Pethidine is
pharmacologically different from morphine in?
A. causing more sedation
B. causing constipation
C. having cough suppresant properties
D. causing spasm of sphincter of Oddi
Ans: B & D
Pethidine - (as compared to morphine)
CNS -
1/8 - 1/10 as potent
analgesic as morphine; almost equal analgesic efficacy
as morphine
local anesthetic action
is seen; corneal anesthesia is seen after systemic doses
equal sedation,
euphoria & similar abuse potential
Respiratory system -
Equal degree of
respiratory depression
Does not
suppress cough effectively
Less histamine release
- hence safer in asthmatics
GIT & Genitourinary - spasmodic action is
less marked so less marked
Constipation
Urinary retention
Biliary spasm
Pharmacokinetically -
orally well absorbed, high oral:parenteral activity
ratio (1/3 to 1/2)
i.m. administration -
onset is more rapid, duration of action is shorter
nearly completely metabolised in liver
acidification of urine - increases excretion of
unchanged pethidine
So, we see that both B) and D) are
the answer as pethidine causes less marked constipation and
biliary spasm
