A 65-year-old male with a history of hypertension, GERD, type 2 diabetes, and atrial fibrillation presents to the pharmacy seeking guidance. He had fever at home (101 F), cough, congestion, and headache. His wife recently tested positive for COVID-19 and therefore he would like to be tested. Testing reveals that he is positive for SARS-CoV-2.  It is currently day 3 of onset of symptom presentation and is having no shortness of breath. He has a pulse oximeter at home and stated it was 98%. Vitals and home medication list are shown below.

He asks you about nirmatrelvir/ritonavir and wants to know if this is an appropriate treatment for him. Below represents information from his most recent clinic note one week ago. 

Regarding nirmatrelvir/ritonavir and this patient, what is the best treatment plan for this patient?

A. Considering the patient’s past medical history and medication list, you recommend initiating nirmatrelvir/ritonavir 300 mg/100 mg orally twice daily for 5 days.

B. Recommend supportive care and monitoring; do not initiate nirmatrelvir/ritonavir as it is past the 48-hour window to administer.

C. Do not recommend nirmatrelvir/ritonavir due to a drug-drug interaction with amiodarone. 

D. Considering the patient’s past medical history and medication list, you recommend initiating nirmatrelvir/ritonavir 150 mg/100 mg orally twice daily for 5 days.

E. Do not recommend nirmatrelvir/ritonavir due to a drug-drug interaction with omeprazole. 

While the COVID-19 pandemic has ended, the endemic nature of COVID-19 continues. At the time of this writing, a significant number of COVID-19 cases are occurring and pharmacists are continuing to vaccinate to prevent COVID-19 as well as dispense prescriptions for treatment. In addition, the FDA has authorized pharmacists to not only dispense, but also prescribe nirmatrelvir/ritonavir under certain circumstances that can be found here: https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-pharmacists-prescribe-paxlovid-certain-limitations. 

Paxlovid is nirmatrelvir tablets co-packaged with ritonavir tablets. They must be co-administered together for the treatment of COVID-19. This medication can be taken with or without food. It is indicated for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization and death. It is not approved for use as pre-exposure or post-exposure prophylaxis for prevention of COVID-19. There are a number of important points with regards to appropriate use of Paxlovid including dosing, timing, and drug interactions. 

Answer with Rationale:

The correct answer is C.  Ritonavir has long been a component of HIV regimens as it is a protease inhibitor that is used to "boost" concentrations of other protease inhibitors used within HIV management. This boosting effect is due to significant CYP 3A properties, which result in significant drug interactions. Before prescribing and dispensing Paxlovid, drug interactions should be screened as a number of scenarios for handling medications potentially to be used with Paxlovid are recommended by the NIH COVID-19 Treatment Guidelines. These include prescribing the medications together, avoiding the combination, or dose adjusting the interacting medication. According to the package insert as well as the NIH guidelines, Paxlovid is contraindicated with certain anti-arrhythmic agents such as amiodarone due to the risk of serious/life-threatening reactions (cardiac arrhythmias). A full list of recommendations can be found here: https://www.covid19treatmentguidelines.nih.gov/therapies/antivirals-including-antibody-products/ritonavir-boosted-nirmatrelvir--paxlovid-/paxlovid-drug-drug-interactions/. 

Answer (A) is not correct due to the interaction with amiodarone. It would be a correct answer if the patient was not taking any interacting medications.

Answer (B) is not correct as Paxlovid is appropriate to be given within 5 days of onset of symptoms. Tamiflu (oseltamivir) must be given within 48 hours of symptom onset when used for influenza.  

Answer (D) is not correct due to the patient having normal renal function, adjustment is only needed with a clearance between 30-60 mL/min. Paxlovid is not recommended in patients with a Clcr < 30ml/min as it has not been evaluated in this population.

Answer (E) is not correct as omeprazole poses no significant interaction with Paxlovid.