Safe Prescribing — MCQs
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A 63-year-old man with type 2 diabetes on insulin therapy presents to his GP with a 3-week history of recurrent hypoglycaemic episodes (glucose readings 2.6-3.4 mmol/L) occurring 2-3 hours after meals. His current regimen is insulin glargine 40 units at bedtime and insulin lispro 14 units before each meal. His HbA1c 3 months ago was 58 mmol/mol. He has recently lost 8kg unintentionally and reports early satiety and occasional vomiting. Examination reveals a succussion splash. What is the most likely explanation for his hypoglycaemia?
Understanding the mechanism of action of anticoagulants, which statement best explains why the anticoagulant effect of warfarin can be enhanced by concurrent administration of broad-spectrum antibiotics?
A 51-year-old man with type 2 diabetes is on insulin glargine 44 units at bedtime and metformin 1g twice daily. He works night shifts (22:00-06:00) three times per week and day shifts (07:00-15:00) the other four days. He reports frequent hypoglycaemic episodes (glucose 2.8-3.5 mmol/L) at around 04:00 during his night shifts. His HbA1c is 51 mmol/mol. What is the most appropriate management strategy to address his hypoglycaemia while maintaining glycaemic control?
A 68-year-old woman on warfarin for atrial fibrillation (target INR 2-3) requires bridging anticoagulation with low molecular weight heparin (LMWH) before elective colonoscopy and polypectomy. Her baseline INR has been stable at 2.6. When should LMWH be commenced in relation to stopping warfarin to provide adequate anticoagulation coverage while minimising bleeding risk during the procedure?
A 56-year-old woman with type 1 diabetes for 30 years has developed end-stage renal failure and is established on peritoneal dialysis. Her insulin requirements have changed significantly since starting dialysis. Which factor most significantly affects insulin requirements in patients on peritoneal dialysis compared to those with normal renal function?
A 72-year-old man with permanent atrial fibrillation on edoxaban 60mg once daily presents to the emergency department with melaena. His haemoglobin is 68 g/L (previous baseline 135 g/L), heart rate 110 bpm, blood pressure 98/62 mmHg. Upper GI endoscopy shows a bleeding duodenal ulcer. His renal function shows creatinine 142 μmol/L (eGFR 44 ml/min/1.73m²). He is haemodynamically unstable despite fluid resuscitation. What is the most appropriate approach to reverse the anticoagulant effect of edoxaban?
A 67-year-old woman attends anticoagulation clinic. She has been on warfarin for 3 years following a mechanical mitral valve replacement. Her target INR is 3.0 (range 2.5-3.5). Today her INR is 7.8 and she reports no bleeding. She has mild bruising on her arms but denies any other symptoms. What is the most appropriate immediate management?
A 64-year-old man with type 1 diabetes is admitted with severe sepsis secondary to pneumonia. He becomes confused and aggressive, refusing all oral intake including medications and food. His capillary blood glucose is 18.2 mmol/L and ketones are 1.2 mmol/L. His regular insulin regimen is insulin glargine 36 units at night and insulin lispro 14 units with meals. What is the most appropriate immediate insulin management?
A 53-year-old woman with newly diagnosed pulmonary embolism is commenced on apixaban. She weighs 58kg and her serum creatinine is 118 μmol/L (eGFR 48 ml/min/1.73m²). She is also taking diltiazem 120mg twice daily for hypertension. What is the most appropriate apixaban dosing regimen?
According to the National Patient Safety Agency (NPSA) guidance, which abbreviation is considered unsafe and must NOT be used when prescribing insulin?
Safe Prescribing UK Medical PG Practice Questions and MCQs
Question 41: A 63-year-old man with type 2 diabetes on insulin therapy presents to his GP with a 3-week history of recurrent hypoglycaemic episodes (glucose readings 2.6-3.4 mmol/L) occurring 2-3 hours after meals. His current regimen is insulin glargine 40 units at bedtime and insulin lispro 14 units before each meal. His HbA1c 3 months ago was 58 mmol/mol. He has recently lost 8kg unintentionally and reports early satiety and occasional vomiting. Examination reveals a succussion splash. What is the most likely explanation for his hypoglycaemia?
