Triamterene Amantadine

Drugs that may affect triamterene include ACE inhibitors, cimetidine, and indomethacin. Drugs that may be affected by triamterene include amantadine and potassium preparations. Triamterene will interfere with the fluorescent measurement of quinidine serum levels. 

Drugs that may affect amantadine include anticholinergic drugs, triamterene and thiazide diuretics, quinidine, quinine, and trimethoprim/sulfamethoxazole. 

Several drug interactions involving amantadine and rimantadine are clinically significant. Anticholinergic drugs can potentiate the toxicity of amantadine. Thiazide-triamterene, trimethoprim-sulfamethoxazole, quinine, and quinidine increase plasma amantadine levels. Cimetidine decreases rimantadine clearance, and aspirin and acetaminophen decrease rimantadine plasma levels. 

A patient has been described who developed amantadine toxicity when given hydrochlorothiazide-triamterene. 

Amantadine toxicity (ataxia, agitation, hallucinations) developed in a patient within a week of starting to take two tablets of Dyazide (hydrochlorothiazide with triamterene) daily. The symptoms rapidly disappeared when all the drugs were withdrawn. In a later study this patient showed about a 50% rise in amantadine plasma levels (from 156 to 243 nanograms/mL) after taking the diuretic for 7 days. ... 

Drugs that make the urine alkaline (e.g. sodium bicarbonate, carbonic anhydrase inhibitors) will reduce the elimination of memantine. Memantine should be used with caution with other NMDA antagonists, such as amantadine, ketamine and dextromethorphan, or concurrent use should be avoided, because of the theoretical increased risk of adverse effects. Memantine is predicted to interact with other drugs eliminated by the same renal secretion mechanism, but no important interaction was seen with glibenclamide, hydrochlorothiazide, metformin or triamterene. 

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