Lamivudine + Zidovudine

Oral
HIV infection

CrCl (mL/min)	Dosage
≤50	Not recommended, use separate preparations.

Severe: Not recommended, use separate preparations.

May be taken with or without food.

Hypersensitivity. Abnormally low neutrophil counts (<0.75 x 10⁹/L) or Hb levels (<7.5 g/dL or 4.65 mmol/L). Lactation. Concomitant use w/ interferon alfa (w/ or w/o ribavirin) in HIV and hepatitis B or C virus co-infected patients.

Patient w/ poor bone marrow reserve prior to treatment; obese women w/ hepatomegaly, hepatitis or other risk factors for liver disease and hepatic steatosis; hepatitis B or C virus co-infection; history or risk factors for pancreatitis. Renal and severe hepatic impairment. Childn. Pregnancy.

Abdominal pain, nausea, vomiting, diarrhoea, dizziness, headache, fever, rash, alopecia, malaise, myalgia, insomnia, cough, nasal symptoms, arthralgia, musculoskeletal pain, immune reconstitution syndrome, lipodystrophy, metabolic abnormalities (e.g. hypertriglyceridaemia, hypercholesterolaemia, insulin resistance, hyperglycaemia, hyperlactataemia), mitochondrial dysfunction (e.g. abnormal behaviour, anaemia, convulsions, hyperlipasaemia, hypertonia, neutropenia), osteonecrosis; increased creatine phosphokinase, liver enzymes, bilirubin and serum amylase; symptomatic myopathy and myositis. Rarely, rhabdomyolysis, pancreatitis, cardiomyopathy.
Potentially Fatal: Lactic acidosis, hepatomegaly w/ steatosis; haematologic toxicity (severe anaemia, neutropenia).

PO: C

Monitor haematological parameters (e.g. CBC w/ platelet count); observe for appearance of opportunistic infections and signs and symptoms of pancreatitis. Periodically monitor LFTs and for several mth following discontinuation of therapy for patients co-infected w/ hepatitis B virus and HIV.

Cross-resistance may develop when given w/ emtricitabine. Exacerbation of anaemia w/ concomitant use of zidovudine w/ ribavirin. Increased adverse effects to zidovudine w/ nephrotoxic or myelosuppressive drugs (e.g. systemic pentamide, dapsone, pyrimethamine, co-trimoxazole, amphotericin, flucytosine, ganciclovir, interferon, vincristine, vinblastine, doxorubicin). Lamivudine and zalcitabine may inhibit the intracellular phosphorylation of one another. Antagonistic effect when zidovudine is used concomitantly w/ stavudine or doxorubicin.
Potentially Fatal: Risk of hepatic decompensation when used concomitantly w/ interferon alfa (w/ or w/o ribavirin) in HIV and hepatitis B or C virus co-infected patients.

Description:
Mechanism of Action: Lamivudine and zidovudine synergistically reduce viral resistance and inhibit reverse transcriptase via DNA chain termination and delay the emergence of mutations conferring resistance.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract. Delayed absorption w/ food. Bioavailability: 80-87% (lamivudine); approx 60-70% (zidovudine). Time to peak plasma concentration: Approx 1 hr.
Distribution: Crosses the blood-brain barrier and placenta; enters breast milk. Detected in semen (zidovudine). Volume of distribution: 1.3 L/kg (lamivudine); 1-2.2 L/kg (zidovudine). Plasma protein binding: Up to 36% (lamivudine); 34-38% (zidovudine).
Metabolism: Both are metabolised intracellularly to the active triphosphate form. Zidovudine undergoes hepatic metabolism, mainly to the inactive glucuronide.
Excretion: Via urine, mainly as unchanged drug. Elimination half-life: 5-7 hr (lamivudine); 0.5-3 hr (zidovudine).

Source: National Center for Biotechnology Information. PubChem Database. Lamivudine, CID=60825, https://pubchem.ncbi.nlm.nih.gov/compound/Lamivudine (accessed on Jan. 22, 2020)

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 35370, Zidovudine. https://pubchem.ncbi.nlm.nih.gov/compound/Zidovudine. Accessed Aug. 18, 2023.

Store between 2-30°C.

Antivirals

J05AR01 - zidovudine and lamivudine ; Belongs to the class of antivirals for treatment of HIV infections, combinations.

Anon. Lamivudine and Zidovudine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/09/2015.

Anon. Lamivudine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/09/2015.

Anon. Zidovudine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/09/2015.

Buckingham R (ed). Lamivudine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/09/2015.

Buckingham R (ed). Zidovudine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/09/2015.

Lamivudine and Zidovudine Tablet, Film Coated (Exelan Pharmaceuticals). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 15/09/2015.