Zidovudine Side Effects

Some side effects of zidovudine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to zidovudine: oral capsule, oral syrup, oral tablet

Get emergency medical help if you have any of these signs of an allergic reaction while taking zidovudine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

This medication may cause lactic acidosis (a build-up of lactic acid in the body, which can be fatal). Lactic acidosis can start slowly and get worse over time. Get emergency medical help if you have even mild symptoms of lactic acidosis, such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

Stop taking zidovudine and call your doctor at once if you have any of these other serious side effects:

• severe muscle pain;

• signs of a new infection such as fever, chills, body aches, flu symptoms, sores in your mouth and throat;

• pale skin, feeling light-headed, rapid heart rate, trouble concentrating;

• easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;

• increased sweating, tremors in your hands, anxiety, feeling irritable, sleep problems (insomnia);

• diarrhea, unexplained weight loss, menstrual changes, impotence, loss of interest in sex;

• swelling in your neck or throat (goiter);

• problems with walking, breathing, speech, swallowing, or eye movement;

• weakness or prickly feeling in your fingers or toes;

• severe lower back pain, loss of bladder or bowel control;

• liver problems--upper stomach pain, itching, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• pancreatitis--severe pain in your upper stomach spreading to your back, nausea and vomiting, fast heart rate; or

• severe skin reaction -- fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Less serious side effects of zidovudine may include:

• sleep problems (insomnia);

• mild nausea, constipation;

• joint pain;

• headache; or

• changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and trunk).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects.

For Healthcare Professionals

Applies to zidovudine: intravenous solution, oral capsule, oral syrup, oral tablet

General

The adverse effects of zidovudine are sometimes difficult to distinguish from the symptomatology observed during the clinical course of AIDS, as well as from the possible adverse effects of other drugs used in the treatment of HIV-1 infection. Many of the side effects associated with nucleoside reverse transcriptase inhibitor therapy (myopathy, pancreatitis, liver failure, lactic acidosis, etc.) are attributable to their direct toxic effect on mitochondria which causes decreased mitochondrial energy-generating capacity.

Nervous system

Nervous system side effects have included headache (up to 63%), insomnia (5% or greater), neuropathy (5% or greater), and numbness. Status epilepticus and Wernicke's syndrome have been rarely reported. Seizures, confusion, dizziness, paresthesia, somnolence, vertigo, hearing loss, and loss of mental acuity have been reported during postmarketing experience.

Hematologic

Bone marrow suppression, the most common reason for cessation of zidovudine therapy, appears to be dose-dependent and may be seen as early as 2 to 6 weeks after initiation of therapy. Recombinant GM-CSF (sargramostim), G-CSF (filgrastim), and erythropoietin (epoetin alfa) have been used to control the hematologic toxicity of zidovudine.

Zidovudine should be used with extreme caution in patients with bone marrow suppression indicated by a granulocyte count below 1000 cells/mm3 or hemoglobin less than 9.5 g/dL. Routine blood counts are recommended, and generally should occur more frequently in patients with advanced disease. If bone marrow toxicity occurs, an interruption or discontinuation of zidovudine therapy may be necessary.

Hematologic side effects have included granulocytopenia (less than 750 cells/mm3; up to 2%), anemia (hemoglobin less than 8 g/dL; up to 1.1%), and increased hemoglobin A2 percentage. Hematologic toxicity, including neutropenia and severe anemia, has been reported, mostly in patients with advanced HIV-1 disease. Exacerbation of anemia due to ribavirin has been reported when zidovudine was part of the HIV-1 regimen. Aplastic anemia, hemolytic anemia, leukopenia, lymphadenopathy, pancytopenia with marrow hypoplasia, and pure red cell aplasia have been reported during postmarketing experience.

Gastrointestinal

Gastrointestinal side effects have included nausea (up to 51.4%), anorexia (up to 20.1%), vomiting (up to 17.2%), constipation (up to 6.4%), dyspepsia (5% or greater), abdominal cramps (5% or greater), abdominal pain (5% or greater), diarrhea, stomatitis, and splenomegaly. Dysphagia, constipation, flatulence, oral mucosa pigmentation, mouth ulcer, and pancreatitis have been reported during postmarketing experience.

Hepatic

One patient with preexisting hepatitis B developed acute hepatic failure two weeks after starting zidovudine therapy.

