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JAMA Network logoLink to JAMA Network
. 2022 Jul 6;5(7):e2220184. doi: 10.1001/jamanetworkopen.2022.20184

Drug Interactions With Nirmatrelvir-Ritonavir in Older Adults Using Multiple Medications

Sydney B Ross 1, Émilie Bortolussi-Courval 2,3, Ryan Hanula 2,3, Todd Campbell Lee 2,3,4, Marnie Goodwin Wilson 5, Emily G McDonald 2,3,6,
PMCID: PMC9260479  PMID: 35793089

Abstract

This quality improvement study uses data from the MedSafer trial to evaluate drug-drug interactions between nirmatrelvir-ritonavir and maintenance medications to identify use of potentially inappropriate medications in older adults with polypharmacy.

Introduction

The antiviral nirmatrelvir-ritonavir reduces the risk of severe complications in high-risk, symptomatic, unvaccinated adults with COVID-19.1 However, the ritonavir component has several important drug-drug interactions (DDIs), particularly through CYP3A4 inhibition. We used data from the MedSafer cluster randomized clinical trial2 (ClinicalTrials.gov Identifier NCT03272607) to identify DDIs between nirmatrelvir-ritonavir and potentially inappropriate medications (PIMs) in older adults with polypharmacy and to craft deprescribing guidance.

Methods

Ethics board approval was obtained from the study sites of the MedSafer trial,2 and participants provided consent to the secondary use of data. Additional details for the present quality improvement study are provided in the eMethods in the Supplement. We followed the SQUIRE reporting guideline.3

Briefly, the MedSafer trial enrolled hospitalized adults 65 years or older who were taking 5 or more medications. Data pertaining to medications and comorbidities were analyzed according to an expert rule set for identifying PIMs (eMethods in the Supplement). Deprescribing reports were provided to the treating teams and compared with usual care to prevent postdischarge adverse drug events.

Herein, we theoretically exposed the trial cohort to treatment with nirmatrelvir-ritonavir to identify DDIs with maintenance medications and, specifically, with PIMs (candidate drugs for deprescribing). We linked these interactions with potential harms, which were classified as other, moderate, or severe (eMethods in the Supplement). The DDIs were identified from the product monograph,4 drug interaction checker website,5 and exclusion criteria from the EPIC-HR trial.1 We crafted mitigation strategies to diminish DDIs. Strategies included (1) anticipatory deprescribing for drugs that cannot simply be held or dose-reduced at the time of nirmatrelvir-ritonavir exposure, and/or (2) deprescribing at the approximate time of nirmatrelvir-ritonavir receipt. Recommendations were based on the literature and our expert opinion (E.G.M., T.C.L., M.G.W., S.B.R.).2,6 Data were analyzed from January 20 to February 8, 2022.

Results

The MedSafer trial2 included 5698 patients (median [IQR] age, 78 [71-86] years; 2858 women [50.2%], 2840 men [49.8%]). The median (IQR) number of daily at-home medications was 10 (8-14) and PIMs was 2 (1-4).

Of 5698 patients, 3869 (67.9%) received at least 1 interacting medication prescription (Table 1). The most common DDIs were with antithrombotic medications (2131 [37.4%]) or statins (1901 [33.4%]). Among the 3869 patients with interacting medication prescriptions, 823 (21.3%) had at least 1 PIM, of whom 627 (76.2%) had a high-risk DDI with nirmatrelvir-ritonavir. Common deprescribing opportunities included dual anticoagulant therapy without a recent coronary event or intervention (200 of 489 [41.0%]), alfuzosin or tamsulosin for benign prostatic hypertrophy in a person with orthostatic hypotension or recurrent falls (174 of 779 [22.3%]), and antipsychotics for sleep or agitation (62 of 274 [22.6%]) (Table 2).

Table 1. Prevalence of Common Oral Medications With Potential Drug-Drug Interactions With Nirmatrelvir-Ritonavira.

