Barbiturates Theophylline

Phenytoin interacts widi many different drugp. For example isoniazid, chloramphenicol, sulfonamides, benzodiazepines, succinimides, and cimetidine all increase phenytoin blood levels. The barbiturates, rifampin, theophylline, and warfarin decrease phenytoin blood levels. When administering the hydantoins with meperidine, die analgesic effect of meperidine is decreased. 

Jatlow, P., Ultraviolet spectrophotometry of theophylline in plasma in the presence of barbiturates, Clin. Chem., 21,1518,1975. 

Agents that may decrease theophylline levels include aminoglutethimide, barbiturates, charcoal, hydantoins, ketoconazole, rifampin, smoking (cigarettes and marijuana), sulfinpyrazone, sympathomimetics ( -agonists), thioamines, carbamazepine, isoniazid, and loop diuretics. 

Drugs that may affect benzodiazepines include alcohol, antacids, barbiturates, cimetidine, disulfiram, fluoxetine, isoniazid, ketoconazole, metoprolol, oral contraceptives, narcotics, probenecid, propoxyphene, propranolol, ranitidine, rifampin, scopolamine, theophylline, and valproic acid. 

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. 

Charcoal hemoperfuslon is useful when a drug can be adsorbed by charcoal (eg, theophylline, barbiturates). 

Estazolam potentiates the CNS depressant effects of phenothiazines, narcotics, antihistamines, MAOIs, barbiturates, alcohol, general anesthetics, and TCAs. Use with cimetidine, disulfiram, oral contraceptives, and isoniazid may diminish hepatic metabolism and result in increased plasma concentrations of estazolam and increased CNS depressant effects. Fleavy smoking (more than 20 cigarettes/day) accelerates estazolam s clearance. Theophylline antagonizes estazolam s pharmacological effects. 

HA, mild pain Action Nonnarco tic analgesic w/ barbiturate Dose 1—2 tabs or caps PO q4-6h PRN i in renal/hepatic impair 4 g/24 h APAP max Caution [C, D, +] Alcoholic liver Dz Contra G6PD deficiency Disp Caps, Liq, tabs SE Drowsiness, dizziness, hangover effect Interactions T Effects OF benzodiazepines, opiate analgesics, sedatives/hypnotics, EtOH, methylphenidate hydrochloride i effects OF MAOIs, TCAs, corticosteroids, theophylline, OCPs, BBs, doxycycline EMS See Acetaminophen may impair coordination, monitor for depression concurrent EtOH use T CNS depression butalbital is habit forming... 

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