- A. Excessive insulin lispro dosing relative to carbohydrate intake
- B. Delayed gastric emptying causing mismatch between insulin action and carbohydrate absorption (Correct Answer)
- C. Improved insulin sensitivity due to weight loss requiring dose reduction
- D. Development of Addison's disease causing increased insulin sensitivity
- E. Surreptitious insulin administration (factitious hypoglycaemia)
Explanation: ***Delayed gastric emptying causing mismatch between insulin action and carbohydrate absorption*** - The patient's symptoms of **early satiety**, **occasional vomiting**, unintentional **weight loss**, and a positive **succussion splash** are highly indicative of **diabetic gastroparesis**. - This condition leads to a delay in food absorption, causing the fast-acting **insulin lispro** to peak before carbohydrates are available, resulting in **post-prandial hypoglycaemia** 2-3 hours after meals.*Excessive insulin lispro dosing relative to carbohydrate intake*- While excessive dosing of rapid-acting insulin can cause hypoglycaemia, it does not explain the presence of **gastrointestinal symptoms** like early satiety, vomiting, and a **succussion splash**.- If the dosing was simply excessive, hypoglycaemia would likely occur more consistently or earlier, without the specific signs of **gastric stasis**.*Improved insulin sensitivity due to weight loss requiring dose reduction*- Unintentional weight loss can improve insulin sensitivity and reduce insulin requirements, potentially leading to hypoglycaemia.- However, this mechanism would not explain the specific **gastrointestinal symptoms** and the finding of a **succussion splash**, which point to a problem with gastric emptying.*Development of Addison's disease causing increased insulin sensitivity*- **Addison's disease** can cause weight loss and hypoglycaemia due to cortisol deficiency, increasing insulin sensitivity.- However, it typically presents with **hyperpigmentation**, fatigue, and **postural hypotension**, and does not cause a **succussion splash** or other signs of gastric outlet obstruction/delayed emptying.*Surreptitious insulin administration (factitious hypoglycaemia)*- **Factitious hypoglycaemia** is a possibility in unexplained recurrent hypoglycaemia, but it rarely presents with clear physiological signs like **early satiety**, vomiting, and a **succussion splash**.- The constellation of gastrointestinal symptoms strongly suggests a genuine medical condition affecting digestion and nutrient absorption, rather than intentional self-harm.
Question 42: Understanding the mechanism of action of anticoagulants, which statement best explains why the anticoagulant effect of warfarin can be enhanced by concurrent administration of broad-spectrum antibiotics?
- A. Antibiotics inhibit cytochrome P450 enzymes that metabolise warfarin, increasing warfarin plasma levels
- B. Antibiotics reduce gut bacteria that synthesise vitamin K, decreasing the availability of vitamin K (Correct Answer)
- C. Antibiotics increase warfarin absorption from the gastrointestinal tract by altering gut pH
- D. Antibiotics compete with warfarin for plasma protein binding sites, increasing free warfarin concentration
- E. Antibiotics enhance the sensitivity of vitamin K-dependent clotting factors to warfarin inhibition
Explanation: ***Antibiotics reduce gut bacteria that synthesise vitamin K, decreasing the availability of vitamin K*** - Broad-spectrum antibiotics deplete **intestinal microflora**, which are responsible for synthesizing approximately 50% of the body's **vitamin K** requirements. - Since **warfarin** works by inhibiting vitamin K-dependent clotting factors (**II, VII, IX, X**), a reduction in available vitamin K potentiates the drug's effect, leading to a higher **INR** and increased bleeding risk. *Antibiotics inhibit cytochrome P450 enzymes that metabolise warfarin, increasing warfarin plasma levels* - While specific antibiotics like **macrolides** or **metronidazole** inhibit **CYP2C9**, this is not a universal mechanism for all broad-spectrum antibiotics. - Gut flora depletion is the more characteristic general mechanism associated with the "broad-spectrum" class rather than specific **enzyme inhibition**. *Antibiotics increase warfarin absorption from the gastrointestinal tract by altering gut pH* - Warfarin absorption is largely completed in the **upper gastrointestinal tract** and is not significantly affected by changes in **gut pH** induced by antibiotics. - **Bioavailability** remains relatively constant regardless of the presence of antibiotics in the intestinal lumen. *Antibiotics compete with warfarin for plasma protein binding sites, increasing free warfarin concentration* - Although many drugs can displace warfarin from **albumin**, this mechanism is rarely clinically significant as the **free fraction** is rapidly metabolized. - Most broad-spectrum antibiotics do not have a high enough affinity for **protein binding sites** to cause a sustained increase in warfarin's anticoagulant effect. *Antibiotics enhance the sensitivity of vitamin K-dependent clotting factors to warfarin inhibition* - Warfarin's efficacy is determined by its inhibition of **vitamin K epoxide reductase**, not by altering the **intrinsic sensitivity** of the clotting factors themselves. - Antibiotics influence the **substrate availability** (vitamin K) rather than altering the biochemical interaction between the drug and its target enzyme.
