A nurse is monitoring a client who is receiving warfarin and has an INR of 4 (0.8 to 1.1). Which of the following medications should the nurse plan to administer?

Choice A rationale

Morphine is a potent opioid analgesic commonly prescribed for moderate to severe pain. A dosage of 4 mg intravenously every four hours as needed for pain is within the typical therapeutic range for post-operative pain management, and the frequency allows for sufficient time between doses to assess the analgesic effect and minimize accumulation.

Choice B rationale

Hydromorphone is a very potent opioid, significantly stronger than morphine. A dosage of 2 mg intravenously every two hours for severe pain is a high dose and a relatively short interval. This combination increases the risk of opioid toxicity, including respiratory depression and profound sedation, necessitating verification with the prescribing provider.

Choice C rationale

Ondansetron is a serotonin receptor antagonist used to prevent and treat nausea and vomiting. A dosage of 4 mg orally every eight hours as needed for nausea is a standard and safe therapeutic dose, commonly employed in the post-operative setting to manage emesis with minimal adverse effects.

Choice D rationale

Docusate sodium is a stool softener that works by increasing water and fat penetration into the stool, making it easier to pass. A dosage of 240 mg orally daily as needed for constipation is a common and appropriate dose for preventing and managing post-operative constipation, which is a frequent side effect of opioid analgesics.

Choice A rationale

An INR (International Normalized Ratio) of 4.0 indicates that the client's blood is much thinner than the therapeutic range for most conditions (usually 2.0-3.0 for warfarin). This significantly increases the risk of bleeding. Vitamin K is the antidote for warfarin because it is essential for the synthesis of clotting factors (II, VII, IX, X) in the liver. Administering vitamin K reverses the anticoagulant effect of warfarin, reducing the risk of hemorrhage by promoting the production of functional clotting proteins.

Choice B rationale

Protamine sulfate is the antidote for heparin. It works by forming a stable ion pair with heparin, neutralizing its anticoagulant effects. It has no effect on the anticoagulant properties of warfarin, which acts by inhibiting vitamin K epoxide reductase, an enzyme crucial for the regeneration of active vitamin K necessary for clotting factor synthesis. Therefore, protamine is not indicated for warfarin overdose.

Choice C rationale

Calcium gluconate is used to treat hypocalcemia and magnesium toxicity. Calcium plays a vital role in numerous physiological processes, including bone health and muscle function, and is essential for blood coagulation. However, it does not directly counteract the effects of warfarin, which targets vitamin K-dependent clotting factors, and is not the appropriate antidote for an elevated INR.

Choice D rationale

Epinephrine is a potent vasoconstrictor and bronchodilator used in anaphylaxis, cardiac arrest, and severe asthma. It acts on alpha and beta-adrenergic receptors, leading to increased heart rate, blood pressure, and bronchodilation. It has no role in reversing the anticoagulant effects of warfarin and is not indicated for managing an elevated INR.