Drug Interactions between efavirenz and ombitasvir / paritaprevir / ritonavir

Ritonavir should be taken with food to lessen gastrointestinal side effects. It is important that you take this medication exactly as prescribed by your doctor. Do not change your treatment or stop treatment without first talking to your doctor.

Taking efavirenz with food increases the amount of medicine in your body, which may increase the frequency of side effects. You should take efavirenz once a day on an empty stomach, preferably at bedtime. Taking it at bedtime may make some side effects such as dizziness, trouble sleeping, drowsiness, trouble concentrating, and/or unusual dreams less bothersome. However, these symptoms may be more severe if efavirenz is used with alcohol or mood-altering (street) drugs. You should avoid driving or operating hazardous machinery until you know how the medication affects you. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Food significantly increases the absorption of paritaprevir. You should take each dose of paritaprevir with a meal. Taking it on an empty stomach may lead to inadequate blood levels and reduced effectiveness of the medication.

HBV reactivation has been reported during or after completion of HCV direct-acting antiviral therapy in HCV/HBV-coinfected patients who were not receiving HBV antiviral therapy; some cases resulted in fulminant hepatitis, hepatic failure, and death. Cases have been reported in hepatitis B surface antigen (HBsAg)-positive patients and patients with serologic evidence of resolved HBV infection (i.e., HBsAg negative and hepatitis B core antibody [anti-HBc] positive). HBV reactivation has also been reported in patients using certain immunosuppressant or chemotherapeutic agents; risk of HBV reactivation associated with HCV direct-acting antiviral therapy may be increased in these patients. All patients should be tested for evidence of current or prior HBV infection by measuring HBsAg and anti-HBc before starting HCV direct-acting antiviral therapy. Patients with serologic evidence of current or prior HBV infection should be monitored for clinical and laboratory signs of hepatitis flare or HBV reactivation during HCV therapy and posttherapy follow-up; appropriate patient management for HBV infection should be started as clinically indicated.

HBV reactivation has been reported during or after completion of HCV direct-acting antiviral therapy in HCV/HBV-coinfected patients who were not receiving HBV antiviral therapy; some cases resulted in fulminant hepatitis, hepatic failure, and death. Cases have been reported in hepatitis B surface antigen (HBsAg)-positive patients and patients with serologic evidence of resolved HBV infection (i.e., HBsAg negative and hepatitis B core antibody [anti-HBc] positive). HBV reactivation has also been reported in patients using certain immunosuppressant or chemotherapeutic agents; risk of HBV reactivation associated with HCV direct-acting antiviral therapy may be increased in these patients. All patients should be tested for evidence of current or prior HBV infection by measuring HBsAg and anti-HBc before starting HCV direct-acting antiviral therapy. Patients with serologic evidence of current or prior HBV infection should be monitored for clinical and laboratory signs of hepatitis flare or HBV reactivation during HCV therapy and posttherapy follow-up; appropriate patient management for HBV infection should be started as clinically indicated.

The use of drugs containing paritaprevir in combination with ombitasvir and ritonavir is contraindicated in patients with moderate to severe hepatic impairment (Child-Pugh B and C). No dosage adjustment is required in patients with mild hepatic impairment (Child-Pugh A).

New onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, hyperglycemia, and some cases of diabetic ketoacidosis have been reported during postmarketing surveillance in HIV-infected patients treated with protease inhibitors. Some patients required either initiation or dosage adjustments of insulin or oral hypoglycemic agents for treatment of these events. In some cases, hyperglycemia persisted despite discontinuation of protease inhibitor therapy. A causal relationship has not been established between protease inhibitor therapy and these events. Monitoring patients for hyperglycemia, new onset diabetes mellitus, or exacerbation of diabetes mellitus should be considered during protease inhibitor therapy.

During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

There have been reports of increased bleeding, including spontaneous skin hematomas and hemarthrosis, in patients with hemophilia type A and B treated with protease inhibitors; however, a causal relationship has not been established. In some patients, additional factor VIII was given. In more than half of the reported cases, protease inhibitor therapy was continued or reintroduced. Patients with hemophilia or other coagulation defects should be monitored closely for bleeding during protease inhibitor therapy.

During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

New onset diabetes mellitus, exacerbation of preexisting diabetes mellitus, hyperglycemia, and some cases of diabetic ketoacidosis have been reported during postmarketing surveillance in HIV-infected patients treated with protease inhibitors. Some patients required either initiation or dosage adjustments of insulin or oral hypoglycemic agents for treatment of these events. In some cases, hyperglycemia persisted despite discontinuation of protease inhibitor therapy. A causal relationship has not been established between protease inhibitor therapy and these events. Monitoring patients for hyperglycemia, new onset diabetes mellitus, or exacerbation of diabetes mellitus should be considered during protease inhibitor therapy.

During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

Ritonavir may prolong the PR interval in some patients. Postmarketing cases of second or third degree atrioventricular block have been reported. Ritonavir should be administered with caution in patients with underlying structural heart disease, preexisting conduction abnormalities, ischemic heart disease, and cardiomyopathies as these patients might be at increased risk for developing cardiac conduction abnormalities.

During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

Treatment with ritonavir alone or in combination with other protease inhibitors (e.g., lopinavir, saquinavir, tipranavir, fosamprenavir) has resulted in substantial increases in the concentration of total cholesterol and triglycerides. These effects have also been reported with other protease inhibitors but may be the most dramatic with ritonavir. The clinical significance of these elevations is unclear. Marked elevation in triglyceride levels is a risk factor for development of pancreatitis. Triglyceride and cholesterol testing is recommended before starting ritonavir (with or without other protease inhibitors) and periodically during therapy. Lipid disorders should be managed as clinically appropriate.

Efavirenz is not recommended for patients with moderate or severe liver dysfunction; insufficient data are available to determine whether dose adjustment is needed. Patients with mild liver dysfunction may receive efavirenz without dose adjustment. Due to extensive CYP450-mediated metabolism and limited clinical experience in patients with liver dysfunction, therapy with efavirenz should be administered cautiously in patients with mild liver dysfunction; careful monitoring is recommended for these patients. In addition, postmarketing cases of hepatitis (including fulminant hepatitis progressing to liver failure requiring transplantation or resulting in death) have occurred during therapy with efavirenz; reports have included patients with underlying liver disease (including coinfection with hepatitis B or C). Monitoring of liver enzymes before and during therapy is recommended for all patients.

Hepatotoxicity (including jaundice, clinical hepatitis, and hepatic transaminase elevations exceeding 5 times the upper limit of normal) has been reported in patients receiving ritonavir alone or in combination with other antiretroviral drugs. Ritonavir should be administered with caution in patients with preexisting liver diseases, liver enzyme abnormalities, or hepatitis; increased monitoring of AST/ALT should be considered in these patients, especially during the first 3 months of ritonavir therapy. Ritonavir is not recommended for use in patients with severe liver dysfunction.

QTc prolongation has been observed with the use of efavirenz. Alternatives to efavirenz should be considered when administered to patients at higher risk of torsade de pointes or when coadministered with a medication with known risk of torsade de pointes.

During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

Convulsions have been observed in adult and pediatric patients receiving efavirenz, generally in the presence of known medical history of seizures. Caution should be taken with any patient with history of seizures. Anticonvulsant medications primarily metabolized by the liver (e.g., phenytoin, phenobarbital) may require periodic monitoring of plasma levels.