Question 43: A 51-year-old man with type 2 diabetes is on insulin glargine 44 units at bedtime and metformin 1g twice daily. He works night shifts (22:00-06:00) three times per week and day shifts (07:00-15:00) the other four days. He reports frequent hypoglycaemic episodes (glucose 2.8-3.5 mmol/L) at around 04:00 during his night shifts. His HbA1c is 51 mmol/mol. What is the most appropriate management strategy to address his hypoglycaemia while maintaining glycaemic control?
- A. Reduce insulin glargine to 35 units at bedtime on all days
- B. Change insulin glargine to twice-daily dosing (22 units morning, 22 units evening)
- C. Switch from insulin glargine to insulin detemir which can be given at variable times (Correct Answer)
- D. Advise taking a 20g carbohydrate snack at 02:00 on night shift days
- E. Reduce insulin glargine to 35 units on night shift days only, continue 44 units on day shift days
Explanation: ***Switch from insulin glargine to insulin detemir which can be given at variable times***- **Insulin detemir** is an intermediate-to-long acting analog that allows for more **flexible timing** compared to glargine because its action profile typically lasts 12-20 hours, making it ideal for variable shift schedules.- By switching to detemir, the patient can adjust the **injection timing** to better align with the specific activity and feeding windows of both night and day shifts, reducing the risk of nocturnal/early morning **hypoglycaemia**.*Reduce insulin glargine to 35 units at bedtime on all days*- This would likely cause a significant **deterioration in glycaemic control**, as the patient's current **HbA1c (51 mmol/mol)** is already at target.- A blanket reduction does not address the specific **temporal mismatch** between insulin peak and activity levels that occurs only during the night shift.*Change insulin glargine to twice-daily dosing (22 units morning, 22 units evening)*- **Insulin glargine** is designed as a peakless, basal insulin intended for once-daily use; splitting the dose is not a standard regimen and typically provides no benefit in managing **shift work variability**.- This approach increases the risk of **insulin stacking** and does not resolve the specific 04:00 hypoglycaemia episodes occurring on work nights.*Advise taking a 20g carbohydrate snack at 02:00 on night shift days*- Adding a mandated carbohydrate snack treats the **symptom** of the mismatch rather than the cause and can lead to **unwanted weight gain** or post-shift hyperglycaemia.- This strategy is often unsustainable for long-term management compared to adjusting the **pharmacokinetic profile** of the insulin regimen itself.*Reduce insulin glargine to 35 units on night shift days only, continue 44 units on day shift days*- Glargine has a duration of action up to **24 hours or longer**; varying the dose day-to-day results in unpredictable **overlap (stacking)** between doses.- Because of its long half-life, the effects of a dose change take **2-3 days** to reach a new steady state, making daily adjustments ineffective and potentially dangerous.
Question 44: A 68-year-old woman on warfarin for atrial fibrillation (target INR 2-3) requires bridging anticoagulation with low molecular weight heparin (LMWH) before elective colonoscopy and polypectomy. Her baseline INR has been stable at 2.6. When should LMWH be commenced in relation to stopping warfarin to provide adequate anticoagulation coverage while minimising bleeding risk during the procedure?
