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June 27, 2023.
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Medicinal products listed are a guide and not considered a comprehensive list of all possible medicinal products that may interact with PAXLOVIDTM (nirmatrelvir tablets and ritonavir tablets). Visit pfizermedicalinformation.ca or call 1-800-463-6001.
DISCLAIMER: The information provided here is for informational purposes only. This tool may not cover all possible drug interactions. Although we attempt to provide accurate and up-to-date information, no guarantee is made to that
effect.
If your inquiry has not been answered, please review the Product Monograph here or contact Pfizer Medical Information via
1-800-463-6001 (Medical Information) or visit pfizermedicalinformation.ca.
Concomitant Drug Class |
Drug Name |
Effect on Concentration of PAXLOVID or Concomitant Drug |
Clinical Comment |
---|---|---|---|
Alpha1-adrenoreceptor Antagonist: |
alfuzosin |
↑ alfuzosin |
Based on results of a drug interaction study with ketoconazole, another potent inhibitor of CYP3A4, a significant increase in alfuzosin exposure is expected in the presence of ritonavir (600 mg twice daily). Therefore, alfuzosin is contraindicated with PAXLOVID (see the CONTRAINDICATIONS section of the Product Monograph). |
Alpha1-adrenoreceptor Antagonist: |
tamsulosin |
↑ tamsulosin |
Avoid concomitant use with PAXLOVID. |
Analgesics, Narcotic: |
fentanyl, hydrocodone, |
↑ fentanyl |
Ritonavir inhibits CYP3A4 and as a result is expected to increase the plasma concentrations of fentanyl. |
Analgesics, Narcotic: |
tramadol, |
↑ tramadol |
Ritonavir inhibits CYP3A4 and as a result is expected to increase the plasma concentrations of tramadol and propoxyphene. |
Analgesics, Narcotic: |
methadone |
↓ methadone |
Monitor methadone-maintained patients closely for evidence of withdrawal effects and adjust the methadone dose accordingly. |
Anesthetic: |
meperdine |
↓ meperidine |
Dosage increase and long-term use of meperidine with ritonavir are not recommended due to the increased concentrations of the metabolite normeperidine which has both analgesic activity and CNS stimulant activity (e.g., seizures). |
Antianginal: |
ranolazine |
↑ ranolazine |
Co-administration contraindicated due to potential for serious and/or life-threatening reactions (see the CONTRAINDICATIONS section of the Product Monograph). |
Antiarrhythmics: |
disopyramide, lidocaine (systemic), mexiletine |
↑ antiarrhythmic |
Plasma concentrations of these drugs are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Antiarrhythmics: |
amiodarone, bepridila, dronedarone, flecainide, propafenone, quinidinea |
↑ antiarrhythmic |
Co-administration may lead to serious and/or life-threatening reactions, such as cardiac arrhythmias. Therefore, use of these antiarrhythmics with PAXLOVID is contraindicated (see the CONTRAINDICATIONS section of the Product Monograph). |
Antibacterial: |
fusidic acid |
↑ fusidic acid |
Co-administration of protease inhibitors, including ritonavir with fusidic acid is expected to increase fusidic acid, as well as the protease inhibitor concentration in plasma (see the CONTRAINDICATIONS section of the Product Monograph). |
Anticancer agents: |
apalutamide |
↓ nirmatrelvir/ritonavir |
Co-administration is contraindicated (see the CONTRAINDICATIONS section of the Product Monograph). |
Anticancer agents: |
abemaciclib, ceritinib, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, vincristine, vinblastine |
↑ anticancer agents |
Serum concentrations increase when co-administered with ritonavir resulting in the potential for increased incidence of adverse events, some of which may be serious. |
Anticancer agents: |
venetoclax |
↑ venetoclax |
Concomitant use of strong CYP3A inhibitors, such as ritonavir, and venetoclax may increase the risk of tumor lysis syndrome at the dose initiation and during the ramp-up phase (see the CONTRAINDICATIONS section of the Product Monograph). |
Anticoagulants: |
apixaban |
↑ apixaban |
