Efavirenz, USP is an HIV-1 specific, non-nucleoside, reverse transcriptase inhibitor (NNRTI). Efavirenz is chemically described as(S)-6-chloro-4-(cyclopropylethynyl)-1,4-dihydro4(trifluoromethyl)-2H-3,1-benzoxazin-2-one. Its empirical formula is C 14 H 9 ClF 3 NO 2 and its structural formula is: Efavirenz,USP is a white to slightly pink crystalline powder with a molecular mass of 315.68. It is practically insoluble in water (<10 microgram/mL). Tablets : Efavirenz USP is available as film-coated tablets for oral administration containing 600 mg of efavirenz and the following inactive ingredients: croscarmellose sodium, hydroxypropyl cellulose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and sodium lauryl sulfate. The film coating contains Opadry Yellow,consisting of hydroxypropylmethyl cellulose, titanium dioxide, polyethylene glycol and iron oxide yellow. efavirenz-structure

Efavirenz in combination with other antiretroviral agents is indicated for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in adults and in pediatric patients at least 3 months old and weighing at least 3.5 kg. Efavirenz is a non-nucleoside reverse transcriptase inhibitor indicated in combination with other antiretroviral agents for the treatment of human immunodeficiency virus type 1 infection in adults and in pediatric patients at least 3 months old and weighing at least 3.5 kg.( 1 )

DOSAGE FORMS & STRENGTHS • Efavirenz Tablets, USP 600 mg 600-mg tablets are yellow, biconvex, capsule-shaped, film-coated tablets, engraved with "ML 12" on one side and plain on the other side. •Tablets: 600 mg

• Efavirenz should be taken orally once daily on an empty stomach, preferably at bedtime. • Recommended adult dose: 600 mg. • With rifampin, increase efavirenz dose to 800 mg once daily for patients weighing 50 kg or more. • Pediatric dosing is based on weight

Hepatic Function Monitor hepatic function prior to and during treatment with efavirenz [ see Warnings and Precautions ]. Efavirenz is not recommended in patients with moderate or severe hepatic impairment (Child Pugh B or C) [ see Warnings and Precautions and Use in Specific Populations ]

Adults The recommended dosage of efavirenz is 600 mg orally, once daily, in combination with a protease inhibitor and/or nucleoside analogue reverse transcriptase inhibitors (NRTIs). It is recommended that efavirenz be taken on an empty stomach, preferably at bedtime. The increased efavirenz concentrations observed following administration of efavirenz with food may lead to an increase in frequency of adverse reactions . Dosing at bedtime may improve the tolerability of nervous system symptoms . Efavirenz capsules or tablets should be swallowed intact with liquid. Concomitant Antiretroviral Therapy Efavirenz must be given in combination with other antiretroviral medications . Dosage Adjustment If efavirenz is coadministered with voriconazole, the voriconazole maintenance dose should be increased to 400 mg every 12 hours and the efavirenz dose should be decreased to 300 mg once daily using the capsule formulation (one 200 mg and two 50 mg capsules or six 50 mg capsules). Efavirenz tablets must not be broken. . If efavirenz is coadministered with rifampin to patients weighing 50 kg or more, an increase in the dose of efavirenz to 800 mg once daily is recommended

Pediatric Patients It is recommended that efavirenz be taken on an empty stomach, preferably at bedtime. Table 1 describes the recommended dose of efavirenz for pediatric patients 3 months of age or older and weighing between 3.5 kg and 40 kg . The recommended dosage of efavirenz for pediatric patients weighing 40 kg or greater is 600 mg once daily. For pediatric patients who cannot swallow capsules, the capsule contents can be administered with a small amount of food or infant formula using the capsule sprinkle method of administration . Table 1: Efavirenz Dosing in Pediatric Patients Patient Body Weight Efavirenz Daily Dose Number of Capsules a or Tablets b and Strength to Administer 3.5 kg to less than 5 kg 100 mg two 50 mg capsules 5 kg to less than 7.5 kg 150 mg three 50 mg capsule 7.5 kg to less than 15 kg 200 mg one 200 mg capsule 15 kg to less than 20 kg 250 mg one 200 mg + one 50 mg capsule 20 kg to less than 25 kg 300 mg one 200 mg + two 50 mg capsules 25 kg to less than 32.5 kg 350 mg one 200 mg + three 50 mg capsules 32.5 kg to less than 40 kg 400 mg two 200 mg capsules at least 40 kg 600 mg one 600 mg tablet OR three 200 mg capsules a Capsules can be administered intact or as sprinkles . b Tablets must not be crushed

