NORVIR

NORVIR (ritonavir) is an inhibitor of HIV protease with activity against the Human Immunodeficiency Virus (HIV). Ritonavir is chemically designated as 10-Hydroxy-2-methyl-5-(1-methylethyl)-1- [2-(1-methylethyl)-4-thiazolyl]-3,6-dioxo-8,11-bis(phenylmethyl)-2,4,7,12- tetraazatridecan-13-oic acid, 5-thiazolylmethyl ester, [5S-(5R*,8R*,10R*,11R*)]. Its molecular formula is C 37 H 48 N 6 O 5 S 2 , and its molecular weight is 720.95. Ritonavir has the following structural formula: Ritonavir is a white-to-light-tan powder. Ritonavir has a bitter metallic taste. It is freely soluble in methanol and ethanol, soluble in isopropanol and practically insoluble in water. NORVIR tablets are available for oral administration in a strength of 100 mg ritonavir with the following inactive ingredients: copovidone, anhydrous dibasic calcium phosphate, sorbitan monolaurate, colloidal silicon dioxide, and sodium stearyl fumarate. The following are the ingredients in the film coating: hypromellose, titanium dioxide, polyethylene glycol 400, hydroxypropyl cellulose, talc, polyethylene glycol 3350, colloidal silicon dioxide, and polysorbate 80. NORVIR oral powder is beige/pale yellow to yellow and is available for oral administration as a packet containing 100 mg of ritonavir with the following inactive ingredients: copovidone, sorbitan monolaurate, and colloidal silicon dioxide. The following structural formula for Ritonavir is chemically designated as 10-Hydroxy-2-methyl-5-(1-methylethyl)-1- [2-(1-methylethyl)-4-thiazolyl]-3,6-dioxo-8,11-bis(phenylmethyl)-2,4,7,12- tetraazatridecan-13-oic acid, 5-thiazolylmethyl ester, [5S-(5R*,8R*,10R*,11R*)]. Its molecular formula is C37H48N6O5S2, and its molecular weight is 720.95.

NORVIR tablets are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. NORVIR oral powder is indicated in combination with other antiretroviral agents for the treatment of pediatric patients with HIV-1 infection. NORVIR tablets are HIV protease inhibitors indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection ( 1 ) NORVIR oral powder is indicated in combination with other antiretroviral agents for the treatment of pediatric patients with HIV-1 infection ( 1 )

Adult patients: 600 mg twice-day with meals ( 2.2 ) Pediatrics patients: The recommended twice daily dose for children greater than one month of age is based on body surface area and should not exceed 600 mg twice daily with meals ( 2.3 ) NORVIR oral powder can only be used for dosing increments of 100 mg ( 2.4 ) Instructions for Use should be followed for preparation and administration of NORVIR oral powder ( 2.4 ) Dose modification for NORVIR is necessary when used with other protease inhibitors ( 2.5 ) 2.1 General Administration Recommendations NORVIR must be used in combination with other antiretroviral agents. NORVIR is administered orally. NORVIR tablets should be swallowed whole, and not chewed, broken or crushed. Take NORVIR with meals. NORVIR oral powder should be mixed with soft food such as apple sauce or vanilla pudding, or mixed with liquid such as water, chocolate milk, or infant formula [see Dosage and Administration ( 2.4 ) and Instructions for Use ] . The bitter aftertaste of NORVIR oral powder may be lessened if administered with food. 2. 2 Dosage Recommendations in Adults Recommended Dosage for Treatment of HIV-1: The recommended dosage of NORVIR is 600 mg twice daily by mouth to be taken with meals. Use of a dose titration schedule may help to reduce treatment-emergent adverse events while maintaining appropriate ritonavir plasma levels. NORVIR should be started at no less than 300 mg twice daily and increased at 2 to 3 day intervals by 100 mg twice daily. The maximum dose of 600 mg twice daily should not be exceeded upon completion of the titration [see Dosage and Administration ( 2.5 )] . 2. 3 Dosage Recommendations in Pediatric Patients NORVIR must be used in combination with other antiretroviral agents [see Dosage and Administration ( 2 ) ] . The recommended dosage of NORVIR in pediatric patients older than 1 month is 350 to 400 mg per m 2 twice daily by mouth to be taken with meals and should not exceed 600 mg twice daily. NORVIR should be started at 250 mg per m 2 twice daily and increased at 2 to 3 day intervals by 50 mg per m 2 twice daily. If patients do not tolerate 400 mg per m 2 twice daily due to adverse events, the highest tolerated dose may be used for maintenance therapy in combination with other antiretroviral agents, however, alternative therapy should be considered [see Dosage and Administration ( 2.5 )] . 