Выражение встречается в следующем контексте:
The roles of P-gp in mediating the membrane permeability of XXXX and the potential inhibition of P-gp-mediated [3H]digoxin transport by XXXX were assessed using human P-gp expressing and control LLC-PK1 cell monolayers (Study No. 1111111). As shown in Table 2.6.4-21, permeation clearance ratios (basal to apical / apical to basal) of XXXX in the P-gp expressing cells at 1, 3, and 10 μmol/L were 10.91, 10.18, and 7.95, respectively. Under the same conditions, the permeation clearance ratio for [3H]digoxin (1 μmol/L), a typical substrate, was 12.21. These results demonstrated that XXXX was a substrate for P-gp.

"Отношение клиренса"?

Заранее спасибо
С уважением, Юрий