Table 1.

Summary of clinical studies investigating methenamine for prevention of UTIs in older adults.

First author	Study design	Methenamine dose and duration	Number of patients	Mean age in years (range)	Incidence of UTI or bacteriuria (methenamine versus placebo, when applicable)	Renal function of patients
Recurrent UTI
Freeman6	Randomized Controlled Trial	Methenamine mandelate 1 g QID × 25 months	122	(20–89) with 58% >60 years	25% versus 86%	Patients excluded if CrCl <41 ml/min
Freeman7	Randomized Controlled Trial	Methenamine mandelate 1 g QID × 2 years	249	59 (21–83)	9% versus 40% (p < 0.001)	6% of patients had renal failure$
Bohensky8	Case Series	Methenamine mandelate 2 g QID × 25 days	90	81.5 (67–102)	28%*	NR
Parvio9	Case Series	Methenamine hippurate 1 g BID × 6 months	52	84.7 (65–96)	42.5%*	NR
McAllister10	Case Reports	Methenamine hippurate 500 mg BID	4	89	Not applicable	Various‡
Genitourinary Surgical Procedures
Schiotz11	Randomized Controlled Trial	Methenamine hippurate 1 g BID × 5 days	145	58.3 (30–87)	2.7% versus 13.9% (p = 0.03)	NR
Tyreman12	Randomized Controlled Trial	Methenamine hippurate 1 g night before surgery, 1 g BID day of surgery, 1 g TID × 5 days after surgery	109	65 (63–67)	2.2% versus 28.6% (p < 0.001)	NR
Wesolowski13	Randomized Controlled Trial	Methenamine mandelate 3–4 g daily	75	67 (54–80)	40% versus 66.6%	NR
Long-term Catheterization
Kostiala14	Randomized Controlled Trial	Methenamine hippurate 1 g BID + 0.5 g ascorbic acid TID × 8 days	123	75	39% versus 100% at 1 week 77% versus 100% at 2 weeks Both 100% at 6 weeks	Patients excluded if SCr >1.5 mg/dl
Norrman15	Prospective Cohort Study	Methenamine hippurate 1 g BID × 4 months	22	75 (70–80)	18.2% versus 77.3%	NR

^*Methenamine only.

^$Defined as SCr >2 mg/100 ml.

^‡One patient had a CrCl of 37 ml/min, one had a CrCl of 43 ml/min, one had ESRD with a CrCl of 8 ml/min, one not reported.

BID, twice daily; NR, not reported; QID, four times daily; SCr, serum creatinine; TID, three times daily; UTI urinary tract infection.