Published: 1 December 2022

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Quiz answers

Prescriber Update 43(4): 66
December 2022

1. Non-steroidal autoinflammatory drugs (NSAIDs) are contraindicated during which trimester of pregnancy?
   NSAIDs are contraindicated in the third trimester of pregnancy. (September 2022)
2. Trimethoprim or _____ can interact with methotrexate to cause bone marrow suppression.
   Co-trimoxazole. (March 2022)
3. List 3 factors that increase the risk of diabetic ketoacidosis in patients taking a sodium-glucose co-transporter 2 (SGLT-2) inhibitor.
   A low carbohydrate diet, dehydration, acute illness, surgery, insulin deficiency from any cause, reduced caloric intake or increased insulin requirements are factors that increase the risk of DKA in patients taking SGLT-2 inhibitors. (December 2022)
4. Systemic ciprofloxacin may [increase/decrease] the serum concentration of levothyroxine.
   Decrease. Systemic ciprofloxacin may decrease the serum concentration of levothyroxine. If patients taking levothyroxine require concomitant ciprofloxacin, instruct them to separate administration by 6 hours; inform them about this potential interaction and the symptoms of hypothyroidism (eg, fatigue, feeling cold, weight gain, constipation); monitor them for any changes in thyroid function. (June 2022)
5. Consider drug–drug interactions with Paxlovid (nirmatrelvir + ritonavir) due to its inhibitory effects on:
   1. CYP3A
   2. CYP2D6
   3. CYP2C9
   4. CYP1A2
   a. Paxlovid is a CYP3A inhibitor.
   Concomitant use with medicines metabolised by CYP3A may lead to clinically serious adverse reactions. (December 2022)
6. Patients taking bimatoprost who have mild enophthalmos, orbital fat atrophy and/or inferior scleral show may be experiencing which condition?
   Prostaglandin-associated periorbitopathy describes clinical and cosmetic changes in the eye associated with prostaglandin analogues. (September 2022)
7. In patients taking combined oral contraceptives (COCs), when is the risk of venous thromboembolism (VTE) the highest?
   The risk of venous thromboembolism (VTE) is highest during the first year after starting a combined oral contraceptive (COC) and when restarting after a break of 4 weeks or more. However, VTE may occur at any time during use of a COC. (March 2022)
8. List 3 opioid medicines that are high-risk for inducing serotonin syndrome when used with serotonergic medicines.
   Pethidine, dextromethorphan and tramadol are high-risk opioids for inducing serotonin syndrome when used with serotonergic antidepressants. (September 2022)
9. Which of the following are suggested mechanisms whereby vitamin E may cause bleeding:
   1. Scavenging of free radicals
   2. Inhibition of platelet aggregation
   3. Tocopheryl quinone has anticoagulant activity
   4. Alpha-tocopherol can interfere with vitamin K metabolism
   b and c. Vitamin E may inhibit platelet aggregation. Tocopheryl quinone (the main oxidation product of alpha-tocopherol) has anticoagulant properties and can interfere with vitamin K metabolism, theoretically causing bleeding. (June 2022)
10. True or False: St John’s Wort can reduce the clinical effects of warfarin.
    True. St John’s Wort can reduce the clinical effects of warfarin. Patients taking warfarin must not use herbal products containing St John’s Wort. (December 2022)