Combined P-gp and strong CYP3A4 inhibitors increase blood levels of apixaban and increase the risk of bleeding. Dosing recommendations for co-administration of apixaban with PAXLOID depend on the apixaban dose. Refer to the apixaban product label for more information. |
Anticoagulants: |
dabigatran |
↑ dabigatran |
Co-administration with PAXLOVID results in increasing dabigatran exposure and an increased risk of bleeding. Depending on dabigatran indication and renal function, reduce dose of dabigatran or avoid concomitant use. Refer to the dabigatran product label for further information. |
Anticoagulants: |
rivaroxaban |
↑ rivaroxaban |
A study has shown that co-administration of ritonavir and rivaroxaban resulted in increased exposure of rivaroxaban which may lead to risk of increased bleeding. Co-administration of PAXLOVID and rivaroxaban is contraindicated (see the CONTRAINDICATIONS section of the Product Monograph). |
Anticoagulants: |
warfarin |
↓ R-warfarin |
Initial frequent monitoring of the INR (International Normalized Ratio) during ritonavir and warfarin co-administration is indicated. |
Anticonvulsants: |
clonazepam, |
↑ clonazepam |
Plasma concentrations of clonazepam and ethosuximide are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed and clinical monitoring is recommended. |
Anticonvulsants: |
carbamazepine, phenobarbital, phenytoin, primidone |
↑ carbamazepine |
Co-administration of PAXLOVID with carbamazepine, phenobarbital, phenytoin or primidone is contraindicated (see the CONTRAINDICATIONS section of the Product Monograph). |
Antidepressants: |
amitriptyline, clomipramine, fluoxetine, imipramine, maprotilinea, nefazodonea, nortriptyline, paroxetine, sertraline, trimipramine, venlafaxine |
↑ antidepressants |
Ritonavir dosed as a pharmacokinetic enhancer is not expected to result in any clinically meaningful increases in CYP2D6 substrates. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Antidepressants: |
bupropion |
↓ bupropion and active metabolite hydroxy bupropion |
Bupropion is primarily metabolized by CYP2B6. Concurrent administration of bupropion with repeated doses of ritonavir decreases bupropion levels. Monitor for an adequate clinical response to bupropion. |
Antidepressants: |
desipramine |
↑ desipramine |
A study has shown that co-administration of ritonavir and desipramine resulted in increased exposure of desipramine. Dosage reduction and concentration monitoring of desipramine is recommended. |
Antidepressants: |
trazodone |
↑ trazodone |
Concomitant use of ritonavir and trazodone increases concentrations of trazodone. Adverse events of nausea, dizziness, hypertension, and syncope have been observed. If trazodone is used with a CYP3A4 inhibitor, such as ritonavir, the combination should be used with caution and a lower dose of trazodone should be considered. |
Antiemetics: |
dronabinola |
↑ dronabinol |
Plasma concentrations of dronabinol are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of dronabinol may be needed. |
Antifungal: |
ketoconazole, isavuconazonium sulfate, itraconazole |
↑ ketoconazole |
High doses of ketoconazole or itraconazole (>200 mg/day) are not recommended. Refer to ketoconazole, isavuconazonium sulfate, and itraconazole product labels for further information. |
Antifungal: |
voriconazole |
↓ voriconazole |
Avoid concomitant use of voriconazole. |
Antigout: |
colchicine |
↑ colchicine |
For patients with renal and/or hepatic impairment: |
Anti-infective: |
clarithromycin, erythromycin |
↑ clarithromycin |
For patients with renal impairment, the following dosage adjustments should be considered: |
Antimycobacterial: |
rifabutin |
↑ rifabutin and rifabutin metabolite |
Dosage reduction of rifabutin by at least three- quarters of the usual dose of 300 mg/day is recommended (e.g., 150 mg every other day or 3 times a week). Further dosage reduction may be necessary. |
Antimycobacterial: |
rifampin |
↓ ritonavir |
Co-administration of PAXLOVID with rifampin is contraindicated due to potential loss of virologic response and possible resistance. Alternate antimycobacterial drugs such as rifabutin should be considered (see the CONTRAINDICATIONS section of the Product Monograph). |
