Completing a Prescription

Directions: For each of the scenarios below, answer the questions below using clinical practice guideline where applicable. Explain the problem and explain how you would address the problem. If prescribing a new drug, write out a complete medication order just as you would if you were completing a prescription. Use at least 3 sources for each scenario and cite sources using APA format.

1. A 52-year-old man was recently discharged from the hospital following treatment for atrial fibrillation. He was discharged on Warfarin 5 mg po q day and Amiodarone 200 mg tid. His INR is 8.8. What interaction has occurred with these 2 medications? What changes in his medications would you make?

2. A 44-year-old women is currently taking Glipizide and Phenytoin. She has a new prescription for Ceftriaxone. All three medications are known to be highly protein bound. What effect does protein binding have on drug availability? How would you manage this patient’s medication?
3. Name two drugs that are highly affected by the first pass effect. As a prescriber, what actions would you take in prescribing these drugs to counter the first pass effect?
4. James is a 49-year-old male that was prescribed atenolol for his high blood
   pressure. James states that he only occasionally takes the medication because he does not like the side effects. What information would you provide to the patient at his visit? How would you manage his medication?

Scenario 1:

Problem Explanation: The patient was discharged on Warfarin and Amiodarone and presents with an elevated INR of 8.8, indicating over-anticoagulation. Warfarin is a vitamin K antagonist used to prevent blood clot formation, while Amiodarone is an antiarrhythmic medication used to treat atrial fibrillation. However, Amiodarone can potentiate the anticoagulant effects of Warfarin, leading to an increased risk of bleeding due to its inhibition of Warfarin metabolism.

Clinical Practice Guidelines: According to the American College of Cardiology (ACC)/American Heart Association (AHA) 2019 guidelines for the management of patients with atrial fibrillation, it’s recommended to avoid concomitant use of Amiodarone and Warfarin due to the increased risk of bleeding. If unavoidable, close monitoring of INR is essential, and dose adjustments of Warfarin may be necessary.

Recommended Action: Given the patient’s elevated INR and the potential interaction between Warfarin and Amiodarone, the following changes would be made:

1. Discontinue Amiodarone if possible or consider an alternative antiarrhythmic agent.
2. Adjust the Warfarin dose based on the patient’s current INR and target INR range to bring it within therapeutic levels.

Sources:

1. January, C. T., et al. (2019). 2019 AHA/ACC/HRS focused update of the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Journal of the American College of Cardiology, 74(1), 104-132.
2. Lexicomp Online. (2024). Drug interaction analysis: Amiodarone and Warfarin.
3. Holbrook, A., et al. (2012). Evidence-based management of anticoagulant therapy. Anticoagulation Therapy, 247-271.

Scenario 2:

Problem Explanation: The patient is taking Glipizide, Phenytoin, and has a new prescription for Ceftriaxone. All three medications are highly protein-bound, which can lead to drug-drug interactions and alterations in drug availability due to competition for binding sites on plasma proteins.

Clinical Practice Guidelines: The FDA-approved drug labeling and guidelines from the American Academy of Neurology (AAN) recommend close monitoring of patients taking highly protein-bound drugs when initiating or discontinuing other medications that may affect protein binding.

Recommended Action: To manage this patient’s medication:

1. Monitor for signs of drug toxicity or decreased efficacy of any of the medications, especially with the addition of Ceftriaxone.
2. Consider adjusting the doses of Glipizide and Phenytoin based on clinical response and therapeutic drug monitoring.
3. Monitor for signs of hypoglycemia or hyperglycemia due to potential alterations in Glipizide levels.
4. Monitor phenytoin levels closely due to potential alterations in protein binding and drug availability.

Sources:

1. U.S. Food and Drug Administration. (2022). Drug Development and Drug Interactions: Table of Substrates, Inhibitors, and Inducers. Retrieved from https://www.fda.gov/drugs/drug-interactions-labeling/drug-development-and-drug-interactions-table-substrates-inhibitors-and-inducers
2. Perucca, E. (2002). Clinically relevant drug interactions with antiepileptic drugs. British Journal of Clinical Pharmacology, 54(6), 551-561.
3. Micromedex Solutions. (2024). Drug Interactions Analysis: Glipizide, Phenytoin, and Ceftriaxone.

Scenario 3:

Problem Explanation: The first-pass effect refers to the metabolism of a drug by the liver before it enters systemic circulation, leading to reduced bioavailability. Two drugs highly affected by the first-pass effect are oral forms of nitroglycerin and propranolol.

Clinical Practice Guidelines: According to the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the management of patients with stable ischemic heart disease, sublingual or topical formulations of nitroglycerin are recommended to bypass the first-pass effect and achieve rapid onset of action.

Recommended Action: To counter the first-pass effect when prescribing these drugs:

1. Prescribe sublingual or topical formulations of nitroglycerin to bypass the first-pass effect and achieve rapid onset of action.
2. Consider alternative routes of administration for propranolol, such as intravenous or transdermal formulations, to bypass the first-pass effect and ensure optimal bioavailability.

Sources:

1. Fihn, S. D., et al. (2014). 2014 ACC/AHA/AATS/PCNA/SCAI/STS focused update of the guideline for the diagnosis and management of patients with stable ischemic heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines, and the American Association for Thoracic Surgery, Preventive Cardiovascular Nurses Association, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Journal of the American College of Cardiology, 64(18), 1929-1949.
2. Sweetman, S. C. (Ed.). (2019). Martindale: The Complete Drug Reference (40th ed.). Pharmaceutical Press.
3. Tatro, D. S. (Ed.). (2023). Drug Interaction Facts: Herbal Supplements and Food. Wolters Kluwer.

Scenario 4:

Problem Explanation: The patient, James, is prescribed atenolol for high blood pressure but reports occasional medication adherence due to side effects.

Clinical Practice Guidelines: According to the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines for the management of hypertension, patient education on the importance of medication adherence and management of side effects is essential for optimizing treatment outcomes.

Recommended Action: To address James’s concerns and manage his medication:

1. Educate James about the importance of consistent medication adherence in controlling his blood pressure and reducing the risk of complications.
2. Discuss the potential side effects of atenolol, including fatigue, dizziness, and sexual dysfunction, and reassure James that not all patients experience these side effects.
3. Explore alternative antihypertensive medications or dosage adjustments if side effects persist or are intolerable.
4. Emphasize lifestyle modifications, such as regular exercise, healthy diet, and stress management, as adjunctive measures to control blood pressure.

Sources:

1. Whelton, P. K., et al. (2018). 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Journal of the American College of Cardiology, 71(19), e127-e248.
2. American Society