Abacavir And Lamivudine

1 INDICATIONS AND USAGE Abacavir and lamivudine tablet, a combination of abacavir and lamivudine, both nucleoside analogue HIV-1 reverse transcriptase inhibitors, is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. ( 1 ) Abacavir and lamivudine tablets, in combination with other antiretroviral agents, are indicated for the treatment of human immunodeficiency virus type 1 (HIV-1) infection.

2 DOSAGE AND ADMINISTRATION Before initiating abacavir and lamivudine tablets, screen for the HLA-B*5701 allele because abacavir and lamivudine tablets contains abacavir. ( 2.1 ) Adults: One tablet orally once daily. ( 2.2 ) Pediatric patients weighing at least 25 kg: One tablet daily. ( 2.3 ) Because abacavir and lamivudine tablets is a fixed-dose tablet and cannot be dose adjusted, abacavir and lamivudine tablets is not recommended in patients with creatinine clearance less than 30 mL per minute or patients with hepatic impairment. ( 2.4 , 4 ) 2.1 Screening for HLA-B*5701 Allele Prior to Starting Abacavir and Lamivudine Tablets Screen for the HLA-B*5701 allele prior to initiating therapy with abacavir and lamivudine tablets [see Boxed Warning , Warnings and Precautions ( 5.1 )] . 2.2 Recommended Dosage for Adult Patients The recommended dosage of abacavir and lamivudine tablets for adults is one tablet taken orally once daily, in combination with other antiretroviral agents, with or without food. 2.3 Recommended Dosage for Pediatric Patients The recommended oral dose of abacavir and lamivudine tablets for pediatric patients weighing at least 25 kg is one tablet daily in combination with other antiretroviral agents [see Clinical Studies ( 14.2 )] . Before prescribing abacavir and lamivudine tablets, pediatric patients should be assessed for the ability to swallow tablets. 2.4 Not Recommended Due to Lack of Dosage Adjustment Because abacavir and lamivudine tablet is a fixed-dose tablet and cannot be dose adjusted, abacavir and lamivudine tablets are not recommended for: patients with creatinine clearance less than 30 mL per minute [see Use in Specific Populations ( 8.6 )] . patients with mild hepatic impairment. Abacavir and lamivudine tablets is contraindicated in patients with moderate or severe hepatic impairment [see Contraindications ( 4 ), Use in Specific Populations ( 8.7 )] . Use of EPIVIR® (lamivudine) oral solution or tablets and ZIAGEN® (abacavir) oral solution may be considered.

6 ADVERSE REACTIONS The most commonly reported adverse reactions of at least moderate intensity (incidence greater than 5%) in an adult HIV-1 clinical trial were drug hypersensitivity, insomnia, depression/depressed mood, headache/migraine, fatigue/malaise, dizziness/vertigo, nausea, and diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Lupin Pharmaceuticals, Inc. at 1-800-399-2561 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. The following adverse reactions are discussed in greater detail in other sections of the labeling: Serious and sometimes fatal hypersensitivity reactions [see Boxed Warning, Warnings and Precautions ( 5.1 )]. Exacerbations of hepatitis B [see Boxed Warning, Warnings and Precautions ( 5.2 )]. Lactic acidosis and severe hepatomegaly with steatosis [see Warnings and Precautions ( 5.3 )]. Immune reconstitution syndrome [see Warnings and Precautions ( 5.4 )]. Myocardial infarction [see Warnings and Precautions ( 5.5 )]. 6.1 Clinical Trials Experience in Adult Subjects Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Serious and Fatal Abacavir-Associated Hypersensitivity Reactions In clinical trials, serious and sometimes fatal hypersensitivity reactions have occurred with abacavir, a component of abacavir and lamivudine tablets [ see Boxed Warning, Warnings and Precautions ( 5.1 ) ]. These reactions have been characterized by 2 or more of the following signs or symptoms: (1) fever; (2) rash; (3) gastrointestinal symptoms (including nausea, vomiting, diarrhea, or abdominal pain); (4) constitutional symptoms (including generalized malaise, fatigue, or achiness); (5) respiratory symptoms (including dyspnea, cough, or pharyngitis). Almost all abacavir hypersensitivity reactions include fever and/or rash as part of the syndrome. Other signs and symptoms have included lethargy, headache, myalgia, edema, arthralgia, and paresthesia. Anaphylaxis, liver failure, renal failure, hypotension, adult respiratory distress syndrome, respiratory failure, myolysis, and death have occurred in association