Phenobarbital Carbamazepine

Monitor for acute and chronic adverse effects of AEDs. Acute adverse effects are best detected by a thorough neurologic examination at clinic visits. Instruct patients to report sedation, ataxia, rash, or other problems immediately. Monitor for chronic adverse effects including a loss of bone mineral density, which should be measured every 2 years in patients taking phenytoin, phenobarbital, carbamazepine, and valproate. 

Phenobarbital, carbamazepine, and phenytoin potentially reduce efficacy of OCs, and many anticonvulsants are known teratogens. The use of condoms in conjunction with high-estrogen OCs or intrauterine devices (IUDs) may be considered for women taking these drugs. 

Drugs that may affect telithromycin include itraconazole, ketoconazole, rifampin, phenytoin, phenobarbital, carbamazepine. 

Drugs that might decrease plasma concentrations of lopinavir/ritonavir include rifampin, phenobarbital, carbamazepine, phenytoin, azole antifungals, delavirdine, rifabutin, St. John s wort, efavirenz, nevirapine, and corticosteroids. 

St. John s wort, rifamycins, and ritonavir. Drugs that may be affected by efavirenz include phenytoin, phenobarbital, carbamazepine, itraconazole, ketoconazole, methadone, ritonavir, amprenavir, benzodiazepines, clarithromycin, ethinyl estradiol, indinavir, nelfinavir, saquinavir, and warfarin. 

Inducers of CYP3A4 such as St. John s wort preparations (H. perforatum), phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile ... 

Delavirdine is extensively metabolized to inactive metabolites by the CYP3A and CYP2D6 enzymes. However, it also inhibits CYP3 A and thus inhibits its own metabolism. In addition to its interactions with other antiretroviral agents (see Table 49 1), delavirdine will result in increased levels of numerous agents (Table 49-3). Dose reduction of indinavir and saquinavir should be considered if they are administered concurrently with delavirdine. Delavirdine plasma concentrations are reduced in the presence of antacids, phenytoin, phenobarbital, carbamazepine, rifabutin, and rifampin concentrations are increased during coadministration with clarithromycin, fluoxetine, dexamethasone, and ketoconazole. 

Special attention is needed when new medications are prescribed to CSA-treated patients. CSA is extensively metabolized by the cytochrome P450 hver microsomal enzyme system [2, 3], and consequently drugs that interfere with this pathway can cause important changes in CSA blood levels (Table 3). Compounds inhibiting P450 enzymes, such as ketoconazole, erythromycin, verapamil, and diltiazem increase concentration of parent CSA and may cause acute nephrotoxicity. On the other hand, drugs that increase P450 enzyme activity, such as phenobarbital, carbamazepine and... 

Drugs induce osteomalacia through various mechanisms. Phenyt-oin, primidone, phenobarbital, carbamazepine, rifampin, and some hypnotic medications may cause osteomalacia, potentially through... 

Bonay M, JonviUe-Bera AP, Diot P, Lemarie E, Lavandier M, Autret E. Possible interaction between phenobarbital, carbamazepine and itraconazole. Drug Safety (1993) 9,309-11. 

The clearance of teniposide was increased two to threefold (from 13 to 32 mL/minute per m ) in 6 children with acute lymphocytic leukaemia when they also took phenytoin or phenobarbital. Another patient had a twofold increase in teniposide clearance when carbamazepine was given. In a retrospective survey, long-term antiepileptic use (phenytoin, phenobarbital, carbamazepine, or a combination) was associated with worse event-free survival, and greater haematological relapse and CNS relapse in children receiving chemotherapy for B-lineage acute lymphoblastic leukaemia. In this study, faster clearance of teniposide was found in those receiving antiepileptics. ... 

Romanyshjm, L.A. Wichmann, J.K. Kucharczyk, N. Shumaker, R.C. Ward, D. Sofia, R.D. Simultaneous determination of felbamate, primidone, phenobarbital, carbamazepine, two carbamazepine metabolites, phenytoin, and one phenytoin metabolite in human plasma by hig -performance liquid chromatography. Ther.Drug Monit., 1994,16,90-99 [plasma extracted metabolites, felbamate, phenobarbital, primidone column temp 40-50 LOQ 195-391 ng/mL simultaneous acetaminophen, aspirin, brompheniramine, caffeine, chlorpheniramine, dextromethorphan, dimethadione, ethosuximide, ethotoin, ibuprofen, iministUbene, mephenytoin, mephobarbital, metharbital, methsuximide, para-methadione, phenacemide, phensuximide, phenylpropanolamine, theophylline, trimethadione noninterfering clonazepam valproic acid]... 

Improved Method for Measurement of Serum Levels of Phenobarbital, Carbamazepine, Primidone and Di-phenylhydantoin by Gas-Liquid Chr omat o gr aphy... 

Simultaneous Analysis of Underivat-ized Phenobarbital, Carbamazepine, and Phenytoin by Isothermal Gas-Liquid Chromatography J. Anal. Toxicol. 2(5) 219-225 (1978) CA 90 33699w... 

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