Triamterene Cimetidine

Drugs eliminated via renal mechanisms Coadministration of drugs that use the same renal cationic system, including hydrochlorothiazide (HCTZ), triamterene, cimetidine, ranitidine, quinidine, and nicotine, potentially could result in altered plasma levels of both agents. 

There is a risk of acute renal failure when iodi-nated contrast material that is used for radiological studies is administered with metformin. Metformin therapy is stopped for 48 hours before and after radiological studies using iodinated material. Alcohol, amiloride, digoxin, morphine, procainamide, quini-dine, quinine ranitidine, triamterene, trimethoprim, vancomycin, cimetidine, and furosemide all increase the risk of hypoglycemia. There is an increased risk of lactic acidosis when metformin is administered with the glucocorticoids. 

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. 

T Pancreatic insulin release Metformin Peripheral insulin sensitivity hepatic glucose output/production i intestinal glucose absorption Dose Ist-line (naive pts), 1.25/250 mg PO daily-bid 2nd-line, 2.5/500 mg or 5/500 mg bid (max 20/2000 mg) take w/ meals, slowly T dose hold before 48 h after ionic contrast media Caution [C, -] Contra SCr >1.4 mg/dL in females or >1.5 mg/dL in males hypoxemic conditions (sepsis, recent MI) alcoholism metabolic acidosis liver Dz Disp Tabs SE HA, hypoglycemia, lactic acidosis, anorexia, N/V, rash Additional Interactions T Effects W/ amiloride, ciprofloxacin cimetidine, digoxin, miconazole, morphine, nifedipine, procainamide, quinidine, quinine, ranitidine, triamterene,... 

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. 

Drugs that can precipitate lactic acidosis in patients taking metformin include ACE inhibitors, thiazide diuretics, NSAIDs, and drugs such as furosemide, nifedipine, cimetidine, amiloride, triamterene, trimethoprim, and digoxin, which are all secreted in the renal tubules, compete with metformin, and can contribute to increased plasma metformin concentrations (76). 

Clinically important, potentially hazardous interactions with allopurinol, amiloride, cimetidine, corticosteroids, cyclosporine, insulin, lithium, potassium sparing diuretics, potassium supplements, procainamide, spironolactone, triamterene... 

A chronic-dosing pharmacokinetic study has been carried out in six healthy subjects to examine the potential for cimetidine to reduce the renal and hepatic clearance of triamterene.66 Blood and urine samples were collected frequently for 24 hours after dosing with triamterene alone (100 mg/day) for 4 days and concomitant cimetidine (400 mg twice daily) for an additional 4 days. Cimetidine reduced the clearance of triamterene by hydroxylation by 32%, renal clearance of triamterene by 28%, with no change in its protein binding. The renal clearance of the active sulfate conjugate was not altered by cimetidine. There was a reduced recovery of triamterene and its metabolites in urine after cimetidine,... 

