“Paxlovid”
How many hours should you wait to take your second dose of PaxLovid?
2 Answers
GeneralPractitionerCOVID-19
12 hours.
This is probably more that you asked for, but here is the whole kit and kaboodle.
Indications
Treatment of COVID-19 in adults at increased risk of progressing to severe COVID-19.
Criteria for Nirmatrelvir Treatment
Confirmed SARS-CoV-2 infection via reverse transcription-polymerase chain reaction (RT-PCR), respiratory sample testing, or antigen/self-test; and
Significant COVID-19 symptoms lasting no more than 5 days; and
At-risk or high-risk patient; and
Outpatient or hospitalized for a condition other than COVID-19.
Note:
For high-risk patients, treatment may be offered based on an individual assessment, even for those with prolonged symptomatic COVID-19.
The definition of at-risk and high-risk patients can be found in the Danish Health Authority's guidelines or under disease progression. The Danish Health Authority has issued guidelines on who should receive nirmatrelvir treatment.
There are also guidelines from the Infectious Disease Society.
See also:
Antiviral agents for COVID-19
Dosage Forms
Film-coated tablets. The package contains two different types of tablets:
Pink tablets containing 150 mg nirmatrelvir
White tablets containing 100 mg ritonavir
Dosage Recommendation
Adults:
300 mg nirmatrelvir (2 tablets of 150 mg) with
100 mg ritonavir (1 tablet of 100 mg)
Every 12 hours for 5 days.
Paxlovid should be administered as soon as possible after a COVID-19 diagnosis and within 5 days of symptom onset.
Important Notes:
Safety and efficacy have not been established in children and adolescents under 18 years old.
Can be taken with or without food.
Must be swallowed whole.
If absolutely necessary, both tablets may be split/crushed, but crushing may reduce ritonavir plasma concentration (white tablet).
General Dosage Guidelines
Handling of Tablets and Capsules
Film-coated tablets (150 mg + 100 mg)
Crushing/opening: Not recommended.
Administration: Swallow whole.
Food and drink: Can be taken with or without food.
Note:
If absolutely necessary, both tablets may be split/crushed, but this may reduce the plasma concentration of ritonavir (white tablet).
Kidney Function Impairment
Caution for Reduced Kidney Function
GFR Warning
<30 ml/min Low risk of toxicity for a 5-day treatment. 150 mg nirmatrelvir / 100 mg ritonavir (1 tablet of each) every 12 hours for 5 days may be given.
30-60 ml/min Dose reduction: 150 mg nirmatrelvir / 100 mg ritonavir (1 tablet of each) every 12 hours for 5 days.
Liver Function Impairment
Contraindicated in severe liver impairment (Child-Pugh C) due to lack of experience.
Hepatitis and other liver-related effects have occurred with ritonavir treatment.
Use with caution in patients with pre-existing liver disease, liver enzyme abnormalities, or hepatitis.
Contraindications
Drug Interactions:
Paxlovid is primarily metabolized via CYP3A4, and its inhibitory effect on CYP3A4 can increase the risk of serious side effects.
Potent CYP3A4 inducers can reduce Paxlovid’s plasma concentration, affecting its virological response and possibly leading to resistance.
Refer to Interactions section and product summary for further details.
Precautions
Monitoring
Bedaquiline/Delamanid: Frequent ECG monitoring recommended.
Steroids (e.g., budesonide): Close monitoring of local and systemic side effects is advised.
Midazolam: Close clinical monitoring is necessary, along with medical intervention in case of respiratory depression or prolonged sedation.
Cases of hypertension (non-severe and temporary) have been reported. Regular blood pressure monitoring is recommended, especially in elderly patients who have a higher risk of severe complications.
Side Effects
This medication has enhanced reporting requirements. All side effects must be reported to the Danish Medicines Agency.
System Organ Class Potentially Serious Side Effects Common (1-10%) Uncommon (0.1-1%) Rare (0.01-0.1%)
Gastrointestinal - Diarrhea, nausea, vomiting, taste disorders (e.g., metallic or bitter taste) Abdominal pain -
Nervous System - Headache - -
Immune System - - Hypersensitivity Anaphylactic reaction, Stevens-Johnson syndrome
Musculoskeletal System - - Myalgia -
Skin & Subcutaneous Tissue - - Itching, rash Toxic epidermal necrolysis (TEN)
Vascular Diseases Hypertension - - -
General Symptoms - - - Malaise
Note: Symptoms like rash and itching may indicate an allergic reaction.
