Cimetidine Beta blockers

Drugs that may affect lidocaine include beta-blockers, cimetidine, procainamide, tocainide, and succinylcholine. 

Drugs that affect all phosphodiesterase type 5 inhibitors include the following alcohol, amlodipine, angiotensin II receptor blockers, antacids, bendroflumethiazide, beta blockers, cimetidine, diuretics, enalaphl, metoprolol, nifedipine, rifampin, tacrolimus. 

BETA-BLOCKERS CIMETIDINE, RANITIDINE t plasma concentrations and effects of labetalol, metoprolol and propranolol t systemic effects of timolol eye drops Cimetidine inhibits CYP2D6, which metabolizes these beta-blockers, and inhibits CYP1A2- and CYP2E1 -mediated metabolism of propanolol. Ranitidine is a weaker inhibitor of CYP2D6 Monitor BP at least weekly until stable... 

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... 

The effects of warfarin may increase when administered with acetaminophen, NSAIDs, beta blockers, disulfiram, isoniazid, chloral hydrate, loop diuretics, aminoglycosides, cimetidine, tetracyclines, and cephalosporins. Oral contraceptives, ascorbic acid, barbiturates, diuretics, and vitamin K decrease the effects of warfarin. Because die effects of warfarin are influenced by many drugp, die patient must notify die nurse or die primary healdi care provider when taking a new drug or discontinuing... 

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 beta blockers include aluminum salts, barbiturates, calcium salts, cholestyramine, cimetidine, colestipol, diphenhydramine, hydroxychloroquine, NSAIDs, penicillins (ampicillin), rifampin, salicylates, SSRIs, sulfinpyrazole, calcium blockers, oral contraceptives, flecainide, haloperidol, hydralazine, loop diuretics,... 

Agents that may increase theophylline levels include allopurinol, beta blockers (nonselective), calcium channel blockers, cimetidine, oral contraceptives, corticosteroids, disulfiram, ephedrine, influenza virus vaccine, interferon, macrolides, mexiletine, quinolones, thiabendazole, thyroid hormones, carbamazepine, isoniazid, and loop diuretics. 

Drugs that may affect antihistamines include aluminum/magnesium-containing acids, cimetidine, erythromycin, ketoconazole, MAO inhibitors, and rifamycins (eg, rifampin). Drugs that may be affected by antihistamines include alcohol and CNS depressants, beta-blockers, MAO inhibitors, metyrapone, nefazodone, selective serotonin reuptake inhibitors (SSRIs), and venlafaxine. 

Drugs that may affect hydroxychloroquine include cimetidine. Drugs that may be affected by hydroxychloroquine include beta blockers, cyclosporine, digoxin, magnesium salts, and mefloquine. 

As it inhibits microsomal cytochrome P450 cimetidine has a high potential for drug interactions not shared by the other H2 receptor antagonists. The oxidative metabolism of agents such as anticoagulants, most antiepileptics, some beta-blockers, warfarin, theophylline and many hypnotics, neuroleptics and antidepressants may be reduced, leading to increased effects. 

Beta-blockers interact with a large number of other medications. The combination of beta-blockers with calcium antagonists should be avoided, given the risk for hypotension and cardiac arrhythmias. Cimetidine, hydralazine, and alcohol all increase blood levels of beta-blockers, whereas rifampicin decreases their concentrations. Beta-blockers may increase blood levels of phenothiazines and other neuroleptics, clonidine, phen-ytoin, anesthetics, lidocaine, epinephrine, monoamine oxidase inhibitors and other antidepressants, benzodiazepines, and thyroxine. Beta-blockers decrease the effects of insulin and oral hypoglycemic agents. Smoking, oral contraceptives, carbamazepine, and nonsteroidal anti-inflammatory analgesics decrease the effects of beta-blockers (Coffey, 1990). 

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 ... 

Sax MJ. Analysis of possible drug interactions between cimetidine (and ranitidine) and beta-blockers. Adv Ther 1988 5 210. 

Answer E. Cimetidine is an inhibitor of the hepatic cytochrome P450 isoform that metabolizes phenytoin, consequently decreases its clearance, and thus increases its elimination half-life. The hepatic metabolism of many other drugs can be inhibited by cimeti-dine, possibly necessitating dose reductions to avoid toxicity, including beta blockers, iso-niazid, procainamide, metronidazole, tricyclic antidepressants, and warfarin. 

Cimetidine 300mg po tid 800 mg po bid 60% 100% 75% 25% Multiple drug-drug interactions beta blockers, sulfonylurea, theophylline, warfarin, etc... 

Barbiturates and heavy smoking induce nortriptyline metabolism and decrease therapeutic efficacy phenothiazines and haloperidol decrease its metabolism, decreasing therapeutic efficacy methylphenidate, cimetidine, oral contraceptives, propoxyphene, and beta-blockers may inhibit nortriptyline metabolism, increasing plasma levels and toxicity (see Tables 5 through 7). 

PO/IV. Well absorbed, 80% metabolized in first pass. 90% protein bound. Metabolites are active. Half-life is 5 hrs but may be up to 20 hrs in patients with cirrhosis. Patient on IV blockers or digitalis. A-V node block, sick sinus syndrome, cardiogenic shock, heart failure, hypotension. Beta blockers or digitalis Increases likelihood of bradycardia or A-V blockade. Quinicfine or prazosin Increases hypotension. Digoxin levels are increased. Cimetidine reduces verapamil clearance. Calcium supplements may inhibit actions of verapamil. Depolarization (leading to contraction) of vascular smooth muscle is dependent on calcium entry. Vasodilation is induced by calcium entry blockers because they inhibit calcium influx. 

PO. 50% bioavailability after oral dose. 75% protein bound, half-life=3 hrs, metabolites are active. Reduce dose in patients with renal dysfunction. AV node block, sick sinus syndrome, hypotension, pulmonary congestion. Beta-blockers and digoxin increase A-V conduction time. Diltiazem increases propranolol levels. Cimetidine and drugs metabolized by P-450 increase diltiazem levels. ... 

A PO/sublingual. Rapid, complete absorption of sublingual dose. 98% protein bound. Metabolites are inactive, half-life = 3 hrs. Hypotension. Beta blockers increase risk of severe hypotension, heart failure, and angina. Nifedipine increases effects of oral anticoagulants. Cimetidine elevates nifedipine levels. Inttiai doses may exacerbate angina. Reduce dose in patients with liver dysfunction. 

Cimetidine not only reduces the metabolism of beta-blockers such as propranolol, it is also known to act as an inhibitor of tubular secretion of a number of organic cations. Therefore it is not surprising to see that the renal clearance of pindolol is substantially and stereoselectively reduced by coadministration of this drug [59]. The administration of 400 mg cimetidine twice a day for 2 days before and 2 days after pindolol administration resulted in 26% and 34% reductions in the renal clearances of S(—)- and R(-t-)-pindolol, respectively. Therefore the plasma concentrations of the R(-l-) enantiomer increased more drastically (47%) than those of the S(—) enantiomer (38%) in the presence of cimetidine [59]. Because renal clearance accounts for only 50% of pindolol elimination, the significant increases in the plasma concentrations of pindolol enantiomers as a result of cimetidine coadministration cannot be explained from the inhibition of its renal clearance only. Apparently, cimetidine also reduces the metabolism of pindolol. 

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