2. 4 Preparation of Norvir Oral Powder For details on the preparation and administration of NORVIR oral powder (see Instructions for Use ). NORVIR oral powder should only be used for dosing increments of 100 mg. Prepare the dose using the required number of packets. For example, use one packet for doses of 100 mg and two packets for doses of 200 mg. Pour and mix the entire contents of each packet over soft food or liquid. All of the powder mixed with soft food or liquid should be administered within 2 hours of preparation. If not administered within 2 hours of preparation, the mixture should be discarded and a new dose prepared. The prescribed dose of NORVIR oral powder can be administered via a feeding tube after being mixed with water (see Instructions for Use ). Follow the instructions for the feeding tube to administer the medicine. 2. 5 Dose Modification due to Drug Interaction Dose reduction of NORVIR is necessary when used with other protease inhibitors: atazanavir, darunavir, fosamprenavir, saquinavir, and tipranavir. Prescribers should consult the full prescribing information and clinical study information of these protease inhibitors if they are co-administered with a reduced dose of ritonavir [see Warnings and Precautions ( 5.1 ) , and Drug Interactions ( 7 ) ] .

When co-administering NORVIR with other protease inhibitors, see the full prescribing information for that protease inhibitor including contraindication information. NORVIR is contraindicated in patients with known hypersensitivity (e.g., toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome) to ritonavir or any of its ingredients. NORVIR is contraindicated with drugs that are highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening reactions [see Drug Interactions ( 7.1 ) and Clinical Pharmacology ( 12.3 )] . ○ Alpha 1- Adrenoreceptor Antagonist : alfuzosin ○ Antianginal: ranolazine ○ Antiarrhythmics: amiodarone, dronedarone, flecainide, propafenone, quinidine ○ Antifungal: voriconazole ○ Anti-gout: colchicine ○ Antipsychotics: lurasidone, pimozide ○ Ergot Derivatives: dihydroergotamine, ergotamine, methylergonovine ○ GI Motility Agent: cisapride ○ HMG-CoA Reductase Inhibitors: lovastatin, simvastatin ○ Microsomal triglyceride transfer protein (MTTP) Inhibitor: lomitapide ○ PDE5 Inhibitor: sildenafil (Revatio ® ) when used for the treatment of pulmonary arterial hypertension ○ Sedative/Hypnotics: triazolam, orally administered midazolam NORVIR is contraindicated with drugs that are potent CYP3A inducers where significantly reduced ritonavir plasma concentrations may be associated with the potential for loss of virologic response and possible resistance and cross-resistance [see Drug Interactions ( 7.2 ) and Clinical Pharmacology ( 12.3 )] . ○ Anticancer Agents: apalutamide ○ Herbal Products: St. John's Wort (hypericum perforatum) NORVIR is contraindicated in patients with known hypersensitivity to ritonavir (e.g., toxic epidermal necrolysis, Stevens-Johnson syndrome) or any of its ingredients ( 4 ) Co-administration with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations may be associated with serious and/or life-threatening events ( 4 ) Co-administration with drugs that significantly reduce ritonavir ( 4 )

The following adverse reactions are discussed in greater detail in other sections of the labeling. Drug Interactions [see Warnings and Precautions ( 5.1 ) ] Hepatotoxicity [see Warnings and Precautions ( 5.2 ) ] Pancreatitis [see Warnings and Precautions ( 5.3 ) ] Allergic Reactions/Hypersensitivity [see Warnings and Precautions ( 5.4 ) ] When co-administering NORVIR with other protease inhibitors, see the full prescribing information for that protease inhibitor including adverse reactions. The most frequently reported adverse drug reactions among patients receiving NORVIR alone or in combination with other antiretroviral drugs were gastrointestinal (including diarrhea, nausea, vomiting, abdominal pain (upper and lower), neurological disturbances (including paresthesia and oral paresthesia), rash, and