General Articles

Abacavir, lamivudine, and zidovudine

U.S. BRAND NAMES — Trizivir®
SYNONYMS — 3TC, Abacavir, and AZT; 3TC, Abacavir, and ZDV; 3TC, Abacavir, and Zidovudine; 3TC, ABC, and AZT; 3TC, ABC, and ZDV; Abacavir, 3TC, and AZT; Abacavir, 3TC, and ZDV; Abacavir, Lamivudine, and Azidothymidine; Abacavir, Zidovudine, and Lamivudine; ABC, 3TC, and AZT; ABC, 3TC, and ZDV; Azidothymidine, Abacavir, and Lamivudine; Azidothymidine, Lamivudine and Abacavir; AZT, Abacavir, and 3TC; AZT, Abacavir, and Lamivudine; AZT, ABC, and 3TC; Compound S, Abacavir, and 3TC; Compound S, Abacavir, and Lamivudine; Compound S, ABC, and 3TC; Lamivudine, Abacavir, and Zidovudine; Lamivudine, Zidovudine, and Abacavir; ZDV, Abacavir, and 3TC; ZDV, Abacavir, and Lamivudine; ZDV, ABC, and 3TC; Zidovudine, Abacavir, and Lamivudine
THERAPEUTIC CATEGORY Antiretroviral AgentHIV Agents (Anti-HIV Agents)Nucleoside Analog Reverse Transcriptase Inhibitor (NRTI)
DOSING — Oral:
(For additional information see “Abacavir, lamivudine, and zidovudine: Drug information”)
Children: Not intended for pediatric use; product is a fixed-dose combination
Adolescents <40 kg: Not recommended; product is a fixed-dose combination
Adolescents 40 kg and Adults: 1 tablet twice daily
Dosage adjustment in hepatic impairment: Use is contraindicated (use individual antiretroviral agents to reduce dosage)
Dosage adjustment in renal impairment: Clcr 50 mL/minute: Not recommended (use individual antiretroviral agents to reduce dosage)
DOSAGE FORMS — Abacavir component is available as abacavir sulfate; mg strength refers to abacavir
Tablet: Trizivir®: Abacavir 300 mg, lamivudine 150 mg, and zidovudine 300 mg
ADMINISTRATION — May be administered without regard to meals
USE — Treatment of HIV-1 infection (either alone or in combination with other antiretroviral agents) (Note: HIV regimens consisting of three antiretroviral agents are strongly recommended; data on the use of this triple NRTI combination regimen in patients with baseline viral loads >100,000 copies/mL is limited)
ADVERSE REACTIONS — See Abacavir, Lamivudine, and Zidovudine
CONTRAINDICATIONS — Hypersensitivity to abacavir, lamivudine, zidovudine, or any component; hepatic impairment. Do not rechallenge patients who have experienced hypersensitivity reactions to abacavir, potentially fatal hypersensitivity reactions may occur (see Warnings)
PRECAUTIONS — Fat redistribution and accumulation [ie, central obesity, peripheral wasting, facial wasting, breast enlargement, dorsocervical fat enlargement (buffalo hump), and cushingoid appearance] have been observed in patients receiving antiretroviral agents (causal relationship not established). Resistance to abacavir develops relatively slowly, but cross resistance between abacavir and other nucleoside reverse transcriptase inhibitors (NRTIs) may occur; limited response may be seen in patients with HIV isolates containing multiple mutations conferring resistance to NRTIs or in patients with a prolonged prior NRTI exposure.
