Liver toxicity and HIV drugs

Many HIV drugs are cleared from the body by the liver, and have the potential to cause liver toxicity, and HCV coinfection increases the risk by 2-3 times.

This could be through the direct action of the drugs themselves.

This is largely a concern with nevirapine (an NNRTI), tipranavir and higher doses of ritonavir (both PIs) – which can be managed by choice of alternative HIV drugs. The use of low dose ritonavir to boost other PIs does not seem to increase this risk.

It could also be through an indirect action related to higher drug levels of NNRTIs and PIs, especially if you have serious liver damage.

Because a damaged liver is working less efficiently, drug levels can be higher and take longer to clear from your body.

Therapeutic drug monitoring (TDM)

Therapeutic drug monitoring (TDM) is a blood test that checks blood levels of a protease inhibitors, NNRTIs, and possibly T-20.

Doses for HIV-drugs are worked out for an average person. However, individual differences in absorption can vary considerably in real life. In people whose liver is seriously damaged, drug levels can be much higher. This can increase the risk of side effects.

TDM is available free in the UK for many people using nelfinavir, saquinavir, indinavir, fosamprenavir, atazanavir or  lopinavir/r through programmes sponsored by the manufacturers.

Even if your clinic has to pay for a test, it will only cost around £60 per drug.

TDM in the UK is available from Delphic: www.delphicdiagnostics.com

TDM is recommended in UK BHIVA guidelines for management of dosing in people with moderate or severe HCV-related liver damage.