Nicotine and cotinine increases the brain penetration of saquinavir in rat.
Endothelial tight junctions and efflux transporters of the blood-brain barrier (BBB) significantly limit brain accumulation of many drugs, including protease inhibitors such as saquinavir. The cholinergic agonist nicotine is one of the most commonly used drugs in the world and the incidence is even higher in the human immune deficiency virus population (∼ 70%). We examined the ability of nicotine and its primary metabolite cotinine to modify brain uptake of saquinavir in rats. Both nicotine and cotinine at pharmacological concentrations matching those in smokers, increased brain saquinavir uptake by two fold. Co-perfusion with nicotinic receptor antagonists and passive permeability markers showed that the effect was not caused by receptor activation or BBB permeability disruption. Transport inhibition studies demonstrated that brain saquinavir uptake is limited by multiple efflux transporters, P-glycoprotein (P-gp), breast cancer resistance protein and multidrug resistance-associated protein. In situ perfusion and in vitro experiments using a classical P-gp substrate rhodamine 123 linked the effect of nicotine to inhibition of BBB P-gp transport. The effect was confirmed in vivo in chronic 14 day nicotine administration animals. These data suggest nicotine increases antiretroviral drug exposure to brain and may represent a significant in vivo drug-drug interaction at the BBB. Although this may slightly benefit CNS antiretroviral efficacy, it may also expose the brain to potential serious neurotoxicity.
Manda
Vamshi K
VK
Texas Tech University Health Sciences Center, School of Pharmacy, Department of Pharmaceutical Sciences, Amarillo, Texas 79106-1712, USA.
Mittapalli
Rajendar K
RK
Bohn
Kaci A
KA
Adkins
Chris E
CE
Lockman
Paul R
PR
D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D001812:Blood-Brain Barrier / Q000187:drug effects / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D045744:Cell Line, Tumor; D003367:Cotinine / Q000008:administration & dosage / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D010539:Permeability / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D019258:Saquinavir / Q000008:administration & dosage / Q000378:metabolism*
D017320:HIV Protease Inhibitors; D003367:Cotinine; D019258:Saquinavir