Differences in the intracellular accumulation of HIV protease inhibitors in vitro and the effect of active transport.
OBJECTIVE
To investigate the intracellular accumulation of HIV protease inhibitors (PI) and to assess the effect of active transport on this accumulation.


METHODS
CEM cells were incubated with a PI for 18 h and the intracellular concentration determined using cell number and radioactivity. The effect of active transport was investigated using cells expressing P-glycoprotein (CEM(VBL)) and cells expressing multidrug resistance-associated protein 1 (MRP1; CEM(E1000)). Incubations were also carried out at 4 degrees C and in the presence of 2-deoxyglucose plus rotenone to examine the effect of inhibiting active transport.


RESULTS
Nelfinavir (NFV) accumulated to the greatest extent (> 80-fold) followed by saquinavir (SQV; approximately 30-fold), ritonavir (RTV; 3-7-fold) and finally indinavir (IDV; extracellular equivalent to intracellular). In CEM(VBL) cells there was a significant reduction in the intracellular accumulation of NFV, SQV and RTV and in CEM(E1000) cells there was reduced accumulation of SQV and RTV. Inhibition of active transport processes caused a reduction in SQV and RTV accumulation but had no effect on IDV accumulation in all cell types. NFV accumulation was increased in CEM(VBL) cells as a result of inhibition of active transport.


CONCLUSIONS
Marked differences can be detected in the intracellular accumulation of HIV PI drugs in vitro. Both P-glycoprotein and MRP1 may play a role in limiting the intracellular concentration of the PI and active influx mechanisms may contribute to drug accumulation.
Jones
K
K
Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK.
Hoggard
P G
PG
Sales
S D
SD
Khoo
S
S
Davey
R
R
Back
D J
DJ
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D001693:Biological Transport, Active; D002460:Cell Line; D017320:HIV Protease Inhibitors / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D019469:Indinavir / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D019888:Nelfinavir / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019438:Ritonavir / Q000378:metabolism; D019258:Saquinavir / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D017320:HIV Protease Inhibitors; D019469:Indinavir; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D019888:Nelfinavir; D019438:Ritonavir; D019258:Saquinavir