fatigue/asthenia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact AbbVie Inc. at 1-800-633-9110 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reactions rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Adverse Reactions in Adults The safety of NORVIR alone and in combination with other antiretroviral agents was studied in 1,755 adult patients. Table 1 lists treatment-emergent Adverse Reactions (with possible or probable relationship to study drug) occurring in greater than or equal to 1% of adult patients receiving NORVIR in combined Phase II/IV studies. The most frequently reported adverse drug reactions among patients receiving NORVIR alone or in combination with other antiretroviral drugs were gastrointestinal (including diarrhea, nausea, vomiting, abdominal pain (upper and lower)), neurological disturbances (including paresthesia and oral paresthesia), rash, and fatigue/asthenia. Table 1. Treatment-Emergent Adverse Reactions (With Possible or Probable Relationship to Study Drug) Occurring in greater than or equal to 1% of Adult Patients Receiving NORVIR in Combined Phase II/IV Studies (N = 1,755) Adverse Reactions n % Eye disorders Blurred vision 113 6.4 Gastrointestinal disorders Abdominal Pain (upper and lower)* 464 26.4 Diarrhea including severe with electrolyte imbalance* 1,192 67.9 Dyspepsia 201 11.5 Flatulence 142 8.1 Gastrointestinal hemorrhage* 41 2.3 Gastroesophageal reflux disease (GERD) 19 1.1 Nausea 1,007 57.4 Vomiting* 559 31.9 General disorders and administration site conditions Fatigue including asthenia* 811 46.2 Hepatobiliary disorders Blood bilirubin increased (including jaundice)* 25 1.4 Hepatitis (including increased AST, ALT, GGT)* 153 8.7 Immune system disorders Hypersensitivity including urticaria and face edema* 114 8.2 Metabolism and nutrition disorders Edema and peripheral edema* 110 6.3 Gout* 24 1.4 Hypercholesterolemia* 52 3.0 Hypertriglyceridemia* 158 9.0 Lipodystrophy acquired* 51 2.9 Musculoskeletal and connective tissue disorders Arthralgia and back pain* 326 18.6 Myopathy/creatine phosphokinase increased* 66 3.8 Myalgia 156 8.9 Nervous system disorders Dizziness* 274 15.6 Dysgeusia* 285 16.2 Paresthesia (including oral paresthesia)* 889 50.7 Peripheral neuropathy 178 10.1 Syncope* 58 3.3 Psychiatric disorders Confusion* 52 3.0 Disturbance in attention 44 2.5 Renal and urinary disorders Increased urination* 74 4.2 Respiratory, thoracic and mediastinal disorders Coughing* 380 21.7 Oropharyngeal Pain* 279 15.9 Skin and subcutaneous tissue disorders Acne* 67 3.8 Pruritus* 214 12.2 Rash (includes erythematous and maculopapular)* 475 27.1 Vascular disorders Flushing, feeling hot* 232 13.2 Hypertension* 58 3.3 Hypotension including orthostatic hypotension* 30 1.7 Peripheral coldness* 21 1.2 * Represents a medical concept including several similar MedDRA PTs Laboratory Abnormalities in Adults Table 2 shows the percentage of adult patients who developed marked laboratory abnormalities. Table 2. Percentage of Adult Patients, by Study and Treatment Group, with Chemistry and Hematology Abnormalities Occurring in greater than 3% of Patients Receiving NORVIR Study 245 Naive Patients Study 247 Advanced Patients Study 462 PI-Naive Patients Variable Limit NORVIR plus ZDV NORVIR ZDV NORVIR Placebo NORVIR plus Saquinavir Chemistry High Cholesterol > 240 mg/dL 30.7 44.8 9.3 36.5 8.0 65.2 CPK > 1000 IU/L 9.6 12.1 11.0 9.1 6.3 9.9 GGT > 300 IU/L 1.8 5.2 1.7 19.6 11.3 9.2 SGOT (AST) > 180 IU/L 5.3 9.5 2.5 6.4 7.0 7.8 SGPT (ALT) > 215 IU/L 5.3 7.8 3.4 8.5 4.4 9.2 Triglycerides > 800 mg/dL 9.6 17.2 3.4 33.6 9.4 23.4 Triglycerides > 1500 mg/dL 1.8 2.6 - 12.6 0.4 11.3 Triglycerides Fasting > 1500 mg/dL 1.5 1.3 - 9.9 0.3 - Uric Acid > 12 mg/dL - - - 3.8 0.2 1.4 Hematology Low Hematocrit < 30% 2.6 - 0.8 17.3 22.0 0.7 Hemoglobin < 8.0 g/dL 0.9 - - 3.8 3.9 - Neutrophils ≤ 0.5 x 10 9 /L - - - 6.0 8.3 - RBC < 3.0 x 10 12 /L 1.8 - 5.9 18.6 24.4 - WBC < 2.5 x 10 9 /L - 0.9 6.8 36.9 59.4 3.5 - Indicates no events reported. Adverse Reactions in Pediatric Patients NORVIR has been studied in 265 pediatric patients greater than 1 month to 21 years of age. The adverse event profile observed during pediatric clinical trials was similar to that for adult patients. Vomiting, diarrhea, and skin rash/allergy were the only drug-related clinical adverse events of moderate to severe intensity observed in greater than or equal to 2% of pediatric patients enrolled in NORVIR clinical trials. Laboratory Abnormalities in Pediatric Patients The following Grade 3-4 laboratory abnormalities occurred in greater than 3% of pediatric patients who received treatment with NORVIR either alone or in combination with reverse transcriptase inhibitors: neutropenia (9%), hyperamylasemia (7%), thrombocytopenia (5%), anemia (4%), and elevated AST (3%). 