Phenobarbital oral contraceptives

Drugs that may affect lamotrigine include acetaminophen, carbamazepine, folate inhibitors, oral contraceptives, phenobarbital, phenytoin, primidone, rifamycins, succinimides, and valproic acid. 

Clinically important, potentially hazardous interactions with aspirin, cyclosporine, digoxin, diuretics, estrogens, ketoconazole, live vaccines, oral contraceptives, phenobarbital, phenytoin, rifampin, warfarin... 

Stopping oral contraceptives - For women not taking carbamazepine, phenytoin, phenobarbital, primidone, or rifampin, the maintenance dose of lamotrigine may need to be decreased by as much as 50% of the maintenance dose with concurrent oral contraceptives. 

Drugs that can decrease carbamazepine serum levels include charcoal, cisplatin, doxorubicin, felbamate, hydantoins, rifampin, phenobarbital, primidone, theophylline. The serum levels of oral contraceptives, haloperidol, bupropion, anticoagulants, felbamate, valproic acid, felodipine, tricyclic antidepressants, acetaminophen, ziprasidone, voriconazole, topiramate, tiagabine, olanzapine, and lamotrigine can be lowered by carbamazepine. 

Drugs that may affect cyclosporine include allopurinol, amiodarone, androgens (eg, danazol, methyltestosterone), anticonvulsants (eg, carbamazepine, phenobarbital, phenytoin), azole antifungals (eg, fluconazole, ketoconazole), beta-blockers, bosentan, bromocriptine, calcium channel blockers, colchicine, oral contraceptives, corticosteroids, fluoroquinolones (eg, ciprofloxacin), foscarnet, HMG-CoA reductase inhibitors, imipenem-cilastatin, macrolide antibiotics, methotrexate, metoclopramide, nafcillin, nefazodone, orlistat, potassium-sparing diuretics, probucol, rifamycins (rifampin, rifabutin), serotonin reuptake inhibitors (SSRIs eg, fluoxetine, sertraline),... 

Lamotrigine is metabolized by glucuronidation, possibly by the UGT 1A4 system. As such, it is vulnerable to other UGT inducers—oral contraceptives, phenytoin, carbamazepine, phenobarbital and primidone, and to a UGT inhibitor, valproate (Hachad et ah, 2002). 

Mercaptopurine Methotrexate Oral contraceptives p-Ami nosalicylate Phenobarbital Phenyloin Primidone Pyrimethamine Sulfasalazine Tetracycline Vinblastine... 

Carbamazepine, phenytoin, phenobarbital and primidone, felbamate, oxcarbazepine, and topiramate stimulate the metabolism of oral contraceptive steroids. 

Clinically important, potentially hazardous interactions with aluminum, aminophylline, aspirin, chlorambucil, cimetidine, clarithromycin, cyclophosphamide, cyclosporine, dicumarol, diuretics, docetaxel, estrogens, grapefruit juice, indomethacin, influenza vaccines, itraconazole, ketoconazole, lansoprazole, live vaccines, methotrexate, montelukast, omeprazole, oral contraceptives, pancuronium, phenobarbital, phenytoin, ranitidine, rifampicin, rifampin, timolol, tolbutamide, vitamin A... 

The most common drugs responsible for acneform eruptions are ACTH, androgenic hormones, anticonvulsants (hydantoin derivatives, phenobarbital, trimethadione), corticosteroids, danazol, disulfiram, halogens (bromides, chlorides, iodides), lithium, oral contraceptives, tuberculostatics (ethionamide, isoniazid, rifampin), vitamins B2, B6, and B12. 

Interpretation In normal subjects, serum cortisol concentration is suppressed to 2 pg/dL or less after administration of 1 mg of dexamethasone. Most patients with Cushing s syndrome do not show adequate suppression, and 0800 hours cortisol concentrations are usually >10pg/dL. Serum cortisol >2pg/dL may also be seen in cases of stress, obesity, infection, acute or chronic illness, alcohol abuse, severe depression, oral contraceptive use, pregnancy, estrogen therapy, failure to take the dexamethasone, or treatment with phenytoin or phenobarbital (enhancement of dexamethasone metabolism). 

Phenobarbital is a potent enzyme inducer and as such can reduce the effects of other drugs, for example oral contraceptives, warfarin and corticosteroids. 

Doses of griseofulvin are 15-20 mg/kg/d for 6 to 8 weeks in children with the microsized form. More frequent side effects are minor headaches, gastrointestinal reactions and cutaneous eruptions. The major drug interactions have been noted with phenobarbital, anticoagulants and oral contraceptives. 

Sedatives or anticonvulsants (e.g., carbamazepine, oxcarbazepine, phenobarbital, and pheny-toin, but not valproate) that induce CYPs (see Chapter S) can enhance the metabolism of antipsychotic and many other agents (including anticoagulants and oral contraceptives), sometimes with significant clinical consequences. Conversely, selective serotonin (5-HT) reuptake inhibitors including fluvoxamine, fluoxetine, paroxetine, venlafaxine, sertraline, and nefazodone (see Chapter 17) compete for these enzymes and can elevate circulating levels of neuroleptics. 

A a X 0 Q, 1 W s o a (D CQ PO/PR. Well absorbed, liver metabolism, kidney excretion. Dozens of standard and long-acting preparations available. Patients with seizure disorder, cardiovascular disorder or peptic ulcer disease. Sympathomimetics T risk of heart and CNS toxicity. Cimetidine, oral contraceptives and several antibiotics t half-life of theophylline - thus T toxicity. Phenobarbital and phenytoin induce metabolism of theophylline, thus i half-life. Dehdydration results from t diuresis with concurrent use of furosemide. Warn patients doubling a dose, even if one is missed, is very dangerous. Intoxication may cause seizures. Treat overdose with ipecac, activated charcoal, and a cathartic. 

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