A 73-year-old man with hypertension is evaluated for right great toe pain. A tap of the toe reveals uric acid crystals. He has a history of hypertension and hyperlipidemia. His current medications are hydrochlorothiazide, amlodipine, and atorvastatin.
Which blood pressure medication would you recommend to replace his hydrochlorothiazide?
A. Furosemide
B. Chlorthalidone
C. Lisinopril
D. Losartan
E. Irbesartan
Losartan
Diuretics should be avoided if possible in a patient with gout, as they increase uric acid levels. Of the other three options, losartan offers the added benefit of lowering uric acid levels. Losartan has uricosuric effects — a property that is unique to losartan of the angiotensin receptor blockers (ARBs) that have been studied.1,2 The uric acid lowering appears to be a probenecid-like effect.
Dr. Douglas S. Paauw
Losartan has also been evaluated to see whether using it in combination with a thiazide diuretic can reduce the rise in uric acid that occurs with thiazides. Matsumura and colleagues looked at data from the COMFORT trial, focusing on the effect of combining losartan with hydrochlorothiazide on uric acid levels.3 They looked at a group of 118 patients on an ARB other than losartan plus a diuretic, who were then randomly assigned to losartan 50 mg/hydrochlorothiazide 12.5 mg or continuation of another ARB plus a diuretic. Blood pressure control was the same between groups, but the patients who received the losartan combination had lower uric acid levels (P = .01).
Ferreira and colleagues looked at the difference in uric acid lowering between high-dose (150 mg/day) vs low-dose losartan (50 mg/day).4 Compared with low-dose, high-dose losartan reduced serum uric acid by 0.27 (0.34 to 0.21) mg/dL, P < .001.
SGLT2 inhibitors
SGLT2 inhibitors also lower uric acid. Suijik and colleagues conducted an analysis of two randomized trials of SGLT2 inhibitors (empagliflozin and dapagliflozin), and concluded that SGLT2 inhibitors induce uric acid excretion, which is strongly linked to urinary glucose excretion.5
Metformin
Metformin is used as a firstline drug for the treatment of diabetes. It also has evidence for decreasing colonic polyps. Cho and colleagues looked at over 12,000 patients with diabetes over a 12-year period; 3775 underwent colonoscopies.6 They compared frequency of polyps in patients who were using metformin with those who were not treated with metformin. The polyp detection rate was lower in the metformin group than in the no metformin group (39.4% vs. 62.4%, P < .01).
Higurashi and colleagues performed a double-blind, placebo-controlled trial of metformin in nondiabetic patients for the prevention of colon polyps.7 The dose of metformin used in this study was very low (250 mg/day). There were significantly fewer adenomas in the metformin group (22 of 71 patients) than in the placebo group (32 of 62) (relative risk, 0.60; 95% confidence interval, 0.39-0.92, P = .016).
Thiazide diuretics
Thiazide diuretics have long been used to help prevent kidney stones in addition to treating hypertension. They decrease urinary calcium excretion, which may reduce kidney stones. Could this reduction in calcium excretion be good for bones?
Xiao and colleagues did a meta-analysis of 11 prospective studies involving 2,193,160 participants.8 Thiazide diuretic users had a significant 14% reduction in the risk of all fractures (RR, 0.86; 95% CI, 0.80-0.93; P = .009) and an 18% reduction in the risk of hip fracture (RR, 0.82; 95% CI, 0.80-0.93; P = .009). Kruse and colleagues found that long duration and continuity of thiazide exposure seemed to be important to obtain this protective effect on fracture risk.9
Pearls:
- Losartan, but not other ARBs, lowers uric acid levels and may be helpful in managing hypertension in gout patients; higher doses lower uric acid more.
- Metformin use appears to decrease colon polyp formation.
- Thiazide diuretics may reduce fracture risk while patients are taking them.
Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and he serves as third-year medical student clerkship director at the University of Washington. He is a member of the editorial advisory board of Internal Medicine News. Dr. Paauw has no conflicts to disclose. Contact him at imnews@mdedge.com.
References
1. Würzner G et al. Comparative effects of losartan and irbesartan on serum uric acid in hypertensive patients with hyperuricaemia and gout. J Hypertens. 2001 Oct;19(10):1855-60.
2. Puig JG et al. Effect of eprosartan and losartan on uric acid metabolism in patients with essential hypertension. J Hypertens. 1999 Jul;17(7):1033-9.
3. Matsumura K et al. Effect of losartan on serum uric acid in hypertension treated with a diuretic: The COMFORT study. Clin Exp Hypertens. 2015;37(3):192-6.
4. Ferreira JP et al. High- versus low-dose losartan and uric acid: An analysis from HEAAL. J Cardiol. 2023 Jul;82(1):57-61.
5. Suijk DLS et al. SGLT2 inhibition and uric acid excretion in patients with type 2 diabetes and normal kidney function. Soc Nephrol. 2022 May;17(5):663-71.
6. Youn Hee Cho et al. Does metformin affect the incidence of colonic polyps and adenomas in patients with type 2 diabetes mellitus? Intestinal Res. 2014 Apr;12(2):139-45.
7. Higurashi T et al. Metformin for chemoprevention of metachronous colorectal adenoma or polyps in post-polypectomy patients without diabetes: A multicentre double-blind, placebo-controlled, randomised phase 3 trial. Lancet Oncol. 2016;17:475-83.
8. Xiao X et al. Thiazide diuretic usage and risk of fracture: a meta-analysis of cohort studies. Osteoporos Int. 2018 Jul;29(7):1515-24.
9. Kruse C et al. Continuous and long-term treatment is more important than dosage for the protective effect of thiazide use on bone metabolism and fracture risk. J Intern Med. 2016 Jan;279(1):110-22.