In vitro P-Glycoprotein-Mediated transport of tadalafil: A comparison with sildenafil

Hiroki Higashi, Nao Watanabe, Rika Tamura, Masato Taguchi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Tadalafil and sildenafil are selective inhibitors of phosphodiesterase type 5, showing marked pharmaco-kinetic variability in patients with pulmonary arterial hypertension. It has been reported that sildenafil is a substrate for P-glycoprotein (P-gp), but whether tadalafil is a substrate for P-gp remains to be determined. The objective of the present study was to elucidate whether tadalafil is a substrate for P-gp. Transcellular transport of sildenafil and tadalafil (5µM each) was examined using renal epithelial LLC-PK1 and P-gp-expressing LLC-GA5-COL150 cell monolayers. The efflux ratio of the basal to apical (B to A) transport of sildenafil to the A to B transport after 120-min incubation in LLC-GA5-COL150 cells (1.52) was significantly higher than that in LLC-PK1 cells (0.711). The efflux ratio of the B to A transport of tadalafil to the A to B transport after 120-min incubation in LLC-GA5-COL150 cells (10.4) was significantly higher than that in LLC-PK1 cells (1.23). In LLC-GA5-COL150 cell monolayers, the Vmax and Km values of sildenafil transport calculated from a modified Michaelis–Menten equation were 101±64pmol/min/cm2 and 112±47µM, respectively. On the other hand, those of tadalafil transport were 13.6±4.8pmol/min/cm2 and 22.7±9.3µM, respectively. In the presence of a P-gp inhibitor (PSC833), the B to A transport of tadalafil was decreased by 28.6% in LLC-GA5-COL150 cells, and the A to B transport of tadalafil was 6.59-fold greater than that in its absence. These results indicate that tadalafil is a substrate for P-gp.

Original languageEnglish
Pages (from-to)1314-1319
Number of pages6
JournalBiological and Pharmaceutical Bulletin
Volume40
Issue number8
DOIs
StatePublished - 2017

Keywords

  • P-glycoprotein
  • Sildenafil
  • Tadalafil

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

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