• QTc prolongation : Consider alternatives to efavirenz in patients taking other medications with a known risk of Torsade de Pointes or in patients at higher risk of Torsade de Pointes. • Do not use as a single agent or add on as a sole agent to a failing regimen. Consider potential for cross resistance when choosing other agents. •Not recommended with ATRIPLA, which contains efavirenz, emtricitabine, and tenofovir disoproxil fumarate, unless needed for dose adjustment when coadministered with rifampin. • Serious psychiatric symptoms : Immediate medical evaluation is recommended for serious psychiatric symptoms such as severe depression or suicidal ideation. ( 5.5 , 17 ) • Nervous system symptoms (NSS): NSS are frequent and usually begin 1-2 days after initiating therapy and resolve in 2-4 weeks. Dosing at bedtime may improve tolerability. NSS are not predictive of onset of psychiatric symptoms. ( 5.6 , 6.1 , 17 ) • Embryo-Fetal Toxicity : Avoid administration in the first trimester of pregnancy as fetal harm may occur. • Hepatotoxicity : Monitor liver function tests before and during treatment in patients with underlying hepatic disease, including hepatitis B or C coinfection, marked transaminase elevations, or who are taking medications associated with liver toxicity. Among reported cases of hepatic failure, a few occurred in patients with no pre-existing hepatic disease. ( 5.9 , 6.1 , 8.6 ) • Rash : Rash usually begins within 1-2 weeks after initiating therapy and resolves within 4 weeks. Discontinue if severe rash develops. ( 5.8 , 6.1 , 17 ) • Convulsions : Use caution in patients with a history of seizures. • Lipids : Total cholesterol and triglyceride elevations. Monitor before therapy and periodically thereafter. • Immune reconstitution syndrome : May necessitate further evaluation and treatment. • Redistribution/accumulation of body fat : Observed in patients receiving antiretroviral therapy. ( 5.13 , 17 ) 5.1 Drug Interactions Efavirenz plasma concentrations may be altered by substrates, inhibitors, or inducers of CYP3A. Likewise, efavirenz may alter plasma concentrations of drugs metabolized by CYP3A or CYP2B6. The most prominent effect of efavirenz at steady-state is induction of CYP3A and CYP2B6

QTc Prolongation QTc prolongation has been observed with the use of efavirenz [ see Drug Interactions and Clinical Pharmacology]. Consider alternatives to efavirenz when coadministered with a drug with a known risk of Torsade de Pointes or when administered to patients at higher risk of Torsade de Pointes

Resistance Efavirenz must not be used as a single agent to treat HIV-1 infection or added on as a sole agent to a failing regimen. Resistant virus emerges rapidly when efavirenz is administered as monotherapy. The choice of new antiretroviral agents to be used in combination with efavirenz should take into consideration the potential for viral cross-resistance

Coadministration with Related Products Coadministration of efavirenz with ATRIPLA (efavirenz 600 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg) is not recommended unless needed for dose adjustment (e.g., with rifampin), since efavirenz is one of its active ingredients

Psychiatric Symptoms Serious psychiatric adverse experiences have been reported in patients treated with efavirenz. In controlled trials of 1008 patients treated with regimens containing efavirenz for a mean of 2.1 years and 635 patients treated with control regimens for a mean of 1.5 years, the frequency (regardless of causality) of specific serious psychiatric events among patients who received efavirenz or control regimens, respectively, were severe depression (2.4%, 0.9%), suicidal ideation (0.7%, 0.3%), nonfatal suicide attempts (0.5%, 0), aggressive behavior (0.4%, 0.5%), paranoid reactions (0.4%, 0.3%), and manic reactions (0.2%, 0.3%). When psychiatric symptoms similar to those noted above were combined and evaluated as a group in a multifactorial analysis of data from Study 006, treatment with efavirenz was associated with an increase in the occurrence of these selected psychiatric symptoms. Other factors associated with an increase in the occurrence of these psychiatric symptoms were history of injection drug use, psychiatric history, and receipt of psychiatric medication at study entry; similar associations were observed in both the efavirenz and control treatment groups. In Study 006, onset of new serious psychiatric symptoms occurred throughout the study for both efavirenz-treated and control-treated patients. One percent of efavirenz -treated patients discontinued or interrupted treatment because of one or more of these selected psychiatric symptoms. There have also been occasional postmarketing reports of death by suicide, delusions, and psychosis-like behavior although a causal relationship to the use of efavirenz cannot be determined from these reports. Postmarketing cases of catatonia have also been reported and may be associated with increased efavirenz exposure. Patients with serious psychiatric adverse experiences should seek immediate medical evaluation to assess the possibility that the symptoms may be related to the use of efavirenz, and if so, to determine whether the risks of continued therapy outweigh the benefits