6.2 Postmarketing Experience The following adverse events (not previously mentioned in the labeling) have been reported during post-marketing use of NORVIR. Because these reactions are reported voluntarily from a population of unknown size, it is not possible to reliably estimate their frequency or establish a causal relationship to NORVIR exposure. Body as a Whole Dehydration, usually associated with gastrointestinal symptoms, and sometimes resulting in hypotension, syncope, or renal insufficiency has been reported. Syncope, orthostatic hypotension, and renal insufficiency have also been reported without known dehydration. Co-administration of ritonavir with ergotamine or dihydroergotamine has been associated with acute ergot toxicity characterized by vasospasm and ischemia of the extremities and other tissues including the central nervous system. Cardiovascular System First-degree AV block, second-degree AV block, third-degree AV block, right bundle branch block have been reported [see Warnings and Precautions ( 5.5 ) ] . Cardiac and neurologic events have been reported when ritonavir has been co-administered with disopyramide, mexiletine, nefazodone, fluoxetine, and beta blockers. The possibility of drug interaction cannot be excluded. Endocrine System Cushing's syndrome and adrenal suppression have been reported when ritonavir has been co-administered with fluticasone propionate or budesonide. Nervous System There have been postmarketing reports of seizure. Also, see Cardiovascular System. Renal and Urinary Disorders Nephrolithiasis Skin and subcutaneous tissue disorders Toxic epidermal necrolysis (TEN) has been reported.

When co-administering NORVIR with other protease inhibitors (atazanavir, darunavir, fosamprenavir, saquinavir, and tipranavir), see the full prescribing information for that protease inhibitor including important information for drug interactions. Co-administration of NORVIR can alter the concentrations of other drugs. The potential for drug-drug interactions must be considered prior to and during therapy ( 4 , 5.1 , 7 , 12.3 ) 7.1 Potential for NORVIR to Affect Other Drugs Ritonavir is an inhibitor of cytochrome P450 3A (CYP3A) and may increase plasma concentrations of agents that are primarily metabolized by CYP3A. Agents that are extensively metabolized by CYP3A and have high first pass metabolism appear to be the most susceptible to large increases in AUC (greater than 3-fold) when co-administered with ritonavir. Thus, co-administration of NORVIR with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events is contraindicated. Co-administration with other CYP3A substrates may require a dose adjustment or additional monitoring as shown in Table 3. Ritonavir also inhibits CYP2D6 to a lesser extent. Co-administration of substrates of CYP2D6 with ritonavir could result in increases (up to 2-fold) in the AUC of the other agent, possibly requiring a proportional dosage reduction. Ritonavir also appears to induce CYP3A, CYP1A2, CYP2C9, CYP2C19, and CYP2B6 as well as other enzymes, including glucuronosyl transferase. These examples are a guide and not considered a comprehensive list of all possible drugs that may interact with ritonavir. The healthcare provider should consult appropriate references for comprehensive information. 