with these hypersensitivity reactions. Physical findings have included lymphadenopathy, mucous membrane lesions (conjunctivitis and mouth ulcerations), and maculopapular or urticarial rash (although some patients had other types of rashes and others did not have a rash). There were reports of erythema multiforme. Laboratory abnormalities included elevated liver chemistries, elevated creatine phosphokinase, elevated creatinine, and lymphopenia and abnormal chest x-ray findings (predominantly infiltrates, which were localized). Additional Adverse Reactions with Use of Abacavir and Lamivudine Tablets: Therapy-Naive Adults: Treatment-emergent clinical adverse reactions (rated by the investigator as moderate or severe) with greater than or equal to 5% frequency during therapy with ZIAGEN 600 mg once daily or ZIAGEN 300 mg twice daily, both in combination with lamivudine 300 mg once daily and efavirenz 600 mg once daily, are listed in Table 1. Table 1. Treatment-Emergent (All Causality) Adverse Reactions of at Least Moderate Intensity (Grades 2 to 4, Greater than or Equal to 5% Frequency) in Therapy-Naive Adults (CNA30021) through 48 Weeks of Treatment a Subjects receiving ZIAGEN 600 mg once daily, experienced a significantly higher incidence of severe drug hypersensitivity reactions and severe diarrhea compared with subjects who received ZIAGEN 300 mg twice daily. Five percent (5%) of subjects receiving ZIAGEN 600 mg once daily had severe drug hypersensitivity reactions compared with 2% of subjects receiving ZIAGEN 300 mg twice daily. Two percent (2%) of subjects receiving ZIAGEN 600 mg once daily had severe diarrhea while none of the subjects receiving ZIAGEN 300 mg twice daily had this event. b CNA30024 was a multi-center, double-blind, controlled trial in which 649 HIV-1-infected, therapy-naive adults were randomized and received either ZIAGEN (300 mg twice daily), EPIVIR (150 mg twice daily), and efavirenz (600 mg once daily); or zidovudine (300 mg twice daily), EPIVIR (150 mg twice daily), and efavirenz (600 mg once daily). CNA30024 used double-blind ascertainment of suspected hypersensitivity reactions. During the blinded portion of the trial, suspected hypersensitivity to abacavir was reported by investigators in 9% of 324 subjects in the abacavir group and 3% of 325 subjects in the zidovudine group. Adverse Event ZIAGEN 600 mg q . d . plus EPIVIR plus Efavirenz ( n = 384 ) ZIAGEN 300 mg b . i . d . plus EPIVIR plus Efavirenz ( n = 386 ) Drug hypersensitivity a , b 9% 7% Insomnia 7% 9% Depression/Depressed mood 7% 7% Headache/Migraine 7% 6% Fatigue/Malaise 6% 8% Dizziness/Vertigo 6% 6% Nausea 5% 6% Diarrhea a 5% 6% Rash 5% 5% Pyrexia 5% 3% Abdominal pain/gastritis 4% 5% Abnormal dreams 4% 5% Anxiety 3% 5% Laboratory Abnormalities Laboratory abnormalities observed in clinical trials of ZIAGEN were anemia, neutropenia, liver function test abnormalities, and elevations of CPK, blood glucose, and triglycerides. Additional laboratory abnormalities observed in clinical trials of EPIVIR were thrombocytopenia and elevated levels of bilirubin, amylase, and lipase. The frequencies of treatment-emergent laboratory abnormalities were comparable between treatment groups in CNA30021. Other Adverse Events In addition to adverse reactions listed above, other adverse events observed in the expanded access program for abacavir were pancreatitis and increased GGT. 6.2 Clinical Trials Experience in Pediatric Subjects The safety of once-daily compared with twice-daily dosing of abacavir and lamivudine, administered as either single products or as abacavir and lamivudine tablets, was assessed in the ARROW trial (n = 336). Primary safety assessment in the ARROW (COL105677) trial was based on Grade 3 and Grade 4 adverse events. The frequency of Grade 3 and 4 adverse events was similar among subjects randomized to once-daily dosing compared with subjects randomized to twice-daily dosing. One event of Grade 4 hepatitis in the once-daily cohort was considered as uncertain causality by the investigator and all other Grade 3 or 4 adverse events were considered not related by the investigator. No additional safety issues were identified in pediatric subjects receiving abacavir and lamivudine once-daily compared with historical data in adults [see Adverse Reactions ( 6.1 )] . 