Edward J. Fuchs

Pharmacokinetics and Safety of AMD-3100, a Novel Antagonist of the CXCR-4 Chemokine Receptor, in Human Volunteers

ABSTRACT AMD-3100, a bicyclam, is a novel agent that uniquely inhibits the entry of human immunodeficiency virus type 1 (HIV-1) into CD4+ T cells via selective blockade of the chemokine CXCR-4 receptor. Twelve healthy volunteers were given AMD-3100 as a single 15-min intravenous infusion at 10, 20, 40, or 80 μg/kg. Five subjects also received a single subcutaneous injection of AMD-3100 (40 or 80 μg/kg). Three subjects received two escalating oral doses each (80 and 160 μg/kg). All subjects tolerated their dose(s) well without any grade 2 toxicity or dose adjustment. Six subjects experienced mild, transient symptoms, primarily gastrointestinal in nature and not dose related. All subjects experienced a dose-related elevation of the white blood cell count, from 1.5 to 3.1 times the baseline, which returned to the baseline 24 h after dosing. AMD-3100 demonstrated dose proportionality for the maximum drug concentration in serum (Cmax) and the area under the concentration-time curve from 0 h to ∞ (AUC0–∞) over the entire dose range. At the highest intravenous dose (80 μg/kg), the medianCmax was 515 (range, 470 to 521) ng/ml and the AUC0–∞ was 1,044 (range, 980 to 1,403) ng-h/ml. The median systemic absorption after subcutaneous dosing was 87% (range, 67 to 106%). No drug was detectable in the blood following oral dosing. Using a two-compartment model, the median pharmacokinetic parameter estimates (ranges) were as follows: volume of distribution, 0.34 (0.27 to 0.36) liter/kg; clearance, 1.30 (0.97 to 1.34) liters/h; elimination half-life, 3.6 (3.5 to 4.9) h. After a single, well-tolerated intravenous dose of AMD-3100, concentrations were sustained for 12 h above the in vitro antiretroviral 90% inhibitory concentrations and for 8 h above antiviral concentrations identified in the SCID-hu Thy/Liv mouse model of HIV infection.

Induction of the Phase 2 Response in Mouse and Human Skin by Sulforaphane-containing Broccoli Sprout Extracts

The isothiocyanate sulforaphane was isolated from broccoli extracts in a bioactivity-guided fractionation as the principal and very potent inducer of cytoprotective phase 2 enzymes and subsequently shown to inhibit tumor development in animal models that involve various carcinogens and target organs. Because broccoli and broccoli sprouts are widely consumed, extracts obtained from them are viewed as convenient vehicles for sulforaphane delivery to humans. In relation to our current interest in devising strategies for protection against UV light–induced skin cancer, it was necessary to examine the safety and efficacy of topical application of sulforaphane-containing broccoli sprout extracts as single and multiple doses in both mice and humans. Topical application of an extract delivering 100 nmol sulforaphane/cm2 increased the protein levels of NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase A1, and heme oxygenase 1, three representative phase 2 enzymes, in mouse skin epidermis. Quantitative assessment of the activity of NQO1 24 h after dosing showed increases of 1.5- and 2.7-fold after application of single and multiple (thrice, every 24 h) doses, respectively. A dose-escalation safety study in healthy human subjects revealed no adverse reactions when doses as high as 340 nmol of sulforaphane in the form of broccoli sprout extracts were applied topically to the center of a 1-cm-diameter circle drawn on the volar forearm. A subsequent efficacy study showed that despite the interindividual differences in basal levels, the enzyme activity of NQO1 in homogenates of 3-mm full thickness skin punch biopsies increased in a dose-dependent manner, with maximum increases of 1.5- and 4.5-fold after application of 150 nmol doses, once or three times (at 24 h-intervals), respectively, thus providing direct evidence for induction of the phase 2 response in humans. (Cancer Epidemiol Biomarkers Prev 2007;16(4):847–51)

Hyperosmolar Sexual Lubricant Causes Epithelial Damage in the Distal Colon: Potential Implication for HIV Transmission