- A. Start LMWH immediately when warfarin is stopped, continue until the day before procedure
- B. Start LMWH when INR falls below 3.0, give last dose 24 hours before procedure
- C. Start LMWH when INR falls below 2.0, give last dose 24 hours before procedure (Correct Answer)
- D. Wait until INR is <1.5, then start LMWH, give last dose 12 hours before procedure
- E. Start LMWH 48 hours after stopping warfarin regardless of INR, stop 24 hours before procedure
Explanation: ***Start LMWH when INR falls below 2.0, give last dose 24 hours before procedure*** - **Bridging anticoagulation** is initiated when the **INR drops below the therapeutic range** (typically <2.0) to minimize the period of subtherapeutic coverage. - The final dose of **LMWH** must be administered **24 hours prior** to the procedure to ensure the drug is sufficiently cleared, thereby reducing the risk of **perioperative bleeding**. *Start LMWH immediately when warfarin is stopped, continue until the day before procedure* - Initiating LMWH while the **INR is still therapeutic** (>2.0) results in an additive anticoagulant effect and significantly increases the **bleeding risk**. - There is no clinical benefit to "stacking" these medications until the effect of **Warfarin** has actually dissipated. *Start LMWH when INR falls below 3.0, give last dose 24 hours before procedure* - Starting LMWH at an **INR of 3.0** is inappropriate because the patient is still within or above the **target therapeutic range** (2.0-3.0). - This approach leads to **over-anticoagulation**, which poses a danger during the transition period before the elective surgery. *Wait until INR is <1.5, then start LMWH, give last dose 12 hours before procedure* - Waiting for an **INR <1.5** leaves the patient without adequate protection for too long, increasing the risk of **thromboembolic events** like stroke. - A **12-hour gap** before the procedure is often insufficient for proper **LMWH clearance**, especially in elderly patients or those with reduced renal function. *Start LMWH 48 hours after stopping warfarin regardless of INR, stop 24 hours before procedure* - A **fixed-time approach** is unsafe because **warfarin metabolism** and its offset vary significantly between individuals based on genetics and diet. - Management must be guided by **INR monitoring** rather than a set timeline to ensure the patient is neither under- nor over-anticoagulated.
Question 45: A 56-year-old woman with type 1 diabetes for 30 years has developed end-stage renal failure and is established on peritoneal dialysis. Her insulin requirements have changed significantly since starting dialysis. Which factor most significantly affects insulin requirements in patients on peritoneal dialysis compared to those with normal renal function?
- A. Increased insulin degradation by the peritoneal membrane
- B. Reduced renal insulin clearance partially offset by glucose absorption from dialysate (Correct Answer)
- C. Enhanced peripheral insulin sensitivity due to uraemia reduction
- D. Increased hepatic insulin extraction compensating for loss of renal clearance
- E. Decreased insulin absorption from subcutaneous sites due to fluid shifts
Explanation: ***Reduced renal insulin clearance partially offset by glucose absorption from dialysate*** - In end-stage renal failure, the loss of **renal insulin clearance** (normally 40-80%) prolongs insulin half-life, which traditionally decreases the required dose to avoid hypoglycemia. - This is counteracted in **peritoneal dialysis** by the absorption of significant amounts of **glucose from the dialysate** (100-200g/day), which increases insulin demand and necessitates careful dose titration. *Increased insulin degradation by the peritoneal membrane* - The **peritoneal membrane** serves as a semi-permeable barrier for exchange but does not possess significant enzymatic pathways for **insulin degradation**. - Insulin can actually be administered **intraperitoneally** in some patients because the membrane allows absorption into the systemic circulation rather than destroying it. *Enhanced peripheral insulin sensitivity due to uraemia reduction* - While effective dialysis reduces **uremic toxins** which can improve insulin sensitivity, this effect is often outweighed by the **glucose load** inherent to the dialysis fluid. - Improving **uremia** typically would decrease insulin requirements, but the clinical reality in PD patients is often an increased need due to **hyperglycemia** from the dialysate. *Increased hepatic insulin extraction compensating for loss of renal clearance* - **Hepatic insulin extraction** remains relatively constant and does not increase to compensate for the pathological loss of **renal filtration and catabolism** of insulin. - The liver primarily clears **endogenous insulin** via the portal vein, whereas exogenous insulin is cleared predominantly by the **kidneys**. *Decreased insulin absorption from subcutaneous sites due to fluid shifts* - Although **local edema** or fluid shifts can theoretically alter absorption, they do not represent the **primary metabolic driver** for changing insulin requirements in PD patients. - Clinical management focuses on the **carbohydrate load** from the dialysate rather than significant alterations in **subcutaneous absorption** pharmacokinetics.