Also analyzed acebutolol, acepromazine, acetaminophen, acetazolamide, acetophenazine, albuterol, amitriptyline, amobarbital, amoxapine, antipsrrine, atenolol, atropine, azata-dine, baclofen, benzocaine, bromocriptine, brompheniramine, brotizolam, bupivacaine, buspirone, butabarbital, butalbital, caffeine, carbamazepine, cetirizine, chlorqyclizine, chlordiazepoxide, chlormezanone, chloroquine, chlorpheniramine, chlorpromazine, chlorpropamide, chlorprothixene, chlorthalidone, chlorzoxazone, cimetidine, cisapride, clomipramine, clonazepam, clonidine, clozapine, cocaine, codeine, colchicine, qyclizine, (yclo-benzaprine, dantrolene, desipramine, diazepam, diclofenac, diflunisal, diltiazem, diphenhydramine, diphenidol, dipheno late, dipyridamole, disopyramide, dobutamine, doxapram, doxepin, droperidol, encainide, ethidium bromide, ethopropazine, fenoprofen, fentanyl, flavoxate, fluoxetine, fluphenazine, flurazepam, flurbiprofen, fluvoxamine, fii-rosemide, glutethimide, glyburide, guaifenesin, haloperidol, homatropine, hydralazine, hydrochlorothiazide, hydrocodone, hydromorphone, hydro g chloroquine, hydroxyzine, ibuprofen, imipramine, indomethacin, ketoconazole, ketoprofen, ketorolac, labetalol, le-vorphanol, lidocaine, loratadine, lorazepam, lovastatin, loxapine, mazindol, mefenamic acid, meperidine, mephenytoin, mepivacaine, mesoridazine, metaproterenol, methadone, methdilazine, methocarbamol, methotrexate, methotrimeprazine, methoxamine, methyl-dopa, methylphenidate, metoclopramide, metolazone, metoprolol, metronidazole, midazolam, moclobemide, morphine, nadolol, nalbuphine, naloxone, naphazoline, naproxen, nifedipine, nizatidine, norepinephrine, nortriptyline, oxazepam, oxycodone, oxymetazo-line, paroxetine, pemoline, pentazocine, pentobarbital, pentoxifylline, perphenazine, pheniramine, phenobarbital, phenol, phenolphthalein, phentolamine, phenylbutazone, phenyltoloxamine, phenytoin, pimozide, pindolol, piroxicam, pramoxine, prazepam, prazosin, probenecid, procainamide, procaine, prochlorperazine, procyclidine, promazine, promethazine, propafenone, propantheline, propiomazine, propofol, propranolol, protriptyline, quazepam, quinidine, quinine, racemethorphan, ranitidine, remoxipride, risperidone, salicylic acid, scopolamine, secobarbital, sertraline, sotalol, spironolactone, sulfinpyrazone, sulindac, temazepam, terbutaline, terfenadine, tetracaine, theophylline, thiethyl-perazine, thiopental, thioridazine, thiothixene, timolol, tocainide, tolbutamide, tolmetin, trazodone, triamterene, triazolam, trifluoperazine, triflupromazine, trimeprazine, trimethoprim, trimipramine, verapamil, warfarin, xylometazoline, yohimbine, zopiclone... 

Noninterfering amitriptyline, amphetamine, atropine, benzoylecgonine, benztropine, caffeine, carbamazepine, carisoprodol, chlorpheniramine, chlorpromazine, chlorprothixene, cimetidine, cocaine, codeine, dextromethorphan, diazepam, diphenhydramine, diphenox-ilate, disopyramide, doxepin, dojylamine, emetine, erythromycin, flurazepam, gluteth-imide, hydrocortisone, hydromorphone, hydroxyzine, imipramine, lidocaine, loxapine, meperidine, meprobamate, methadone, methamphetamine, methapyrilene, methaqualone, methocarbamol, methylphenidate, nicotine, nordiazepam, nortriptyline, orphenadrine, papaverine, pentazocine, phenacetin, phencyclidine, phenmetrazine, phenolphthalein, phentermine, phenylpropanolamine, phenytoin, prazepam, procaineimide, procaine, propoxyphene, propranolol, protriptyline, pseudoephediine, pyrilamine, quinine, salicylam-ide, spironolactone, strychnine, terpin hydrate, thioridazine, thiothixene, triamterene, trifluoperazine, triflupromeizine, trihexyphenidyl, trimeprazine, trimethobenzamide, trimethoprim, tripeleimamine... 

Memantine is predicted to interact with other drugs that use the same renal cationic transport system leading to increased levels of memantine and/or the other drug. The manufacturer lists cimetidine, ranitidine, hydrochlorothiazide, metformin, procainamide, qninidine, qninine and triamterene as possible examples. However, in an interaction study, the concurrent use of memantine and hydrochlorothiazide/triamterene did not result in any change in the steady-state AUC of memantine or triamterene, and the AUC of hydrochlorothiazide showed a modest reduction of about 20%. This degree of change is unlikely to be clinically relevant. Therefore, whether any clinically important interactions occur via this mechanism remains to be established. 

Muirhead MR, Somoni AA, Rolan PE, Bochner F, Effect of cimetidine on renal and hepatic drugs elimination studies with triamterene, Clin Pharmacol Ther (1986) 40, 400-7,... 

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