Immune reconstitution syndrome (an acute inflammatory response to residual or indolent opportunistic infections) may occur in HIV patients during initial treatment with combination antiretroviral agents, including abacavir, lamivudine, and zidovudine; this syndrome may require further patient assessment and therapy. Systemic exposure of abacavir at 6-32 times the normal human exposure, increased the incidence of tumors (malignant and nonmalignant) in mice and rats; myocardial degeneration was seen in mice and rats receiving abacavir for 2 years at 7-24 times the expected human exposure; the clinical relevance of these findings is currently unknown
WARNINGS — Serious and sometimes fatal hypersensitivity reactions to abacavir may occur; discontinue therapy immediately in patients who show signs or symptoms of 2 or more of the following: Fever, skin rash, respiratory symptoms (including cough, dyspnea, or pharyngitis) and GI symptoms (including nausea, vomiting, diarrhea, or abdominal pain), and constitutional symptoms (including fatigue, malaise, or achiness). Carefully consider the diagnosis of hypersensitivity reaction in patients who present with acute onset respiratory symptoms, even if other diagnoses, such as bronchitis, flu-like illness, pharyngitis, or pneumonia, are possible. Permanently discontinue abacavir-containing medications if hypersensitivity reaction cannot be ruled out, even when other diagnoses are possible. Skin rash may be maculopapular or urticarial, but can be variable in appearance; erythema multiforme has been reported; hypersensitivity reaction may occur without a rash. Other symptoms may include edema, lethargy, myolysis, paresthesia, shortness of breath, mouth ulcerations, conjunctivitis, lymphadenopathy, and abnormal findings on chest x-ray (ie, infiltrates that can be localized). Anaphylaxis, renal failure, hepatic failure, respiratory failure, ARDS, hypotension, and death may also occur in association with hypersensitivity reactions. Laboratory abnormalities include increases in liver function tests, elevated CPK or serum creatinine, and lymphopenia.
Do not restart abacavir, Trizivir®, or any other abacavir-containing product after a hypersensitivity reaction occurs; more severe symptoms can recur within hours and may include life-threatening hypotension and death. Fatal hypersensitivity reactions have occurred following the reintroduction of abacavir in patients whose therapy was interrupted for other reasons. These patients had no identified history or had unrecognized symptoms of abacavir hypersensitivity. Reactions occurred within hours. In some cases, signs of a hypersensitivity reaction may have been previously present, but attributed to other medical conditions (acute onset respiratory diseases, gastroenteritis, reactions to other medications). If abacavir, Trizivir®, or any other abacavir-containing product is to be restarted following an interruption in therapy, the patient must first be evaluated for previously unsuspected symptoms of hypersensitivity. Do not restart abacavir, Trizivir®, or any other abacavir-containing product if hypersensitivity is suspected or cannot be ruled out. Hypersensitivity reactions occur in ~8% of adult and pediatric patients; most hypersensitivity reactions occur within the first 6 weeks of therapy, but can occur at any time; call the Abacavir Hypersensitivity Reaction Registry at 1-800-270-0425 to facilitate reporting and collection of information on patients experiencing abacavir hypersensitivity reactions (see Additional Information).
Cases of lactic acidosis, severe hepatomegaly with steatosis, and death have been reported in patients receiving nucleoside analogues; most of these cases have been in women; prolonged nucleoside use, obesity, and prior liver disease may be risk factors; use with extreme caution in patients with other risk factors for liver disease; discontinue Trizivir® in patients who develop laboratory or clinical evidence of lactic acidosis or pronounced hepatotoxicity.
The major clinical toxicity of lamivudine in pediatric patients is pancreatitis; discontinue therapy if clinical signs, symptoms, or laboratory abnormalities suggestive of pancreatitis occur. HIV-infected patients who are coinfected with hepatitis B may experience clinical symptoms or laboratory evidence of hepatitis when a lamivudine-containing medication is discontinued; most cases are self-limited, but fatalities have been reported; monitor patients closely for at least several months after discontinuation of abacavir, lamivudine, and zidovudine. Concomitant use of combination antiretroviral therapy with interferon alfa (with or without ribavirin) has resulted in hepatic decompensation (with some fatalities) in patients coinfected with HIV and HCV; monitor patients closely, especially for hepatic decompensation, neutropenia, and anemia; consider discontinuation of abacavir, lamivudine, and zidovudine if needed; consider dose reduction or discontinuation of interferon alfa, ribavirin,

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or both if clinical toxicities, including hepatic decompensation, worsen.
Zidovudine is associated with hematologic toxicity including granulocytopenia and severe anemia requiring transfusions; use with caution in patients with ANC <1000 cells/mm3 or hemoglobin <9.5 g/dL; discontinue treatment in children with an ANC <500 cells/mm3 until marrow recovery is observed; use of erythropoietin, or filgrastim may be necessary in some patients; prolonged use of zidovudine may cause myositis and myopathy; zidovudine has been shown to be carcinogenic in rats and mice.
