ABSTRACT
Efavirenz (EFV) is principally metabolized by CYP2B6 to 8-hydroxy-efavirenz (8OH-EFV) and to a lesser extent by CYP2A6 to 7-hydroxy-efavirenz (7OH-EFV). So far, most metabolite profile analyses have been restricted to 8OH-EFV, 7OH-EFV, and EFV-N-glucuronide, even though these metabolites represent a minor percentage of EFV metabolites present in vivo. We have performed a quantitative phase I and II metabolite profile analysis by tandem mass spectrometry of plasma, cerebrospinal fluid (CSF), and urine samples in 71 human immunodeficiency virus patients taking efavirenz, prior to and after enzymatic (glucuronidase and sulfatase) hydrolysis. We have shown that phase II metabolites constitute the major part of the known circulating efavirenz species in humans. The 8OH-EFV-glucuronide (gln) and 8OH-EFV-sulfate (identified for the first time) in humans were found to be 64- and 7-fold higher than the parent 8OH-EFV, respectively. In individuals (n = 67) genotyped for CYP2B6, 2A6, and CYP3A metabolic pathways, 8OH-EFV/EFV ratios in plasma were an index of CYP2B6 phenotypic activity (P < 0.0001), which was also reflected by phase II metabolites 8OH-EFV-glucuronide/EFV and 8OH-EFV-sulfate/EFV ratios. Neither EFV nor 8OH-EFV, nor any other considered metabolites in plasma were associated with an increased risk of central nervous system (CNS) toxicity. In CSF, 8OH-EFV levels were not influenced by CYP2B6 genotypes and did not predict CNS toxicity. The phase II metabolites 8OH-EFV-gln, 8OH-EFV-sulfate, and 7OH-EFV-gln were present in CSF at 2- to 9-fold higher concentrations than 8OH-EFV. The potential contribution of known and previously unreported EFV metabolites in CSF to the neuropsychological effects of efavirenz needs to be further examined in larger cohort studies.
Subject(s)
Anti-HIV Agents/pharmacokinetics , Benzoxazines/adverse effects , Benzoxazines/pharmacokinetics , HIV Infections/drug therapy , Metabolomics/methods , Reverse Transcriptase Inhibitors/pharmacokinetics , Tandem Mass Spectrometry , Alkynes , Anti-HIV Agents/adverse effects , Anti-HIV Agents/blood , Anti-HIV Agents/cerebrospinal fluid , Anti-HIV Agents/urine , Benzoxazines/blood , Benzoxazines/cerebrospinal fluid , Benzoxazines/urine , Cyclopropanes , Cytochrome P-450 CYP2A6/genetics , Cytochrome P-450 CYP2A6/metabolism , Cytochrome P-450 CYP2B6/genetics , Cytochrome P-450 CYP2B6/metabolism , Cytochrome P-450 CYP3A/genetics , Cytochrome P-450 CYP3A/metabolism , Genotype , Glucuronides/blood , Glucuronides/cerebrospinal fluid , Glucuronides/urine , HIV Infections/diagnosis , HIV Infections/metabolism , Humans , Hydroxylation , Metabolic Detoxication, Phase I , Metabolic Detoxication, Phase II , Neurotoxicity Syndromes/etiology , Neurotoxicity Syndromes/genetics , Neurotoxicity Syndromes/metabolism , Phenotype , Reverse Transcriptase Inhibitors/adverse effects , Reverse Transcriptase Inhibitors/blood , Reverse Transcriptase Inhibitors/cerebrospinal fluid , Reverse Transcriptase Inhibitors/urine , Risk Assessment , Sulfates/blood , Sulfates/cerebrospinal fluid , Sulfates/urineABSTRACT
We measured sequential plasma and CSF levodopa and CSF dopamine sulfate levels following a single dose of levodopa/carbidopa in two patients with advanced Parkinson's disease (PD). We obtained CSF from an Ommaya reservoir implanted in the lateral ventricle several months earlier at the time of transplantation of adrenal medulla to caudate nucleus and could detect dopamine only in its sulfconjugated form. Peak CSF levodopa and dopamine sulfate levels occurred 1 to 1.5 hours after peak plasma concentration of levodopa. The time course of clinical improvement and worsening correlated precisely with the appearance and disappearance of both levodopa and dopamine sulfate in the CSF. The precise correlation between CSF dopamine sulfate and levodopa indicates that in patients with advanced PD the brain retains some capacity to convert levodopa to dopamine. The transient nature of the correlation between motor fluctuations, CSF levodopa, and CSF dopamine sulfate is consistent with suggestions that in patients with advanced PD there is a diminished capacity to store dopamine synthesized from exogenous levodopa. Dopamine sulfate appears to be a useful index of the availability of dopamine in the parkinsonian brain.
