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Methenamine Disease Interactions

There are 3 disease interactions with methenamine.

Major

Methenamine (applies to methenamine) crystalluria

Major Potential Hazard, High plausibility. Applicable conditions: 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.

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Major

Methenamine (applies to methenamine) gout

Major Potential Hazard, Moderate plausibility.

Methenamine mandelate (salts), should be avoided in patients with gout as it may precipitate urate crystals in their urine. A similar situation may arise in patients with a predisposition to the formation of uric acid stones.

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Major

Methenamine (applies to methenamine) liver disease

Major Potential Hazard, High plausibility.

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.

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Methenamine drug interactions

There are 50 drug interactions with methenamine.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
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 interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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