BACKGROUND Many sexual lubricants are hyperosmolar. Hyperosmolar enemas induce epithelial damage, and enema use has been associated with an increased risk of HIV infection. To inform the development of rectal microbicide formulation, we evaluated the effects of hyperosmolar gels on the rectal mucosa. METHODS Two commercial lubricants were compounded into iso-osmolar and hyperosmolar mixtures (283 and 3429 mOsm/kg, respectively). Each gel was radiolabeled with 500 micro Ci of (99m)Technetium-diethylene triaminepentaacetic acid, and 10 mL was given rectally to 10 subjects in random sequence. Sigmoidoscopy by an endoscopist blinded to treatment assignment was performed 90 min later to obtain luminal and mucosal samples. Urine radiolabel detection was used to assess mucosal permeability. RESULTS Epithelial denudation 10 cm from the anus occurred to a greater degree with the hyperosmolar gel than with the iso-osmolar formulation (median toxicity grade, 2.50 vs. 1.17 out of 3, respectively; P=.009). The hyperosmolar gel was also associated with lower isotope luminal concentration at 10 cm, compared with the iso-osmolar gel (median, 8.9% vs. 54.6% of administered concentration, respectively). Mucosal permeability measured through 12 h was reduced with the hyperosmolar gel (P=.037). CONCLUSION Rectally applied hyperosmolar gels induce greater epithelial denudation and luminal secretion than iso-osmolar gels. Because denudation plausibly increases the risk of HIV transmission, hyperosmolar gels make poor rectal microbicide formulations, and hyperosmolar sexual lubricants may increase susceptibility to HIV infection.

Balancing Justice and Autonomy in Clinical Research With Healthy Volunteers

In clinical research, ethics review generally first examines whether study risks are reasonable in light of benefits provided. Through informed consent, then, prospective subjects consider whether the risk/benefit balance and procedures are reasonable for them. Unique ethics issues emerge in clinical research with healthy volunteers. Certain types of studies only recruit healthy volunteers as participants. Phase 1 studies, for example, including first time in human studies of investigational drugs and vaccines, generally are conducted in healthy volunteers. Although such research carries inherent and often unknown risks, healthy subjects provide the most efficient target population in which to conduct such research, as these volunteers generally are free of concurrent diseases or medications that could confound interpretation of toxicity. Other studies enrolling healthy volunteers often are simply looking for the most scientifically sound population for the study of normal human physiology.

Pharmacokinetics and Pharmacodynamics of Methadone Enantiomers After Coadministration with Amprenavir in Opioid‐Dependent Subjects

Study Objective. To compare steady‐state pharmacokinetics and pharmacodynamics of methadone enantiomers when coadministered with fosamprenavir 700 mg‐ritonavir 100 mg twice/day.

Distribution of cell-free and cell-associated HIV surrogates in the colon after simulated receptive anal intercourse in men who have sex with men.

ObjectivesDescribing the distribution and clearance of HIV surrogates within the gastrointestinal tract to inform rectal microbicide development. DesignRadiolabeled simulated HIV-infected semen was administered, imaged, and biopsied to simulate and measure colonic HIV distribution after anal intercourse. MethodsHealthy male subjects with a history of receptive anal intercourse and experience with the use of anal sex toys were recruited to this study. Apheresis isolated leukocytes were collected before simulated intercourse. These autologous leukocytes, radiolabeled with 9.25 MBq 111Indium-oxine (cell-associated HIV surrogate), and sulfur colloid particles, labeled with 37 MBq 99mTechnectium (cell-free HIV surrogate), were mixed in 3 mL autologous seminal plasma. This simulated HIV-infected semen was administered to subjects via an artificial phallus with urethra after 5 minutes of simulated intercourse. Postdosing dual isotope Single photon emission computed tomography coupled with traditional computed tomography (SPECT/CT) images were acquired at 1, 4, 8, and 24 hours. At 5 hours postdosing, colon biopsies were collected, CD4 cells were extracted, and samples analyzed for radioactivity. ResultsSPECT/CT images showed similar luminal distribution for both surrogates, with migration limited to the rectosigmoid colon in all subjects. SPECT showed at least 75% overlap in distribution of both surrogates up to 4 hours after dosing. Biopsies indicate that 2.4% of CD4 cells extracted from rectosigmoid colon tissue were exogenously administered. ConclusionsOur HIV surrogates stayed within the rectosigmoid colon for 24 hours. Exogenously dosed autologous lymphocytes and HIV-sized particles migrate to similar locations and associate with the colonic tissue in the lumen.

