- If antiretroviral regimen contains zidovudine or strong cytochrome P450, family 3, subfamily A, polypeptide 4 (Cyp3A4) inhibitors (e.g. ritonavir or cobicistat-boosted protease inhibitors) and viral load is suppressed (as measured by HIV viral load =< 200/mL), then antiretroviral therapy must be adjusted to a less toxic therapy not containing these antivirals and enrollment may proceed without waiting 12 weeks