In this episode, I’ll discuss acetazolamide instead of metolazone as an adjunct to loop diuretics.
When a patient with volume overload has an insufficient response to loop diuretics, adjunctive therapy with a 2nd diuretic is used. This is referred to as sequential nephron blockade which uses two different mechanisms of action to block sodium reabsorption at different, consecutive sites along the kidney nephron.
Although metolazone has typically been used for this purpose, acetazolamide is another potential option, albeit with less data. A group of authors sought to investigate this further by conducting a retrospective cohort study published in AJHP.
Data from 120 adult patients receiving adjunctive acetazolamide or metolazone with loop diuretics for volume overload were analyzed. The primary outcome was cumulative urine output within 48 hours. Secondary outcomes included high diuretic response (defined as urine output above the cohort median), hypotension, acute kidney injury, hypokalemia, and metabolic acidosis.
Acetazolamide performed very well in the data. The mean cumulative urine output was significantly greater with acetazolamide – almost double – at 10,637 vs 5,752 mL. After adjustment, acetazolamide remained significantly associated with greater urine output. High diuretic response occurred 64% of the time with acetazolamide compared to just 40% with metolazone, a difference that was statistically significant. The findings were consistent when the authors applied propensity score–matched analyses. Adverse event rates were similar between the groups.
The authors concluded:
Adjunctive acetazolamide was associated with greater urine output and a higher likelihood of achieving a robust diuretic response compared with metolazone. Given the retrospective study design, these findings are hypothesis generating and warrant confirmation in prospective comparative studies.
Patients given metolazone were older and had higher baseline serum creatinine levels, so this single center retrospective comparison isn’t the robust data we’d like to have to make a blanket recommendation. However this adds to the available information on the topic and may help inform direction for future studies.
The article in this episode is a selection from my Hospital Pharmacy Academy’s weekly literature digest. Have you ever felt like your physician colleagues are one step ahead of you with new literature developments? Every week, Academy members are provided a summary curated and explained by me of the top hospital pharmacy-related articles published that week from over 20 major journals and sources to save you time and keep you up to date with the literature. To get immediate access, go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
Leave a Reply