Quinidine Beta blockers

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... 

Drugs that may affect disopyramide include antiarrhythmics, beta blockers, cisapride, clarithromycin, erythromycin, fluoroquinolones, hydantoins, quinidine, thioridazine, rifampin, verapamil, and ziprasidone. Drugs that may be affected by disopyramide include quinidine, anticoagulants, and digoxin. 

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... 

Drugs that may affect barbiturates include alcohol, charcoal, chloramphenicol, MAO inhibitors, rifampin, and valproic acid. Drugs that may be affected by barbiturates include acetaminophen, anticoagulants, beta blockers, carbamazepine, chloramphenicol, clonazepam, oral contraceptives, corticosteroids, digitoxin, doxorubicin, doxycycline, felodipine, fenoprofen, griseofulvin, hydantoins, methoxyflurane, metronidazole, narcotics, phenmetrazine, phenylbutazone, quinidine, theophylline, and verapamil. 

Rifampin is known to induce the hepatic microsomal enzymes that metabolize various drugs such as acetaminophen, oral anticoagulants, barbiturates, benzodiazepines, beta blockers, chloramphenicol, clofibrate, oral contraceptives, corticosteroids, cyclosporine, disopyramide, estrogens, hydantoins, mexiletine, quinidine, sulfones, sulfonylureas, theophyllines, tocainide, verapamil, digoxin, enalapril, morphine, nifedipine, ondansetron, progestins, protease inhibitors, buspirone, delavirdine, doxycycline, fluoroquinolones, losartan, macrolides, sulfonylureas, tacrolimus, thyroid hormones, TCAs, zolpidem, zidovudine, and ketoconazole. The therapeutic effects of these drugs may be decreased. 

Drugs that may interact with rifabutin include the following Anticoagulants, azole antifungal agents, benzodiazepines, beta blockers, buspirone, corticosteroids, cyclosporine, delavirdine, doxycycline, hydantoins, indinavir, rifamycins, losartan, macrolide antibiotics, methadone, morphine, nelfinavir, quinine, quinidine, theophylline, aminophylline, tricyclic antidepressants, and zolpidem. 

Drugs that may affect ophthalmic beta blockers include catecholamine-depleting drugs, digitalis, and quinidine. 

Drug Interactions Other antihypertensive agents Carbamazepine (vasodilators, ACE inhibitors, Rifampin diuretics, and beta-blockers) Phenobarbital Digoxin Cyclosporine Disopyramide Theophylline Flecainide Inhalation anesthetics Quinidine Neuromuscular blocking agents Cimetidine Lithium ... 

Diastereomeric complexes can also be formed by ion-pairing of an enantiomer with a chiral counterion. In order to form this diastereomeric complex, it has been postulated that at least three interaction points between the ion pair are required [250]. Nearly all of these form weak complexes in aqueous mobile phases. Consequently, the chromatographic methods that have been developed have been either silica or diol columns with low-polarity mobile phases. Enantiomeric amines, such as the beta-blockers, have been optically resolved when (-l-)-lO-camphorsulfonic acid was used as the chiral counterion [251]. Enantiomers of norephedrine, ephedrine, pseudoephedrine, and phenyramidol have all been resolved from their respective enantiomers with n-dibutyltartrate [252]. Enantiomers of naproxen, a chiral carboxylic acid, are resolved from each other by either using quinidine or quinine in the mobile phase [253]. In these studies, silica... 

Quinidine overdose should be treated with symptomatic and supportive therapy. Quinidine should be used with caution when coadministering with calcium channel blockers, diuretics, beta-blockers, antibacterials, antifungals, and antiarrhythmics.97... 

Patients should be advised to rest and to avoid extreme heat. They should be warned that symptoms may be aggravated by illness, stress, malnutrition, pain, or surgery. Various drugs have been shown to worsen symptoms of myasthenia gravis. These include the aminoglycoside antibiotics such as tobramycin, gentamicin, and neomycin tetracyclines such as doxycycline and minocycline class 1 antiarrhythmics such as lidocaine, quinidine, and procainamide magnesium in calcium and multivitamin supplements beta-blockers such as timolol and propranolol calcium channel blockers such as verapamil and penicillamine. 

The membrane-stabilizing activity of beta-blockers can play a major role in toxicity. Of 208 deaths in subjects who had taken beta-blockers, 206 occurred with drugs that have membrane-stabilizing activity. This quinidine-like effect can be reversed by sodium bicarbonate, which is also used to counteract the cardiotoxic effects of cyclic antidepressants, which also have membrane-stabilizing activity. 

