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Uro-Phosphate (methenamine / sodium biphosphate) Disease Interactions

There are 2 disease interactions with Uro-Phosphate (methenamine / sodium biphosphate):


Methenamine (Includes Uro-Phosphate) ↔ Crystalluria

Severe Potential Hazard, High plausibility

Applies to: Renal Dysfunction, Dehydration

The use of methenamine salts (i.e. methenamine hippurate or mandelate), but not the base, is contraindicated in patients with severe renal impairment or dehydration. Methenamine is excreted by the kidney and concentrated in the urine. In patients with low urinary output, the salts can precipitate and cause crystalluria.


  1. "Product Information. Mandelamine (methenamine)." Parke-Davis, Morris Plains, NJ.
  2. Gleckman R, Alvarez S, Joubert D, Matthews S "Drug therapy reviews: methenamine mandelate and methenamine hippurate." Am J Hosp Pharm 36 (1979): 1509-12
  3. Klinge E, Mannisto P, Mantyla R, Lamminsivu U, Ottoila P "Pharmacokinetics of methenamine in healthy volunteers." J Antimicrob Chemother 9 (1982): 209-16
View all 6 references

Methenamine (Includes Uro-Phosphate) ↔ Liver Disease

Severe Potential Hazard, High plausibility

Applies to: Liver Disease

The use of methenamine and its salts (i.e. methenamine hippurate or mandelate) is contraindicated in patients with severe hepatic impairment. Methenamine is hydrolyzed to ammonia and formaldehyde in the urine under acidic conditions. Patients with liver disease may already have elevated ammonia levels, which can cause or exacerbate hepatic encephalopathy. Methenamine hippurate has also been associated with isolated cases of transient elevations in serum transaminases. The manufacturer recommends periodic liver function tests during therapy, particularly in patients with preexisting liver dysfunction.


  1. Strom J, Jun H "Kinetics of hydrolysis of methenamine." Pharm Bull 23 (1975): 651
  2. "Product Information. Mandelamine (methenamine)." Parke-Davis, Morris Plains, NJ.
  3. Gleckman R, Alvarez S, Joubert D, Matthews S "Drug therapy reviews: methenamine mandelate and methenamine hippurate." Am J Hosp Pharm 36 (1979): 1509-12
View all 5 references

Uro-Phosphate (methenamine / sodium biphosphate) drug Interactions

There are 719 drug interactions with Uro-Phosphate (methenamine / sodium biphosphate)

Uro-Phosphate (methenamine / sodium biphosphate) alcohol/food Interactions

There is 1 alcohol/food interaction with Uro-Phosphate (methenamine / sodium biphosphate)

Drug Interaction Classification

The classifications below are a general guideline only. It is difficult to determine the relevance of a particular drug interaction to any individual given the large number of variables.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No information available.

Do not stop taking any medications without consulting your healthcare provider.

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