Interacting drug class Patients with interacting medication, No. (%)b Interacting medication Interaction Severity Potential interaction with nirmatrelvir-ritonavir
Antiarrhythmics 155 (2.7) Quinidine, flecainide, propafenone, amiodarone, dronedaronec Severe CYP3A4 inhibition may increase the serum concentrations; potential for serious and/or life-threatening reactions, such as cardiac arrhythmias
225 (4.0) Digoxinc Severe P-gp substrate inhibition may increase the serum concentration of digoxin, increasing toxic effect.
0 Ranolazine Severe Potential for serious and/or life-threatening reactions
Oral antithrombotic agents 551 (9.7) Warfarinc Moderate CYP3A4 inhibition may decrease serum concentrations; potential for reduced anticoagulation
111 (1.9) Dabigatranc Moderate Mixed P-gp substrate inhibition and induction; increased risk of bleeding and possible toxic effect
375 (6.6) Rivaroxabanc Severe CYP3A4 and P-gp substrate inhibition may increase the serum concentrations, increasing toxic effect and risk of bleeding
602 (10.6) Apixabanc Moderate
3 (<0.1) Edoxabanc Moderate P-gp inhibition may increase plasma concentrations
42 (0.7) Ticagrelorc Severe CYP3A4 inhibition may increase plasma concentrations
447 (7.8) Clopidogrelc Severe CYP3A4 induction, decreased plasma concentration, and increased risk of atherothrombotic events
Anticonvulsants 87 (1.5) Phenobarbital, carbamazepine, phenytoinc Other CYP3A4 induction, decreased plasma concentration, and reduced clinical effects of nirmatrelvir-ritonavir
Lipid modifying agents 176 (3.1) Lovastatin, simvastatinc Severe CYP3A4 inhibition may increase serum concentrations; potential for serious myopathy or rhabdomyolysis
1725 (30.3) Atorvastatinc Moderate
PDE5i 28 (0.5) Sildenafil, vardenafilc Severe CYP3A4 inhibition may increase serum concentrations; potential for serious hypotension or syncope
α1-blockers 35 (0.6) Alfuzosinc Severe CYP3A4 inhibition may increase serum concentrations; potential for serious reactions, such as hypotension
744 (13.1) Tamsulosinc Moderate
Antipsychotics 274 (4.8) Clozapine, lurasidone, quetiapine, pimozidec Severe CYP3A4 inhibition may increase serum concentrations; potential for serious and/or life-threatening reactions, such as cardiac arrhythmias, hematologic abnormalities, and coma
NSAIDs 1 (<0.1) Piroxicamc Severe Potential for life-threatening cardiac arrhythmias
GI motility drugs 0 Cisapridec Severe Potential for life-threatening cardiac arrhythmias
Opioids 56 (1.0) Fentanylc Severe CYP3A4 inhibition may increase serum concentrations; serious or life-threatening respiratory depression
20 (0.4) Methadonec Other CYP3A4 induction, decreased plasma concentration, and reduced clinical effect of methadone
Immunosuppressants 89 (1.6) Tacrolimus Severe CYP3A4 inhibition may increase plasma concentrations; substantial risk for rapid onset of tacrolimus toxic effect
Ergot derivatives 0 Ergotamine, ergonovine Severe CYP3A4 inhibition may increase serum concentrations; potential for serious and/or life-threatening reactions such as ischemia of extremities, coma, and even death
Sedative hypnotics 35 (0.6) Diazepam, midazolam, triazolamc Severe CYP3A4 inhibition may increase serum concentrations; potential for extreme sedation or respiratory depression
Antigout agents 117 (2.1) Colchicinec Severe CYP3A4 inhibition may increase serum concentrations; potential for serious and/or life-threatening toxic effect

Abbreviations: GI, gastrointestinal; NSAID, nonsteroidal anti-inflammatory drug; PDE5i, phosphodiesterase type 5 inhibitors; P-gp, P-glycoprotein.

a

Not listed are the following medications with important drug-drug interactions with nirmatrelvir-ritonavir: estrogen containing hormone contraceptives, chemotherapy drugs, antifungals (eg, voriconazole [n = 2, <0.1%]), antimycobacterials (eg, rifampin [n = 8, 0.1%]), long-acting inhaled β agonists (eg, salmeterol [n = 424, 7.4%]), and St John’s Wort (not captured).

b

Many of these medications are potentially inappropriate only under certain clinical circumstances (Table 2 details potential triggering conditions or triggering medications).

c

Potentially inappropriate medications (candidate drugs for deprescribing).

Table 2. Management for Potentially Inappropriate Medications With Nirmatrelvir-Ritonavir Drug-Drug Interactions.

