ABACAVIR, LAMIVUDINE and ZIDOVUDINE tablets

ABACAVIR, LAMIVUDINE and ZIDOVUDINE tablets

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ABACAVIR, LAMIVUDINE and ZIDOVUDINE tablets

Abacavir, lamivudine and zidovudine tablets contain the following 3 synthetic nucleoside analogues: abacavir (ZIAGEN ), lamivudine (also known as EPIVIR or 3TC), and zidovudine (also known as RETROVIR , azidothymidine, or ZDV) with inhibitory activity against HIV-1.

Abacavir, lamivudine and zidovudine tablets are for oral administration. Each film-coated tablet contains the active ingredients 300 mg of abacavir as abacavir sulfate, 150 mg of lamivudine, and 300 mg of zidovudine, and the inactive ingredients crospovidone, magnesium stearate, microcrystalline cellulose, povidone, and yellow ferric oxide. The tablets are coated with a film opadry green that is made of FD&C blue no. 2, polyethylene glycol, polyvinyl alcohol, talc, titanium dioxide and yellow ferric oxide.

Abacavir Sulfate: The chemical name of abacavir sulfate is (1S,cis)-4-[2-amino-6- (cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol sulfate (salt) (2:1). Abacavir sulfate is the enantiomer with 1S, 4R absolute configuration on the cyclopentene ring. It has a molecular formula of (C14H18N6O) H2SO and a molecular weight of 670.76 g per mol.

Lamivudine: The chemical name of lamivudine is (2R,cis)-4-amino-1-(2-hydroxymethyl1,3-oxathiolan-5-yl)-(1H)-pyrimidin-2-one. Lamivudine is the (-)enantiomer of a dideoxy analogue of cytidine. Lamivudine has also been referred to as (-)2′,3′-dideoxy, 3′- thiacytidine. It has a molecular formula of C8H11N3O3S and a molecular weight of 229.3 g per mol.

Zidovudine: The chemical name of zidovudine is 3′-azido-3′-deoxythymidine. It has a molecular formula of C10H13N5O4 and a molecular weight of 267.24 g per mol.

Indications and usage

Abacavir, lamivudine and zidovudine tablet, a combination of abacavir, lamivudine, and zidovudine, each nucleoside analogue HIV-1 reverse transcriptase inhibitors, is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection.

Mechanism of action

Abacavir: Abacavir is a carbocyclic synthetic nucleoside analogue. Abacavir is converted by cellular enzymes to the active metabolite, carbovir triphosphate (CBV-TP), an analogue of deoxyguanosine-5′-triphosphate (dGTP). CBV-TP inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA.

Lamivudine: Lamivudine is a synthetic nucleoside analogue. Intracellularly, lamivudine is phosphorylated to its active 5′-triphosphate metabolite, lamivudine triphosphate (3TC-TP). The principal mode of action of 3TC-TP is inhibition of RT via DNA chain termination after incorporation of the nucleotide analogue.

Zidovudine: Zidovudine is a synthetic nucleoside analogue. Intracellularly, zidovudine is phosphorylated to its active 5′-triphosphate metabolite, zidovudine triphosphate (ZDV-TP). The principal mode of action of ZDV-TP is inhibition of RT via DNA chain termination after incorporation of the nucleotide analogue.

Dosage and administration

  • Before initiating abacavir, lamivudine and zidovudine tablets, screen for the HLA-B*5701 allele because abacavir, lamivudine and zidovudine tablet contains abacavir.
  • Adults and pediatric patients weighing at least 40 kg: 1 tablet twice daily.
  • Because abacavir, lamivudine and zidovudine tablet is a fixed-dose tablet and cannot be dose adjusted, abacavir, lamivudine and zidovudine tablets are not recommended in patients requiring dosage adjustment or patients with hepatic impairment.

Contraindications

  • Presence of HLA-B*5701 allele.
  • Prior hypersensitivity reaction to abacavir, lamivudine, or zidovudine
  • Moderate or severe hepatic impairment.

Adverse reactions

The most commonly reported adverse reactions (incidence at least 10%) in clinical trials were nausea, headache, malaise and fatigue, and nausea and vomiting.

Warnings and precautions

Hypersensitivity Reactions: Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir, a component of abacavir, lamivudine and zidovudine tablets. These hypersensitivity reactions have included multi-organ failure and anaphylaxis and typically occurred within the first 6 weeks of treatment with abacavir (median time to onset was 9 days); although abacavir hypersensitivity reactions have occurred any time during treatment. Patients who carry the HLA-B*5701 allele are at a higher risk of abacavir hypersensitivity reactions; although, patients who do not carry the HLA-B*5701 allele have developed hypersensitivity reactions. Hypersensitivity to abacavir was reported in approximately 206 (8%) of 2,670 patients in 9 clinical trials with abacavir-containing products where HLA-B*5701 screening was not performed. The incidence of suspected abacavir hypersensitivity reactions in clinical trials was 1% when subjects carrying the HLA-B*5701 allele were excluded. In any patient treated with abacavir, the clinical diagnosis of hypersensitivity reaction must remain the basis of clinical decision making.

