A phase I study of high-dose rosuvastatin with standard dose erlotinib in patients with advanced solid malignancies.

BACKGROUND: Synergistic cytotoxicity with high-dose statins and erlotinib has been demonstrated in preclinical models across a number of tumour types. In this phase I study, we evaluated the safety and potential anti-tumour activity of escalating doses of rosuvastatin in combination with the standard clinical dose of erlotinib in heavily pretreated patients with advanced solid tumours. METHODS: This was a single-center, phase I open-label study to determine the safety and recommended phase two dose (RPTD) of rosuvastatin in combination with 150 mg/day standard dose of erlotinib. Using a 3 + 3 study design and 28-day cycle, escalating doses of rosuvastatin from 1 to 8 mg/kg/day × 2 weeks (cycle 1) and 3 weeks (subsequent cycles) given concurrently with erlotinib were evaluated. In order to expand the experience and to gain additional safety and pharmacokinetic data, two expansions cohorts using concurrent or alternating weekly dosing regimens at the RPTD were also evaluated. RESULTS: All 24 patients enrolled were evaluable for toxicity, and 22 for response. The dose-limiting toxicity (DLT) of reversible muscle toxicity was seen at the 2 mg/kg/day dose level. Maximal tolerated dose (MTD) was determined to be 1 mg/kg/day. Thirty-three percent of patients developed at least 1 ≥ grade 2 muscle toxicity (rhabdomyolysis: 1/24, myalgia: 7/24) resulting in one study-related death. Durable stable disease for more than 170 days was seen in 25 % of patients that received concurrent treatment and were evaluable for response (n = 16). Plasma erlotinib levels on study were unaffected by the addition of rosuvastatin. CONCLUSIONS: The observed disease stabilization rate of 25 % with combination therapy in this heavily pretreated population is encouraging, however, the high levels of muscle toxicities observed limited this combination strategy.

Role of P-glycoprotein in the distribution of the HIV protease inhibitor atazanavir in the brain and male genital tract.

The blood-testis barrier and blood-brain barrier are responsible for protecting the male genital tract and central nervous system from xenobiotic exposure. In HIV-infected patients, low concentrations of antiretroviral drugs in cerebrospinal fluid and seminal fluid have been reported. One mechanism that may contribute to reduced concentrations is the expression of ATP-binding cassette drug efflux transporters, such as P-glycoprotein (P-gp). The objective of this study was to investigate in vivo the tissue distribution of the HIV protease inhibitor atazanavir in wild-type (WT) mice, P-gp/breast cancer resistance protein (Bcrp)-knockout (Mdr1a-/-, Mdr1b-/-, and Abcg2-/- triple-knockout [TKO]) mice, and Cyp3a-/- (Cyp) mice. WT mice and Cyp mice were pretreated with a P-gp/Bcrp inhibitor, elacridar (5 mg/kg of body weight), and the HIV protease inhibitor and boosting agent ritonavir (2 mg/kg intravenously [i.v.]), respectively. Atazanavir (10 mg/kg) was administered i.v. Atazanavir concentrations in plasma (Cplasma), brain (Cbrain), and testes (Ctestes) were quantified at various times by liquid chromatography-tandem mass spectrometry. In TKO mice, we demonstrated a significant increase in atazanavir Cbrain/Cplasma (5.4-fold) and Ctestes/Cplasma (4.6-fold) ratios compared to those in WT mice (P<0.05). Elacridar-treated WT mice showed a significant increase in atazanavir Cbrain/Cplasma (12.3-fold) and Ctestes/Cplasma (13.5-fold) ratios compared to those in vehicle-treated WT mice. In Cyp mice pretreated with ritonavir, significant (P<0.05) increases in atazanavir Cbrain/Cplasma (1.8-fold) and Ctestes/Cplasma (9.5-fold) ratios compared to those in vehicle-treated WT mice were observed. These data suggest that drug efflux transporters, i.e., P-gp, are involved in limiting the ability of atazanavir to permeate the rodent brain and genital tract. Since these transporters are known to be expressed in humans, they could contribute to the low cerebrospinal and seminal fluid antiretroviral concentrations reported in the clinic.

Correlates of efavirenz exposure in Chilean patients affected with human immunodeficiency virus reveals a novel association with a polymorphism in the constitutive androstane receptor.

OBJECTIVE: To explore the effect of demographics and single-nucleotide polymorphisms in cytochrome P450 (CYP) 2B6, 2A6, UDP-glucuronosyltransferase (UGT) 2B7, and the constitutive androstane receptor (CAR) genes on efavirenz pharmacokinetics in a Chilean cohort affected with human immunodeficiency virus. METHODS: Timed plasma samples obtained throughout the dosing interval were analyzed for efavirenz concentrations with liquid chromatography/tandem mass spectrometry. DNA from whole-blood samples was used for genetic analysis. Data were analyzed using a Mann-Whitney statistical test; furthermore, a Pearson or Spearman correlation was used. A multivariate analysis was then conducted using multiple linear regression by best subset analysis. RESULTS: Overall 219 patients were included, 208 patients had measurable efavirenz levels and available genetic samples. The overall median (interquartile range) of efavirenz concentration was 2.6 (2.1-3.7) mcg/mL. In multivariate regression analysis, CYP2B6 516G>T (P < 0.0001) and CAR rs2307424 C>T (P = 0.002) were significantly related to efavirenz plasma concentrations. CONCLUSION: This novel association between CAR rs2307424 and efavirenz plasma concentrations now requires validation in other cohorts.