PIMa Interacting medication or class flagged as PIM, No./total No. (%)b Triggering condition or medication for PIM alertc General rationale for deprescribing Preemptive deprescribing required? Suggested medication management for nirmatrelvir-ritonavir interaction if unable to deprescribe in advance
Amiodarone 61/126 (48.4) Atrial fibrillation Amiodarone is associated with multiple toxic effects, including thyroid disease, pulmonary disorders, and QT interval prolongation. Consider a safer alternative. Yes Do not coadminister. If unable to deprescribe well in advance (wks), likely precludes use of nirmatrelvir-ritonavir given increased risk of life-threatening cardiac arrhythmias.
Dronedarone 12/29 (41.4) Atrial fibrillation Potential to increase mortality in older adults with heart failure. Yes Do not coadminister. If unable to deprescribe well in advance (d), likely precludes use of nirmatrelvir-ritonavir given increased risk of life-threatening cardiac arrhythmias.
Quinidine, flecainide, propafenone NA Atrial fibrillation Data suggest that rate control yields better balance of benefits and harms than pharmacological rhythm control for most older adults. No Do not coadminister. If unable to deprescribe or hold, likely precludes use of nirmatrelvir-ritonavir given increased risk of life-threatening cardiac arrhythmias.
Digoxin 31/225 (13.8) Atrial fibrillation, CHF, CKD A higher dose of digoxin (>125 µg daily) has an increased risk of toxic effect. No Adjust dose. Exercise caution. Individualize dose or dosing schedule based on plasma concentration, kidney function, and treatment indication. If digoxin levels are not available, evaluate the risks and benefits of coadministration.
Warfarin 0/551 (0) In combination with a second anticoagulant Dual antithrombotic therapy increases the risk of major hemorrhage. No Adjust dose. Closely monitor anticoagulation parameters (INR) during coadministration. Warfarin dose may need to be increased.
Dabigatran 6/111 (5.4) eGFR <30 or in combination with a second anticoagulant Dabigatran is not recommended at an eGFR<30; consider switching to apixaban or coumadin. Dual antithrombotic therapy increases the risk of major hemorrhage. No Adjust dose. Coadministration possible with dose reduction to 110 mg twice daily and clinical monitoring for signs of bleeding.
Rivaroxaban, apixaban 0/977 (0) In combination with a second anticoagulant Dual antithrombotic therapy increases the risk of major hemorrhage. No Do not coadminister. Hold medication during coadministration with nirmatrelvir-ritonavir. Treatment should resume 3 d after last dose. Rivaroxaban carries a high risk for bleeding. Apixaban carries a moderate risk of bleeding. Some product monographs indicate a lower dose of apixaban (2.5 mg twice daily) may be coadministered.
Edoxaban 0/3 (0) In combination with a second anticoagulant Dual antithrombotic therapy increases the risk of major hemorrhage. No Adjust dose. Coadministration is possible with dose reduction to 30 mg daily and clinical monitoring for signs of bleeding.
Ticagrelor, clopidogrel 200/489 (41.0) In combination with a second anticoagulant or reduced life expectancy/palliative Dual antithrombotic therapy increases the risk of major hemorrhage. In general, dual antiplatelet therapy is time-limited after the insertion of a drug-eluting stent. Primary prevention with antiplatelet agents could be reconsidered in patients with limited life expectancy. No Do not coadminister; drug substitution. Prasugrel can be prescribed instead, unless the patient's clinical condition contraindicates its use. Coadministration with ticagrelor leads to increased risk of bleeding. Coadministration with clopidogrel leads to reduced efficacy and risk of thrombosis.
Phenobarbital NA Older adults without a seizure disorder or psychiatric condition High rate of physical dependence, tolerance to sleep benefits, and risk of overdose at low doses. Yes Do not coadminister. If unable to deprescribe well in advance (wks), precludes use of nirmatrelvir-ritonavir because of decreased efficacy of nirmatrelvir-ritonavir and risk of developing virologic resistance.
Lovastatin, simvastatin, atorvastatin 41/1901 (2.6) Primary prevention in people with reduced life expectancy or receipt of palliative care In patients with restricted life expectancy based on their age, demographics, and recent health care use, statins may offer little benefit and possible harm. No Hold medication during coadministration with nirmatrelvir-ritonavir. Treatment should only resume 3 d after last dose. Risk of severe myopathy and rhabdomyolysis.
Sildenafil, vardenafil 2/28 (7.1) In combination with isosorbide dinitrate High risk of cardiovascular collapse. Avoid this combination of medications. No Do not coadminister. Hold medication during coadministration with nirmatrelvir-ritonavir. Treatment should resume 3 d after last dose.
Alfuzosin, tamsulosin 174/779 (22.3) Orthostatic hypotension or recurrent falls High risk of orthostatic hypotension. Not recommended as routine treatment for hypertension. Alfuzosin is not recommended as routine treatment for hypertension. No Do not coadminister. Hold during therapy, and monitor for emergence of symptoms. Alfuzosin is absolutely contraindicated because of risk of severe orthostatic hypotension. Tamsulosin carries a moderate risk.
Clozapine, lurasidone, quetiapine, pimozide 62/274 (22.6) All older adults without a psychiatric disorder, such as schizophrenia or bipolar affective disorder Do not routinely use antipsychotics for parkinsonism, dementia, and treatment of insomnia or sleep disorders. Increased risk of stroke, falls, confusion, extrapyramidal adverse effects, aspiration, and death. In parkinsonism, quetiapine and clozapine have a lower risk, but in general their use should be avoided. Yes (for high doses) Do not coadminister. If low dose for sleep or agitation (eg, <25 mg of quetiapine daily), consider holding during nirmatrelvir-ritonavir coadministration, and monitor closely for emergence of behavioral symptoms. For higher doses, do not coadminister. High risk of serious sedation and coma. Deprescribing usually requires tapering for higher doses.
Piroxicam 1/1 (100) Most older adults Avoid NSAIDS with a history of ischemic heart disease, GI hemorrhages, hypertension, gastritis, CKD, GERD, or peptic ulcers because they may exacerbate the underlying condition. No Do not coadminister. Hold medication during coadministration because of potential for respiratory depression or hematologic abnormalities.
Fentanyl 23/76 (30.3) Older adults without cancer Avoid opioids for chronic noncancer-related pain. Yes Do not coadminister. Fatal respiratory depression can occur. Temporarily holding maintenance, regular use opioids is not advised as this can precipitate withdrawal in the absence of tapering. Deprescribing requires tapering.
Methadone 0/20 (0) Older adults without cancer or treatment of substance use disorder Avoid opioids for chronic noncancer-related pain. Yes Adjust dose. Increased methadone dose may be necessary when coadministered.
Diazepam, midazolam (oral), triazolam 26/35 (74.3) Older adults without a seizure disorder or severe anxiety In general, all benzodiazepines increase risk of cognitive impairment, delirium, falls, fractures, and motor vehicle accidents in older adults. Yes Do not coadminister. If unable to deprescribe well in advance (wks), likely precludes use of nirmatrelvir-ritonavir. Deprescribing requires tapering.
Cisapride NA All older adults Can cause extrapyramidal effects, including tardive dyskinesia. Risk may be greater in frail older adults and with prolonged exposure. No Do not coadminister. Hold medication during coadministration with nirmatrelvir-ritonavir because of known risk of life-threatening cardiac arrhythmias.
Colchicine 41/117 (35.0) Older adults with a reduced eGFR There is a risk of colchicine toxic effects at reduced eGFR. Xanthine-oxidase inhibitors (eg, allopurinol and febuxostat) are first choice for prophylactic drugs in gout. No Do not coadminister. This interaction can be deadly, especially in patients with kidney and/or hepatic impairment. Life-threatening and fatal drug interactions have occurred with coadministration.