Patients with a history of liver disease should be monitored for further deterioration in liver function.

Hepatic side effects have included increased ALT (greater than 5 times ULN; up to 3.1%) and AST (greater than 5 times ULN; up to 1%), hyperbilirubinemia (less than or equal to 0.8%), fulminate hepatitis, and hepatic failure. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination, including zidovudine and other antiretrovirals. Hepatic decompensation (some fatal) has been reported in patients coinfected with HIV-1 and hepatitis C receiving combination antiretroviral therapy for HIV-1 and interferon alfa with or without ribavirin. Hepatitis, hepatomegaly with steatosis, lactic acidosis, and jaundice have been reported during postmarketing experience.

Other

Other side effects have included malaise (up to 53.2%), asthenia (up to 9%), fatigue (5% or greater), chills (5% or greater), and fever. Zidovudine therapy has been associated with lower levels of vitamins B2 and C, folate, and zinc despite adequate dietary intake. Back pain, chest pain, influenza-like syndrome, generalized pain, syncope, and taste perversion have been reported during postmarketing experience.

In one case of zidovudine-associated fever, no source of infection was found after an extensive evaluation, but an anti-zidovudine immunoglobulin was isolated, indicating a possible hypersensitivity reaction.

Musculoskeletal

Musculoskeletal side effects have included arthralgia, myalgia, and musculoskeletal pain in greater than or equal to 5% of patients. Myopathy, myositis, muscle tenderness, and weakness in the arms and legs have been reported and were generally associated with an elevation in serum creatine kinase. Increased creatine phosphokinase, muscle spasm, myopathy and myositis with pathological changes (similar to that produced by HIV-1 disease), rhabdomyolysis, and tremor have been reported during postmarketing experience.

In one study, myalgias and elevated creatine kinase occurred in 8% of treated patients with a CD4 cell count less than 200/mm3, and in none of the patients with higher CD4 cell counts. Dosage reduction has not affected the course of myopathy, although drug discontinuation sometimes resulted in improvement of symptoms, generally within a month. Muscle biopsy has shown atrophic and sometimes necrotic fibers, ragged-red fibers, and large accumulations of mitochondrial and fibrillar sarcoplasmic inclusions.

Myopathy and myositis with pathological changes, similar to that produced by HIV-1 disease, have been associated with prolonged use of zidovudine.

Psychiatric

Psychiatric side effects have included isolated cases of depression, mania, anxiety, and grandiosity. Anxiety, depression, and mania have been reported during postmarketing experience.

Dermatologic

Bluish or brownish-black discoloration of nails has developed during the first month or two of zidovudine therapy and usually disappeared within 2 months if the drug was discontinued. Discoloration has occurred as longitudinal streaks or transverse bands.

Dermatologic side effects have included case reports of nailbed hyperpigmentation, particularly in black people. Rarely, nail hyperpigmentation has been accompanied by mucocutaneous pigmentation or hypertrichosis. Skin rashes and leukocytoclastic vasculitis with eosinophilia and fever have also been reported. Changes in skin and nail pigmentation, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, sweat, and urticaria have been reported during postmarketing experience.

Cardiovascular

Cardiovascular side effects have included rare cases of reversible congestive heart failure and vasodilation. Cardiomyopathy and vasculitis have been reported during postmarketing experience.

Hypersensitivity

Hypersensitivity side effects have included allergic skin rash. Sensitization reactions including anaphylaxis and angioedema have been reported during postmarketing experience.

Metabolic

Metabolic side effects have included hyperlipidemia. Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement, peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving antiretroviral therapy. Increased lactate dehydrogenase and redistribution/accumulation of body fat have been reported during postmarketing experience.

Respiratory

Respiratory side effects have included cough, dyspnea, rhinitis, and sinusitis during postmarketing experience.

Immunologic

Immunologic side effects have included immune reconstitution syndrome. Autoimmune disorders (e.g., Graves' disease, polymyositis, and Guillain-Barre syndrome) have been reported in the setting of immune reconstitution.

Ocular

Ocular side effects have included amblyopia, macular edema, and photophobia during postmarketing experience.

A case of macular edema in a patient with a history of anterior uveitis secondary to syphilis has been reported.

Genitourinary

Genitourinary side effects have included gynecomastia, urinary frequency, and urinary hesitancy during postmarketing experience.

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