Name: Urasal Granules
Hypersensitivity to methenamine or tartrazine (FD&C Yellow No. 5)
Renal or severe hepatic insufficiency
Concurrent sulfonamides or acetazolamide may form insoluble precipitate in urine
Large doses may cause bladder irritation, urinary frequency, albuminuria, hematuria
Maintain acidic pH of urine, especially when treating urea-splitting organisms, e.g. Proteus, Pseudomonas
Monitor LFTs, especially in patients with history of liver impairment
Safe use not established during pregnancy, especially 1st and 2nd trimester
May precipitate uric acid stones in patients with gout
Pregnancy & Lactation
Pregnancy Category: C
Lactation: excreted in breast milk; no adverse effects documented
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Half-Life: 4.3 hr
Onset: 30 min
Peak Plasma Time: 3-8 hr
Vd: 0.56 L/kg
Excretion: urine; methenamine 90% excreted w/in 24 hr; mandelic or hippuric acid may accumulate in pts. with severe renal impairment
Mechanism of Action
Methenamine hydrolyzes to ammonia and formaldehyde (nonspecific antibacterial) in acidic urine
Mandelic acid or hippuric acid acidify the urine