Antiparasitics: |
atovaquone |
↓ atovaquone |
Plasma concentrations of atovaquone are expected to decrease by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose increase of atovaquone may be needed. |
Antiparasitics: |
quinine |
↑ quinine |
Plasma concentrations of quinine are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of quinine may be needed. |
Anxiolytics/Sedative/Hypnotics: |
triazolam, midazolam, orala |
↑ triazolam |
Midazolam is extensively metabolized by CYP3A4. Increases in the concentration of midazolam are expected to be significantly higher with oral than parenteral administration. Co-administration is contraindicated due to potential for extreme sedation and respiratory depression (see the CONTRAINDICATIONS section of the Product Monograph). |
Anxiolytics/Sedative/Hypnotics: |
midazolam, parenteral |
↑ midazolam |
Concomitant use of parenteral midazolam with ritonavir may increase plasma concentrations of midazolam. Coadministration should be done in a setting which ensures close clinical monitoring and appropriate medical management in case of respiratory depression and/or prolonged sedation. Dosage reduction for midazolam should be considered, especially if more than a single dose of midazolam is administered. |
Anxiolytics/Sedative/Hypnotics: |
buspirone, clorazepate, diazepam, estazolama, flurazepam, zolpidem |
↑ Anxiolytics/ Sedatives/ Hypnotics |
Plasma concentrations of these drugs are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Benign prostatic hyperplasia agents: |
silodosin |
↑ silodosin |
Co-administration is contraindicated due to potential for postural hypotension (see the CONTRAINDICATIONS section of the Product Monograph). |
Beta-blockers: |
metoprolol, timolol |
↑ beta-blockers |
Plasma concentrations of these drugs are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Bronchodilator: |
theophylline |
↓ theophylline |
Increased dosage of theophylline may be required; therapeutic monitoring should be considered. |
Calcium channel blockers: |
amlodipine, diltiazem, felodipine, nicardipine, nifedipine, verapamil |
↑ calcium channel blocker |
Plasma concentrations of these drugs are expected to increase by co-administration with ritonavir. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Cardiovascular agents: |
eplerenone |
↑ eplerenone |
Co-administration with eplerenone is conraindicated due to potential for hyperkalemia (see the CONTRAINDICATIONS section of the Product Monograph). |
Cardiovascular agents: |
ivabradine |
↑ ivabradine |
Co-administration with ivabradine is conraindicated due to potential for bradycardia or conduction disturbances (see the CONTRAINDICATIONS section of the Product Monograph). |
Cardiovascular agents: |
aliskiren, ticagrelor, vorapraxar, clopidogrel |
↑ aliskiren |
Avoid concomitant use with PAXLOVID. |
Corticosteroids: |
budesonide, fluticasone propionate, triamcinolone |
↑ fluticasone |
Concomitant use of ritonavir and inhaled, injectable, or intranasal fluticasone propionate, budesonide, triamcinolone, or other glucocorticoids that are metabolized by CYP3A4 are not recommended unless the potential benefit of treatment outweighs the risk of systemic corticosteroid side effects, including Cushing’s syndrome and adrenal suppression. |
Corticosteroids: |
dexamethasone |
↑ dexamethasone |
Dexamethasone, which increases CYP3A activity, would be expected to increase the clearance of ritonavir resulting in decreased ritonavir plasma concentrations. |
Corticosteroids: |
prednisone |
↑ prednisone |
Plasma concentrations of dexamethasone and prednisone are expected to increase by |
Corticosteroids: |
digoxin |
↑ digoxin |
A literature report has shown that |
Cystic fibrosis transmembrane conductance regulator potentiators: |
lumacaftor/ivacaftor |
↓ nirmatrelvir/ritonavir |
Co-administration is contraindicated due to potential loss of virologic response and possible resistance (see the CONTRAINDICATIONS section of the Product Monograph). |