Hematologic Toxicity/Bone Marrow Suppression: Zidovudine, a component of abacavir, lamivudine and zidovudine tablet, has been associated with hematologic toxicity including neutropenia and anemia, particularly in patients with advanced HIV-1 disease. Abacavir, lamivudine and zidovudine tablets should be used with caution in patients who have bone marrow compromise evidenced by granulocyte count less than 1,000 cells per mm3 or hemoglobin less than 9.5 grams per dL.

Frequent blood counts are strongly recommended in patients with advanced HIV-1 disease who are treated with abacavir, lamivudine and zidovudine tablets. Periodic blood counts are recommended for other HIV-1-infected patients. If anemia or neutropenia develops, dosage interruption may be needed.

Myopathy: Myopathy and myositis, with pathological changes similar to that produced by HIV-1 disease, have been associated with prolonged use of zidovudine, and therefore may occur with therapy with abacavir, lamivudine and zidovudine tablets.

Lactic Acidosis and Severe Hepatomegaly with Steatosis: Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues, including abacavir, lamivudine and zidovudine (components of abacavir, lamivudine and zidovudine tablets). A majority of these cases have been in women. Female sex and obesity may be risk factors for the development of lactic acidosis and severe hepatomegaly with steatosis in patients treated with antiretroviral nucleoside analogues. See full prescribing information for ZIAGEN (abacavir), EPIVIR (lamivudine), and RETROVIR (zidovudine). Treatment with abacavir, lamivudine and zidovudine tablets should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations).

Exacerbations of Hepatitis B: Severe acute exacerbations of hepatitis B have been reported in patients who are co-infected with hepatitis B virus (HBV) and HIV-1 and have discontinued lamivudine, a component of abacavir, lamivudine and zidovudine tablets. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue abacavir, lamivudine and zidovudine tablets and are co-infected with HIV-1 and HBV. If appropriate, initiation of anti- hepatitis B therapy may be warranted

Use with Interferon- and Ribavirin-Based Regimens: Patients receiving interferon alfa with or without ribavirin and abacavir, lamivudine and zidovudine tablets should be closely monitored for treatment-associated toxicities, especially hepatic decompensation, neutropenia, and anemia. See full prescribing information for RETROVIR (zidovudine). Discontinuation of abacavir, lamivudine and zidovudine tablets should be considered as medically appropriate. Dose reduction or discontinuation of interferon alfa, ribavirin, or both should also be considered if worsening clinical toxicities are observed, including hepatic decompensation (e.g., ChildPugh greater than 6) (see full prescribing information for interferon and ribavirin). Exacerbation of anemia has been reported in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine. Coadministration of ribavirin and abacavir, lamivudine and zidovudine tablet is not advised.

Immune Reconstitution Syndrome:

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Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including abacavir, lamivudine and zidovudine tablets. During the initial phase of combination antiretroviral treatment, patients whose immune systems respond 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, and Guillain-BarrÉ syndrome) 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.

Lipoatrophy: Treatment with zidovudine, a component of abacavir, lamivudine and zidovudine tablets, has been associated with loss of subcutaneous fat. The incidence and severity of lipoatrophy are related to cumulative exposure. This fat loss, which is most evident in the face, limbs, and buttocks, may be only partially reversible and improvement may take months to years after switching to a non-zidovudine-containing regimen. Patients should be regularly assessed for signs of lipoatrophy during therapy with zidovudinecontaining products, and if feasible, therapy should be switched to an alternative regimen if there is suspicion of lipoatrophy.

Myocardial Infarction: Several prospective, observational, epidemiological studies have reported an association with the use of abacavir and the risk of myocardial infarction (MI). Meta-analyses of randomized, controlled clinical trials have observed no excess risk of MI in abacavirtreated subjects as compared with control subjects. To date, there is no established biological mechanism to explain a potential increase in risk. In totality, the available data from the observational studies and from controlled clinical trials show inconsistency; therefore, evidence for a causal relationship between abacavir treatment and the risk of MI is inconclusive.

As a precaution, the underlying risk of coronary heart disease should be considered when prescribing antiretroviral therapies, including abacavir, and action taken to minimize all modifiable risk factors (e.g., hypertension, hyperlipidemia, diabetes mellitus, smoking).

