Check Dose and Duration With COVID-19 or Flu Treatments

COVID-19 or influenza antivirals will pop up on home med lists.

Help avoid mishaps when patients are admitted on these meds.

COVID-19 meds. Nirmatrelvir/ritonavir (Paxlovid) will be used for most at-risk outpatients age 12 and up...within 5 days of symptom onset.

It still seems effective at preventing hospitalization and death...even with circulating variants.

Document details about nirmatrelvir/ritonavir on med histories...especially strength and when the course was started.

Most patients will get a 300 mg/100 mg dose pack...and take 2 nirmatrelvir tabs plus 1 ritonavir tab bid for 5 days.

But some patients with kidney disease may need 150 mg/100 mg... 1 nirmatrelvir tab and 1 ritonavir tab bid for 5 days.

Be aware, drug interactions can be an issue...such as with most statins (simvastatin, etc) and some blood thinners (apixaban, etc).

Ask if any home meds were stopped...or doses adjusted...when nirmatrelvir/ritonavir was started. Clinicians will need this info so they can readjust or restart doses when appropriate.

Expect to use a patient’s own med if nirmatrelvir/ritonavir is continued. Alert a pharmacist if there’s still an active order when the supply is depleted...the stop date may be missing or wrong.

Flu meds. Oseltamivir (Tamiflu) or baloxavir (Xofluza) will be saved for certain outpatients...within 48 hours of symptom onset.

These meds only reduce flu symptoms by about a day.

Watch doses carefully. They’re weight-based for both meds.

Oseltamivir is usually 75 mg bid for patients over 40 kg...but may be lower for patients who weigh less. For baloxavir, it’s 80 mg if patients weigh 80 kg or more...or 40 mg if they weigh 40 to 80 kg.

Note when a course started on med histories. Oseltamivir is usually given for 5 days...but baloxavir is 1 dose.

Anticipate having oseltamivir on hand for inpatients with flu...and for some flu patients in the ED. Oseltamivir has the most data for inpatient use...and it costs much less than baloxavir.

If you do dispense baloxavir, prevent waste...especially with oral suspension. It’s only good for 10 hours after mixing with water.

Compare other antivirals for flu treatment and prevention in our resource, Antivirals for Influenza. Get our algorithm, Outpatient COVID-19 Treatment Options, for more meds.

Key References

  • CDC. Interim Clinical Considerations for COVID-19 Treatment in Outpatients. October 4, 2023. (Accessed October 13, 2023.)
  • NIH. COVID-19 Treatment Guidelines. Clinical Management of Adults. October 10, 2023. (Accessed October 16, 2023.)
  • CDC. Influenza Antiviral Medications:  Summary for Clinicians. September 27, 2023. (Accessed October 2, 2023.)
  • Medication pricing by Elsevier, accessed Oct 2023.
Hospital Pharmacy Technician's Letter. November 2023, No 391103


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