Drug Interactions
Nirmatrelvir is a CYP3A inhibitor and may increase plasma concentrations of drugs metabolized by CYP3A.
Ritonavir inhibits CYP3A and CYP2D6, which can lead to interactions with antidepressants, antipsychotics, and opioids.
Serious interactions with calcineurin inhibitors and mTOR inhibitors (used as immunosuppressants) can be life-threatening.
Regular monitoring of immunosuppressant serum concentrations is necessary during and after Paxlovid treatment.
Significant Interactions (Non-Exhaustive List)
Adrenergic α1-receptor antagonist: Alfuzosin
Cancer medications: Neratinib, Venetoclax
Antiarrhythmics: Amiodarone, Dronedarone, Flecainide, Propafenone
Anti-infectives: Fusidic acid, Rifampicin, Itraconazole
Antiepileptics: Carbamazepine, Phenobarbital, Phenytoin
Gout medication: Colchicine
Antipsychotics: Lurasidone, Pimozide, Clozapine, Quetiapine
Ergot alkaloids: Ergotamine
Herbal medicine: St. John’s Wort
Lipid-lowering drugs: Simvastatin, Lomitapide
PDE5 inhibitors (for erectile dysfunction): Avanafil, Sildenafil, Vardenafil
Sedatives/hypnotics: Diazepam, Oral Midazolam, Triazolam
HIV drugs: Efavirenz, Maraviroc
Immunosuppressants: Ciclosporin, Tacrolimus, Everolimus, Sirolimus
Refer to product summary section 4.5 for detailed interactions.
Pregnancy & Breastfeeding
Not recommended due to insufficient data.
No sufficient human data for nirmatrelvir to estimate risks.
Ritonavir monotherapy appears safe, as per Norvir®.
Blood Donation
Not allowed for blood donation (2-week quarantine).
No quarantine required for plasma donation for fractionation.
Doping
No restrictions.
Alcohol Consumption
No interaction between alcohol and Paxlovid.
However, always follow the Danish Health Authority’s recommendations.
Indications
Treatment of COVID-19 in adults at increased risk of progressing to severe COVID-19.
Criteria for Nirmatrelvir Treatment
Confirmed SARS-CoV-2 infection via reverse transcription-polymerase chain reaction (RT-PCR), respiratory sample testing, or antigen/self-test; and
Significant COVID-19 symptoms lasting no more than 5 days; and
At-risk or high-risk patient; and
Outpatient or hospitalized for a condition other than COVID-19.
Note:
For high-risk patients, treatment may be offered based on an individual assessment, even for those with prolonged symptomatic COVID-19.
The definition of at-risk and high-risk patients can be found in the Danish Health Authority's guidelines or under disease progression. The Danish Health Authority has issued guidelines on who should receive nirmatrelvir treatment.
There are also guidelines from the Infectious Disease Society.
See also:
Antiviral agents for COVID-19
Dosage Forms
Film-coated tablets. The package contains two different types of tablets:
Pink tablets containing 150 mg nirmatrelvir
White tablets containing 100 mg ritonavir
Dosage Recommendation
Adults:
300 mg nirmatrelvir (2 tablets of 150 mg) with
100 mg ritonavir (1 tablet of 100 mg)
Every 12 hours for 5 days.
Paxlovid should be administered as soon as possible after a COVID-19 diagnosis and within 5 days of symptom onset.
Important Notes:
Safety and efficacy have not been established in children and adolescents under 18 years old.
Can be taken with or without food.
Must be swallowed whole.
If absolutely necessary, both tablets may be split/crushed, but crushing may reduce ritonavir plasma concentration (white tablet).
General Dosage Guidelines
Handling of Tablets and Capsules
Film-coated tablets (150 mg + 100 mg)
Crushing/opening: Not recommended.
Administration: Swallow whole.
Food and drink: Can be taken with or without food.
Note:
If absolutely necessary, both tablets may be split/crushed, but this may reduce the plasma concentration of ritonavir (white tablet).
