Question

Which of the following is not true of local anesthesia?

	A.	They are used to supply anesthesia to only a specific area of the body.
	B.	The onset of most local anesthetics is slow, and they last for a prolonged periods.
	C.	They may have epinephrine added to prolong their action and produce vasoconstriction.
	D.	They usually end in "-caine".

Answer 1

ANSWER IS B......

Lets analyse each option

A)They are used to supply anesthesia to only a specific area of the body.This statement is true because local anaesthesia is used to supply anesthesia to only a specific area of body supplied by a particular group of nerves in vicinity of which the local anaesthetic agent is administered.

B)The onset of most local anesthetics is slow,and they last for a prolonged periods.This statement is not true because onset of most local anaesthetics is fast(3-5minutes),and the local anaesthetics can be divided into three categories based on duration of actions

short acting(45 min-90min)-2-chloroprocaine

intermediate acting(90 min-180 min)-lidocaine,mepivicaine

long acting (4-18 hours)- bupivacaine,ropivicaine

c)They may have epinephrine added to prolong their action and produce vasoconstriction.This statement is true.The epinephrine is added to local anesthesia which results in vasoconstriction by stimulating adrenergic receptors, which results in slow systemic absorbtion and which inturns increases duration of action of local anesthesia.

D) They usually end in "-caine".This statement is true because name of most local anaesthetic agents end in -caine.local anaesthetic can be divided into three groups based on structure :

amide linked -lidocaine,bupivicaine

ester linked-procaine,tetracaine,cocaine

Quinoline-Example-Centbucridine