Saturday, January 19, 2008

Abacavir and lamivudine

U.S. BRAND NAMES — Epzicom™
PHARMACOLOGIC CATEGORY Antiretroviral Agent, Reverse Transcriptase Inhibitor (Nucleoside)
DOSING: ADULTS — HIV: Oral: One tablet (abacavir 600 mg and lamivudine 300 mg) once daily
DOSING: RENAL IMPAIRMENT — Clcr <50 mL/minute: Use not recommended
DOSING: HEPATIC IMPAIRMENT — Use contraindicated.
DOSAGE FORMS — Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet: Epzicom™: Abacavir 600 mg and lamivudine 300 mg
DOSAGE FORMS: CONCISE Tablet: Epzicom™: Abacavir 600 mg and lamivudine 300 mg
GENERIC EQUIVALENT AVAILABLE — No
ADMINISTRATION — May be administered with or without food.
USE — Treatment of HIV infections in combination with other antiretroviral agents
ADVERSE REACTIONS SIGNIFICANT — See individual agents.
Postmarketing and/or case reports: Alopecia, anaphylaxis, anemia, aplastic anemia, breath sounds abnormal, CPK increased, erythema multiforme, fat redistribution, hepatic steatosis, hepatitis B exacerbation, hyperglycemia, hypersensitivity reaction, lactic acidosis, lymphadenopathy, muscle weakness, pancreatitis, paresthesia, peripheral neuropathy, rhabdomyolysis, seizure, splenomegaly, Stevens-Johnson syndrome, stomatitis, urticaria, weakness, wheezing
CONTRAINDICATIONS — Hypersensitivity to abacavir, lamivudine, or any component of the formulation; hepatic impairment. Do not rechallenge patients who have experienced hypersensitivity to abacavir.
WARNINGS / PRECAUTIONS Box warnings: Chronic hepatitis B: . HIV: Appropriate use: . Hypersensitivity reactions: . Lactic acidosis/hepatomegaly: .
Concerns related to adverse effects: Fat redistribution: May cause redistribution of fat (eg, buffalo hump, peripheral wasting with increased abdominal girth, cushingoid appearance). Hypersensitivity reactions: [U.S. Boxed Warning]: Fatal hypersensitivity reactions have occurred in patients taking abacavir (in Epzicom™). Patients exhibiting symptoms of fever, skin rash, fatigue, respiratory symptoms (eg, pharyngitis, dyspnea, cough) and/or GI symptoms (eg, abdominal pain, nausea, vomiting, diarrhea) should discontinue therapy immediately and call for medical attention. Epzicom™ should be permanently discontinued if hypersensitivity cannot be ruled out, even when other diagnoses are possible. Epzicom™ SHOULD NOT be restarted because more severe symptoms may occur within hours, including LIFE-THREATENING HYPOTENSION AND DEATH. Fatal hypersensitivity reactions have occurred following the reintroduction of abacavir in patients whose therapy was interrupted (eg, interruption in drug supply, temporary discontinuation while treating other conditions). Reactions occurred within hours. In some cases, signs of hypersensitivity may have been previously present, but attributed to other medical conditions (eg, acute onset respiratory diseases, gastroenteritis, reactions to other medications). If Epzicom™ is to be restarted following an interruption in therapy, first evaluate the patient for previously unsuspected symptoms of hypersensitivity. Do not restart if hypersensitivity is suspected or cannot be ruled out. To report these events on Epzicom™ hypersensitivity, a registry has been established (1-800-270-0425). Immune reconstitution syndrome: Patients may develop immune reconstitution syndrome resulting in the occurrence of an inflammatory response to an indolent or residual opportunistic infection; further evaluation and treatment may be required. Lactic acidosis/hepatomegaly: [U.S Boxed Warning]: Lactic acidosis and severe hepatomegaly with steatosis have been reported with nucleoside analogues, including fatal cases; use with caution in patients with risk factors for liver disease (risk may be increased with female gender, obesity, pregnancy or prolonged exposure) and suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or hepatotoxicity (transaminase elevation may/may not accompany hepatomegaly and steatosis).
Disease-related concerns: Chronic hepatitis B: [U.S. Boxed Warning]: Following discontinuation of lamivudine, severe acute exacerbations of hepatitis B in patients coinfected with HBV and HIV have been reported. Monitor patients closely for several months following discontinuation of therapy for chronic hepatitis B; clinical exacerbations may occur. HIV: Appropriate use: [U.S. Boxed Warning]: This combination should only be used as part of a multidrug regimen for which the individual components are indicated. Renal impairment: Due to fixed dose of combination product, use is not recommended with renal impairment (Clcr <50 mL/minute).
Concurrent drug therapy issues: Interferon alfa: Use with caution in combination with interferon alfa with or without ribavirin in HIV/HBV coinfected patients; monitor closely for hepatic decompensation, anemia, or neutropenia; dose reduction or discontinuation of interferon and/or ribavirin may be required if toxicity evident.
Special populations: Pediatrics: Due to fixed dose of combination product, use is not recommended in children.
RESTRICTIONS — An FDA-approved medication guide and warning card (summarizing symptoms of hypersensitivity) must be distributed when dispensing an outpatient prescription (new or refill) where this medication is to be used without direct supervision of a healthcare provider. Medication guides are available at http://www.fda.gov/cder/Offices/ODS/medication_guides.htm.
DRUG INTERACTIONS See individual agents.
PREGNANCY RISK FACTOR — C (show table)
PREGNANCY IMPLICATIONS — See individual agents.
LACTATION — See individual agents.
BREAST-FEEDING CONSIDERATIONS — HIV-infected mothers are discouraged from breast-feeding to decrease potential transmission of HIV. See individual agents.
DIETARY CONSIDERATIONS — May be taken with or without food.
PRICING — (data from drugstore.com)Tablets (Epzicom) 600-300 mg (30): $790.34
MONITORING PARAMETERS — Amylase, bilirubin, liver enzymes, hematologic parameters, viral load, and CD4 count
TOXICOLOGY / OVERDOSE COMPREHENSIVE — See individual agents.
CANADIAN BRAND NAMES — Kivexa™
INTERNATIONAL BRAND NAMES — Kivexa (AR, AT, BE, BG, CA, CH, CL, CZ, DE, DK, ES, FI, FR, GB, GR, HU, IE, IT, NL, NO, PT, RU, SE, TR)
MECHANISM OF ACTION — Nucleoside reverse transcriptase inhibitor combination.
Abacavir is a guanosine analogue which is phosphorylated to carbovir triphosphate which interferes with HIV viral RNA-dependent DNA polymerase resulting in inhibition of viral replication.
Lamivudine is a cytosine analog. After lamivudine is triphosphorylated, the principle mode of action is inhibition of HIV reverse transcription via viral DNA chain termination; inhibits RNA-dependent DNA polymerase activities of reverse transcriptase.
PHARMACODYNAMICS / KINETICS — See individual agents.

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