Lamivudine and Zidovudine Dosing Guide – What You Need to Know

If you or someone you care for is on HIV therapy, the two drugs lamivudine (3TC) and zidovudine (AZT) show up a lot. They’re part of the same NRTI class, work by stopping the virus from copying itself, and are often paired with other meds. Knowing the right dose can keep the virus in check while minimizing side‑effects.

Lamivudine (3TC) Dosage Basics

For most adults, the standard lamivudine dose is 300 mg taken once daily. Some doctors prefer 150 mg twice a day, especially when it’s combined with other NRTIs that require multiple daily doses. Pediatric dosing follows weight‑based rules: 4 mg per kilogram of body weight per day, given in one or two doses.

If you have kidney problems, the dose needs a tweak. When creatinine clearance drops below 50 ml/min, cut the dose in half; below 30 ml/min, consider 150 mg every other day. The drug is cleared by the kidneys, so a simple blood test tells you whether to adjust.

Common side‑effects include mild nausea or headache, which usually fade after a week. If you notice persistent fatigue, talk to your clinician – it could be a sign the dose is too high or that another medication is interacting.

Zidovudine (AZT) Dosage Essentials

Zidovudine’s adult dose is 300 mg taken twice daily, so you’re looking at a total of 600 mg per day. Kids get a weight‑based dose of 2 mg per kilogram every 12 hours. Remember, zidovudine is a bit tougher on the bone marrow, so regular blood counts are a must.

If you have anemia or low blood counts, doctors may lower the dose to 150 mg twice a day or switch to an alternative NRTI. Kidney function also matters: for creatinine clearance under 50 ml/min, reduce the dose by 25‑30 %.

Typical side‑effects include fatigue, headache, and a mild rash. The big one to watch for is anemia; if you feel unusually weak or short of breath, get a blood test right away.

Both lamivudine and zidovudine are taken with food to improve absorption and reduce stomach upset. If you’re on a fixed‑dose combination pill (like 3TC + AZT + another drug), follow the exact schedule your doctor gave you – don’t split the tablet unless told to.

Drug interactions matter, too. Trimethoprim‑sulfamethoxazole can raise zidovudine levels, while some antacids may lower lamivudine absorption. Always list every prescription and over‑the‑counter product to your healthcare provider.

Bottom line: stick to the prescribed schedule, get regular lab checks, and report any new symptoms promptly. With the right dose, lamivudine and zidovudine keep the virus off‑balance and support a healthier life.