7.2 Established and Other Potentially Significant Drug Interactions Table 3 provides a list of established or potentially clinically significant drug interactions. Alteration in dose or regimen may be recommended based on drug interaction studies or predicted interaction [see Contraindications ( 4 ), Warnings and Precautions ( 5.1 ), and Clinical Pharmacology ( 12.3 )] for magnitude of interaction. Table 3. Established and Other Potentially Significant Drug Interactions Concomitant Drug Class: Drug Name Effect on Concentration of Ritonavir or Concomitant Drug Clinical Comment HIV-Antiviral Agents HIV-1 Protease Inhibitor: atazanavir darunavir fosamprenavir ↑ amprenavir ↑ atazanavir ↑ darunavir See the complete prescribing information for fosamprenavir, atazanavir, darunavir for details on co-administration with ritonavir. HIV-1 Protease Inhibitor: indinavir ↑ indinavir Appropriate doses for this combination, with respect to efficacy and safety, have not been established. HIV-1 Protease Inhibitor: saquinavir ↑ saquinavir See the complete prescribing information for saquinavir for details on co-administration of saquinavir and ritonavir. Saquinavir/ritonavir in combination with rifampin is not recommended due to the risk of severe hepatotoxicity (presenting as increased hepatic transaminases) if the three drugs are given together. HIV-1 Protease Inhibitor: tipranavir ↑ tipranavir See the complete prescribing information for tipranavir for details on co-administration of tipranavir and ritonavir. Non-Nucleoside Reverse Transcriptase Inhibitor: delavirdine ↑ ritonavir Appropriate doses of this combination with respect to safety and efficacy have not been established. HIV-1 CCR5 – antagonist: maraviroc ↑ maraviroc See the complete prescribing information for maraviroc for details on co-administration of maraviroc and ritonavir-containing protease inhibitors. Integrase Inhibitor: raltegravir ↓ raltegravir The effects of ritonavir on raltegravir with ritonavir dosage regimens greater than 100 mg twice daily have not been evaluated, however raltegravir concentrations may be decreased with ritonavir coadministration. Other Agents Alpha 1- Adrenoreceptor Antagonist: alfuzosin ↑ alfuzosin Contraindicated due to potential hypotension [see Contraindications ( 4 ) ] . Antianginal: ranolazine ↑ ranolazine Contraindicated due to potential for serious and/or life-threatening reactions [see Contraindications ( 4 ) ] . Analgesics, Narcotic: tramadol, propoxyphene, methadone, fentanyl ↑ analgesics ↓ methadone ↑ fentanyl A dose decrease may be needed for these drugs when co-administered with ritonavir. Dosage increase of methadone may be considered. Careful monitoring of therapeutic and adverse effects (including potentially fatal respiratory depression) is recommended when fentanyl is concomitantly administered with NORVIR. Anesthetic: meperidine ↓ meperidine/ ↑ normeperidine (metabolite) 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). Antiarrhythmics: amiodarone, dronedarone, flecainide, propafenone, quinidine ↑ antiarrhythmics Contraindicated due to potential for cardiac arrhythmias [see Contraindications ( 4 ) ] . Antiarrhythmics: disopyramide, lidocaine, mexiletine ↑ antiarrhythmics Caution is warranted and therapeutic concentration monitoring is recommended for antiarrhythmics when co-administered with ritonavir, if available. Anticancer Agents: abemaciclib, apalutamide, dasatinib, encorafenib, ibrutinib, ivosidenib, neratinib, nilotinib, venetoclax, vinblastine, vincristine ↑ anticancer agents ↓ ritonavir # Apalutamide is contraindicated due to potential for loss of virologic response and possible resistance to NORVIR or to the class of protease inhibitors [see Contraindications ( 4 ) ] . Avoid co-administration of encorafenib or ivosidenib with NORVIR due to potential risk of serious adverse events such as QT interval prolongation. If co-administration of encorafenib with NORVIR cannot be avoided, modify dose as recommended in encorafenib USPI. If co-administration of ivosidenib with NORVIR cannot be avoided, reduce ivosidenib dose to 250 mg once daily. Avoid use of neratinib, venetoclax or ibrutinib with NORVIR. For vincristine and vinblastine, consideration should be given to temporarily withholding the ritonavir containing antiretroviral regimen in patients who develop significant hematologic or gastrointestinal side effects when ritonavir is administered concurrently with vincristine or vinblastine. Clinicians should be aware that if the ritonavir containing regimen is withheld for a prolonged period, consideration should be given to altering the regimen to not include a CYP3A or P-gp inhibitor in order to control HIV-1 viral load. A decrease in the dosage or an adjustment of the dosing interval of nilotinib and dasatinib may be necessary for patients requiring co-administration with strong CYP3A inhibitors such as NORVIR. Please refer to the nilotinib and