Cystic fibrosis transmembrane conductance regulator potentiators: |
ivacaftor |
↑ ivacaftor |
Reduce dosage when co-administered with PAXLOVID. |
Cystic fibrosis transmembrane conductance regulator potentiators: |
elexacaftor/tezacaftor/ivacaftor, tezacaftor/ivacaftor |
↑elexacaftor/tezacaftor/ivacaftor |
Refer to individual product labels for more information. |
Dipeptidyl peptidase 4 (DPP4) inhibitors: |
saxagliptin |
↑ saxagliptin |
Dosage adjustment of saxagliptin is recommended. Refer to the saxagliptin product label for more information. |
Endothelin receptor antagonist: |
bosentan |
↑ bosentan |
Discontinue use of bosentan at least 36 hours prior to initiation of PAXLOVID. |
Ergot derivatives: |
dihydroergotamine, ergotamine, methylergonovinea |
↑ dihydroergotamine |
Co-administration is contraindicated due to potential for acute ergot toxicity characterized by vasospasm and ischemia of the extremities and other tissues including the central nervous system (see the CONTRAINDICATIONS section of the Product Monograph). |
Gonadotropin releasing hormone (GnRH) receptor antagonist: |
elagolix |
↑ elagolix |
Coadministration of elagolix with ritonavir could increase elagolix exposure due to inhibition of CYP3A and P-gp. Known serious adverse events for elagolix include suicidal ideation and hepatic transaminase elevations. In addition, elagolix is a weak/moderate inducer of CYP3A, which may decrease exposure of ritonavir. Refer to the elagolix label for dosing information with strong CYP3A4 inhibitors. |
HCV-Antiviral Agents |
elbasvir/grazoprevir, glecaprevir/pibrentasvir, ombitasvir/paritaprevir/ritonavir with or without dasabuvira, sofosbuvir/velpatasvir/voxilaprevir |
↑ antiviral |
Increased grazoprevir concentrations can result in ALT elevations. |
HCV-Antiviral Agents |
simeprevira |
↑ simeprevir |
A pharmacokinetic study demonstrated that concomitant administration of simeprevir 200 mg once daily with ritonavir 100 mg twice daily resulted in an increase in simeprevir concentrations. It is not recommended to co-administer PAXLOVID with simeprevir. |
Herbal products: |
St. John's Wort (hypericum perforatum) |
↓ nirmatrelvir/ritonavir |
Co-administration is contraindicated due to potential loss of virologic response and possible resistance (see the CONTRAINDICATIONS section of the Product Monograph). |
HIV-Antiretroviral Agents |
fosamprenavir |
↑ amprenavir |
Refer to the fosamprenavir Product Monograph for details on co-administration of fosamprenavir 700 mg twice daily with ritonavir 100 mg twice daily or fosamprenavir 1400 mg once daily with ritonavir 200 mg once daily. |
HIV-Antiretroviral Agents |
atazanavir |
↑ atazanavir |
Atazanavir plasma concentrations achieved with atazanavir 300 mg once daily and ritonavir 100 mg once daily are higher than those achieved with atazanavir 400 mg once daily. |
HIV-Antiretroviral Agents |
darunavir |
↑ darunavir |
Refer to the darunavir Product Monograph for details on co-administration of darunavir |
HIV-Antiretroviral Agents |
indinavira |
↑ indinavir |
Alterations in concentrations are noted when reduced doses of indinavir are co-administered with reduced dose of ritonavir. |
HIV-Antiretroviral Agents |
nelfinavir |
↑ M8 (major active metabolite of nelfinavir) |
Ritonavir increases the concentrations of nelfinavir major active metabolite, M8. This interaction is likely to involve cytochrome P450 inhibition and induction. |
HIV-Antiretroviral Agents |
saquinavir |
↑ saquinavir |
The recommended dosage regimen is saquinavir 1000 mg with ritonavir 100 mg twice daily taken within 2 hours after a meal. Dose adjustment may be needed if other HIV-protease inhibitors are used in combination with saquinavir and ritonavir. Saquinavir and ritonavir should not be given together with rifampin due to risk of severe hepatotoxicity (presenting as increased hepatic transaminases) if the 3 drugs are given together. |
HIV-Antiretroviral Agents |
tipranavir |
↑ tipranavir |
Refer to the tipranavir Product Monograph for details on co-administration of tipranavir |