Quantification of the spatial distribution of rectally applied surrogates for microbicide and semen in colon with SPECT and magnetic resonance imaging

AIMS We sought to describe quantitatively the distribution of rectally administered gels and seminal fluid surrogates using novel concentration-distance parameters that could be repeated over time. These methods are needed to develop rationally rectal microbicides to target and prevent HIV infection. METHODS Eight subjects were dosed rectally with radiolabelled and gadolinium-labelled gels to simulate microbicide gel and seminal fluid. Rectal doses were given with and without simulated receptive anal intercourse. Twenty-four hour distribution was assessed with indirect single photon emission computed tomography (SPECT)/computed tomography (CT) and magnetic resonance imaging (MRI), and direct assessment via sigmoidoscopic brushes. Concentration-distance curves were generated using an algorithm for fitting SPECT data in three dimensions. Three novel concentration-distance parameters were defined to describe quantitatively the distribution of radiolabels: maximal distance (D(max) ), distance at maximal concentration (D(Cmax) ) and mean residence distance (D(ave) ). RESULTS The SPECT/CT distribution of microbicide and semen surrogates was similar. Between 1 h and 24 h post dose, the surrogates migrated retrograde in all three parameters (relative to coccygeal level; geometric mean [95% confidence interval]): maximal distance (D(max) ), 10 cm (8.6-12) to 18 cm (13-26), distance at maximal concentration (D(Cmax) ), 3.8 cm (2.7-5.3) to 4.2 cm (2.8-6.3) and mean residence distance (D(ave) ), 4.3 cm (3.5-5.1) to 7.6 cm (5.3-11). Sigmoidoscopy and MRI correlated only roughly with SPECT/CT. CONCLUSIONS Rectal microbicide surrogates migrated retrograde during the 24 h following dosing. Spatial kinetic parameters estimated using three dimensional curve fitting of distribution data should prove useful for evaluating rectal formulations of drugs for HIV prevention and other indications.

CYP3A5 Genotype Impacts Maraviroc Concentrations in Healthy Volunteers

CYP3A5 plays a prominent role in the metabolism of maraviroc, an approved drug for human immunodeficiency virus (HIV)-1 treatment and a candidate for HIV-1 prevention. We studied the effect of the CYP3A5 genotype on pharmacokinetics of maraviroc and a primary CYP3A5-dependent metabolite of maraviroc denoted as metabolite 1 (M1). Volunteers were screened for health status and CYP3A5 genotype (wild-type allele *1 and dysfunctional alleles *2, *3, *6, and *7) to obtain 24 evaluable subjects in three groups (n = 8 each): homozygous dysfunctional (two dysfunctional alleles), heterozygous (one *1 allele and one dysfunctional allele), and homozygous wild-type (two *1 alleles). Subjects received 300 mg maraviroc orally followed by blood collection for 32 hours. The homozygous wild-type group exhibited lower mean plasma maraviroc concentrations at almost all sampling times. The median (interquartile range) maraviroc area under the plasma concentration-time curves from time 0 to infinity (AUC0–inf) were 2099 (1422–2568) ng⋅h/ml, 1761 (931–2640) ng⋅h/ml, and 1238 (1065–1407) ng⋅h/ml for the homozygous dysfunctional, heterozygous, and homozygous wild-type groups, respectively. The homozygous wild-type group had 41% lower maraviroc AUC0–inf and 66% higher apparent clearance compared with the homozygous dysfunctional group (P = 0.02). The AUC0–inf ratios of maraviroc to M1 in heterozygous and homozygous wild-type subjects were lower by 51 and 64% relative to the homozygous dysfunctional group, respectively (P < 0.001). In conclusion, the lower maraviroc concentrations in the homozygous wild-type group indicate that maraviroc may be underdosed in people homozygous for the CYP3A5*1 allele, including almost one-half of African Americans.

