How large is the ritonavir interaction?
About 11-fold on AUC. That is the US Viagra number. It is why the board does not treat ritonavir as 'just another CYP note.'
Borrowing a friend's 100 mg because a review said food is the only issue is how this interaction gets missed. CYP3A4 outranks the plate.
What did erythromycin do to the same tablet?
Cmax up about 160%. AUC up about 182%. The labeled start in that setting is 25 mg. Erythromycin does not copy the 48-hour ritonavir lock on this file.
A week of erythromycin is still an interaction week. Do not keep 100 mg out of habit during that course.
What is the labeled ritonavir cap?
25 mg prior to sexual activity. Maximum 25 mg in a 48-hour period. That is tighter than the ordinary once-per-day cap on 25-100 mg.
A 50 mg tablet split in half is a pharmacy conversation about scoring. Do not assume every generic breaks cleanly. The plan should say 25 mg if 25 mg is the cap.
Who should see both bottles?
One prescriber should see the HIV regimen and the ED line together. Both bottles belong next to the sildenafil panel. The 25 mg start scan lists the other consider-25 flags.
Nitrates remain contraindicated on ritonavir or off it. The interaction does not create a nitrate loophole.
Is grapefruit the same as ritonavir?
No. Grapefruit juice is a weaker gut CYP3A4 nudge. It can still raise levels. It is a poor experiment on a new dose, not an 11-fold event.
Skip the juice the evening you dose if you want a clean 25 mg trial. Do not treat juice as a ritonavir equivalent.