Abbreviations: CHF, congestive heart failure; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; GERD, gastroesophageal reflux disease; GI, gastrointestinal; INR, international normalized ratio; NA, not applicable; NSAID, nonsteroidal anti-inflammatory drug; PIM, potentially inappropriate medication.

a

Medication or medication class that interacts with nirmatrelvir-ritonavir.

b

Proportion of the interacting medication or medication class that was found to be potentially inappropriate by MedSafer. For example, 117 patients received colchicine prescription in the trial and 41 (35%) had the medication flagged as potentially inappropriate because of reduced kidney clearance.

c

Rationale for a medication being triggered as potentially inappropriate in the trial population. Examples included predisposing medical conditions (eg, orthostatic hypotension) or a second interacting medication (eg, 2 or more antithrombotic medications in the absence of a recent cardiac event or coronary artery stenting).

Discussion

In a population of older adults with polypharmacy, DDIs with nirmatrelvir-ritonavir were common. Many DDIs involved PIMs, which were candidate drugs for deprescribing. Because of these DDIs, many older adults with polypharmacy could not safely receive nirmatrelvir-ritonavir. Not all DDIs could be mitigated by simply holding or dose-reducing a medication. Some medications required anticipatory deprescribing to prevent adverse drug withdrawal events attributed to sudden stopping (eg, benzodiazepines) or prolonged half-life (eg, amiodarone).

Intercurrent health conditions can be an opportune time to deprescribe PIMs.2 Symptomatic COVID-19 and potential treatment with nirmatrelvir-ritonavir should prompt a thorough medication review for DDIs, at which point deprescribing could be considered for PIMs. A study limitation was the theoretical nature of exposure to nirmatrelvir-ritonavir; however, with tens of millions of treatment courses purchased worldwide and with older adults at risk for both severe COVID-19 and polypharmacy, nirmatrelvir-ritonavir will be relatively common.

Overall, anticipatory deprescribing could increase the proportion of older adults who benefit from nirmatrelvir-ritonavir. Furthermore, deprescribing PIMs, rather than simply represcribing after receipt of nirmatrelvir-ritonavir, could be beneficial for older adults with polypharmacy.

Supplement.

eMethods.

eReferences

References

Associated Data

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Supplementary Materials

Supplement.

eMethods.

eReferences


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