Drug interactions

Methadone: In a trial of 11 HIV-1-infected subjects receiving methadone-maintenance therapy with 600 mg of ZIAGEN® twice daily (twice the currently recommended dose), oral methadone clearance increased. This alteration will not result in a methadone dose modification in the majority of patients; however, an increased methadone dose may be required in a small number of patients.

Riociguat: Coadministration with fixed-dose abacavir/dolutegravir/lamivudine resulted in increased riociguat exposure, which may increase the risk of riociguat adverse reactions. The riociguat dose may need to be reduced.

Sorbitol: Coadministration of single doses of lamivudine and sorbitol resulted in a sorbitol dose- dependent reduction in lamivudine exposures. When possible, avoid use of sorbitolcontaining medicines with lamivudine-containing medicines

Agents Antagonistic with Zidovudine: Concomitant use of zidovudine with the following drugs should be avoided since an antagonistic relationship has been demonstrated in vitro:

  • Stavudine
  • Doxorubicin
  • Nucleoside analogues, e.g., ribavirin

Hematologic/Bone Marrow Suppressive/Cytotoxic Agents: Coadministration with the following drugs may increase the hematologic toxicity of zidovudine:

  • Ganciclovir
  • Interferon alfa
  • Ribavirin
  • Other bone marrow suppressive or cytotoxic agents
Use in specific populations

Pregnancy: Not enough data

Lactation: The Centers for Disease Control and Prevention recommends that HIV-1-infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection. Abacavir, lamivudine and zidovudine are present in human milk. There is no information on the effects of abacavir, lamivudine and zidovudine on the breastfed infant or the effects of the drug on milk production. Because of the potential for (1) HIV-1 transmission (in HIV-negative infants), (2) developing viral resistance (in HIV-positive infants), and (3) adverse reactions in a breastfed infant similar to those seen in adults, instruct mothers not to breastfeed if they are receiving abacavir, lamivudine and zidovudine tablets.

Pediatric Use: Abacavir, lamivudine and zidovudine tablet is not recommended in children who weigh less than 40 kg because it is a fixed-dose tablet that cannot be adjusted for these patient populations

Geriatric Use: Clinical trials of abacavir, lamivudine, and zidovudine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, caution should be exercised in the administration of abacavir, lamivudine and zidovudine tablets in elderly patients reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Patients with Impaired Renal Function: Abacavir, lamivudine and zidovudine tablet is not recommended for patients with creatinine clearance less than 50 mL per min because abacavir, lamivudine and zidovudine tablet is a fixed-dose combination and the dosage of the individual components cannot be adjusted. If a dose reduction of the lamivudine or zidovudine components of abacavir, lamivudine and zidovudine tablet is required for patients with renal impairment then the individual components should be used.

Patients with Impaired Hepatic Function: Abacavir, lamivudine and zidovudine tablet is a fixed-dose combination and the dosage of the individual components cannot be adjusted. If a dose reduction of abacavir, a component of abacavir, lamivudine and zidovudine tablet, is required for patients with mild hepatic impairment (Child-Pugh Class A), then the individual components should be used.

The safety, efficacy, and pharmacokinetic properties of abacavir have not been established in patients with moderate (Child-Pugh Class B) or severe (Child-Pugh Class C) hepatic impairment; therefore, abacavir, lamivudine and zidovudine tablets are contraindicated in these patients.

Zidovudine is primarily eliminated by hepatic metabolism and zidovudine concentrations are increased in patients with impaired hepatic function, which may increase the risk of hematologic toxicity. Frequent monitoring of hematologic toxicities is advised.

Overdosage

There is no known specific treatment for overdose with abacavir, lamivudine and zidovudine tablets. If overdose occurs, the patient should be monitored and standard supportive treatment applied as required.

Abacavir: It is not known whether abacavir can be removed by peritoneal dialysis or hemodialysis.

Lamivudine: Because a negligible amount of lamivudine was removed via (4-hour) hemodialysis, continuous ambulatory peritoneal dialysis, and automated peritoneal dialysis, it is not known if continuous hemodialysis would provide clinical benefit in a lamivudine overdose event.

Zidovudine: Acute overdoses of zidovudine have been reported in pediatric patients and adults. These involved exposures up to 50 grams. No specific symptoms or signs have been identified following acute overdosage with zidovudine apart from those listed as adverse events such as fatigue, headache, vomiting, and occasional reports of hematological disturbances. Patients recovered without permanent sequelae. Hemodialysis and peritoneal dialysis appear to have a negligible effect on the removal of zidovudine, while elimination of its primary metabolite, 3′- azido-3′-deoxy-5′-O-β-D- glucopyranuronosylthymidine (GZDV), is enhanced.

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