Lorazepam Cimetidine

Cimetidine can impair benzodiazepine metabolism and lead to adverse effects (SEDA-18, 43). In contrast, a few benzodiazepines are metabolized exclusively by glucuro-nide conjugation (lorazepam, oxazepam, temazepam), and are therefore unaffected by concomitant therapy with cimetidine and other oxidation inhibitors (123). 

BZDs (NOT LORAZEPAM OR TEMAZEPAM) H2 RECEPTOR BLOCKERS -CIMETIDINE, RANITIDINE t efficacy and adverse effects of BZD, e.g. sedation Cimetidine is an inhibitor of CYP3A4, CYP2D6, CYP2C19 and CYP1A2 Not clinically significant for most patients. Conflicting information for some BZDs. Monitor more closely, and i dose if necessary... 

The metabolism of lorazepam (e.g., Ativan), oxazepam (e.g., Serax), and temazepam (e.g., Restoril) are not likely to be affected, and one of these agents may be preferred when a benzodiazepine is indicated in a patient being treated with cimetidine. The experience with ranitidine (e.g., Zantac), famotidine (Pepcid), and nizatidine (Axid) suggests that these agents are not likely to inhibit hepatic enzyme systems, and these other histamine H2-receptor antagonists are less likely than cimetidine to interact with other drugs that are metabolized via these pathways. 

A 39-year-old woman developed a dystonic reaction (masseter spasm, lip smacking, oculogyric crisis, and mild neck spasm) within 5 minutes of intravenous administration of cimetidine 300 mg for epigastric pain. She had epilepsy and had not taken her antiepileptic medication regularly. She had developed a similar dystonic reaction to prochlorperazine 1 week before. She recovered within 5 minutes of treatment with intravenous diphenhydramine and lorazepam. 

Greenblatt DJ, Abernethy DR, Koepke HH, Shader RL Interaction of cimetidine with oxazepam, lorazepam, and flurazepam. J Chn Pharmacol 1984 24(4) 187-93. 

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... 

Wong, S.H.Y. McHugh, S.L. Dolan, J. Cohen, K.A. Tricyclic antidepressant analysis by reversed-phase liquid chromatography using phenyl columns. J.Liq.Chromatogr., 1986, 9, 2511-2538 [also acetaminophen, amobarbital, amoxapine, barbital, chlordiazepoxide, chlorpromazine, cimetidine, clomipramine, codeine, desipramine, desmethyldoxepin, diazepam, doxepin, fluphenazine, flurazepam, glutethimide, hydroxyamoxapine, imipramine, lorazepam, maprotiline, meperidine, metabolites, nortriptyline, oxazepam, pentobarbital, perphenazine, phenobarbital, phenytoin, propoxyphene, protriptyline, secobarbital, thioridazine, trazodone]... 

Noninterfering acetaminophen, amiloride, aspirin, atenolol, chlorothiazide, cimetidine, cyclopenthiazide, diazepam, furosemide, indapamide, labetalol, lorazepam, metoprolol, phenytoin, propranolol, ranitidine, salicylic acid, theophylline... 

Simultaneous amoxapine, chlordiazepoxide, chlorpromazine, cimetidine, desipramine, diazepam, doxepin, flurazepam, imipramine, lorazepam, norfluoxetine, nortriptyline, oxazepam, pentobarbital, perphenazine, phenobarbital, phen5doin, prochlorperazine, secobarbital, thioridazine, trifluoperazine Noninterfering acetaminophen, codeine, meperidine Interfering amitriptyline, propo q>hene... 

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