Nervous System Symptoms Fifty-three percent (531/1008) of patients receiving efavirenz in controlled trials reported central nervous system symptoms (any grade, regardless of causality) compared to 25% (156/635) of patients receiving control regimens . These symptoms included, but were not limited to, dizziness (28.1% of the 1008 patients), insomnia (16.3%), impaired concentration (8.3%), somnolence (7.0%), abnormal dreams (6.2%), and hallucinations (1.2%). These symptoms were severe in 2.0% of patients; and 2.1% of patients discontinued therapy as a result. These symptoms usually begin during the first or second day of therapy and generally resolve after the first 2-4 weeks of therapy. After 4 weeks of therapy, the prevalence of nervous system symptoms of at least moderate severity ranged from 5% to 9% in patients treated with regimens containing efavirenz and from 3% to 5% in patients treated with a control regimen. Patients should be informed that these common symptoms were likely to improve with continued therapy and were not predictive of subsequent onset of the less frequent psychiatric symptoms . Dosing at bedtime may improve the tolerability of these nervous system symptoms . Analysis of long-term data from Study 006 (median follow-up 180 weeks, 102 weeks, and 76 weeks for patients treated with efavirenz + zidovudine + lamivudine, efavirenz + indinavir, and indinavir + zidovudine + lamivudine, respectively) showed that, beyond 24 weeks of therapy, the incidences of new-onset nervous system symptoms among efavirenz-treated patients were generally similar to those in the indinavir-containing control arm. Late-onset neurotoxicity, including ataxia and encephalopathy (impaired consciousness, confusion, psychomotor slowing, psychosis, delirium), may occur months to years after beginning efavirenz therapy. Some events of late-onset neurotoxicity have occurred in patients with CYP2B6 genetic polymorphisms which are associated with increased efavirenz levels despite standard dosing of efavirenz. Patients presenting with signs and symptoms of serious neurologic adverse experiences should be evaluated promptly to assess the possibility that these events may be related to efavirenz use, and whether discontinuation of efavirenz is warranted. Patients receiving efavirenz should be alerted to the potential for additive central nervous system effects when efavirenz is used concomitantly with alcohol or psychoactive drugs. Patients who experience central nervous system symptoms such as dizziness, impaired concentration, and/or drowsiness should avoid potentially hazardous tasks such as driving or operating machinery

Embryo-Fetal Toxicity Efavirenz may cause fetal harm when administered during the first trimester to a pregnant woman. Advise females of reproductive potential who are receiving efavirenz to avoid pregnancy

Rash In controlled clinical trials, 26% (266/1008) of adult patients treated with 600 mg efavirenz experienced new-onset skin rash compared with 17% (111/635) of those treated in control groups . Rash associated with blistering, moist desquamation, or ulceration occurred in 0.9% (9/1008) of patients treated with efavirenz. The incidence of Grade 4 rash (e.g., erythema multiforme, Stevens-Johnson syndrome) in adult patients treated with efavirenz in all studies and expanded access was 0.1%. Rashes are usually mild-to-moderate maculopapular skin eruptions that occur within the first 2 weeks of initiating therapy with efavirenz (median time to onset of rash in adults was 11 days) and, in most patients continuing therapy with efavirenz, rash resolves within 1 month (median duration, 16 days). The discontinuation rate for rash in adult clinical trials was 1.7% (17/1008). Rash was reported in 59 of 182 pediatric patients (32%) treated with efavirenz . Two pediatric patients experienced Grade 3 rash (confluent rash with fever, generalized rash), and four patients had Grade 4 rash (erythema multiforme). The median time to onset of rash in pediatric patients was 28 days (range 3-1642 days). Prophylaxis with appropriate antihistamines before initiating therapy with efavirenz in pediatric patients should be considered. Efavirenz can generally be reinitiated in patients interrupting therapy because of rash. Efavirenz should be discontinued in patients developing severe rash associated with blistering, desquamation, mucosal involvement, or fever. Appropriate antihistamines and/or corticosteroids may improve the tolerability and hasten the resolution of rash. For patients who have had a life-threatening cutaneous reaction (e.g., Stevens-Johnson syndrome), alternative therapy should be considered