dasatinib prescribing information for dosing instructions. Anticoagulant: warfarin ↑↓ warfarin Initial frequent monitoring of the INR during ritonavir and warfarin co-administration is recommended. Anticoagulant: rivaroxaban ↑ rivaroxaban Avoid concomitant use of rivaroxaban and ritonavir. Co-administration of ritonavir and rivaroxaban may lead to risk of increased bleeding. Anticonvulsants: carbamazepine, clonazepam, ethosuximide ↑ anticonvulsants A dose decrease may be needed for these drugs when co-administered with ritonavir and therapeutic concentration monitoring is recommended for these anticonvulsants, if available. Anticonvulsants: divalproex, lamotrigine, phenytoin ↓ anticonvulsants A dose increase may be needed for these drugs when co-administered with ritonavir and therapeutic concentration monitoring is recommended for these anticonvulsants, if available. Antidepressants: nefazodone, selective serotonin reuptake inhibitors (SSRIs): e.g. fluoxetine, paroxetine, tricyclics: e.g. amitriptyline, nortriptyline ↑ antidepressants A dose decrease may be needed for these drugs when co-administered with ritonavir. Antidepressant: bupropion ↓ bupropion ↓ active metabolite, hydroxybupropion Patients receiving ritonavir and bupropion concurrently should be monitored for an adequate clinical response to bupropion. Antidepressant: desipramine ↑ desipramine Dosage reduction and concentration monitoring of desipramine is recommended. Antidepressant: trazodone ↑ trazodone Adverse events of nausea, dizziness, hypotension and syncope have been observed following co-administration of trazodone and NORVIR. A lower dose of trazodone should be considered. Antiemetic: dronabinol ↑ dronabinol A dose decrease of dronabinol may be needed when co-administered with ritonavir. Antifungals: ketoconazole itraconazole voriconazole ↑ ketoconazole ↑ itraconazole ↓ voriconazole High doses of ketoconazole or itraconazole (greater than 200 mg per day) are not recommended. Co-administration of voriconazole and ritonavir doses of 400 mg every 12 hours or greater is contraindicated due to the potential for loss of antifungal response [see Contraindications ( 4 ) ] . Co-administration of voriconazole and ritonavir 100 mg should be avoided, unless an assessment of the benefit/risk to the patient justifies the use of voriconazole. Anti-gout: colchicine ↑ colchicine Contraindicated due to potential for serious and/or life-threatening reactions in patients with renal and/or hepatic impairment [see Contraindications ( 4 ) ] . For patients with normal renal or hepatic function: Treatment of gout flares-co-administration of colchicine in patients on ritonavir: 0.6 mg (one tablet) for one dose, followed by 0.3 mg (half tablet) one hour later. Dose to be repeated no earlier than three days. Prophylaxis of gout flares-co-administration of colchicine in patients on ritonavir: If the original colchicine regimen was 0.6 mg twice a day, the regimen should be adjusted to 0.3 mg once a day.If the original colchicine regimen was 0.6 mg once a day, the regimen should be adjusted to 0.3 mg once every other day. Treatment of familial Mediterranean fever (FMF)-co-administration of colchicine in patients on ritonavir: Maximum daily dose of 0.6 mg (may be given as 0.3 mg twice a day). Anti-infective: clarithromycin ↑ clarithromycin For patients with renal impairment, adjust clarithromycin dose as follows: For patients with CL CR 30 to 60 mL per min the dose of clarithromycin should be reduced by 50%. For patients with CL CR less than 30 mL per min the dose of clarithromycin should be decreased by 75%. No dose adjustment for patients with normal renal function is necessary. Antimycobacterial: bedaquiline ↑ bedaquiline Bedaquiline should only be used with ritonavir if the benefit of co-administration outweighs the risk. Antimycobacterial: rifabutin ↑ rifabutin and rifabutin metabolite Dosage reduction of rifabutin by at least three-quarters of the usual dose of 300 mg per day is recommended (e.g., 150 mg every other day or three times a week). Further dosage reduction may be necessary. Antimycobacterial: rifampin ↓ ritonavir May lead to loss of virologic response. Alternate antimycobacterial agents such as rifabutin should be considered. Antiparasitic: atovaquone ↓ atovaquone Clinical significance is unknown; however, increase