Ketoconazole Cimetidine

Drugs that may affect galantamine include succinylcholine and bethanechol. Drugs that may be affected by galantamine include succinylcholine, bethanechol, cimetidine, ketoconazole, paroxetine, and erythromycin. 

CYP2C19 Cimetidine, ketoconazole, omeprazole, ticlo-pidine"... 

As the induction of hepatic microsomal oxidative activity by a lipid-soluble drug (e.g. phenobarbitone) or xenobiotic could decrease the duration of action of therapeutic agents that are mainly eliminated by microsomal oxidation, the effect of induction would be considered a form of biochemical antagonism. Drug-induced inhibition of microsomal oxidative activity, without adjustment of dosage of a concomitantly administered therapeutic agent that undergoes extensive hepatic metabolism, could lead to toxicity. Cimetidine, ketoconazole and chloramphenicol inhibit hepatic microsomal enzyme activity. 

After single-dose administration, the mean bioavailability of quetiapine is 9% with significant interindividual variation. If a CYP 3A4 inhibitor (e.g., cimetidine, ketoconazole, nefazodone, grapefruit juice, or erythromycin) is added to quetiapine, increased side effects (e.g., sedation or orthostasis) may occur. Fluoxetine may also decrease clearance of a medication such as quetiapine metabolized through CYP 3A4. However, with fluoxetine, it is the long-acting metabolite norfluoxetine, and not fluoxetine, that is the primary inhibitor of 3 A4 metabolism. If an enzyme inducer such as carbamazepine or St. lohn s wort is added to quetiapine, then decreased antipsychotic effects may occur. ... 

The most common side effect of sucralfate is constipation (-2%). some aluminum can be absorbed, sucralfate should be avoided in patients with renal failure who are at risk for aluminum overload. Likewise, aluminum-containing antacids should not be combined with sucralfate in these patients. Sucralfate forms a viscous layer in the stomach that may inhibit absorption of other drugs, including phenytoin, digoxin, cimetidine, ketoconazole, and fluoroquinolone antibiotics. 

Ketoconazole. For treatment of systemic mycoses with amphotericin B or miconazole, the patient must be admitted to a hospital. This is not always possible, particularly in areas where systemic mycoses occur frequently, nor is it always desirable, because of the expense. For these reasons, it was desirable to find an antimycotic that combined safety and broad-spectmm activity with oral adraiinistration. Ketoconazole (10), which is orally active, met most of these requirements. This inhibitor of the ergosterol biosynthesis is an A/-substituted imidazole, that differs from its precursors by the presence of a dioxolane ring (6,7). Ketoconazole is rapidly absorbed in the digestive system after oral adrninistration. Sufficient gastric acid is required to dissolve the compound and for absorption. Therefore, medication that affects gastric acidity (for example, cimetidine and antacids) should not be combined with ketoconazole. 

Dofetilide See below3 patients must be hospitalized for 3 days during initiation of therapy Cimetidine, hy d roch I o roth iaz i de, ketoconazole, medroxyprogesterone, promethazine, trimethoprim, verapamil (all inhibit dofetilide elimination)... 

Certain medications (e.g., cimetidine, diltiazem, erythromycin, fluoxetine, fluvoxamine, isoniazid, itraconazole, ketoconazole, nefazodone, propoxyphene, and verapamil) added to carbamazepine therapy may cause carbamazepine toxicity. 

Sildenafil doses should be decreased when any potent cytochrome P450 3A4 inhibitor is used (e g., cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and saquinavir). Vardenafil doses vary accordingto which agent is used (2.5 mg q 72 h for ritonavir, 2.5 mg q 24 h for indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily and 5 mg q 24 h for ketoconazole 200 mg daily, itraconazole200 mg daily, and erythromycin). Tadalafil doses are reduced only when it is used with the most potent cytochrome P450 3A4 inhibitors (e g., ketoconazole or ritonavir). 

QT prolongation common. Concurrent use with cimetidine, verapamil, ketoconazole contraindicated. 

CYP450 Dutasteride may increase in the presence of inhibitors of CYP3A4, such as ritonavir, ketoconazole, verapamil, diltiazem, cimetidine, and ciprofloxacin. 