Hepatotoxicity Postmarketing cases of hepatitis, including fulminant hepatitis progressing to liver failure requiring transplantation or resulting in death, have been reported in patients treated with efavirenz. Reports have included patients with underlying hepatic disease, including coinfection with hepatitis B or C, and patients without pre-existing hepatic disease or other identifiable risk factors. Efavirenz is not recommended for patients with moderate or severe hepatic impairment. Careful monitoring is recommended for patients with mild hepatic impairment receiving efavirenz. [ see Adverse Reactions and Use in Specific Populations ]. Monitoring of liver enzymes before and during treatment is recommended for all patients [ see Dosage and Administration] . Consider discontinuing efavirenz in patients with persistent elevations of serum transaminases to greater than five times the upper limit of the normal range. Discontinue efavirenz if elevation of serum transaminases is accompanied by clinical signs or symptoms of hepatitis or hepatic decompensation

Convulsions Convulsions have been observed in adult and pediatric patients receiving efavirenz, generally in the presence of known medical history of seizures [ see Nonclinical Toxicology]. Caution should be taken in any patient with a history of seizures. Patients who are receiving concomitant anticonvulsant medications primarily metabolized by the liver, such as phenytoin and phenobarbital, may require periodic monitoring of plasma levels

Lipid Evaluations Treatment with efavirenz has resulted in increases in the concentration of total cholesterol and triglycerides . Cholesterol and triglyceride testing should be performed before initiating efavirenz therapy and at periodic intervals during therapy

Immune Reconstitution Syndrome Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including efavirenz. During the initial phase of combination antiretroviral treatment, patients whose immune system responds may develop an inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia [PCP], or tuberculosis), which may necessitate further evaluation and treatment. Autoimmune disorders (such as Graves disease, polymyositis, Guillain-Barré syndrome, and autoimmune hepatitis) have also been reported to occur in the setting of immune reconstitution; however, the time to onset is more variable, and can occur many months after initiation of treatment

Fat Redistribution Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.

Coadministration of efavirenz can alter the concentrations of other drugs and other drugs may alter the concentrations of efavirenz. The potential for drug-drug interactions should be considered before and during therapy

Potential for efavirenz to Affect other Drugs Efavirenz has been shown in vivo to induce CYP3A and CYP2B6. Other compounds that are substrates of CYP3A or CYP2B6 may have decreased plasma concentrations when coadministered with efavirenz 7.2 Potential for Other Drugs to Affect efavirenz Drugs that induce CYP3A activity (e.g., phenobarbital, rifampin, rifabutin) would be expected to increase the clearance of efavirenz resulting in lowered plasma concentrations

QT Prolonging Drugs There is limited information available on the potential for a pharmacodynamic interaction between efavirenz and drugs that prolong the QTc interval. QTc prolongation has been observed with the use of efavirenz . Consider alternatives to efavirenz when coadministered with a drug with a known risk of Torsade de Pointes

