Hi Paul,Coincidently I had the same question this morning regarding a specific product.
If they travel/live in US, Canada, or Western Europe most regimens would be available and so I wouldn't worry at all for drug selection purposes.
if they go to any LMIC then it's a different story. The predominant STRs are TDF/3TC/DTG and EFV/TDF/3TC. Additionally individual components are available for those products. to my knowledge there are not any TAF or BIC regimens available in LMICs.
there's no renal issue? Just surprises me that he's on ABC instead of a tenofovir product.An easy bet would be to use a DTG based regimen - with 3TC as a STR or combine with TDF/FTC or TAF/FTC. It won't be perfect but would allow for some easy conversion outside the US.Hope that helps!Katy