Question 46: A 72-year-old man with permanent atrial fibrillation on edoxaban 60mg once daily presents to the emergency department with melaena. His haemoglobin is 68 g/L (previous baseline 135 g/L), heart rate 110 bpm, blood pressure 98/62 mmHg. Upper GI endoscopy shows a bleeding duodenal ulcer. His renal function shows creatinine 142 μmol/L (eGFR 44 ml/min/1.73m²). He is haemodynamically unstable despite fluid resuscitation. What is the most appropriate approach to reverse the anticoagulant effect of edoxaban?
- A. Administer prothrombin complex concentrate (PCC) 50 units/kg (Correct Answer)
- B. Administer fresh frozen plasma 15 ml/kg
- C. Give oral activated charcoal 50g if within 2 hours of last dose
- D. Administer intravenous tranexamic acid 1g three times daily
- E. Administer vitamin K 10mg intravenously
Explanation: ***Administer prothrombin complex concentrate (PCC) 50 units/kg*** - In cases of life-threatening bleeding associated with **Factor Xa inhibitors** like **edoxaban**, and where specific reversal agents like andexanet alfa are unavailable, **four-factor PCC** at a dose of **50 units/kg** is the recommended treatment to restore haemostasis. - PCC provides a high concentration of **clotting factors II, VII, IX, and X**, bypassing the inhibition and facilitating thrombin generation in the face of ongoing instability. *Administer fresh frozen plasma 15 ml/kg* - **FFP** is not recommended for the reversal of DOACs as it contains insufficient concentrations of clotting factors to effectively neutralise the anticoagulant effect. - The volume required for any potential benefit carries a high risk of **fluid overload** and is too slow to administer in an emergency with **haemodynamic instability**. *Give oral activated charcoal 50g if within 2 hours of last dose* - **Activated charcoal** only prevents the absorption of the drug and is only useful if the patient presents within **2 hours** of ingestion; this patient is likely far beyond that window. - While it may be a supportive measure early on, it does not provide the **acute reversal** required for a patient currently in **haemorrhagic shock**. *Administer intravenous tranexamic acid 1g three times daily* - **Tranexamic acid** is an **antifibrinolytic** that can be used as an adjunct to help stabilize clots, but it does not directly reverse the pharmacological effect of **Factor Xa inhibitors**. - Relying on this alone would be insufficient for a patient with a massive **haemoglobin drop** and **life-threatening duodenal bleeding**. *Administer vitamin K 10mg intravenously* - **Vitamin K** is only effective for reversing **Vitamin K antagonists** like **warfarin** by facilitating the synthesis of new clotting factors, a process that takes several hours. - It has no role in the reversal of **direct oral anticoagulants (DOACs)** like edoxaban, which work by direct enzyme inhibition rather than factor depletion.
Question 47: A 67-year-old woman attends anticoagulation clinic. She has been on warfarin for 3 years following a mechanical mitral valve replacement. Her target INR is 3.0 (range 2.5-3.5). Today her INR is 7.8 and she reports no bleeding. She has mild bruising on her arms but denies any other symptoms. What is the most appropriate immediate management?
- A. Omit warfarin for 2 days and restart at reduced dose when INR <5.0, recheck INR in 2 days
- B. Admit immediately for intravenous vitamin K 5mg and prothrombin complex concentrate
- C. Give oral vitamin K 1-3mg and omit warfarin, recheck INR in 24 hours (Correct Answer)
- D. Continue warfarin at reduced dose and recheck INR in 1 week
- E. Omit warfarin and recheck INR daily until it falls below 5.0, then restart at previous dose
Explanation: ***Give oral vitamin K 1-3mg and omit warfarin, recheck INR in 24 hours*** - For an **INR between 5.0 and 9.0** with **minor bleeding** (such as bruising), consensus guidelines recommend **oral Vitamin K** (1-3mg) to gently lower the INR. - **Withholding warfarin doses** and repeating the INR in **24 hours** ensures the level returns to the therapeutic range while minimizing the risk of thrombosis in a patient with a **mechanical mitral valve**. *Omit warfarin for 2 days and restart at reduced dose when INR <5.0, recheck INR in 2 days* - Simply **withholding warfarin** without Vitamin K is only appropriate if the INR is 5.0–9.0 and there is **no bleeding** at all. - This patient presents with **minor bleeding** (bruising), which necessitates active reversal with low-dose **oral Vitamin K**. *Admit immediately for intravenous vitamin K 5mg and prothrombin complex concentrate* - This aggressive approach is reserved for **major or life-threatening hemorrhage**, regardless of the INR level, which is not present here. - Using **Prothrombin Complex Concentrate (PCC)** and high-dose **IV Vitamin K** would be excessive for mild bruising and could cause prolonged **warfarin resistance**, increasing the risk of valve thrombosis. *Continue warfarin at reduced dose and recheck INR in 1 week* - Continuing warfarin with an **INR of 7.8** is dangerous and substantially increases the risk of a major **hemorrhagic stroke** or internal bleed. - Rechecking in **one week** is too late, as immediate clinical intervention is required to bring the INR down to safe levels within 24-48 hours. *Omit warfarin and recheck INR daily until it falls below 5.0, then restart at previous dose* - While omitting doses is part of the management, failing to give **Vitamin K** when minor bleeding is present delays the correction of the coagulopathy. - Restarting at the **previous dose** is incorrect; the maintenance dose must be **adjusted downwards** to prevent a recurrence of supratherapeutic INR.
