title: Lopinavir concentrations in cerebrospinal fluid exceed the 50% inhibitory concentration for HIV.
abstract: BACKGROUND
  Lopinavir (LPV) is highly bound to plasma proteins and is a substrate for active drugs transporters, which may greatly limit the access of LPV to the central nervous system (CNS). However, even low lopinavir concentrations may be sufficient to inhibit HIV replication. Prior anecdotal reports indicated that lopinavir concentrations were below detection in cerebrospinal fluid (CSF).
  
  
  METHODS
  LPV was measured by liquid chromatography/mass spectrometry in 31 CSF-plasma pairs from 26 HIV-infected individuals who were taking LPV-containing antiretroviral regimens. The lower limit of quantification was 3.7 microg/l.
  
  
  RESULTS
  Seven of the sample pairs had very low plasma (and CSF) LPV concentrations, with a mean estimated plasma trough of 274 microg/l (range, < 3.7 to 608; typical trough values approximately 4000 microg/l), suggesting poor recent adherence. In the remaining 24 sample pairs, the median LPV concentration was 5889 microg/l [interquartile range (IQR), 4805-9620] and all CSF samples had measurable LPV concentrations: median 17.0 microg/l (IQR, 12.1-22.7). The median CSF-plasma ratio was 0.23% (range, 0.12-0.75). All CSF concentrations in these samples were more than double the 50% inhibitory concentration for wild-type HIV virus.
  
  
  CONCLUSIONS
  In patients with typical plasma levels of LPV, the drug is detectable in the CSF at concentrations that exceed those needed to inhibit HIV replication. Despite being > 98% bound to plasma proteins, LPV penetrates into the CNS and may contribute to the control of HIV in this potential reservoir.
authors.affiliation: Pediatric Pharmacology Research Unit, University of California San Diego, La Jolla, California 92093-8214, USA. ecapparelli@ucsd.edu
authors.forename: Edmund V
authors.initials: EV
authors.lastname: Capparelli
authors.forename: Diane
authors.initials: D
authors.lastname: Holland
authors.forename: Charles
authors.initials: C
authors.lastname: Okamoto
authors.forename: Bryan
authors.initials: B
authors.lastname: Gragg
authors.forename: Janis
authors.initials: J
authors.lastname: Durelle
authors.forename: Jennifer
authors.initials: J
authors.lastname: Marquie-Beck
authors.forename: Geoffrey
authors.initials: G
authors.lastname: van den Brande
authors.forename: Ron
authors.initials: R
authors.lastname: Ellis
authors.forename: Scott
authors.initials: S
authors.lastname: Letendre
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D002853:Chromatography, Liquid; D005260:Female; D015658:HIV Infections / Q000097:blood / Q000134:cerebrospinal fluid* / Q000188:drug therapy; D017320:HIV Protease Inhibitors / Q000097:blood / Q000134:cerebrospinal fluid* / Q000627:therapeutic use; D015497:HIV-1; D006801:Humans; D061466:Lopinavir; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D011446:Prospective Studies; D011744:Pyrimidinones / Q000097:blood / Q000134:cerebrospinal fluid* / Q000627:therapeutic use
chemical_list: D017320:HIV Protease Inhibitors; D011744:Pyrimidinones; D061466:Lopinavir