Dextromethorphan Amiodarone

Drugs that may affect amiodarone include hydantoins, cholestyramine, fluoroquinolones, rifamycins, ritonavir, and cimetidine. Drugs that may be affected by amiodarone include anticoagulants, beta-blockers, calcium channel blockers, cyclosporine, dextromethorphan, digoxin, disopyramide, fentanyl, flecainide, hydantoins, lidocaine, methotrexate, procainamide, quinidine, and theophylline. Drug/Lab test interactions Amiodarone alters the results of thyroid function tests, causing an increase in serum T4 and serum reverse T3 levels and a decline in... 

Dextromethorphan (Mediquell, Benylin DM, PediaCare 1, Delsym, Others) [OTC] [Antitussive] Uses Control nonproductive cough Action Suppresses medullary cough center Dose Adults. 10-30 mg PO q4h PRN (max 120 mg/24 h) Peds. 2-6 y 2.5-7.5 mg q4-8h (max 30 mg/24 h) 7-12 y 5-10 mg q4-8h (max 60 mg/24/h) Caution [C, /-] Not for persistent or chronic cough Contra < 2 y. Disp Caps, lozenges, syrup, Liq SE GI disturbances Interactions T Effects W/ amiodarone, fluoxetine, quinidine, terbinafme T risk of serotonin synd Wf sibutramine, MAOIs T CNS depression Wf antihistamines, antidepressants, sedative, opioids, EtOH EMS Will not affect cough caused by asthma,... 

Reported bioanalytical applications that use SS-LLE products include both tlie cartridge (tube) format and the microplate format. Some of these applications include the determination of mexiletine [44], amiodarone [45] and other antiarrhythmic drugs [46], proxyphylline [47], 16(3-hydroxystanozolol [48], dextromethorphan [49], and simvastatin [50] from biological fluids. Microplate applications for SS-LLE include a crude purification of crude combinatorial library samples [51], carboxylic acid-based matrix metallo-protease inhibitors [52], and a p3-adrenergic receptor agonist [53]. 

Acetaminophen, aldrin, alfentanil, amiodarone, aminopyrine, amitriptyline, amprenavir, androstenedione,antipyrine, astemizole, benzphetamine, budesonide, carbamazepine, celecoxib, chlorpromazine, chlorzoxazone, cisapride, clarithromycin, clozapine, cocaine, codeine, cortisol, cyclophosphamide,cyclosporin, dapsone, delavirdine, dextromethorphan, digitoxin, diltiazem, diazepam, erythromycin, 17j3-estradiol, ethinylestradiol, etoposide, felbamate, fentanyl, flutamide, hydroxyarginine, ifosphamide, imipramine, indinavir, ketoconazole, lansoprazole, loratidine, losartan, lovastatin, (iS)"mephen3d in, methadone, mianserin, miconazole, mifepristone, nelfinavir, nevirapine, nicardipine, nifedipine, odansetron, omeprazole, orphenadrine, proguanil, propafenone, quinidine, quinine, rapamycin, retinoic acid, ritonavir, saquinavir, selegiline, serindole, sufentanil, sulfinpyrazone, tacrolimus, tamoxifen, tamsulosin, taxol, teniposide, terfenadine, tetrahydrocannabinol, theophylline, toremifene, triazolam, trimethadone, trimethoprim, troleandomycin, verapamil, warfarin, zatosetron, Zolpidem, zonisamide... 

CYP2D6 5 25 S-metoprolol Carvedilol Dextromethorphan Nortriptyline Propanolol Odansetron Chlorpromazine Codeine Flecainide Fluoxetine Haloperidol Amiodarone Fluoxetine Methadone Celecoxib Doxorubicin ... 

Other authors have reported this interaction, and suggest reducing the flecainide dosage by between one-third to one-half when amiodarone is added. " Another study found that amiodarone raised steady-state flecainide plasma levels by 37% in extensive metabolisers, and 55% in poor me-tabolisers of dextromethorphan (a probe drug for CYP2D6 activity). In a later report of this study the authors concluded that these differences were nof clinically imporfanf, and that CYP2D6 phenotype does not affect the extent of the flecainide-amiodarone interaction. An isolated report describes torsade de pointes in a patient on amiodarone when given flecainide. ... 

Amiodarone can reduce the clearance of dextromethorphan. Clinical evidence... 

A study in 8 patients with cardiac arrhythmias found that amiodarone (1 g daily for 10 days followed by 200 to 400 mg daily for a mean duration of 76 days) changed their excretion of dextromethorphan 40 mg and its metabolite. The amount of unchanged dextromethorphan in the urine rose by nearly 150%, whereas the amount of its metabolite (dextrorphan) fell by about 25%. ... 

In vitro studies using liver microsomes have shown that amiodarone inhibits the metabolism (O-demethylation) of dextromethorphan by inhibiting the cytoehrome P450 isoenzyme CYKD6 within the liver. Thus the dextromethorphan is eleared more slowly. 

Information seems to be limited to this study. The elinieal implieations are that amiodarone may interfere with the results of phenotyping if dextromethorphan is used to determine CYP2D6 aetivity, and that dextromethorphan toxieity (exeitation, eonfusion) may possibly develop in patients taking amiodarone. Be alert for any signs of toxieity if both are used. As yet, too little is known about this interaetion to say by how mueh the dextromethorphan dosage should be reduced. Remember that dextromethorphan oeeurs in a eonsiderable number of proprietary eough preparations. 

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