烏洛托品 / 孟德立酸烏洛托品
烏洛托品（又稱六亞甲基四胺）是一種泌尿道抗菌劑，主要用於預防和長期管理反覆發作的下泌尿道感染。 **臨床提示：** 它不是傳統的抗生素，而是一種前驅藥。因為它的療效完全依賴於在酸性環境中轉化為甲醛，所以它在鹼性尿液中或對全身性感染無效。細菌對甲醛不會自然產生抗藥性，這使其非常適合用於慢性感染管理。
作用機制: Methenamine is a prodrug that is hydrolyzed in an acidic environment (urine pH < 5.5) → **ammonia** and **formaldehyde**. Formaldehyde acts as a non-specific bactericidal agent that denatures bacterial proteins and nucleic acids. It requires sufficient time in the bladder to convert and exert its effects.
給藥途徑
禁忌症
- Renal insufficiency (can exacerbate systemic acidosis)
- Severe hepatic disease (due to ammonia production)
- Severe dehydration
- Metabolic acidosis
- Concurrent use of sulfonamides
不良反應
- Gastrointestinal upset (nausea, vomiting, diarrhea)
- Dysuria or pollakiuria (due to formaldehyde irritation)
- Hematuria
- Crystalluria (at high doses)
藥物相互作用
- Sulfonamides · Formaldehyde forms an insoluble precipitate with sulfonamides, increasing the risk of crystalluria and renal damage. · major
- Urinary alkalinizers (e.g., Potassium citrate, Sodium bicarbonate) · Raises urine pH, preventing the conversion of methenamine to its active form (formaldehyde). · major
- Thiazide diuretics · May increase urine pH and promote diuresis, reducing formaldehyde concentration and contact time in the bladder. · moderate
監測
- Urine pH (target < 5.5)
- Urinalysis (monitor for crystalluria or hematuria)
- Renal function
- Hepatic function (in prolonged use)
過量
Overdosage primarily manifests as severe gastrointestinal distress (vomiting, diarrhea) and urinary tract irritation (hematuria, dysuria, crystalluria). Treatment is supportive and symptomatic. Alkalinizing the urine can halt further conversion to formaldehyde and reduce urinary irritation.
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