Kidney Function Impairment
Caution for Reduced Kidney Function
GFR Warning
<30 ml/min Low risk of toxicity for a 5-day treatment. 150 mg nirmatrelvir / 100 mg ritonavir (1 tablet of each) every 12 hours for 5 days may be given.
30-60 ml/min Dose reduction: 150 mg nirmatrelvir / 100 mg ritonavir (1 tablet of each) every 12 hours for 5 days.
Liver Function Impairment
Contraindicated in severe liver impairment (Child-Pugh C) due to lack of experience.
Hepatitis and other liver-related effects have occurred with ritonavir treatment.
Use with caution in patients with pre-existing liver disease, liver enzyme abnormalities, or hepatitis.
Contraindications
Drug Interactions:
Paxlovid is primarily metabolized via CYP3A4, and its inhibitory effect on CYP3A4 can increase the risk of serious side effects.
Potent CYP3A4 inducers can reduce Paxlovid’s plasma concentration, affecting its virological response and possibly leading to resistance.
Refer to Interactions section and product summary for further details.
Precautions
Monitoring
Bedaquiline/Delamanid: Frequent ECG monitoring recommended.
Steroids (e.g., budesonide): Close monitoring of local and systemic side effects is advised.
Midazolam: Close clinical monitoring is necessary, along with medical intervention in case of respiratory depression or prolonged sedation.
Cases of hypertension (non-severe and temporary) have been reported. Regular blood pressure monitoring is recommended, especially in elderly patients who have a higher risk of severe complications.
Side Effects
This medication has enhanced reporting requirements. All side effects must be reported to the Danish Medicines Agency.
System Organ Class Potentially Serious Side Effects Common (1-10%) Uncommon (0.1-1%) Rare (0.01-0.1%)
Gastrointestinal - Diarrhea, nausea, vomiting, taste disorders (e.g., metallic or bitter taste) Abdominal pain -
Nervous System - Headache - -
Immune System - - Hypersensitivity Anaphylactic reaction, Stevens-Johnson syndrome
Musculoskeletal System - - Myalgia -
Skin & Subcutaneous Tissue - - Itching, rash Toxic epidermal necrolysis (TEN)
Vascular Diseases Hypertension - - -
General Symptoms - - - Malaise
Note: Symptoms like rash and itching may indicate an allergic reaction.
Drug Interactions
Nirmatrelvir is a CYP3A inhibitor and may increase plasma concentrations of drugs metabolized by CYP3A.
Ritonavir inhibits CYP3A and CYP2D6, which can lead to interactions with antidepressants, antipsychotics, and opioids.
Serious interactions with calcineurin inhibitors and mTOR inhibitors (used as immunosuppressants) can be life-threatening.
Regular monitoring of immunosuppressant serum concentrations is necessary during and after Paxlovid treatment.
Significant Interactions (Non-Exhaustive List)
Adrenergic α1-receptor antagonist: Alfuzosin
Cancer medications: Neratinib, Venetoclax
Antiarrhythmics: Amiodarone, Dronedarone, Flecainide, Propafenone
Anti-infectives: Fusidic acid, Rifampicin, Itraconazole
Antiepileptics: Carbamazepine, Phenobarbital, Phenytoin
Gout medication: Colchicine
Antipsychotics: Lurasidone, Pimozide, Clozapine, Quetiapine
Ergot alkaloids: Ergotamine
Herbal medicine: St. John’s Wort
Lipid-lowering drugs: Simvastatin, Lomitapide
PDE5 inhibitors (for erectile dysfunction): Avanafil, Sildenafil, Vardenafil
Sedatives/hypnotics: Diazepam, Oral Midazolam, Triazolam
HIV drugs: Efavirenz, Maraviroc
Immunosuppressants: Ciclosporin, Tacrolimus, Everolimus, Sirolimus
Refer to product summary section 4.5 for detailed interactions.
Pregnancy & Breastfeeding
Not recommended due to insufficient data.
No sufficient human data for nirmatrelvir to estimate risks.
Ritonavir monotherapy appears safe, as per Norvir®.
Blood Donation
Not allowed for blood donation (2-week quarantine).
No quarantine required for plasma donation for fractionation.
Doping
No restrictions.
Alcohol Consumption
No interaction between alcohol and Paxlovid.
However, always follow the Danish Health Authority’s recommendations.
