Analgesic 2

Question 1

Aspirin is well absorbed from………….. and……………

Answer 1

stomach and upper intestine

Question 2

Injectable aspirin available as?

Answer 2

lysine acetylsalicylate

Question 3

Mention the effect of aspirin during pregnancy especially last trimester?

Answer 3

> Cross placental barrier
1. prolong gestation period as it suppress uterine PGs production (Delayed labor).
2. Increase risk of post-partum hemorrhage.
3. Premature (early) closure of ductus arteriosus

Question 4

Explain elimination kinetic of aspirin is dose dependent ?

Answer 4

> small dose of aspirin obey 1st order kinetic and t//2 is about 3hrs

> large dose of aspirin( >4gm/day) obey zero order kinetic due to saturation of metabolizing enzymes “t//2 = 15hrs

Question 5

Mechanism of action of aspirin?

Answer 5

non selective irreversible inhibition of cox enzyme by acetylation which cause inhibition in synthesis of PGs& TXA2

Question 6

Mention the peripheral and central
mechanism of analgesia?

Answer 6

Peripheral : Aspirin inhibit PGs synthesis which decrease sensitivity of pain receptors to action of pain mediators

Central : Depression of pain transmission at a subcortical site

Question 7

Mention mechanism of antipyretic effect of aspirin in case of fever?

Answer 7

1- Inhibition of cox-II enzyme centrally which inhibit pathological PGs synthesis and cause re-setting of set point to normal

2- increase heat loss by sweating

3- Vasodilation of superficial (cutaneous) blood vessels to increase heat loss by radiation

Question 8

Give reason toxic dose of aspirin produce hyperpyrexia?

Answer 8

uncoupling of oxidative phosphorylation and result in produce energy not utilized for ATP synthesis and released as heat

Question 9

Mention the effect of NSAIDs on bronchi?

Answer 9

inhibition of cox-enzyme and shift of
arachidonic acid metabolism into lipo-oxygenase pathway which increase leukotrienes synthesis which induce bronchospasm and may cause asthmatic attack

Question 10

leukotrienes action on bronchi can be reversed by leukotriene antagonist as?

Answer 10

Montelukast

Question 11

T OR F / Small therapeutic dose of aspirin cause respiratory alkalosis?

Answer 11

F / (<5 gm/day) has no effect on acid-base imbalance

Question 12

Mention the effect of full therapeutic dose of aspirin on (>5 gm/day) on Acid-base imbalance?

Answer 12

Stimulate respiratory center leading to hyperventilation, that hyperventilation increase wash out of Co2 from plasma causing respiratory alkalosis

Question 13

Give reason the kidney can compensate the respiratory alkalosis caused by full therapeutic dose of aspirin?

Answer 13

the kidney increase the renal excretion of bicarbonate and PH return normal

Question 14

Mention the effect of toxic dose of analgesics in both respiratory and metabolic?

Answer 14

I. Respiratory acidosis due to depression of respiratory center that cause Co2 retention.

II. Metabolic acidosis due to accumulation of acids caused by:
> Accumulation of salicylic acid radicals
> Disturbance of carbohydrates metabolism which cause accumulation of lactic, pyruvic and acetoacetic acid.

Question 15

Mention the effect of analgesics on GIT?

Answer 15

> GIT irritation and epigastric distress
Nausea and vomiting due to:
A. stimulation of CTZ
B. local irritant effect on GIT
Salicylates induce gastric ulceration and even hemorrhage