Venlafaxine Cimetidine

Venlafaxine + cimetidine —> increased plasma venlafaxine concentration due to impaired metabolism. Increased side effects. 

Venlafaxine Cimetidine Reduced clearance of venlafaxine by 43% AUC and peak serum concentration of venlafaxine increased by 60%... 

The effects of buspirone are decreased when the drug is administered with fluoxetine Increased serum levels of buspirone occur if the drug is taken with erythromycin or itraconazole Should any of these combinations be required, the dosage of buspirone is decreased to 2.5 mg BID, and the patient is monitored closely. Venlafaxine blood levels increase with a risk of toxicity when administered witii MAOIs or cimetidine There is an increased risk of toxicity when trazodone is administered with the phenothiazines and decreased effectiveness of trazodone when it is administered with carbamazepine Increased serum digoxin levels have occurred when digoxin is administered with trazodone There is a risk for increased phenytoin levels when phenytoin is administered witii trazodone... 

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 may affect venlafaxine include cimetidine, cyproheptadine, and MAOIs. Drugs that may be affected by venlafaxine include clozapine, desipramine, haloperidol, indinavir, St. John s wort, trazodone, sibutramine, sumatriptan, and warfarin. 

D6 Tricyclic antidepressants (TCAs), benztropine, perphenazine, clozapine, haloperidol, codeine/oxycodone, risperidone, class Ic antiarrhythmics, 3 blockers, trazodone, paroxetine, maprotiline, amoxapine, duloxetine, mirtazapine (partly), venlafaxine, bupropion Fluoxetine, paroxetine, duloxetine, hydroxybupropion, methadone, cimetidine, haloperidol, quinidine, ritonavir Phenobarbital, rifampin... 

Venlafaxine Hydrochloride Venlafaxine must be avoided with MAOIs and cimetidine. 

VENLAFAXINE H2 RECEPTOR BLOCKERS -CIMETIDINE t efficacy and adverse effects Inhibition of metabolism Not thought to be clinically significant but take care in elderly people and in patients with hepatic impairment... 

Concomitant use with cimetidine may reduce clearance of venlafaxine and raise venlafaxine levels... 

The steady-state plasma concentration of venlafaxine increases by 61 % when it is combined with cimetidine. Therefore, caution is advised with the use of cimetidine and venlafaxine in elderly patients, in patients with pre-existing hypertension, and in patients with hepatic or renal dysfunction. 

Cimetidine may increase duloxetine and venlafaxine plasma levels, which may lead to an increase in their adverse effects. Famotidine does not appear to interact with duloxetine. 

Cimetidine 800 mg daily for 5 days was found to reduce the oral clearance of venlafaxine 50 mg every 8 hours by 40%, and to increase the AUC by 62% in 18 healthy subjects. It had no effect on the formation or elimination of the major active metabolite of venlafaxine, O-desmethylvenla-faxine (ODV). The total level of venlafaxine with ODV was found to be increased by only 13%. Thus the overall pharmacological activity of the two was only slightly increased by cimetidine and no special precautions would seem to be necessary on concurrent use. However, the manufacturers of venlafaxine suggest that the elderly and those with hepatic impairment may possibly show a more pronounced effect, and such patients should be monitored more closely, for venlafaxine adverse effects. 

Troy SM, Rudolph R, Mayersohn M, Chiang ST. The influence of cimetidine on the disposi-tic kinetics of the antidepressant venlafaxine. J Clin Pharmacol (1998) 38, 467-74. 

Serotonin syndrome. A 39-year-old woman with depression and panic attacks was taking cimetidine, trazodone, clonazepam and fluoxetine. Within 24 hours of abruptly stopping clonazepam and fluoxetine and starting lorazepam and venlafaxine, she developed the serotonin syndrome (diaphoresis, tremors, slurred speech, myoclonus, restlessness and diarrhoea). ... 

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