Factors Decreasing PT/INR Response Listed By Drug Class - 2000

 

 

Adrenal cortical steroid inhibitors

Antacids

Antianxiety agents

Antiarrhythmics

Antibiotics

Anticonvulsants

Antidepressants

Antihistamines

Antineoplastics

Antipsychotic medications

Antithyroid drugs

Barbituates

Diuretics

Enteral nutritional supplements

Fungal medications, systemic

Gastiric acidity and peptic ulcer agents

Hypnotics

Hypolipidemics

Immunosuppressives

Oral contraceptives

Estrogen containing steroids, adrenocortical

Tuberculosis agents

Vitamins

Because a patient may be exposed to a combination of the above factors, the net effect of Coumadin on PT/INR response may be unpredictable. More frequent PT/INR monitoring is therefore advisable. Medications of unknown interaction with coumarins are best regarded with caution. When these medications are started or stopped, more frequent PT/INR monitoring is advisable.

It has been reported that concomitant administration of warfarin and ticlopidine may be associated with cholestatic hepatitis.

Effect on Other Drugs: Coumarins may also affect the action of other drugs. Hypoglycemic agents (chlorpropamide and tolbutamide) and anticonvulsants (phenytoin and phenobarbital) may accumulate in the body as a result of interference with either their metabolism or excretion.

 

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