ventricular arrhythmia?

Answer 2

Lidocaine ( IV only )

Question 3

Pharmacological (systemic) actions of LAs on muscles : Smooth , skeletal

Answer 3

• spasmolytic effect
• In large dose –>relaxation of the skeletal muscles due to neuro-muscular blockade (block sodium ion channels of the nicotinic receptors)

Question 4

Mention the toxic effect of LAs (Systemic actions)?

Answer 4

1. Hypersensitivity reactions: Dermatitis, asthma, anaphylactic shock
2. Sudden Circulatory Collapse with hypotension and cardiac arrest (If given IV)
3. CNs stimulation: excitement, Irritability, restlessness and even convulsions, CNS stimulation is followed by CNs depression.

Question 5

Mention the vasoconstrictor agents injected with LAs to Prolong the duration of action of LAs?

Answer 5

Epinephrine, Phenylephrine

Question 6

vasoconstrictor agents should be injected with all local anesthetics EXCEPT?

Answer 6

Cocaine
which is vasoconstrictor by Its self

Question 7

Mention the advantages of Vasoconstrictor agent?

Answer 7

1- Decrease absorption of LA from site of injection => prolong duration of action of LA

2- . Decrease systemic absorption will decrease systemic toxicity of LA

3- Vasoconstriction of blood vessels decrease bleeding and provide clean, bloodless field of operation.

Question 8

Mention the disadvantages Vasoconstrictor agent?

Answer 8

1- systemic absorption of the vasoconstrictor agents => hypertension

2- Vasoconstrictor agents produce hypoxia
(decrease blood supply) => tissue damage (Gangrene)/ delay wound healing

Question 9

All local anesthetics can be used for surface anesthesia except?

Answer 9

Procaine, Mepivacaine

they are not absorbed from skin, Mucous membrane

Question 10

Technique of Local anesthesia used to relieve pain of ulcer, fissures and burns, ophthalmic, urological examinations , ENT& dentistry?

Answer 10

Surface anesthesia

Question 11

drug used as Surface
anesthesia for ophthalmic?

Answer 11

tetracaine

Question 12

drug used as Surface
anesthesia for ophthalmic?

Answer 12

tetracaine

Question 13

common example of Infiltration anesthesia in which LAs is injected S.C in circular manner around field of operation?

Answer 13

Ring block

Question 14

mention the LAs that injected subcutaneous
around field of operation to block nerve endings?
(As in dental extraction)

Answer 14

lidocaine, procaine or mepivacaine

Infiltration technique of local anesthesia