Dosing of Abacavir and Lamivudine in Intermittent Hemodialysis
For patients on intermittent hemodialysis, abacavir requires no dose adjustment and can be given at the standard dose of 300 mg twice daily or 600 mg once daily, while lamivudine should be dosed as a 50 mg loading dose followed by 25 mg once daily. 1
Lamivudine Dosing in Hemodialysis
Lamivudine requires significant dose reduction in hemodialysis patients due to renal elimination:
- Loading dose: 50 mg orally as the first dose 1
- Maintenance dose: 25 mg orally once daily 1
- The dose should be administered after hemodialysis on dialysis days, though the timing is less critical given the once-daily schedule 1
Alternative practical approach: Some clinicians use the lowest available tablet strength (100 mg or 150 mg once daily) to avoid liquid formulations, given lamivudine's favorable safety profile, though this represents off-guideline dosing 1
The rationale for dose reduction is that lamivudine is primarily eliminated unchanged by the kidney through active organic cationic secretion, with renal clearance representing 71% of total clearance 2. In patients with creatinine clearance <5 mL/min or on hemodialysis, drug accumulation occurs without dose adjustment 1.
Abacavir Dosing in Hemodialysis
Abacavir requires no dose adjustment regardless of renal function:
- Standard dose: 300 mg orally twice daily OR 600 mg orally once daily 1
- No adjustment needed for any degree of renal impairment including hemodialysis 1
- Can be administered independently of the dialysis schedule 3
The lack of dose adjustment is supported by pharmacokinetic studies showing that abacavir is extensively metabolized by the liver (primarily via glucuronidation and alcohol dehydrogenase), with less than 2% excreted unchanged in urine 3, 4. Studies in HIV-infected patients with end-stage renal disease demonstrated no significant differences in absorption, elimination, or distribution compared to patients with normal renal function 3. Even during hemodialysis, only 24% of the drug is removed during a 4-hour session with high-permeability membranes, which is clinically insignificant 3.
Critical Considerations
Fixed-dose combination products containing lamivudine must be avoided in hemodialysis patients:
- Products like Combivir (lamivudine/zidovudine) or Epzicom (lamivudine/abacavir) should NOT be used 1, 5
- These combinations prevent appropriate dose reduction of lamivudine while maintaining standard dosing of the other component 5
- Administer as separate medications to allow proper individualized dosing 1, 5
Monitoring requirements:
- Baseline and periodic renal function assessment is essential, though lamivudine and abacavir are among the safer antiretrovirals in renal disease 1
- Unlike tenofovir, neither drug causes direct nephrotoxicity 6, 7
- Abacavir does not require renal monitoring beyond standard HIV care 1
Drug interaction note: Neither abacavir nor lamivudine is significantly metabolized by cytochrome P450 enzymes, minimizing drug-drug interactions common in HIV patients on polypharmacy 2, 4