Quinidine Metoprolol

The answer is b. (Hardmanr p 906.) Cimetidine reversibly inhibits cytochrome P450. This is important in phase I bio transformation reactions and inhibits the metabolism of such drugs as warfarin, phenytoin, propranolol, metoprolol, quinidine, and theophylline. None of the other enzymes are significantly affected. 

Colesevelam appears to be less likely to interfere with the absorption of concurrently administered drugs. No significant decreases in absorption were seen when colesevelam was coadministered with either digoxin, lovastatin, warfarin, metoprolol, quinidine, or valproic acid. Because of potential interactions, especially for drugs with a low therapeutic index, the administration of drugs that have not been directly studied in combination with colesevelam should be spaced accordingly, as described above tor cholestryamine and colestipol (7,15). 

Mepivacine, bupivacine, doxapram, quinine, quinidine, atenolol, metoprolol, propranolol, pethidine, methadone (5)-N-(3,5-dinitro-benzoyl) tyrosine Acetonitrile—ammo 208 nium acetate (60 40)... 

Codeine, dextromethorphan, haloperidol, thioridazine, perphenazine, nortriptyline, desipramine, fluoxetine, norfluoxetine, TCAs (hydroxylation), beta-blockers such as timolol and metoprolol, type 1C antiarrhythmics encainide, flecainide TCAs (desmethylation), triazolam, alprazolam, midazolam, carbamazepine, terfenadine, quinidine, lidocaine, erythromycin, cyclosporin... 

Inhibitors codeine, encainide, flecainide, fluoxetine, haloperidol, hydrocodone, 4-methoxy-amphetamine, metoprolol, mexiletine, oxycodone, paroxetine, propafenone, propoxyphene, risperidone, selegiline (deprenyl), thioridazine, most tricyclic antidepressants, timolol Fluoxetine, haloperidol, paroxetine, quinidine... 

Concurrent administration of propafenone with digoxin, warfarin, propranolol, or metoprolol increases the serum concentrations of the latter four drugs. Cimetidine slightly increases the propafenone serum concentrations. Additive pharmacological effects can occur when lidocaine, procainamide, and quinidine are combined with propafenone. 

Omeprazole can inhibit the metabolism of drugs metabolised mainly by the cytochrome P-450 enzyme subfamily 2C (diazepam, phenytoin), but not of those metabolished by subfamilies lA (caffeine, theophylline), 2D (metoprolol, propranolol), and 3A (ciclosporin, lidocaine (lignocaine), quinidine). Since relatively few drugs are metabolised mainly by 2C compared with 2D and 3A, the potential for omeprazole to interfere with the metabolism of other drugs appears to be limited, but the half lives of diazepam and phenytoin are prolonged as much as by cimetidine. 

Rifampin Coumarin anticoagulants, digitoxin, glucocorticoids, itraconazole, methadone, metoprolol, oral contraceptives, prednisone, propranolol, quinidine, saquinavir... 

Drug interactions Catecholamine-depleting drugs such as reserpine may have an additive effect in combination with betablockers. Drugs that inhibit CYP2D6 (quinidine, fluoxetine, paroxetine, and propafenone) increase metoprolol concentration. 

Otton SV, Crewe HK, Lennard MS, et al. Use of quinidine inhibition to define the role of the sparteine/debrisoquine cytochrome P450 in metoprolol oxidation by human liver microsomes. J Pharmacol Exp Ther 1988 247 242-247. 

Figure 6.17 The classification of 42 drugs in the (solubility-dose ratio, apparent permeability) plane of the QBCS. The intersection of the dashed lines drawn at the cutoff points form the region of the borderline drugs. Key 1 acetyl salicylic acid 2 atenolol 3 caffeine 4 carbamazepine 5 chlorpheniramine 6 chlorothiazide 7 cimetidine 8 clonidine 9 corticosterone 10 desipramine 11 dexamethasone 12 diazepam 13 digoxin 14 diltiazem 15 disopyramide 16 furosemide 17 gancidovir 18 glycine 19 grizeofulvin 20 hydrochlorothiazide 21 hydrocortisone 22 ibuprofen 23 indomethacine 24 ketoprofen 25 mannitol 26 metoprolol 27 naproxen 28 panadiplon 29 phenytoin 30 piroxicam 31 propanolol 32 quinidine 33 ranitidine 34 salicylic acid 35 saquinavir 36 scopolamine 37 sulfasalazine 38 sulpiride 39 testosterone 40 theophylline 41 verapamil HC1 42 zidovudine.

C19 2D6 Mephenytoin (4-hydroxy metabolite), Omeprazole Bufuralol, Dextromethorphan Metoprolol, Debrisquine, Codeine Tranylcypromine Quinidine Ticlopidine (but also inhibits 2D6), Nootkatone (but also inhibits 2A6)... 

Leemaim T, Dayer P, Meyer UA. Single-dose quinidine treatment inhibits metoprolol oxidation in extensive meta-bolizers. Em J CUn Pharmacol 1986 29(6) 739-41. 

Quinidine inhibits drug hydroxylation and can thus convert extensive hydroxylators to poor hydroxylators, as in the case of metoprolol (79). Inhibition of hydroxylation does not occur in poor hydroxylators. 

C Diltiazem. Quinidine can be used to maintain normal sinus rhythm (NSR) after cardioversion of atrial fibrillation. Metoprolol is commonly used to control ventricular rate before conversion to NSR. However, this patient has two contraindications (COPD and diabetes) for beta-blocker use. Unlike diltiazem, amlodipine and nimodipine do not block AV nodal conduction therefore, they would be ineffective at rate control. 

Clinically important, potentially hazardous interactions with acebutolol, amiodarone, aspirin, atenolol, atorvastatin, betaxolol, carbamazepine, carteolol, celiprolol, donidine, dabigatran, dantrolene, digoxin, dofetilide, epirubicin, eplerenone, erythromycin, esmolol, eucalyptus, everolimus, lovastatin, metoprolol, mistletoe, nadolol, oxprenolol, penbutolol, pindolol, propranolol, quinidine, ranolazine, sibutramine, simvastatin, timolol, trabectedin... 

Genetic polymorphisms in CYP450 isoenzymes are common. Among whites, 5-10% of the population carries a mutation of CYP450 2D6, causing them to be slow metabolizers of debriso-quine, mephenytoin, quinidine, metoprolol and dextromethorphan standard doses are more likely to be associated with adverse events as a consequence, especially when a second substrate drag is interacting. 

Albumin, bovine serum X 4 4 X X Mannitol, Metoprolol, Propranolol, Inogatran, Digoxin, Quinidine, Doxorubicin Neuhoff et al. 2005... 

Genotypic variations in hydroxylation (fast and slow) substrates include ] codeine, debrisoquin, and metoprolol inhibited by haloperidol and quinidine I not inducible. 

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... 

Simultaneous disopyramide, lidocaine, metoprolol, nadolol, procainamide, quinidine, timolol, verapamil... 

---