in atovaquone dose may be needed. Antiparasitic: quinine ↑ quinine A dose decrease of quinine may be needed when co-administered with ritonavir. Antipsychotics: lurasidone pimozide ↑ lurasidone ↑ pimozide Contraindicated due to potential for serious and/or life-threatening reactions [see Contraindications ( 4 ) ] . Contraindicated due to potential for serious and/or life-threatening reactions such as cardiac arrhythmias [see Contraindications ( 4 ) ] . Antipsychotics: perphenazine, risperidone, thioridazine ↑ antipsychotics A dose decrease may be needed for these drugs when co-administered with ritonavir. Antipsychotics: quetiapine ↑ quetiapine Initiation of NORVIR in patients taking quetiapine: Consider alternative antiretroviral therapy to avoid increases in quetiapine exposures. If coadministration is necessary, reduce the quetiapine dose to 1/6 of the current dose and monitor for quetiapine-associated adverse reactions. Refer to the quetiapine prescribing information for recommendations on adverse reaction monitoring. Initiation of quetiapine in patients taking NORVIR: Refer to the quetiapine prescribing information for initial dosing and titration of quetiapine. β-Blockers: metoprolol, timolol ↑ beta-blockers Caution is warranted and clinical monitoring of patients is recommended. A dose decrease may be needed for these drugs when co-administered with ritonavir. Bronchodilator: theophylline ↓ theophylline Increased dosage of theophylline may be required; therapeutic monitoring should be considered. Calcium channel blockers: diltiazem, nifedipine, verapamil ↑ calcium channel blockers Caution is warranted and clinical monitoring of patients is recommended. A dose decrease may be needed for these drugs when co-administered with ritonavir. Digoxin ↑ digoxin Concomitant administration of ritonavir with digoxin may increase digoxin levels. Caution should be exercised when co-administering ritonavir with digoxin, with appropriate monitoring of serum digoxin levels. Endothelin receptor antagonists: bosentan ↑ bosentan Co-administration of bosentan in patients on ritonavir: In patients who have been receiving ritonavir for at least 10 days, start bosentan at 62.5 mg once daily or every other day based upon individual tolerability. Co-administration of ritonavir in patients on bosentan: Discontinue use of bosentan at least 36 hours prior to initiation of ritonavir. After at least 10 days following the initiation of ritonavir, resume bosentan at 62.5 mg once daily or every other day based upon individual tolerability. GnRH Receptor Antagonists: elagolix ↑ elagolix ↓ ritonavir Concomitant use of elagolix 200 mg twice daily and NORVIR for more than 1 month is not recommended due to potential risk of adverse events such as bone loss and hepatic transaminase elevations. Limit concomitant use of elagolix 150 mg once daily and NORVIR to 6 months. Ergot Derivatives: dihydroergotamine, ergotamine, methylergonovine ↑ ergot derivatives 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 Contraindications ( 4 ) ] . GI Motility Agent: cisapride ↑ cisapride Contraindicated due to potential for cardiac arrhythmias [see Contraindications ( 4 ) ] . Hepatitis C direct acting antiviral: glecaprevir/pibrentasvir simeprevir ↑ glecaprevir ↑ pibrentasvir ↑simeprevir It is not recommended to co-administer ritonavir with glecaprevir/pibrentasvir, or simeprevir. Herbal Products: St. John's Wort (hypericum perforatum) ↓ ritonavir Contraindicated due to potential for loss of virologic response and possible resistance to NORVIR or to the class of protease inhibitors [see Contraindications ( 4 ) ] . Lipid-modifying agents HMG-CoA Reductase Inhibitor: lovastatin simvastatin atorvastatin rosuvastatin Microsomal triglyceride transfer protein (MTTP) Inhibitor: lomitapide ↑ lovastatin ↑ simvastatin ↑ atorvastatin ↑ rosuvastatin ↑ lomitapide Contraindicated due to potential for myopathy including rhabdomyolysis [see Contraindications ( 4 ) ] . Titrate atorvastatin and rosuvastatin dose carefully and use the lowest necessary dose.If NORVIR is used with another protease inhibitor, see the complete prescribing information for the concomitant protease inhibitor for details on co-administration with atorvastatin and rosuvastatin. Lomitapide is a sensitive substrate for CYP3A4 metabolism. CYP3A4 inhibitors increase