If you have HIV, improvements in treatment and care in the UK mean that the prognosis for your wellness is excellent. However, the way in which medicines work in your body changes as you get older, yet researchers have known little about how ageing affects your wellbeing in terms of its impact on plasma concentrations of antiretroviral drugs – until now.
In the Journal of Antimicrobial Chemotherapy, UK researchers have reported that plasma concentrations of protease inhibitors increase with age, and each ten-year increment in age was associated with a significant increase in concentrations of protease inhibitors in plasma. However, the researchers did not find an association between age and plasma levels of non-nucleoside reverse transcriptase inhibitor (NNRTI) levels.
As the researchers wrote in their report, ‘We have observed a statistically significant association between standardised plasma drug concentrations and protease inhibitors and age, with greater drug exposure associated with increasing age.’ The study involved 2,447 people with HIV who had therapeutic drug monitoring as part of their routine care between 1999-2005 and 2008-10. The researchers analysed the impact of age on concentrations of protease inhibitors and NNRTIs, as well as data concerning liver function to see if alterations in drug concentrations led to an increased risk of toxicities.
The researchers found that, as age increased, plasma concentrations of NNRTIs remained largely stable but the relationship between increasing age and increasing concentrations of protease inhibitors, on the other hand, was clear, remaining significant after the researchers adjusted for other factors. The study authors surmised that this may be because concentrations in protease inhibitors are metabolised using the P450 enzyme. ‘Strengthening this hypothesis is our observation that a stronger effect of age was observed between standardized plasma concentration of ritonavir measurements compared with other protease inhibitors,’ they commented.
When it came to drug concentrations and liver toxicities, the researchers found no evidence of a relationship, and older age was associated with increased time to changing treatment for reasons other than virological failure. Though the researchers were unsure how their findings are clinically significant, they concluded by saying their results ‘may assist in the design of future work assessing the effects of lifelong antiretroviral therapy in subjects ageing with HIV infection.’
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