Established and Other Potentially Significant Drug Interactions Drug interactions with efavirenz are summarized in Table 5. For pharmacokinetics data, Tables 7 and 8. This table includes potentially significant interactions, but is not all inclusive Table 5: Established and Other Potentially Significant Drug Interactions: Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Studies or Predicted Interaction Concomitant Drug Class: Drug Name Effect Clinical Comment HIV antiviral agents Protease inhibitor: Fosamprenavir calcium ↓ amprenavir Fosamprenavir (unboosted): Appropriate doses of the combinations with respect to safety and efficacy have not been established. Fosamprenavir/ritonavir: An additional 100 mg/day (300 mg total) of ritonavir is recommended when efavirenz tablets are administered with fosamprenavir/ritonavir once daily. No change in the ritonavir dose is required when efavirenz tablets are administered with fosamprenavir plus ritonavir twice daily. Protease inhibitor: Atazanavir ↓ atazanavir * Treatment –naïve patients : When co-administered with efavirenz tablets , the recommended dose of atazanavir is 400 mg with ritonavir 100 mg (together once daily with food) and efavirenz tablets 600 mg ( once daily on an empty stomach, preferably at bedtime). Treatment-experienced patients: Co-administration of efavirenz tablets and atazanavir is not recommended. Protease inhibitor: Indinavir ↓ indinavir * The optimal dose of indinavir, when given in combination with efavirenz tablets are not known. Increasing the indinavir dose to 1000 mg every 8 hours does not compensate for the increased indinavir metabolism due to efavirenz . Protease inhibitor: Lopinavir/ritonavir ↓ lopinavir * Lopinavir/ritonavir once daily dosing is not recommended when co-administered with efavirenz. The dose of lopinavir/ritonavir must be increased when co-administered with efavirenz. See the lopinavir/ritonavir prescribing information for dose adjustments of lopinavir/ritonavir when co-administered with efavirenz in adult and pediatric patients. Protease inhibitor: Ritonavir ↑ ritonavir * ↑ efavirenz * Monitor for elevation of liver enzymes and for adverse clinical experiences (e.g., dizziness, nausea, paresthesia) when efavirenz is co-administered with ritonavir. Protease inhibitor: Saquinavir ↓ saquinavir * Appropriate doses of the combination of efavirenz and saquinavir/ritonavir with respect to safety and efficacy have not been established. NNRTI: Other NNRTIs ↑ or ↓ efavirenz and/ or NNRTI Combining two NNRTIs has not been shown to be beneficial. efavirenz should not be coadministered with other NNRTIs. CCR5 co-receptor antagonist: Maraviroc ↓ maraviroc* Refer to the full prescribing information for maraviroc for guidance on co-administration with efavirenz. Hepatitis C antiviral agents Boceprevir ↓ boceprevir* Concomitant administration of boceprevir with efavirenz is not recommended because it may result in loss of therapeutic effect of boceprevir Elbasvir/Grazoprevir ↓ elbasvir ↓ grazoprevir Co-administration o efavirenz with elbasvir/grazoprevir is contraindicated because it may lead to loss of virologic response to elbasvir/grazoprevir. Pibrentasvir/Glecaprevir ↓ pibrentasvir Co-administration of efavirenz is not recommended because it may lead to reduced therapeutic effect of pibrentasvir/glecaprevir Simeprevir ↓simeprevir* ↔efavirenz* Concomitant administration of simeprevir with efavirenz is not recommended because it may result in loss oftherapeutic effect of simeprevir. Velpatasvir/ Sofosbuvir ↓ velpatasvir Co-administration of efavirenz and sofosbuvir/velpatasvir is not recommended because it may result in loss of therapeutic effect of sofosbuvir/velpatasvir Velpatasvir /Sofosbuvir/Voxilaprevir ↓ velpatasvir ↓ voxilaprevir Co-administration of efavirenz and sofosbuvir/velpatasvir/voxilaprevir is not recommended because it may result in loss of therapeutic effect of sofosbuvir/velpatasvir/voxilaprevir. Other agents Anticoagulant: Warfarin ↑ or ↓ warfarin Monitor INR and adjust warfarin dosage if necessary. Anticonvulsants: Carbamazepine ↓ carbamazepine * ↓ efavirenz * There are insufficient data to make a dose recommendation for efavirenz. Alternative anticonvulsant treatment should be used. Phenytoin Phenobarbital ↓ anticonvulsant ↓ efavirenz Potential for reduction in anticonvulsant and/or efavirenz plasma levels; periodic monitoring of anticonvulsant plasma levels should be conducted. Antidepressant: Bupropion Sertraline ↓bupropion* ↓ sertraline * Increases in bupropion dosage should be guided by clinical response. Bupropion dose should not exceed the maximum recommended dose. Increases in sertraline dosage should be guided by clinical