Not reported in the public reviews. Reviewers summarise selectively, so this usually means it wasn't discussed publicly, not that it wasn't studied.
Biodistribution & persistence
Rat QWBA: highest levels in liver, kidney, pancreas and adrenal; no quantifiable brain penetration
“The tissues with the highest Cmax values (Tmax = 4 hours for most tissues) excluding the gastrointestinal tract were observed in the liver, kidney, pancreas, and adrenal gland. [14C]nirmatrelvir-derived radioactivity did not cross the blood:brain barrier to a quantifiable extent.”