HIV-Antiretroviral Agents |
didanosinea |
↓ didanosine |
Dosing of didanosine and ritonavir should be separated by 2.5 hours to avoid formulation incompatibility. |
HIV-Antiretroviral Agents |
tenofovir |
↑ tenofovir |
Lopinavir/ritonavir has been shown to increase tenofovir concentrations. Higher tenofovir concentrations could potentiate tenofovir- associated adverse events, including renal disorders. Patients receiving ritonavir and tenofovir disoproxil fumarate should be monitored for tenofovir-associated adverse events. Refer to the tenofovir Product Monograph for more information. |
HIV-Antiretroviral Agents |
zidovudine, emtricitabine |
↓ zidovudine |
For further information, refer to the respective anti-HIV drugs prescribing information. |
HIV-Antiretroviral Agents |
delavirdinea |
↑ ritonavir |
When used in combination with delavirdine, a dose reduction of ritonavir should be considered. Based on comparison to historical data, the pharmacokinetics of delavirdine did not appear to be affected by ritonavir. The safety and efficacy of this combination (delavirdine/ ritonavir) have not been established. |
HIV-Antiretroviral Agents |
efavirenz |
↑ efavirenz |
In healthy volunteers receiving 500 mg ritonavir twice daily with efavirenz 600 mg once daily, the steady state AUC was increased by 21%. An associated increase in the AUC of ritonavir of 17% was observed. |
HIV-Antiretroviral Agents |
nevirapine |
↑ nevirapine |
For further information, refer to the respective anti-HIV drugs prescribing information. |
HIV-Antiretroviral Agents |
raltegravir |
↓ raltegravir |
A pharmacokinetic study showed that co-administration of ritonavir 100 mg twice daily and raltegravir 400 mg single dose resulted in a reduction in raltegravir plasma concentration. |
HIV-Antiretroviral Agents |
bictegravir |
↑ bictegravir |
For further information, refer to the respective anti-HIV drugs prescribing information. |
HIV-Antiretroviral Agents |
maraviroc |
↑ maraviroc |
When co-administered with reduced doses of ritonavir plasma levels of maraviroc increases. The dose of maraviroc should be decreased during co-administration with ritonavir. Refer to the maraviroc Product Monograph for details on co-administration of maraviroc 150 mg twice daily with ritonavir. |
Hypolipidemics, HMG-CoA Reductase Inhibitors: |
lovastatin, simvastatin |
↑ lovastatin, simvastatin |
The HMG-CoA reductase inhibitors simvastatin and lovastatin are highly dependent on CYP3A for metabolism, thus concomitant use of ritonavir with simvastatin or lovastatin is contraindicated due to an increased risk of myopathy including rhabdomyolysis (see the CONTRAINDICATIONS section of the Product Monograph). Discontinue use of lovastatin and simvastatin at least 12 hours prior to initiation of PAXLOVID, during the 5 days of PAXLOVID treatment and for 5 days after completing PAXLOVID. |
Hypolipidemics, HMG-CoA Reductase Inhibitors: |
lomitapide |
↑ lomitapide |
Lomitapide is a sensitive substrate for CYP3A4 metabolism. CYP3A4 inhibitors increase the exposure of lomitapide, with strong inhibitors increasing exposure approximately 27-fold. |
Hypolipidemics, HMG-CoA Reductase Inhibitors: |
atorvastatin, rosuvastatin |
↑ atorvastatin, rosuvastatin |
Caution must also be exercised, and reduced doses should be considered if ritonavir is used concurrently with atorvastatin, which is metabolized to a lesser extent by CYP3A4. |
Immunosuppressants: |
cyclosporine, tacrolimus, everolimus, sirolimus, rapamycina |
↑ immunosuppressants |
Avoid use of PAXLOVID when close monitoring of immunosuppressant concentrations is not feasible. If co-administered, dose adjustment of the imunosuppressant and monitoring for immunosuppressant concentrations and immunosuppressant-associated adverse reactions is recommended. Refer to the individual immunosuppressant product label for further information and obtain expert consultation from the patient's immunosuppressive therapy specialist. |
Janus kinase (JAK) inhibitors: |
tofacitinib |
↑ tofacitinib |