The negative inotropic effects of class I antidysrhythmic agents, such as disopyramide, procainamide, quinidine, and tocainide can be accentuated by beta-blockers this is most pronounced in patients with pre-existing myocardial disease and can result in left ventricular failure or even asystole (413). Digoxin can obviate the negative inotropic effect of beta-blockers in patients with poor left ventricular function. 

Mibefradil inhibits CYP3A4 (2). Other drugs that are metabolized by this pathway accumulate as a result. Drugs that were commonly affected included amiodarone, astemizole, ciclosporin, cisapride, erythromycin, imi-pramine, lovastatin, propafenone, quinidine, simvastatin (9), tacrohmus (10), tamoxifen, terfenadine, thioridazine, and drugs that impair sinoatrial node function (for example beta-blockers) (6). 

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 alcohol, amiodarone, beta-blockers, cimetidine, donidine, digoxin, diltiazem, disopyramide, ephedrine, epinephrine, ergot alkaloids, guanethidine, halothane, isoprenaline, lidocaine, noradrenaline, NSAIDs, phenylephrine, quinidine, reserpine, verapamil... 

Common drug causes of lichenoid eruptions are antimalarials, beta-blockers, chlorpropamide, furosemide, gold, methyldopa, phenothiazines, quinidine, thiazides, and tolazamide. 

The following drugs have been commonly associated with inducing, aggravating or unmasking SLE beta-blockers, carbamazepine, chlorpromazine, estrogens, griseofulvin, hydralazine, isoniazid (INH), lithium, methyldopa, minoxidil, oral contraceptives, penicillamine, phenytoin (diphenylhydantoin), procainamide, propylthiouracil, quinidine, and testosterone. 

Drugs that can precipitate psoriasis are, among others, beta-blockers and lithium. Drugs that are reported to aggravate psoriasis are antimalarials, beta-blockers, lithium, NSAIDs, quinidine, and photosensitizing drugs. The effect and extent of these drug-induced psoriatic eruptions are dose-dependent. 

Answer D. An increase in AV conduction is characteristic of quinidine, which exerts quite marked blocking actions on muscarinic receptors in the heart. Thus, an atrial rate, formerly transmitted to the ventricles in a 2 1 ratio, may be transmitted in a 1 1 ratio after quinidine. This effect of quinidine can be offset by the prior administration of an antiar-rhythmic drug that decreases AV nodal conduction, such as digoxin or verapamil. All of the drugs listed (except quinidine) slow AV nodal conduction, but adenosine and esmolol (a beta blocker) are very short-acting agents used IV only. 

Which beta-blockers exhibit quinidine-like activity ... 

Answer E. Increased sympathetic activity is a major problem in hyperthyroidism and is best managed by use of beta blockers, which can offset cardiac stimulatory effects. Propranolol has an ancillary action in thyrotoxicosis in that it prevents conversion of T to Tj via its inhibition of 5 deiodinase. Amiodarone causes difficult-to-predict adverse effects on thyroid function and would not be appropriate in a patient with hyperthyroidism. Quinidine is a class lA antiarrhythmic, which is associated with tachycardia as a side effect. Digoxin is not ideal because of its complex actions on the heart, which include both inhibition and stimulation. 

Actions of direct-acting catecholamines are sharply increased. Reduces effectiveness of mixed or indirect sympathomimetics. Causes severe hypertension with MAO inhibitors. Causes severe bradycardia, heart block or failure with digitalis, quinidine, or beta blockers. Potentiates actions of antihypertensive agents or CNS-depressants. 

Propranolol and other beta blockers Encainide and flecainide Quinidine, procainamide, and disopyramide Tricyclic antidepressants... 

Beta blockers (mainly propranolol) Encalnide and flecalnide Quinidine, procainamide, and disopyramide Propoxyphene Tricyclic antidepressants Others Barbiturates... 

Class Ib antiarrhythmics are usually associated with shortening of the QT interval, and could therefore be expected to reduce the QT prolongation and risk of torsade de pointes seen with amiodarone alone (for examples of this effect of mexiletine see also Mexiletine + Beta blockers, p.268 and Mexiletine + Quinidine , p.269. However, note that the UK manufacturer of mexiletine says that it may exacerbate arrhythmias [as all antiarrhythmics may], but also that it may be used concurrently with amiodarone. The two drugs have been used together successfully. ... 

A man taking propranolol 40 mg four times daily developed orthostatic hypotension, with symptoms of dizziness and faintness on standing, when he took quinidine 200 mg four times daily. This resolved when quinidine was withdrawn. The same authors subsequently briefly reported another two cases of orthostatic hypotension when quinidine was given with unnamed beta blockers. ... 

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