Endocrine effects Statins interfere with cholesterol synthesis and lower circulating cholesterol levels and, as such, might theoretically blunt adrenal or gonadal steroid hormone production. Small declines in total testosterone with no commensurate elevation in LH have been noted with the use of fluvastatin. Pravastatin showed inconsistent results with regard to possible effects on basal steroid hormone levels atorvastatin, lovastatin, rosuvastatin, and simvastatin did not reduce basal plasma cortisol concentration or basal plasma testosterone concentration or impair adrenal reserve. Appropriately evaluate patients who display clinical evidence of endocrine dysfunction. Exercise caution when administering HMG-CoA reductase inhibitors with drugs that affect steroid levels or activity, such as ketoconazole, spironolactone, and cimetidine. 

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 affect NSAIDs include the following Bisphosphonates, cholestyramine, cimetidine, colestipol, cyclosporine, diflunisal, DMSO, fluconazole, ketoconazole, phenobarbital, phenylbutazone, probenecid, rifampin, ritonavir, salicylates, sucralfate. 

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. 

Because trimetrexate is metabolized by a P450 enzyme system, drugs that induce or inhibit this drug metabolizing enzyme system may elicit important drug interactions that may alter trimetrexate plasma concentrations, which include erythromycin, rifampin, rifabutin, ketoconazole, fluconazole, cimetidine, nitrogen substituted imidazole drugs (eg, clotrimazole, ketoconazole, miconazole). 

Coadminister known CYP3A4 inhibitors (eg, erythromycin, itraconazole, ketoconazole, fluconazole, calcium channel blockers, cimetidine) with caution in patients with widespread or erythrodermic disease. 

Flurazepam (Dalmane) [C-IV] [Sedative/Hypnotic/ Benzodiazepine] Uses Insomnia Action Benzodiazepine Dose Adults Beds >15 y. 15-30 mg PO qhs PRN X in elderly Caution [X, /-] Elderly, low albumin, hepatic impair Contra NAG PRG Disp Caps SE Hangover d/t accumulation of metabolites, apnea, anaphylaxis, angioedema, amnesia Interactions T CNS depression W/ antidepressants, antihistamines, opioids, EtOH T effects OF digoxin, phenytoin T effects W/ cimetidine, disulfiram, fluoxetine, iso-niazid, ketoconazole, metoprolol, OCPs, propranolol, SSRIs, valproic acid. 

Uses Obesity Action Blocks uptake of norepinephrine, serotonin, dopamine Dose 10 mg/d PO, may to 5 mg after 4 wk Caution [C, -] w/ SSRIs, Li, dextromethorphan, opioids Contra MAOI w/in 14 d, uncontrolled HTN, arrhythmias Disp Caps SE HA, insomnia, xerostomia, constipation, rhinitis, tach, HTN Interactions T Risk of serotonin synd W/ dextromethorphan, ergots, fentanyl, Li, meperidine, MAOIs, naratriptan, pentazocine, rizatriptan, sumatriptan, SSRIs, tryptophan, zolmitriptan, St. John s wort effects W/ cimetidine, erythromycin, ketoconazole T CNS depression W/ EtOH EMS Use fentanyl w/ caution, may T risk of serotonin synd concurrent EtOH use can T CNS depression OD May cause tach, HTN, diaphoresis, HA, fever, agitation, muscle tremors, and Szs symptomatic and supportive... 

CYP3A4 HIV antivirals (e.g.. Ritonavir), amiodarone, cimetidine, diltiazem, erythromycin", grapefruit juice, ketoconazole... 

Contraindications include baseline prolongation of the QT interval, use of other QT-prolonging drugs history of torsades de pointes a creatinine clearance of less than 20 mL/minute simultaneous use of verapamil, cimetidine, or ketoconazole uncorrected hypokalemia or hypomagnesemia and pregnancy or breast-feeding. 

Verapamil increases serum dofetilide levels, as do drugs that inhibit cationic renal secretion, such as ketoconazole and cimetidine, raise serum levels. 

Ketoconazole Antacids, anticholinergic drugs, cimetidine, ranitidine Decreased absorption. 

Cardiac depressant effects may occur when verapamil or diltiazem is combined with a (p-adrenoceptor antagonoist or a cardiac glycoside. Nifedipine and verapamil are metabolised by cytochrome P-450 3A4. Inhibitors of this enzyme, e.g. HIV-protease inhibitors, cimetidine, fluoxetine, ketoconazole, erythromycin, will increase plasma levels and the dose should be carefully monitored. Conversely, enzyme inducers, e.g. carbamazepine, rifampicin, phenytoin, will decrease their plasma concentrations. 

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