Dosage adjustment of tofacitinib is recommended. Refer to the tofacitinib product label for more information. |
Janus kinase (JAK) inhibitors: |
upadacitinib |
↑ upadacitinib |
Dosing recommendations for co-PAXLOVID depends on upadacitinib indication. Refer to the upadacitinib product label for more information. |
Kinase inhibitors (also see Anticancer agents above): |
fostamatinib |
↑ fostamatinib |
Co-administration of fostamatinib with ritonavir could increase fostamatinib metabolite R406 exposure resulting in dose-related adverse events such as hepatotoxicity and neutropenia. Monitor for toxicities of fostamatinib that may require fostamatinib dose modification (see fostamatinib Product Monograph). |
Long-acting beta adenoceptor agonist: |
salmeterol |
↑ salmeterol |
Co-administration is not recommended. Avoid concomitant use with PAXLOVID. The combination may result in increased risk of cardiovascular adverse events associated with salmeterol, including QT prolongation, palpitations, and sinus tachycardia. |
Migraine medications: |
eletriptan |
↑ eletriptan |
Co-administration of eletriptan within at least 72 hours of PAXLOVID is contraindicated due to potential for serious adverse reactions including cardiovascular and cerebrovascular events (see the CONTRAINDICATIONS section of the Product Monograph). |
Migraine medications: |
ubrogepant |
↑ ubrogepant |
Co-administration of ubrogepant with PAXLOVID is contraindicated due to potential for serious adverse reactions (see the CONTRAINDICATIONS section of the Product Monograph). |
Mineralocorticoid receptor antagonists: |
finerenone |
↑ finerenone |
Co-administration is contraindicated due to potential for serious adverse reactions including hyperkalemia, hypotension, and hyponatremia (see the CONTRAINDICATIONS section of the Product Monograph). |
Muscarinic receptor antagonists: |
darifenacin |
↑ darifenacin |
The darifenacin daily dose should not exceed 7.5 mg when co-administered with PAXLOVID. Refer to the darifenacin product label for more information. |
Neuroleptics/Antipsychotics: |
clozapine |
↑ clozapine |
If co-administration is necessary, consider reducing the clozapine dose and monitor for adverse reactions. |
Neuroleptics/Antipsychotics: |
lurasidone |
↑ lurasidone |
Due to CYP3A inhibition by ritonavir, concentrations of lurasidone are expected to increase. Co-administration of lurasidone with PAXLOVID is contraindicated (see the CONTRAINDICATIONS section of the Product Monograph). |
Neuroleptics/Antipsychotics: |
perphenazine, risperidone, thioridazinea |
↑ neuroleptics |
Ritonavir dosed as a pharmacokinetic enhancer is not expected to result in any clinically meaningful increases in CYP2D6 substrates. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Neuroleptics/Antipsychotics: |
pimozide |
↑ pimozide |
Co-administration of PAXLOVID with pimozide is contraindicated as it may lead to serious and/or life-threatening reactions, such as cardiac arrhythmias (see the CONTRAINDICATIONS section of the Product Monograph). |
Neuroleptics/Antipsychotics: |
quetiapine |
↑ quetiapine |
Due to inhibition of CYP3A by PAXLOVID (ritonavir), co-administration of PAXLOVID with quetiapine may result in increased quetiapine concentrations. Serious and life-threatening quetiapine-related adverse reactions have been reported with CYP3A inhibitors. PAXLOVID should not be used in combination with quetiapine. |
Neuropsychiatric agents: |
suvorexanta, aripiprazole, brexpiprazole, cariprazine, iloperidonea, lumateperonea, pimavanserina |
↑ suvorexant |
Avoid concomitant use of suvorexant with PAXLOVID. |
Opioid antagonists: |
naloxegol |
↑ naloxegol |
Co-administration is contraindicated due to the potential for opioid withdrawal symptoms (see the CONTRAINDICATIONS section of the Product Monograph). |
Oral Contraceptive or Patch Contraceptive: |
ethinyl estradiol |
↓ ethinyl estradiol |
Co-administration with ritonavir results in reduced ethinyl estradiol concentrations. Dosage increase or alternate contraceptive measures should be considered. An additional, non-hormonal method of contraception should be considered during the 5 days of PAXLOVID treatment and until one menstrual cycle after stopping PAXLOVID. |
