Methenamine
| Clinical data | |
|---|---|
| Pronunciation | meh-THEH-na-meen[1] |
| Trade names | Antihydral, Hiprex, Urex, Urotropin, others |
| Other names | Hexamethylenetetramine; HMTA; Hexamine; Hexamethylenamine; Hexamethyleneamine; Metenamine; Urometine; Hippramine; E-239; R-657; 1,3,5,7-Tetraazaadamantane |
| Routes of administration | Oral,[2][3][4] topical[5][6] |
| Drug class | Antiseptic; Antibacterial |
| ATC code | |
| Pharmacokinetic data | |
| Bioavailability | High (≥70%)[7][8][2] |
| Protein binding | Unknown[3] |
| Metabolism | Hydrolysis in acidic urine[3] |
| Metabolites | • Formaldehyde[3][9] • Ammonia[3][9] • Formic acid[10][11] |
| Onset of action | ≤30 minutes[3][4] |
| Elimination half-life | 2–6 hours[2][7][3] |
| Excretion | Urine: 70–90% unchanged within 24 hours[3] |
| Identifiers | |
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| Chemical and physical data | |
| Formula | C6H12N4 |
| Molar mass | 140.190 g·mol−1 |
| 3D model (JSmol) | |
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Methenamine, also known as hexamine or hexamethylenetetramine and sold under the brand names Hiprex, Urex, and Urotropin among others, is a urinary tract antiseptic and antibacterial medication which is used in the prevention of recurrent urinary tract infections (UTIs).[4][3][1][8][12] It is not an antibiotic, and unlike antibiotics, has no risk of bacterial resistance.[9][13][8] Methenamine can reduce the risk of UTIs by 44 to 86% and has been found to be non-inferior to low-dose prophylactic antibiotics.[12][14][15] It is taken by mouth.[3][8] The drug is available both by prescription and at lower doses over the counter.[2][16][4][17] Besides for UTI prevention, methenamine is also available in a topical form to treat hyperhidrosis.[5][6][18]
Side effects of methenamine are generally minor and include upset stomach, nausea, and headache, among others.[3][19][7] Methenamine is a prodrug of formaldehyde in acidic urine.[3][8][9] Formaldehyde is a non-specific antiseptic and bactericide which works via denaturation of bacterial proteins and nucleic acids.[2][3][8][9] Conversion of methenamine into formaldehyde only occurs in acidic environments and hence its actions show selectivity for tissues like the bladder and stomach.[8][20] Chemically, methenamine is a simple cyclized hydrocarbon and is similar in structure to adamantane.[13][7][8]
Methenamine was discovered in 1859[7] and was first introduced for medical use as a urinary antiseptic in 1895.[21][22] It was formally approved for medical use in the United States in 1967.[23] Though it became a "forgotten drug" following the discovery of antibiotics in 1928, there has been a resurgence in interest in methenamine since 2010 owing to increasing rates of bacterial resistance with antibiotics.[2][8][7][14][24] Larger and higher-quality clinical trials of methenamine for UTI prevention have started to be published in the 2020s and it may soon be recommended by more medical guidelines.[2][14][19][25][15] Methenamine has been found to be more cost-effective than low-dose prophylactic antibiotics for preventing UTIs.[26]
- ^ a b "Methenamine Uses, Side Effects & Warnings". Drugs.com. 20 May 2024. Retrieved 11 October 2024.
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- ^ a b c d [1] fda.gov]
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LeeBhutaSimpson2012was invoked but never defined (see the help page). - ^ a b Sihra N, Goodman A, Zakri R, Sahai A, Malde S (December 2018). "Nonantibiotic prevention and management of recurrent urinary tract infection". Nat Rev Urol. 15 (12): 750–776. doi:10.1038/s41585-018-0106-x. PMID 30361493.
- ^ a b c Gu C, Ackerman AL (June 2023). "An oldie but a goodie: Methenamine as a nonantibiotic solution to the prevention of recurrent urinary tract infections". PLOS Pathog. 19 (6): e1011405. doi:10.1371/journal.ppat.1011405. PMC 10270343. PMID 37319137.
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HardingMossopHomer2022was invoked but never defined (see the help page). - ^ Brodin M (1998). The Over-The-Counter Drug Book. Pocket Books. p. 182. ISBN 978-0-671-01380-6. Retrieved 11 October 2024.
- ^ "Search Results for methenamine". DailyMed. 2 February 2016. Retrieved 11 October 2024.
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AriënsHanselaarHenderson1982was invoked but never defined (see the help page). - ^ Cite error: The named reference
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Sauberan2018was invoked but never defined (see the help page). - ^ Kale S, Somani BK (November 2023). "The resurgence of methenamine hippurate in the prevention of recurrent UTIs in women- a systematic review". Curr Opin Urol. 33 (6): 488–496. doi:10.1097/MOU.0000000000001108. PMID 37337660.
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KwokMcGoergeMayer-Coverdale2022was invoked but never defined (see the help page). - ^ King W, Homer T, Harding C, Mossop H, Chadwick T, Abouhajar A, et al. (April 2024). "Cost-effectiveness of methenamine hippurate compared with antibiotic prophylaxis for the management of recurrent urinary tract infections in secondary care: a multicentre, open-label, randomised, non-inferiority trial". BMJ Open. 14 (4): e074445. doi:10.1136/bmjopen-2023-074445. PMC 11086477. PMID 38684270.