Relationships between Serum Levels of Atazanavir and Renal Toxicity or Lithiasis

Renal stone composed of ritonavir

Nephrolithiasis is a well-known side effect of many HIV protease inhibitors. However, there have not been reports of stones associated with ritonavir use. Here, we report the case of a 33-year-old woman with HIV on antiretroviral therapy who presented with sharp left flank pain and passed a stone that was later found to contain only ritonavir. Of note, the patient’s treatment regimen had not included ritonavir for 2 years prior to this incidence. This case is notable both for the novel finding of a renal calculus composed entirely of ritonavir and the development of nephrolithiasis years after cessation of the aggravating drug. This finding suggests that patients on ritonavir should be more closely monitored and for longer periods of time for potential lithiasis formation.

Renal effects of non-tenofovir antiretroviral therapy in patients living with HIV

A review of literature published regarding non-tenofovir antiretroviral agents causing renal adverse effects was conducted. The literature involving renal adverse effects and antiretroviral therapy is most robust with protease inhibitors, specifically atazanavir and indinavir, and includes reports of crystalluria, leukocyturia, nephritis, nephrolithiasis, nephropathy and urolithiasis. Several case reports describe potential nephropathy (including Fanconi syndrome) secondary to administration of abacavir, didanosine, lamivudine and stavudine. Case reports documented renal events such as acute renal failure, nephritis, proteinuria and renal stones with efavirenz administration. Regarding rilpivirine, a small increase of serum creatinine levels (SCr) was found in clinical trials; however, the clinical significance and impact on actual renal function is unknown. The integrase strand transfer inhibitors and enfuvirtide have a relatively safe renal profile, although studies have shown dolutegravir and raltegravir cause mild elevations in SCr without an impact on actual renal function. This is similar to the reaction observed with cobicistat, the pharmacokinetic enhancer frequently given with elvitegravir.

Efficacy and safety of "unboosting" atazanavir in a randomized controlled trial among HIV-infected patients receiving tenofovir DF

OBJECTIVES

To assess safety and efficacy of a switch to unboosted atazanavir (ATV) among HIV-infected adults receiving ATV/ritonavir (r) and tenofovir disoproxil fumarate (TDF).

METHODS

HIV-infected adults with viral load (VL) <40 copies/mL at screening and <150 copies/mL consistently for ≥3 months while receiving a regimen including ATV/r and TDF were randomized to continue ATV/r 300/100 mg daily (control) or change to ATV 400 mg daily (switch), while maintaining their TDF backbone. The primary outcome was proportion of subjects without treatment failure (regimen switch or VL > 200 copies/mL twice consecutively) at 48 weeks.

RESULTS

Fifty participants (46 male, median age 47 years) were randomized, 25 to each arm. At week 48, treatment success occurred in 76% in the control arm and 92% in the switch arm (ITT, p = 0.25). ATV trough levels at week 9 were higher in controls (median 438 ng/mL) than in the switch arm (median 124 ng/mL) (p = 0.003), as was total bilirubin at week 48 (median 38 μmol/L and 28 μmol/L, respectively; p = 0.02). Estimated glomerular filtration rate (eGFR) decreased in the control arm (p = 0.007), but did not change in the switch arm. At week 48, eGFR was higher in the switch arm (median 96 mL/min) than in the control arm (median 85 mL/min) (p = 0.035), but the arms were similar with respect to fasting glucose, C-reactive protein, and lipid parameters.

CONCLUSIONS

Switching from ATV/r to unboosted ATV appears to be safe and effective in selected virologically suppressed patients receiving TDF-containing regimens, and may have favorable effects on bilirubin and renal function.