6.3 Postmarketing Experience The following adverse reactions have been identified during postmarketing use. Because these reactions are reported voluntarily from a population of unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Abacavir Cardiovascular: Myocardial infarction. Skin: Suspected Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported in patients receiving abacavir primarily in combination with medications known to be associated with SJS and TEN, respectively. Because of the overlap of clinical signs and symptoms between hypersensitivity to abacavir and SJS and TEN, and the possibility of multiple drug sensitivities in some patients, abacavir should be discontinued and not restarted in such cases. There have also been reports of erythema multiforme with abacavir use [see Adverse Reactions ( 6.1 )] . Abacavir and Lamivudine Body as a Whole: Redistribution/accumulation of body fat . Digestive: Stomatitis. Endocrine and Metabolic: Hyperglycemia. General: Weakness. Hemic and Lymphatic: Aplastic anemia, anemia (including pure red cell aplasia and severe anemias progressing on therapy), lymphadenopathy, splenomegaly. Hepatic: Lactic acidosis and hepatic steatosis [see Warnings And Precautions ( 5.3 )] , posttreatment exacerbation of hepatitis B [see Warnings And Precautions ( 5.2 )]. Hypersensitivity: Sensitization reactions (including anaphylaxis), urticaria. Musculoskeletal: Muscle weakness, creatinine phosphokinase (CPK) elevation, rhabdomyolysis. Nervous: Paresthesia, peripheral neuropathy, seizures. Respiratory: Abnormal breath sounds/wheezing. Skin: Alopecia, erythema multiforme, Stevens-Johnson syndrome.

12.3 Pharmacokinetics Pharmacokinetics in Adults In a single-dose, 3-way crossover bioavailability trial of 1 abacavir and lamivudine tablet versus 2 ZIAGEN tablets (2 x 300 mg) and 2 EPIVIR tablets (2 x 150 mg) administered simultaneously in healthy subjects (n = 25), there was no difference in the extent of absorption, as measured by the area under the plasma concentration-time curve (AUC) and maximal peak concentration (C max ), of each component. Abacavir: Following oral administration, abacavir is rapidly absorbed and extensively distributed. After oral administration of a single dose of 600 mg of abacavir in 20 subjects, C max was 4.26 ± 1.19 mcg per mL (mean ± SD) and AUC ∞ was 11.95 ± 2.51 mcg•hour per mL. Binding of abacavir to human plasma proteins is approximately 50% and was independent of concentration. Total blood and plasma drug-related radioactivity concentrations are identical, demonstrating that abacavir readily distributes into erythrocytes. The primary routes of elimination of abacavir are metabolism by alcohol dehydrogenase to form the 5'-carboxylic acid and glucuronyl transferase to form the 5'-glucuronide. Lamivudine: Following oral administration, lamivudine is rapidly absorbed and extensively distributed. After multiple-dose oral administration of lamivudine 300 mg once daily for 7 days to 60 healthy subjects, steady-state C max (C max , ss ) was 2.04 ± 0.54 mcg per mL (mean ± SD) and the 24-hour steady-state AUC (AUC 24 , ss ) was 8.87 ± 1.83 mcg•hour per mL. Binding to plasma protein is low. Approximately 70% of an intravenous dose of lamivudine is recovered as unchanged drug in the urine. Metabolism of lamivudine is a minor route of elimination. In humans, the only known metabolite is the trans-sulfoxide metabolite (approximately 5% of an oral dose after 12 hours). In humans, abacavir and lamivudine are not significantly metabolized by cytochrome P450 (CYP) enzymes. The pharmacokinetic properties of abacavir and lamivudine in fasting subjects are summarized in Table 2. Table 2: Pharmacokinetic Parameters Data presented as mean ± standard deviation except where noted. for Abacavir and Lamivudine in Adults Parameter Abacavir Lamivudine Oral bioavailability (%) 86 ± 25 n = 6 86 ± 16 n = 12 Apparent volume of distribution (L/kg) 0.86 ± 0.15 n = 6 1.3 ± 0.4 n = 20 Systemic clearance (L/h/kg) 0.80 ± 0.24 n = 6 0.33 ± 0.06 n = 20 Renal clearance (L/h/kg) 0.007 ± 0.008 n = 6 0.22 ± 0.06 n = 20 Elimination half-life (h) 1.45 ± 0.32 n = 20 13 to 19 Approximate range Effect of Food on Absorption of Abacavir and Lamivudine Tablets Abacavir and lamivudine tablets may be administered with or without food. Administration with a high-fat meal in a single-dose bioavailability trial resulted in no change in AUC last , AUC ∞ , and C max for lamivudine. Food did not alter the extent of systemic exposure to abacavir (AUC ∞ ), but the rate of absorption (C max ) was decreased approximately 24% compared with fasted conditions (n = 25). These results are similar to those