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HIV drugs cleared by the kidneys
If you are using tenofovir, there is a also a caution against using other drugs that are cleared by the kidney.
Several HIV drugs are cleared by the kidney. These include tenofovir, 3TC, FTC, AZT and ddI. The dose for these meds (and maraviroc in some combinations) may need to be changed depending on your eGFR level. The prescribing information for each drug includes detailed information.
Tenofovir and kidney toxicity Tenofovir is one of the most widely used HIV drugs and it is mainly processed by the kidneys. Although serious kidney related side effects (including Fanconi’s Syndrome) were reported in studies, these were rare. They also often reversed when tenofovir was stopped. Tenofovir also changes laboratory markers such as reducing creatinine clearance, low phosphate levels and increased protein levels in urine (called proteinuria). The importance of these changes in markers in the long-term is unknown, but it is likely to be more important if you already start with reduced kidney function.
It is not recommended to use creatinine supplements with tenofovir, as this will affect the interpretation of your monitoring tests.
Kidney stones: atazanavir and efavirenz There have been several reports of kidney stones that contained high levels of atazanavir or efavirenz, showing that this can be a rare side effect with these drugs. Kindey stones were also linked to to early protease inhibitor indinavir but this is now rarely used. The side effect of kidney stones was reduced by drinking an additional 1-2 litres of water daily. Detailed information on kidney stones and indinavir is online. http://i-base.info/guides/side/kidneytoxicity
Because tenofovir can also reduce eGFR compared to some other HIV drugs, it is not recommended in people who have eGFR below 75-80 if there are other HIV drugs to chose from. Similarly, if you are using tenofovir and your eGFR drops to this level, then switching to a different drug is recommended.
July 2012
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