title: Decreased hypoprothrombinemic response to warfarin secondary to the warfarin-nafcillin interaction.
abstract: Patients who are receiving multiple medications must be screened for significant drug interactions. The specific mechanism of a drug interaction determines whether the patient may experience a subtherapeutic effect or a potentially toxic reaction. Three cases of relative warfarin resistance, possibly related to high-dose nafcillin, are described in this report. Several reports have suggested that penicillinase-resistant penicillins, such as nafcillin and dicloxacillin, exert an important enzyme-inducing effect in patients receiving warfarin. This potential interaction must be appropriately recognized and managed in order to maintain adequate anticoagulation in this patient population.
authors.affiliation: Department of Pharmacy, South Side Hospital, Pittsburgh, PA 15203.
authors.forename: V A
authors.initials: VA
authors.lastname: Shovick
authors.forename: T L
authors.initials: TL
authors.lastname: Rihn
mesh_terms: D000368:Aged; D004347:Drug Interactions; D006801:Humans; D007020:Hypoprothrombinemias / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D009254:Nafcillin / Q000008:administration & dosage* / Q000009:adverse effects; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D009254:Nafcillin; D014859:Warfarin