from previous trials of the effect of food on abacavir and lamivudine tablets administered separately. Specific Populations Patients with Renal Impairment: The pharmacokinetics for the individual lamivudine component of abacavir and lamivudine tablets has been evaluated in patients with renal impairment (see the U.S. prescribing information for the individual lamivudine component). Patients with Hepatic Impairment: The pharmacokinetics for the individual components of abacavir and lamivudine tablets have been evaluated in patients with varying degrees of hepatic impairment (see the U.S. prescribing information for the individual abacavir and lamivudine components). Pregnant Women: Abacavir: Abacavir pharmacokinetics were studied in 25 pregnant women during the last trimester of pregnancy receiving abacavir 300 mg twice daily. Abacavir exposure (AUC) during pregnancy was similar to those in postpartum and in HIV-infected non-pregnant historical controls. Consistent with passive diffusion of abacavir across the placenta, abacavir concentrations in neonatal plasma cord samples at birth were essentially equal to those in maternal plasma at delivery. Lamivudine : Lamivudine pharmacokinetics were studied in 36 pregnant women during 2 clinical trials conducted in South Africa. Lamivudine pharmacokinetics in pregnant women were similar to those seen in non-pregnant adults and in postpartum women. Lamivudine concentrations were generally similar in maternal, neonatal, and umbilical cord serum samples. Pediatric Patients: Abacavir and lamivudine The pharmacokinetic data for abacavir and lamivudine following administration of abacavir and lamivudine tablets in pediatric subjects weighing 25 kg and above are limited. The dosing recommendations in this population are based on the safety and efficacy established in a controlled trial conducted using either the combination of EPIVIR and ZIAGEN or abacavir and lamivudine tablets. Refer to the EPIVIR and ZIAGEN USPI for pharmacokinetic information on the individual products in pediatric patients [see Dosage and Administration ( 2.3 ), Adverse Reactions ( 6.2 ), Clinical Studies ( 14.2 )] . Geriatric Patients: The pharmacokinetics of abacavir and lamivudine have not been studied in subjects over 65 years of age. Male and Female Patients: There are no significant or clinically relevant gender differences in the pharmacokinetics of the individual components (abacavir or lamivudine) based on the available information that was analyzed for each of the individual components. Racial Groups: There are no significant or clinically relevant racial differences in pharmacokinetics of the individual components (abacavir or lamivudine) based on the available information that was analyzed for each of the individual components. Drug Interaction Studies: The drug interactions described are based on trials conducted with abacavir or lamivudine as single entities; no drug interaction trials have been conducted with abacavir and lamivudine tablets. Effect of Abacavir and Lamivudine on the Pharmacokinetics of Other Agents: In vitro studies have shown that abacavir has potential to inhibit CYP1A1 and limited potential to inhibit metabolism mediated by CYP3A4. Lamivudine does not inhibit or induce CYP3A4. Abacavir and lamivudine do not inhibit or induce other CYP enzymes (such as CYP2C9, or CYP2D6) Based on in vitro study results, abacavir and lamivudine at therapeutic drug exposures are not expected to affect the pharmacokinetics of drugs that are substrates of the following transporters: organic anion transporter polypeptide (OATP)1B1/3, breast cancer resistance protein (BCRP) or P-glycoprotein (P-gp), organic cation transporter (OCT)1, OCT2, OCT3 (lamivudine only), or multidrug and toxic extrusion protein (MATE)1 and MATE2-K. Riociguat: Coadministration of a single dose of riociguat (0.5 mg) to HIV-1–infected subjects receiving fixed-dose abacavir/dolutegravir/lamivudine is reported to increase riociguat AUC( ) compared with riociguat AUC( ) reported in healthy subjects due to CYP1A1 inhibition by abacavir. The exact magnitude of increase in riociguat exposure has not been fully characterized based on findings from two studies [see Drug Interactions (7.3)] . Effect of Other Agents on the Pharmacokinetics of Abacavir or Lamivudine: Abacavir and lamivudine are not significantly metabolized by CYP enzymes; therefore, CYP enzyme inhibitors or inducers are not expected to affect their concentrations. In vitro, abacavir