A nurse is teaching a client who has a prescription for warfarin. Which of the following statements by the client indicates an understanding of the teaching?

Warfarin is a Vitamin K antagonist that interferes with the synthesis of clotting factors II, VII, IX, and X. It has a narrow therapeutic window and is subject to numerous cytochrome P450 interactions with herbal supplements and foods. Maintaining a consistent intake of Vitamin K and avoiding platelet-inhibiting substances is vital to prevent hemorrhage or thromboembolic events. Rationale: A. Using a hard bristle toothbrush is incorrect because warfarin therapy increases the risk of gingival bleeding due to impaired coagulation. Clients are instructed to use a soft-bristle toothbrush to minimize trauma to the oral mucosa and prevent bleeding episodes. Any source of mechanical irritation can lead to significant hemorrhage in a patient who is therapeutically anticoagulated. B. Getting an INR checked once a year is dangerously infrequent for a patient on warfarin therapy. The International Normalized Ratio (INR) must be monitored every few days when starting therapy and at least monthly once a stable dose is established. Frequent monitoring is necessary to adjust the dosage and ensure the patient stays within the therapeutic range of 2.0 to 3.0. C. St. John's wort is a potent inducer of hepatic enzymes that significantly increases the metabolism of warfarin, leading to subtherapeutic levels. If the client takes this supplement, they are at a much higher risk of developing dangerous blood clots or suffering a stroke. Avoiding this herbal interaction indicates the client understands how to maintain the effectiveness of their anticoagulant. D. Eating cantaloupe is generally safe for patients on warfarin as it does not contain high levels of Vitamin K that would interfere with the medication. The client should instead be taught to maintain a consistent intake of dark, leafy green vegetables like spinach or kale. Restricting fruits like cantaloupe is an unnecessary dietary limitation that does not affect the drug's efficacy.