Question 48: A 64-year-old man with type 1 diabetes is admitted with severe sepsis secondary to pneumonia. He becomes confused and aggressive, refusing all oral intake including medications and food. His capillary blood glucose is 18.2 mmol/L and ketones are 1.2 mmol/L. His regular insulin regimen is insulin glargine 36 units at night and insulin lispro 14 units with meals. What is the most appropriate immediate insulin management?
- A. Administer intramuscular insulin glargine 36 units as he is refusing subcutaneous injections
- B. Continue subcutaneous insulin injections and consider restraint if necessary as diabetes control is critical
- C. Commence a variable rate intravenous insulin infusion (VRIII) with concurrent intravenous dextrose and monitoring (Correct Answer)
- D. Withhold all insulin until the patient is cooperative to avoid risk of hypoglycaemia while confused
- E. Administer insulin lispro 20 units subcutaneously every 6 hours to cover the elevated glucose
Explanation: ***Commence a variable rate intravenous insulin infusion (VRIII) with concurrent intravenous dextrose and monitoring*** - A **VRIII** is the most appropriate management for a **type 1 diabetic** patient who is acutely unwell (severe sepsis, pneumonia), confused, refusing oral intake, and has elevated glucose and ketones (indicating impending DKA). - It provides **precise and adjustable insulin delivery**, preventing **DKA** while allowing concurrent **intravenous dextrose** to prevent hypoglycemia, especially when the patient is nil by mouth. *Administer intramuscular insulin glargine 36 units as he is refusing subcutaneous injections* - **Insulin glargine** is a long-acting insulin analog designed for **subcutaneous administration**; intramuscular injection can lead to unpredictable absorption and erratic glucose control. - Administering a fixed dose of **basal insulin intramuscularly** does not provide the flexibility needed for acute illness, severe sepsis, or fluctuating insulin requirements. *Continue subcutaneous insulin injections and consider restraint if necessary as diabetes control is critical* - Using **physical restraint** for routine medical procedures like insulin administration in a confused patient raises serious **ethical and legal concerns** and is generally not an acceptable practice. - Continuing **subcutaneous mealtime insulin (lispro)** when a patient is refusing all food and fluids carries a very high risk of severe **hypoglycaemia**, which would worsen the patient's confusion and overall condition. *Withhold all insulin until the patient is cooperative to avoid risk of hypoglycaemia while confused* - **Withholding all insulin** in a patient with **type 1 diabetes** is critically dangerous as they have **absolute insulin deficiency** and will rapidly progress to severe **diabetic ketoacidosis (DKA)**, which is life-threatening. - Even if the patient is not eating, **basal insulin** or an intravenous substitute is essential to prevent unchecked ketogenesis and glucose elevation. *Administer insulin lispro 20 units subcutaneously every 6 hours to cover the elevated glucose* - Administering fixed doses of **short-acting insulin (lispro)** every 6 hours without considering nutritional intake and in the context of sepsis is prone to causing **hypoglycaemia** and does not provide adequate **basal insulin coverage**. - This regimen lacks the **dynamic titration** and continuous delivery offered by a **VRIII**, which is necessary for stable and safe glucose management in this acute setting.
Question 49: A 53-year-old woman with newly diagnosed pulmonary embolism is commenced on apixaban. She weighs 58kg and her serum creatinine is 118 μmol/L (eGFR 48 ml/min/1.73m²). She is also taking diltiazem 120mg twice daily for hypertension. What is the most appropriate apixaban dosing regimen?
