Ritonavir (Page 2 of 9)

2.6 Dose Modification due to Drug Interaction

Dose reduction of ritonavir 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)].


• Ritonavir Tablets USP, 100 mg White to off white, capsule shaped, film coated tablets debossed with ‘H’ on one side and ‘R9’ on other side.


• When co-administering ritonavir with other protease inhibitors, see the full prescribing information for that protease inhibitor including contraindication information.
• Ritonavir is contraindicated in patients with known hypersensitivity (e.g., toxic epidermal necrolysis (TEN) or Stevens-Johnson syndrome) to ritonavir or any of its ingredients.
• Ritonavir 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)].
o Alpha 1- Adrenoreceptor Antagonist : alfuzosin
o Antianginal: ranolazine
o Antiarrhythmics: amiodarone, dronedarone, flecainide, propafenone, quinidine
o Antifungal: voriconazole
o Anti-gout: colchicine
o Antipsychotics: lurasidone, pimozide
o Ergot Derivatives: dihydroergotamine, ergotamine, methylergonovine
o GI Motility Agent: cisapride
o HMG-CoA Reductase Inhibitors: lovastatin, simvastatin
o Microsomal triglyceride transfer protein (MTTP) Inhibitor: lomitapide
o PDE5 Inhibitor: sildenafil (Revatio®) when used for the treatment of pulmonary arterial hypertension
o Sedative/Hypnotics: triazolam, orally administered midazolam
• Ritonavir 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)].
o Anticancer Agents: apalutamide o Herbal Products: St. John’s Wort (hypericum perforatum)


5.1 Risk of Serious Adverse Reactions Due to Drug Interactions

Initiation of ritonavir, a CYP3A inhibitor, in patients receiving medications metabolized by CYP3A or initiation of medications metabolized by CYP3A in patients already receiving ritonavir, may increase plasma concentrations of medications metabolized by CYP3A. Initiation of medications that inhibit or induce CYP3A may increase or decrease concentrations of ritonavir, respectively. These interactions may lead to:
• Clinically significant adverse reactions, potentially leading to severe, life-threatening, or fatal events from greater exposures of concomitant medications.
• Clinically significant adverse reactions from greater exposures of ritonavir.
• Loss of therapeutic effect of ritonavir and possible development of resistance.
When co-administering ritonavir with other protease inhibitors, see the full prescribing information for that protease inhibitor including important Warnings and Precautions. See Table 4 for steps to prevent or manage these possible and known significant drug interactions, including dosing recommendations [see Drug Interactions ( 7)]. Consider the potential for drug interactions prior to and during ritonavir therapy; review concomitant medications during ritonavir therapy, and monitor for the adverse reactions associated with the concomitant medications [see Contraindications ( 4) and Drug Interactions ( 7)].

5.2 Toxicity in Preterm Neonates

Ritonavir oral solution contains the excipients alcohol and propylene glycol. When administered concomitantly with propylene glycol, alcohol competitively inhibits the metabolism of propylene glycol, which may lead to elevated concentrations. Preterm neonates may be at an increased risk of propylene glycol-associated adverse events due to diminished ability to metabolize propylene glycol, thereby leading to accumulation and potential adverse events. Postmarketing life-threatening cases of cardiac toxicity (including complete AV block, bradycardia, and cardiomyopathy), lactic acidosis, acute renal failure, CNS depression and respiratory complications leading to death have been reported, predominantly in preterm neonates receiving lopinavir/ritonavir oral solution which also contains the excipients ethanol and propylene glycol. Ritonavir oral solution should not be used in preterm neonates in the immediate postnatal period because of possible toxicities. However, if the benefit of using ritonavir oral solution to treat HIV infection in infants immediately after birth outweighs the potential risks, infants should be monitored closely for increases in serum osmolality and serum creatinine, and for toxicity related to ritonavir oral solution including: hyperosmolality, with or without lactic acidosis, renal toxicity, CNS depression (including stupor, coma, and apnea), seizures, hypotonia, cardiac arrhythmias and ECG changes, and hemolysis. Total amounts of ethanol and propylene glycol from all medicines that are to be given to infants should be taken into account in order to avoid toxicity from these excipients [see Dosage and Administration ( 2.4) and Overdosage ( 10)].

5.3 Hepatotoxicity

Hepatic transaminase elevations exceeding 5 times the upper limit of normal, clinical hepatitis, and jaundice have occurred in patients receiving ritonavir alone or in combination with other antiretroviral drugs (see Table 3). There may be an increased risk for transaminase elevations in patients with underlying hepatitis B or C. Therefore, caution should be exercised when administering ritonavir to patients with pre-existing liver diseases, liver enzyme abnormalities, or hepatitis. Increased AST/ALT monitoring should be considered in these patients, especially during the first three months of ritonavir treatment [see Use in Specific Populations ( 8.6)]. There have been postmarketing reports of hepatic dysfunction, including some fatalities. These have generally occurred in patients taking multiple concomitant medications and/or with advanced AIDS.

5.4 Pancreatitis

Pancreatitis has been observed in patients receiving ritonavir therapy, including those who developed hypertriglyceridemia. In some cases fatalities have been observed. Patients with advanced HIV disease may be at increased risk of elevated triglycerides and pancreatitis [see Warnings and Precautions ( 5.7)]. Pancreatitis should be considered if clinical symptoms (nausea, vomiting, abdominal pain) or abnormalities in laboratory values (such as increased serum lipase or amylase values) suggestive of pancreatitis should occur. Patients who exhibit these signs or symptoms should be evaluated and ritonavir therapy should be discontinued if a diagnosis of pancreatitis is made.

5.5 Allergic Reactions/Hypersensitivity

Allergic reactions including urticaria, mild skin eruptions, bronchospasm, and angioedema have been reported. Cases of anaphylaxis, toxic epidermal necrolysis (TEN), and Stevens-Johnson syndrome have also been reported. Discontinue treatment if severe reactions develop.

5.6 PR Interval Prolongation

Ritonavir prolongs the PR interval in some patients. Post marketing cases of second or third degree atrioventricular block have been reported in patients.
Ritonavir should be used with caution in patients with underlying structural heart disease, preexisting conduction system abnormalities, ischemic heart disease, cardiomyopathies, as these patients may be at increased risk for developing cardiac conduction abnormalities. The impact on the PR interval of co-administration of ritonavir with other drugs that prolong the PR interval (including calcium channel blockers, beta-adrenergic blockers, digoxin and atazanavir) has not been evaluated. As a result, co-administration of ritonavir with these drugs should be undertaken with caution, particularly with those drugs metabolized by CYP3A. Clinical monitoring is recommended [see Drug Interactions ( 7) and Clinical Pharmacology ( 12.3)].

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