Trizivir® contains abacavir, lamivudine, and zidovudine as a fixed-dose combination; do not use in patients weighing <40 kg, in patients with renal dysfunction (Clcr 50 mL/minute) who require lamivudine and zidovudine dosage adjustment, or in patients with hepatic dysfunction (Note: Patients with mild to moderate hepatic dysfunction or liver cirrhosis require zidovudine dosage adjustment; abacavir is contraindicated in patients with moderate to severe hepatic dysfunction; patients with mild hepatic impairment require abacavir dosage reduction). Do not administer Trizivir® with abacavir, lamivudine, emtricitabine, or zidovudine-containing products.
DRUG INTERACTIONS — See Abacavir, Lamivudine, and Zidovudine
FOOD INTERACTIONS — Food decreases the rate, but not the extent of absorption (see Yuen, 2001).
MONITORING PARAMETERS — Signs and symptoms of abacavir hypersensitivity reaction, lactic acidosis, pronounced hepatotoxicity, anemia, bone marrow suppression, and pancreatitis; serum glucose and triglycerides, viral load, CD4 counts, CBC with differential, platelets, hemoglobin, MCV, reticulocyte count, liver enzymes, serum amylase, bilirubin, renal and hepatic function tests. HIV patients should be screened for hepatitis B infection before starting lamivudine (see Warnings).
STABILITY — Store at room temperature 25ºC (77ºF)
MECHANISM OF ACTION — See Abacavir, Lamivudine, and Zidovudine
PHARMACOKINETICS — One Trizivir® tablet is bioequivalent, in the extent (AUC) and rate of absorption (peak concentration and time to peak concentration), to one abacavir 300 mg tablet, one lamivudine 150 mg tablet, plus one zidovudine 300 mg tablet; See Abacavir, Lamivudine, and Zidovudine
PATIENT INFORMATION — Trizivir® is not a cure for HIV. Take Trizivir® every day as prescribed; do not change dose or discontinue without physician’s advice. If Trizivir® is stopped for any reason, notify physician before restarting therapy. If a dose is missed, take it as soon as possible, then return to normal dosing schedule; if a dose is skipped, do not double the next dose. Avoid alcohol. Notify physician if persistent severe abdominal pain, nausea, or vomiting occurs.
(For additional information see “Abacavir, lamivudine, and zidovudine: Patient drug information”)
Trizivir® contains abacavir (also called Ziagen®). Abacavir may cause serious and sometimes fatal allergic (hypersensitivity) reaction. Read the Patient Medication Guide that you receive with each prescription and refill of abacavir, lamivudine, and zidovudine. Stop taking Trizivir® and notify physician immediately if 2 or more of the following sets of symptoms occur: Fever, rash, GI symptoms (nausea, vomiting, diarrhea, or abdominal pain), flu-like symptoms (severe tiredness, achiness, or generally ill feeling), or respiratory symptoms (sore throat, shortness of breath, cough). If you experience an allergic (hypersensitivity) reaction to Trizivir® (or abacavir, Ziagen®, or Epzicom™), never take Trizivir®, abacavir, Ziagen®, or Epzicom™ again.
Trizivir® contains zidovudine which may cause a decrease in white blood cells or red blood cells (anemia); routine blood tests can help detect these blood problems. Zidovudine may also cause muscle weakness with prolonged use, which may be a serious problem; notify physician if muscle weakness occurs.
HIV medications may cause changes in body fat, including an increase in fat in the upper back and neck, breasts, and trunk; a loss of fat from the face, arms, and legs may also occur. Some HIV medications (including abacavir, lamivudine, and zidovudine) may cause a serious, but rare, condition called lactic acidosis with an increase in liver size (hepatomegaly). Before starting Trizivir®, inform your physician about your medical conditions, including any blood, kidney, or liver problems (including hepatitis B infection). Do not take Trizivir ® with Combivir ®, Emtriva™, Epivir®, Epivir-HBV®, Epzicom®, Retrovir®, Truvada®, or Ziagen®.
NURSING IMPLICATIONS — Inform patients of the possibility of a fatal abacavir hypersensitivity reaction and the signs and symptoms (see Warnings and Patient Information)
ADDITIONAL INFORMATION — The Patient Medication Guide, which includes written manufacturer information, should be dispensed to the patient with each new prescription and refill; a Warning Card describing the hypersensitivity reaction should be given to the patient to carry with them

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January 2008
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