- A. Apixaban 10mg twice daily for 7 days, then 5mg twice daily
- B. Apixaban 10mg twice daily for 7 days, then 2.5mg twice daily (Correct Answer)
- C. Apixaban 5mg twice daily continuously
- D. Apixaban 2.5mg twice daily continuously
- E. Apixaban is contraindicated; use warfarin instead
Explanation: ***Apixaban 10mg twice daily for 7 days, then 2.5mg twice daily***- For treatment of **pulmonary embolism**, the standard loading dose of **apixaban** is **10mg twice daily for 7 days**.- The maintenance dose is reduced to **2.5mg twice daily** because the patient meets two criteria for dose reduction: **body weight ≤60kg** (58kg) and concomitant use of **diltiazem**, a **moderate CYP3A4 inhibitor**.*Apixaban 10mg twice daily for 7 days, then 5mg twice daily*- While the initial **loading dose** is correct, the maintenance dose of **5mg twice daily** is inappropriate for this patient.- The patient's **low body weight (58kg)** and use of **diltiazem** (a moderate CYP3A4 inhibitor) increase apixaban exposure, necessitating a lower maintenance dose to reduce **bleeding risk**.*Apixaban 5mg twice daily continuously*- This regimen is incorrect as it lacks the essential **initial 10mg twice daily loading dose for 7 days** required for acute **pulmonary embolism** treatment.- It also fails to account for the patient's specific characteristics (low weight, diltiazem use) that warrant a **2.5mg twice daily maintenance dose** if a loading dose were properly administered.*Apixaban 2.5mg twice daily continuously*- Administering **2.5mg twice daily continuously** is insufficient for the acute management of a **pulmonary embolism** as it omits the critical **10mg twice daily loading phase for 7 days**.- While 2.5mg twice daily is the appropriate *maintenance* dose for this patient, starting with it would lead to **inadequate anticoagulation** during the acute phase.*Apixaban is contraindicated; use warfarin instead*- Apixaban is not contraindicated here; the patient's **eGFR (48 ml/min/1.73m²)** is above the usual threshold (typically <15 ml/min/1.73m²) for avoiding direct oral anticoagulants (**DOACs**).- **DOACs** like apixaban are generally preferred over **warfarin** for **pulmonary embolism** treatment due to their more favorable **safety profile** and ease of use.
Question 50: According to the National Patient Safety Agency (NPSA) guidance, which abbreviation is considered unsafe and must NOT be used when prescribing insulin?
- A. BD (twice daily)
- B. SC (subcutaneous)
- C. U (units) (Correct Answer)
- D. OD (once daily)
- E. TDS (three times daily)
Explanation: ***U (units)*** - The abbreviation **'U'** is strictly prohibited by the **National Patient Safety Agency (NPSA)** because it can be easily misread as a zero (**0**), four (**4**), or **'cc'**, leading to a potentially fatal **10-fold dosing error**. - To ensure patient safety, the word **'units'** must always be written in full when prescribing **insulin** or other narrow therapeutic index drugs. *BD (twice daily)* - **BD** is a standard abbreviation for **bis in die** and is generally considered acceptable in conventional prescribing to denote a frequency of twice a day. - While hospital guidelines increasingly favor plain English, **BD** is not specifically prohibited as a dangerous abbreviation in the same high-risk category as **'U'**. *SC (subcutaneous)* - **SC** is a commonly used abbreviation for the **subcutaneous** route of administration and is familiar to healthcare professionals across most clinical settings. - Although writing the route in full is always safer, the **NPSA** does not classify **'SC'** as an inherently unsafe abbreviation compared to unit-based indicators. *OD (once daily)* - **OD** stands for **omne in die** and is used to signify a **once-daily** regimen; it is a standard prescription term that does not carry the same misinterpretation risk as insulin units. - Safety concerns for **OD** are minimal compared to **'U'**, as misreading the frequency is less likely to cause the immediate, severe metabolic crisis seen with tenfold insulin errors. *TDS (three times daily)* - **TDS (ter die sumendum)** is widely recognized for medications taken **three times a day** and is standard practice in many medical records and drug charts. - While clear communication is encouraged, there is no high-risk safety alert from the **NPSA** specifically banning **TDS** in the context of insulin therapy.
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