the exposure of lomitapide, with strong inhibitors increasing exposure approximately 27-fold. Concomitant use of moderate or strong CYP3A4 inhibitors with lomitapide is contraindicated due to potential for hepatotoxicity [see Contraindications ( 4 ) ] . Immunosuppressants: cyclosporine, tacrolimus, sirolimus (rapamycin) ↑ immunosuppressants Therapeutic concentration monitoring is recommended for immunosuppressant agents when co-administered with ritonavir. Kinase Inhibitors: fostamatinib (also see anticancer agents above) ↑ fostamatinib metabolite R406 Monitor for toxicities of R406 exposure resulting in dose-related adverse events such as hepatotoxicity and neutropenia. Fostamatinib dose reduction may be required. Long-acting beta-adrenoceptor agonist: salmeterol ↑ salmeterol Concurrent administration of salmeterol and ritonavir is not recommended. The combination may result in increased risk of cardiovascular adverse events associated with salmeterol, including QT prolongation, palpitations and sinus tachycardia. Oral Contraceptives or Patch Contraceptives: ethinyl estradiol ↓ ethinyl estradiol Alternate methods of contraception should be considered. PDE5 Inhibitors: avanafil sildenafil, tadalafil, vardenafil ↑ avanafil ↑ sildenafil ↑ tadalafil ↑ vardenafil Sildenafil when used for the treatment of pulmonary arterial hypertension (Revatio ® ) is contraindicated due to the potential for sildenafil-associated adverse events, including visual abnormalities, hypotension, prolonged erection, and syncope [see Contraindications ( 4 ) ] . Do not use ritonavir with avanafil because a safe and effective avanafil dosage regimen has not been established. Particular caution should be used when prescribing sildenafil, tadalafil or vardenafil in patients receiving ritonavir. Coadministration of ritonavir with these drugs may result in an increase in PDE5 inhibitor associated adverse events, including hypotension, syncope, visual changes, and prolonged erection. Use of PDE5 inhibitors for pulmonary arterial hypertension (PAH): Sildenafil (Revatio ® ) is contraindicated [see Contraindications ( 4 ) ] . The following dose adjustments are recommended for use of tadalafil (Adcirca ® ) with ritonavir: Co-administration of ADCIRCA in patients on ritonavir: In patients receiving ritonavir for at least one week, start ADCIRCA at 20 mg once daily. Increase to 40 mg once daily based upon individual tolerability. Co-administration of ritonavir in patients on ADCIRCA: Avoid use of ADCIRCA during the initiation of ritonavir. Stop ADCIRCA at least 24 hours prior to starting ritonavir. After at least one week following the initiation of ritonavir, resume ADCIRCA at 20 mg once daily. Increase to 40 mg once daily based upon individual tolerability. Use of PDE5 inhibitors for the treatment of erectile dysfunction: It is recommended not to exceed the following doses: Sildenafil: 25 mg every 48 hours Tadalafil: 10 mg every 72 hours Vardenafil: 2.5 mg every 72 hours Use with increased monitoring for adverse events. Sedative/hypnotics: buspirone, clorazepate, diazepam, estazolam, flurazepam, zolpidem ↑ sedative/hypnotics A dose decrease may be needed for these drugs when co-administered with ritonavir. Sedative/Hypnotics: triazolam, orally administered midazolam ↑ triazolam ↑ midazolam Contraindicated due to potential for prolonged or increased sedation or respiratory depression [see Contraindications ( 4 ) ] . Sedative/hypnotics: Parenteral midazolam ↑ midazolam Co-administration 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. Stimulant: methamphetamine ↑ methamphetamine Use with caution. A dose decrease of methamphetamine may be needed when co-administered with ritonavir. Systemic/Inhaled/ Nasal/Ophthalmic Corticosteroids: e.g., betamethasone budesonide ciclesonide dexamethasone fluticasone methylprednisolone mometasone prednisone triamcinolone ↑ glucocorticoids Coadministration with corticosteroids whose exposures are significantly increased by strong CYP3A inhibitors can increase the risk for Cushing’s syndrome and adrenal suppression.Alternative corticosteroids including beclomethasone and prednisolone (whose PK and/or PD are less affected by strong CYP3A inhibitors relative to other studied steroids) should be considered, particularly for long-term use. # refers to interaction with apalutamide.