PDE5 inhibitors (erectile dysfunction agents): |
sildenafil, tadalafil, vardenafil |
↑ sildenafil |
Particular caution should be used when prescribing PDE5 inhibitors for the treatment of erectile dysfunction in patients receiving PAXLOVID. Co-administration of PAXLOVID with these drugs is expected to substantially increase their concentrations and may result in increase in associated adverse events, such as hypotension, syncope, visual changes, and prolonged erection. |
PDE5 inhibitors (pulmonary hypertension agents): |
sildenafil (Revatio®) |
↑ sildenafil |
Co-administration of sildenafil with PAXLOVID is contraindicated due to the potential for sildenafil |
PDE5 inhibitors (pulmonary hypertension agents): |
tadalafil (Adcirca®) |
↑ tadalafil |
Avoid concomitant use of tadalafil with PAXLOVID. |
sGC stimulators (pulmonary hypertension agents): |
riociguat |
↑ riociguat |
Dosage adjustment is recommended for riociguat. Refer to the riociguat product label for more information. |
Serotonin receptor 1A agonist/ serotonin receptor 2A antagonist: |
flibanserin |
↑ flibanserin |
Co-administration is contraindicated due to potential for hypotension, syncope, and CNS depression (see the CONTRAINDICATIONS section of the Product Monograph). |
Stimulants: |
methamphetamine |
↑ methamphetamine |
Ritonavir dosed as a pharmacokinetic enhancer is not expected to result in any clinically meaningful increases in CYP2D6 substrates. Therefore, PAXLOVID should be used with caution, dose reduction of these drugs may be needed. |
Vasopressin receptor antagonists: |
tolvaptan |
↑ tolvaptan |
Co-administration is contraindicated due to potential for dehydration, hypovolemia and hyperkalemia (see the CONTRAINDICATIONS section of the Product Monograph). |
Medicinal Product |
Medicinal Products |
Clinical Comments |
---|---|---|
Antiarrhythmics |
amiodarone, |
Potentially increased concentration of these antiarrhythmics drugs. If coadministered, refer to individual product label for antiarrhythmics for further information. |
Anticancer agents |
abemaciclib, |
Potentially increased concentration of these anticancer agents. Coadministration should be considered only if the benefits outweigh the risks. For further information, refer to individual product label for anticancer drug. |
Anticoagulants |
warfarin rivaroxaban |
Potentially decreased R-warfarin concentrations, which may lead to reduced anticoagulation. Potentially increased rivaroxaban concentrations, which may lead to an increased bleeding risk. Coadministration should be considered only if the benefits outweigh the risks. |
Anticonvulsants |
carbamazepine |
Decreased PAXLOVID™ concentrations. Potentially increased carbamazepine plasma concentrations. Potentially decreased phenytoin and phenobarbital concentrations. Coadministration of PAXLOVID™ with carbamazepine, phenobarbital, or phenytoin is not recommended. |
Antidepressants |
bupropion trazodone |
Potentially decreased bupropion and active metabolite, hydroxy-bupropion, concentrations. Coadministration should be considered only if the benefits outweigh the risks. Potentially increased trazodone concentrations. Adverse reactions of nausea, dizziness, hypotension, and syncope have been observed following coadministration of trazodone and ritonavir. Refer to trazadone product label for further information. |
Antifungals |
ketoconazole, |
Potentially increased concentrations of ketoconazole, itraconazole, and isavuconazonium sulfate. Potentially |
Anti-HIV protease inhibitors |
amprenavir, |
Potentially increased concentrations of protease inhibitors. Coadministration should be considered only if the benefits outweigh the risks. For further information, refer to therespective protease inhibitors’ prescribing information. |
Anti-HIV |
didanosine, |
