Urine Color Changes with Abacavir and Lamivudine
Neither abacavir nor lamivudine are known to cause changes in urine color based on available clinical evidence and guidelines.
Evidence Review
The provided guidelines and research studies extensively document the pharmacokinetics, adverse effects, and clinical management of both abacavir and lamivudine, but none mention urine discoloration as a recognized side effect 1.
Abacavir Safety Profile
- The most commonly reported adverse events with abacavir include nausea, vomiting, malaise, fatigue, headache, diarrhea, sleep disorders, and rash 2, 3.
- The major safety concern with abacavir is hypersensitivity reaction (occurring in 3-5% of patients), which typically presents with fever, rash, and multiorgan involvement—not urine color changes 2, 3.
- Abacavir is extensively metabolized by the liver with less than 2% excreted unchanged in urine, making urine discoloration pharmacologically unlikely 4.
Lamivudine Safety Profile
- Lamivudine requires dose adjustment in renal impairment (CrCl <50 mL/min), but urine color changes are not documented as part of its adverse effect profile 1, 5.
- The drug is primarily renally excreted, but this does not translate to visible urine discoloration 1.
Clinical Considerations
- If a patient on abacavir or lamivudine reports urine color changes, investigate alternative causes including other medications, dietary factors, dehydration, or underlying pathology 6.
- Both drugs can affect renal function (particularly when combined with tenofovir), which may manifest as proteinuria or glycosuria—but not as visible urine color changes 1.
- Urinalysis abnormalities such as proteinuria or glycosuria from proximal tubular dysfunction (especially with concurrent tenofovir use) do not cause visible color changes but require monitoring 1.
Important Caveats
- While these medications do not cause urine discoloration, patients may be taking other antiretrovirals or medications that could affect urine color 6.
- Atazanavir (a protease inhibitor sometimes used with these NRTIs) can cause hyperbilirubinemia leading to dark urine, but this is unrelated to abacavir or lamivudine themselves 1.