Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Question 1

Are NSAIDs weak acids or bases?

Answer 1

They are weak organic acids and are therefore absorbed rapidly in the stomach and small intestine. The stomach has a lower pH than the small intestine and, therefore, more drug is in the absorbable unionised form. However, the main source of absorption is the small intestine due to its larger surface area.

Question 2

Do NSAIDs have high, moderate or low bioavailability?

Answer 2

NSAIDs have a high bioavailability due to limited first-pass hepatic metabolism. However, bioconversion is mostly hepatic.

Question 3

Are NSAIDs highly or poorly protein bound? What is the potential adverse consequence of this?

Answer 3

They are highly protein-bound molecules and, as a result, can displace other protein-bound medications, leading to increased free drug concentrations and increased risk of adverse events, e.g. displacement of warfarin from albumin leading to an increased risk of bleeding.

Question 4

What co-concurrent medications are known to increase bleeding risk if taking NSAIDs?

Answer 4

They may increase bleeding risk if taken with anticoagulants, selective serotonin release inhibitors or other NSAIDs. There is specific interaction with warfarin as it is highly protein bound, therefore displaced by NSAIDs. This can increase the effect of warfarin on INR.

Question 5

Name 2 drugs that NSAIDs are known to increase risk of toxicity.

Answer 5

Lithium
Methotrexate

Question 6

Regarding physiology and the pharmacology of NSAIDs (true or false):

COX-1 is inducible

Answer 6

False. COX-2 is inducible.

Question 7

Regarding physiology and the pharmacology of NSAIDs (true or false):

COX-1 is found in high concentration in the stomach

Answer 7

True

Question 8

Regarding physiology and the pharmacology of NSAIDs (true or false):

COX-1 inhibition is responsible for the desired therapeutic effects of NSAIDs

Answer 8

False. COX-2 is largely responsible for the beneficial therapeutic effects.

Question 9

Regarding physiology and the pharmacology of NSAIDs (true or false):

COX-2 inhibitors lead to increased cardiovascular risk

Answer 9

True

Question 10

Regarding the pharmacokinetics of NSAIDs (true or false):

NSAIDs cannot be administered parenterally

Answer 10

False. Some NSAIDS, e.g. parecoxib and diclofenac, are available as IV preparations.

Question 10

Regarding physiology and the pharmacology of NSAIDs (true or false):

Arachidonic acid is derived from the cellular phospholipid bilayer

Answer 10

True. NSAIDs reduce inflammation by inhibiting the enzyme cyclooxygenase (COX), which converts arachidonic acid into prostaglandins, thromboxanes, and prostacyclins

Question 11

Regarding the pharmacokinetics of NSAIDs (true or false):

NSAIDs are weak organic bases

Answer 11

False. NSAIDS are weak acids.

Question 12

Regarding the pharmacokinetics of NSAIDs (true or false):

NSAIDs are mainly absorbed in the stomach

Answer 12

False. NSAIDS are mainly absorbed from the small bowel. This is despite them being weak acids and therefore unionised in the stomach. However because of the much higher surface area, most of the absoprtion is done in the small intestine.

Question 13

Regarding the pharmacokinetics of NSAIDs (true or false):

NSAIDs undergo limited first pass metabolism

Answer 13

True

Question 14

Regarding the pharmacokinetics of NSAIDs (true or false):

NSAIDs are highly protein bound

Answer 14

True

Question 15

Regarding physiology and the pharmacology and clinical uses of NSAIDs (true or false):

NSAIDs produce their antipyretic actions through increased prostaglandin synthesis in the CNS

Answer 15

False. NSAIDs produce their antipyretic effects by inhibiting the production of prostaglandins.

Question 16

Regarding physiology and the pharmacology and clinical uses of NSAIDs (true or false):

Thromboxane A2 (TxA2) is a potent platelet inhibitor

Answer 16

False. Thromboxane A2 is a potent platelet aggregator.

Question 17

Regarding physiology and the pharmacology and clinical uses of NSAIDs (true or false):

NSAIDs cause bronchospasm in prone asthmatics due to increased leukotriene production

Answer 17

True

Question 18

Regarding physiology and the pharmacology and clinical uses of NSAIDs (true or false):

NSAIDs are safe to use in the antenatal period

Answer 18

False. NSAIDs can cause premature closure of the ductus arteriosis and oligohydramnios.

Question 19

Regarding physiology and the pharmacology and clinical uses of NSAIDs (true or false):

NSAID use is a contraindication for neuraxial anaesthesia

Answer 19

False. Neuraxial techniques can safely be performed in patients on NSAIDs.

Question 20

Regarding the safe use of NSAIDS (true or false):

NSAIDS may increase the risk of bleeding when concomitantly used in patients on warfarin

Answer 20

True

Question 21

Regarding the safe use of NSAIDS (true or false):

NSAIDs are ideal analgesia agents in patients with chronic kidney disease

Answer 21

False. NSAIDs can cause acute on chronic renal failure in this patient group.

Question 22

Regarding the safe use of NSAIDS (true or false):

Aspirin can safely be used in paediatric patients

Answer 22

False. There is a risk of Reye’s syndrome in paediatric patients

Question 23

Regarding the safe use of NSAIDS (true or false):

NSAIDs may increase the possibility of lithium toxicity

Answer 23

True

Question 24

Regarding the safe use of NSAIDS (true or false):

Proton pump inhibitors (PPIs) should be considered with long term NSAID use

Answer 24

True