Potentially increased plasma concentrations of didanosine, efavirenz, and maraviroc. Potentially decreased plasma concentrations of raltegravir and zidovudine. For further information, refer to the respective anti-HIV drugs’ prescribing information. |
Anti-infective |
clarithromycin, |
Potentially increased plasma concentrations of clarithromycin and erythromycin. Coadministration should be considered only if the benefits outweigh the risks. |
Antimycobacterial |
bedaquiline rifabutin |
Potentially increased plasma concentrations of bedaquiline and rifabutin. Coadministration should be considered only if the benefits outweigh the risks. If coadministered with rifabutin, refer to rifabutin product label for further information. |
Antipsychotics |
quetiapine |
Potentially increased concentrations of quetiapine. Coadministration is not recommended. If coadministered, refer to quetiapine product label for further information. |
Calcium channel blockers |
amlodipine, |
Potentially increased concentrations of these calcium channel blockers. If coadministered, refer to individual product label for calcium channel blocker for further information. |
Cardiac glycosides |
digoxin |
Potentially increased concentrations. |
Endothelin receptor antagonists |
bosentan |
Potentially increased concentrations. |
Hepatitis C direct-acting antivirals |
elbasvir/grazoprevir, |
Potentially increased concentrations. Increased grazoprevir concentrations can result in ALT elevations. Coadministration should be considered only if the benefits outweigh the risks. Coadministration is not recommended. |
HMG-CoA reductase |
atorvastatin, rosuvastatin |
Potentially increased concentrations. Consider temporary discontinuation of atorvastatin and rosuvastatin during treatment with PAXLOVID™. |
Hormonal contraceptive |
ethinyl estradiol |
Potentially decreased ethinyl estradiol concentrations. An additional, nonhormonal method of contraception should be considered. |
Immunosuppressants |
cyclosporine, |
Potentially increased concentrations of cyclosporine, tacrolimus, and sirolimus. If coadministered, refer to individual product label for immununosuppressant for further information. |
Long-acting beta-adrenoceptor agonist |
salmeterol |
Increased concentrations of salmeterol. Coadministration may result in increased risk of cardiovascular adverse events associated with salmeterol, including QT prolongation, palpitations, and sinus tachycardia. Coadministration should be considered only if the benefits outweigh the risks. |
Narcotic analgesics |
fentanyl methadone |
Potentially increased concentrations of fentanyl possibly leading to fatal respiratory depression. Potentially decreased plasma concentrations of methadone. Coadministration should be considered only if the benefits outweigh the risks. |
Sedative/hypnotics |
midazolam (administered |
Potentially increased concentrations of midazolam, possibly leading to respiratory depression and/or prolonged sedation. Coadministration is not recommended. |
Systemic corticosteroids |
betamethasone, |
Potentially increased concentrations of corticosteroids. Coadministration should be considered only if the benefits outweigh the risks. |
a. Product not marketed in Canada
↑ Indicates increase; ↓ indicates decrease; ↔ indicates no change.
Medical Questions
Call 1-800-463-6001 (Medical Information) or visit pfizermedicalinformation.ca.
General Inquiries
Call our customer service line at 1-888-888-9221 or email us at [email protected].
Reporting a Side Effect
We encourage you to visit our designated safety web portal, where you can efficiently and seamlessly report your experience with PAXLOVID. You can access this web portal at www.pfizersafetyreporting.com.
Recipients or their caregivers should contact their healthcare professional if they experience an adverse event after receiving PAXLOVID. Please refer them to the Patient Medication Information.
Media Requests
Call 1-866-9PFIZER (1-866-973-4937) or email [email protected].
This material was developed by Pfizer, as part of the risk minimization plan for PAXLOVID. This material is not intended for promotional use.
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