Beneficial pharmacokinetic interaction between atazanavir and lopinavir/ritonavir

Background:The combination of lopinavir/ritonavir (LPV/r) and atazanavir (ATV) with nucleoside reverse transcriptase inhibitors has been used as a salvage regimen in HIV-infected patients. Because these agents, to various degrees, are substrates, inducers, and inhibitors of CYP450 3A4, there is concern for alterations in the pharmacokinetics (PK) of these combined agents. Objective:To determine the steady-state PK interactions between ATV, ritonavir (RTV), and LPV when coadministered at various doses. Methods:HIV-negative subjects (n = 15) received a combination of ATV, RTV, and LPV in the following sequence: period I (days 1-10), ATV/r at a dose of 300/100 mg once daily; period II (days 11-24), ATV at a dose of 300 mg once daily plus LPV/r at a dose of 400/100 mg twice daily; and period III (days 25-34), ATV/r at a dose of 300/100 mg once daily plus LPV/r at a dose of 400/100 mg twice daily. Intensive PK analysis was performed on days 10, 24, and 34. A paired t test was used for pairwise comparison of log-transformed PK parameters of ATV and LPV. Results:In period II, the ATV minimum concentration (Cmin) geometric mean (GM) was higher compared with period I (GM: 0.75 vs. 0.51 μg/mL, geometric mean ratio (GMR) = 1.45, 90% confidence interval [CI]: 1.19 to 1.77; P = 0.006). The ATV area under the concentration-time curve from dosing to 24 hours after the dose (AUC0-24; GM: 36.40 vs. 39.62 μg·h/mL, GMR = 0.92, 90% CI: 0.80 to 1.05; P = 0.28) did not differ, however. The addition of 100 mg of RTV in period III did not significantly increase the ATV Cmin (GM: 0.84 vs. 0.75 μg/mL, GMR = 1.13, 90% CI: 0.91 to 1.40; P = 0.34) or ATV AUC0-24 (GM: 39.59 vs. 36.40 μg·h/mL, GMR = 1.09, 90% CI: 0.99 to 1.20; P = 0.14) compared with period II. The additional RTV in period III resulted in a higher LPV Cmin (GM: 5.12 vs. 3.99 μg/mL, GMR = 1.28, 90% CI: 1.15 to 1.43; P = 0.001), but the LPV areas under the concentration-time curve from dosing to 12 hours after the dose and maximum concentration were not significantly different. LPV PK parameters in period II were comparable to those of historical control subjects receiving LPV/r at a dose of 400/100 mg twice daily. All studied regimens were well tolerated. Indirect hyperbilirubinemia was the only grade 3 and 4 abnormality reported, which was expected given that ATV competitively inhibits UGTIA1 and has not been shown to result in other hepatic abnormalities. Conclusions:The combination of ATV at a dose of 300 mg once daily plus LPV/r at a dose of 400/100 mg twice daily resulted in an appropriate PK profile for ATV and LPV and could be further evaluated in treatment-experienced patients requiring a dual-boosted protease inhibitor-containing regimen.

Quantitative Assessment of Altered Rectal Mucosal Permeability Due to Rectally Applied Nonoxynol-9, Biopsy, and Simulated Intercourse

BACKGROUND Microbicide toxicity may reduce the efficacy of topical preexposure prophylaxis for human immunodeficiency virus (HIV) transmission. Noninvasive quantitative measures of microbicide toxicity would usefully inform microbicide development. METHODS Ten subjects received 3 one-time interventions: 5 mL of Normosol-R fluid alone (negative control), 5 mL of 2% nonoxynol-9 (N-9) gel, and 5 mL of Normosol-R with coital simulation and sigmoidoscopic biopsy (CS + BX). Each dose of N-9 and Normosol-R contained 500 µCi of (99m)technetium-diethylene triamine pentaacetic acid. Plasma and urine radioactivity was assessed over 24 hours. RESULTS The plasma radioisotope concentration peaked 1 hour after N-9 dosing. The mean maximum radioisotope concentration after N-9 receipt was 12.0 times (95% confidence interval [CI], 6.8-21.0) and 8.4 times (95% CI, 5.2-13.5) the mean concentration after Normosol-R control receipt and CS + BX receipt, respectively; paired differences persisted for 24 hours. After N-9 dosing, the urine isotope level was 3.6 times (95% CI, 1.1-11.4) the level observed 8 hours after Normosol-R control receipt and 4.0 times (95% CI, 1.4-11.4) the level observed 4 hours after CS + BX receipt. Permeability after CS + BX receipt was greater than that after Normosol-R control receipt in 0-2-hour urine specimens only (mean permeability, 2.4; 95% CI, 1.0-5.8) but was not greater in blood. CONCLUSIONS Plasma sampling after rectal radioisotope administration provided quantitative estimates of altered mucosal permeability after chemical and mechanical stresses. Permeability testing may provide a useful noninvasive adjunct to assess the mucosal effects of candidate microbicides. Clinical Trials Registration. NCT00389311.