response. Antifungals: Voriconazole ↓ voriconazole * ↑ efavirenz * Efavirenz and voriconazole should not be co-administered at standard doses. When voriconazole is co-administered with efavirenz, voriconazole maintenance dose should be increased to 400 mg every 12 hours and efavirenz dose should be decreased to 300 mg once daily using the capsule formulation. Efavirenz tablets must not be broken. Itraconazole ↓ itraconazole * ↓ hydroxyitraconazole * Since no dose recommendation for itraconazole can be made, alternative antifungal treatment should be considered. Ketoconazole ↓ ketoconazole Drug interaction studies with efavirenz and ketoconazole have not been conducted. efavirenz has the potential to decrease plasma concentrations of ketoconazole. Posaconazole ↓ posaconazole* Avoid concomitant use unless the benefit outweighs the risks. Anthelmintic: Praziquantel ↓ praziquantel Co-administration with efavirenz is not recommended due to significant decrease in plasma concentrations of praziquantel, with risk of treatment failure due to increased hepatic metabolism by efavirenz. Anti-infective: Clarithromycin ↓ clarithromycin * ↑ 14-OH metabolite * Consider alternatives to macrolide antibiotics because of the risk of QT interval prolongation. Antimycobacterial: Rifabutin ↓ rifabutin * Increase daily dose of rifabutin by 50%. Consider doubling the rifabutin dose in regimens where rifabutin is given 2 or 3 times a week. Rifampin ↓ efavirenz * Increase efavirenz to 800 mg once daily when co-administered with rifampin to patients weighing 50 kg or more. Antimalarials: Artemether/ lumefantrine ↓ artemether* ↓ dihydroartemisinin* ↓ lumefantrine* Consider alternatives to artemether/lumefantrine because of the risk of QT interval prolongation. Atovaquone/ proguanil ↓ atovaquone ↓ proguanil Concomitant administration is not recommended. Calcium channel blockers: Diltiazem ↓ diltiazem * ↓ desacetyl diltiazem * ↓ N-monodesmethyl diltiazem * Diltiazem dose adjustments should be guided by clinical response (refer to the complete prescribing information for diltiazem). No dose adjustment of efavirenz is necessary when administered with diltiazem. Others (e.g., felodipine, nicardipine, nifedipine, verapamil) ↓ calcium channel blocker When co-administered with efavirenz, dosage adjustment of calcium channels blocker may be needed and should be guided by clinical response (refer to the full prescribing information for the calcium channel blocker). HMG-CoA reductase inhibitors: Atorvastatin Pravastatin Simvastatin ↓ atorvastatin * ↓ pravastatin * ↓ simvastatin * Plasma concentrations of atorvastatin, pravastatin, and simvastatin decreased. Consult the complete prescribing information for the HMG-CoA reductase inhibitor for guidance on individualizing the dose. Hormonal contraceptives: Oral Ethinyl estradiol/ Norgestimate Implant Etonogestrel ↓ active metabolites of Norgestimate * ↓ Etonogestrel A reliable method of barrier contraception should be used in addition to hormonal contraceptives. A reliable method of barrier contraception should be used in addition to hormonal contraceptives. Decreased exposure of etonogestrel may be expected. There have been post marketing reports of contraceptive failure with etonogestrel in efavirenz-exposed patients. Immunosuppressants: Cyclosporine, tacrolimus, sirolimus, and others metabolized by CYP3A ↓ immunosuppressant Dose adjustments of the immunosuppressant may be required. Close monitoring of immunosuppressant concentrations for at least 2 weeks (until stable concentrations are reached) is recommended when starting metabolized by or stopping treatment with efavirenz. Narcotic analgesic: Methadone ↓ methadone * Monitor for signs of methadone withdrawal and increase methadone dose if required to alleviate withdrawal symptoms. * The interaction between efavirenz and the drug was evaluated in a clinical study. All other drug interactions shown are predicted. This table is not all-inclusive

Drugs Without Clinically Significant Interactions with Efavirenz No dosage adjustment is recommended when efavirenz is given with the following: aluminum/magnesium hydroxide antacids, azithromycin, cetirizine, famotidine, fluconazole, lorazepam, nelfinavir, nucleoside reverse transcriptase inhibitors (abacavir, emtricitabine, lamivudine, stavudine, tenofovir disoproxil fumarate, zidovudine), paroxetine, and raltegravir

Cannabinoid Test Interaction Efavirenz does not bind to cannabinoid receptors. False-positive urine cannabinoid test results have been reported with some screening assays in uninfected and HIV-infected subjects receiving efavirenz. Confirmation of positive screening tests for cannabinoids by a more specific method is recommended.