is not a substrate of OATP1B1, OATP1B3, OCT1, OCT2, OAT1, MATE1, MATE2-K, multidrug resistance-associated protein 2 (MRP2) or MRP4; therefore, drugs that modulate these transporters are not expected to affect abacavir plasma concentrations. Abacavir is a substrate of BCRP and P-gp in vitro; however, considering its absolute bioavailability (83%), modulators of these transporters are unlikely to result in a clinically relevant impact on abacavir concentrations. Lamivudine is a substrate of MATE1, MATE2-K, and OCT2 in vitro. Trimethoprim (an inhibitor of these drug transporters) has been shown to increase lamivudine plasma concentrations. This interaction is not considered clinically significant as no dose adjustment of lamivudine is needed. Lamivudine is a substrate of P-gp and BCRP; however, considering its absolute bioavailability (87%), it is unlikely that these transporters play a significant role in the absorption of lamivudine. Therefore, coadministration of drugs that are inhibitors of these efflux transporters is unlikely to affect the disposition and elimination of lamivudine. Abacavir: Lamivudine and/or Zidovudine Fifteen HIV-1-infected subjects were enrolled in a crossover-designed drug interaction trial evaluating single doses of abacavir (600 mg), lamivudine (150 mg), and zidovudine (300 mg) alone or in combination. Analysis showed no clinically relevant changes in the pharmacokinetics of abacavir with the addition of lamivudine or zidovudine or the combination of lamivudine and zidovudine. Lamivudine exposure (AUC decreased 15%) and zidovudine exposure (AUC increased 10%) did not show clinically relevant changes with concurrent abacavir. Lamivudine: Zidovudine No clinically significant alterations in lamivudine or zidovudine pharmacokinetics were observed in 12 asymptomatic HIV-1-infected adult subjects given a single dose of zidovudine (200 mg) in combination with multiple doses of lamivudine (300 mg every 12 h). Other Interactions Ethanol Abacavir has no effect on the pharmacokinetic properties of ethanol. Ethanol decreases the elimination of abacavir causing an increase in overall exposure. Interferon Alfa There was no significant pharmacokinetic interaction between lamivudine and interferon alfa in a trial of 19 healthy male subjects. Methadone In a trial of 11 HIV-1-infected subjects receiving methadone-maintenance therapy (40 mg and 90 mg daily), with 600 mg of ZIAGEN twice daily (twice the currently recommended dose), oral methadone clearance increased 22% (90% CI: 6% to 42%) [see Drug Interactions ( 7 )]. The addition of methadone has no clinically significant effect on the pharmacokinetic properties of abacavir. Ribavirin In vitro data indicate ribavirin reduces phosphorylation of lamivudine, stavudine, and zidovudine. However, no pharmacokinetic (e.g., plasma concentrations or intracellular triphosphorylated active metabolite concentrations) or pharmacodynamic (e.g., loss of HIV-1/HCV virologic suppression) interaction was observed when ribavirin and lamivudine (n = 18), stavudine (n = 10), or zidovudine (n = 6) were coadministered as part of a multi-drug regimen to HIV-1/HCV co-infected subjects. Sorbitol (Excipient) Lamivudine and sorbitol solutions were coadministered to 16 healthy adult subjects in an open-label, randomized-sequence, 4-period, crossover trial. Each subject received a single 300-mg dose of lamivudine oral solution alone or coadministered with a single dose of 3.2 grams, 10.2 grams, or 13.4 grams of sorbitol in solution. Coadministration of lamivudine with sorbitol resulted in dose-dependent decreases of 20%, 39%, and 44% in the AUC (0-24) ; 14%, 32%, and 36% in the AUC (∞) ; and 28%, 52%, and 55% in the C max ; of lamivudine, respectively. The effects of other coadministered drugs on abacavir or lamivudine are provided in Table 3. Table 3: Effect of Coadministered Drugs on Abacavir or Lamivudine ↑ = Increase; ↔ = No significant change; AUC = Area under the concentration versus time curve; CI = Confidence interval. Coadministered Drug Drug and n Concentrations of Abacavir or Lamivudine Concentration of and Dose Dose AUC Variability Coadministered Drug Ethanol 0.7 g/kg Abacavir Single 600 mg 24 ↑41% 90% CI: 35% to 48% ↔ The drug-drug interaction was only evaluated in males Nelfinavir 750 mg every 8 h x 7 to 10 days Lamivudine Single 150 mg 11 ↑10% 95% CI: 1% to 20% ↔ Trimethoprim 160 mg/ Sulfamethoxazole 800 mg daily x 5 days Lamivudine Single 300 mg 14 ↑43% 90% CI: 32% to 55% ↔