Subject(s)
Dopamine/cerebrospinal fluid , Parkinson Disease/cerebrospinal fluid , Carbidopa/therapeutic use , Cerebral Ventricles/metabolism , Dopamine/blood , Dopamine/metabolism , Drug Combinations , Female , Humans , Levodopa/blood , Levodopa/cerebrospinal fluid , Levodopa/metabolism , Levodopa/therapeutic use , Male , Middle Aged , Motor Activity , Movement , Parkinson Disease/drug therapy , Parkinson Disease/metabolism , Parkinson Disease/physiopathology , Sulfates/blood , Sulfates/cerebrospinal fluid , Sulfates/metabolismSubject(s)
Acetaminophen/pharmacology , Sulfates/cerebrospinal fluid , Adult , Aged , Female , Humans , Male , Middle AgedABSTRACT
Inorganic sulfate in cerebrospinal fluid (CSF) from 25 infants and children was measured by controlled-flow anion chromatography. The mean CSF concentration was 0.133 +/- 0.066 mumol/l for the group. Mean CSF sulfate is age dependent being 0.170 mmol/l in the newborn and 0.095 mmol/l (range: 0.059-0.165) in children over 3 years of age. The fall in CSF sulfate parallels a corresponding age-dependent change in serum sulfate. Accordingly, the CSF:serum ratio (0.334 +/- 0.019; mean +/- SE) remains constant in infants and children. The CSF:serum ratio departs significantly from that predicted by the Gibbs-Donnan equilibrium relation (predicted ratio, 1.21). CSF sulfate content appears to reflect mediated transport of sulfate out of CSF.
Subject(s)
Sulfates/cerebrospinal fluid , Adolescent , Aging , Cerebrospinal Fluid Proteins/metabolism , Child , Child, Preschool , Chlorides/cerebrospinal fluid , Chromatography , Glucose/cerebrospinal fluid , Humans , Infant , Infant, Newborn , Sulfates/bloodABSTRACT
The application of controlled flow anion chromatography to the assay of inorganic sulfate in biological fluids is described. The sulfate anion is separated from other anions by ion-exchange chromatography and quantitated conductimetrically. Coefficient of variance is 3.4%, about half that for the barium precipitation assay. Interference from heparin in plasma samples and unknown sources in tissue extract analysis is avoided. Sulfate levels in plasma are not different from those measured in serum after protein precipitation. Normal levels for sulfate concentration in human plasma, cerebrospinal fluid and hepatic tissue extract are reported.
Subject(s)
Sulfates/blood , Adult , Animals , Child , Chromatography, Ion Exchange , Humans , Infant , Infant, Newborn , Infant, Premature , Liver/analysis , Mice , Sulfates/cerebrospinal fluidABSTRACT
Fluid from the notochordal canal of the coelacanth, Latimeria chalumnae, was analyzed for major inorganic and organic constituents and compared with blood serum from the same fish. Significantly or suggestively lower levels of sodium, magnesium, calcium, bicarbonate, sulfate, total carbohydrates, glucose, lactate, cholesterol, bound phosphate and total proteins were found in notochordal fluid than in serum, whereas potassium, chloride, urea, trimethylamine oxide, and total free amino acids were higher and inorganic phosphorus essentially identical. Osmolarity of notochordal fluid (1058 mOsm) exceeds that of serum (942 mOsm). A whitish precipitate in the fluid consisted of a matrix of fibers 100 A in diameter and of indefinite length. It resembled a sialoglycoprotein in composition and was stabilized by disulfide bonds. The fluid contained cellular debris.