Factors affecting antiretroviral pharmacokinetics in HIV-infected women with virologic suppression on combination antiretroviral therapy: a cross-sectional study.

BACKGROUND: Although some studies show higher antiretroviral concentrations in women compared to men, data are limited. We conducted a cross-sectional study of HIV-positive women to determine if protease inhibitor (PI) and non-nucleoside reverse transcriptase inhibitor (NNRTI) C(min) and Cmax values were significantly different than historical general population (predominantly male) averages and to evaluate correlates of higher concentrations. METHODS: HIV-positive women with virologic suppression (viral load < 50copies/mL) on their first antiretroviral regimen were enrolled. Timed blood samples for C(min) and Cmax were drawn weekly for 3 weeks. The ratio of each individual's median C(min) and Cmax to the published population mean values for their PI or NNRTI was calculated and assessed using Wilcoxon sign-rank. Intra- and inter-patient variability of antiretroviral drug levels was assessed using coefficient of variation and intra-class correlation. Linear regression was used to identify correlates of the square root-transformed C(min) and Cmax ratios. RESULTS: Data from 82 women were analyzed. Their median age was 41 years (IQR=36-48) and duration of antiretrovirals was 20 months (IQR=9-45). Median antiretroviral C(min) and Cmax ratios were 1.21 (IQR=0.72-1.89, p=0.003) (highest ratios for nevirapine and lopinavir) and 0.82 (IQR=0.59-1.14, p=0.004), respectively. Nevirapine and efavirenz showed the least and unboosted atazanavir showed the most intra- and inter-patient variability. Higher CD4+ count correlated with higher C(min). No significant correlates for Cmax were found. CONCLUSIONS: Compared to historical control data, C(min) in the women enrolled was significantly higher whereas Cmax was significantly lower. Antiretroviral C(min) ratios were highly variable within and between participants. There were no clinically relevant correlates of drug concentrations. TRIAL REGISTRATION: NCT00433979.

Impact of cytogenetic abnormalities on treatment outcomes in patients with amyloid light-chain amyloidosis: subanalyses from the ANDROMEDA study.

BACKGROUND: Cytogenetic abnormalities are common in patients with amyloid light-chain (AL) amyloidosis; some are associated with poorer outcomes. This post hoc analysis of ANDROMEDA evaluated the impact of certain cytogenetic abnormalities on outcomes in this patient population. METHODS: Patients with newly diagnosed AL amyloidosis were randomised 1:1 to daratumumab, bortezomib, cyclophosphamide, and dexamethasone (D-VCd) or VCd. Outcomes were evaluated in the intent-to-treat (ITT) population and in patients with t(11;14), amp1q21, del13q14, and del17p13. RESULTS: Overall, 321 patients had cytogenetic testing (D-VCd, n = 155; VCd, n = 166); most common abnormalities were t(11;14) and amp1q21. At a median follow-up of 20.3 months, haematologic complete response rates were higher with D-VCd vs VCd across all cytogenetic subgroups and organ response rates were numerically higher with D-VCd vs VCd across most subgroups. Point estimates for hazard ratio of major organ deterioration-PFS and -EFS favoured D-VCd over VCd for all cytogenetic subgroups. Deep haematologic responses (involved minus uninvolved free light chains [FLC] <10 mg/L or involved FLC ≤20 mg/L) were seen in more patients with D-VCd than VCd in all ITT and t(11;14) cohorts. CONCLUSIONS: These results support the use of D-VCd as standard of care in patients with newly diagnosed AL amyloidosis regardless of cytogenetic abnormalities.

A pilot, prospective, open-label simplification study to evaluate the safety, efficacy, and pharmacokinetics of once-daily lopinavir-ritonavir monotherapy in HIV-HCV coinfected patients: the MONOCO study.

BACKGROUND: A safe, effective, easy-to-dose antiretroviral therapy that minimizes hepatic complication risk is essential in optimizing HIV-HCV treatment. Nucleoside-sparing boosted protease inhibitor monotherapy may achieve this goal. METHODS: A prospective, open-label pilot simplification study of once-daily lopinavir/ritonavir (LPV/r) monotherapy in HIV-HCV coinfected patients was conducted in patients on HAART with undetectable HIV RNA for ≥6 months. The primary outcome was maintenance of HIV RNA<50 copies/mL through week 48. HIV RNA, immune measures, metabolic markers, and pharmacokinetics were assessed. RESULTS: Twenty participants received once-daily LPV/r monotherapy. Mean baseline age was 46.9 years and CD4 467 cells/L. By per protocol analysis, 71.4% (95% CI, 45.4-88.3) remained on once-daily LPV/r monotherapy with virologic suppression at week 48. Virologic breakthrough (HIV RNA>50 copies/mL on 2 consecutive measures) occurred in 7 patients (mean standard error [SE] time to breakthrough, 38.3 [4.8] weeks). Resuppression occurred with improved adherence in 2 participants and improved adherence plus addition of nucleosides in 2 others. LPV C min was <1 mg/L in 8 patients and was associated with virologic breakthrough in 2 cases but with no development of resistance. No clinically significant changes in CD4, lipids, or glucose were noted. Three participants developed transient≥5-fold liver enzyme elevations. None of 9 severe adverse events were LPV/r- or liver-related. Six discontinued participation for withdrawal of consent (n=1), poor adherence (n=3), or drug intolerance (n=2). CONCLUSIONS: Once-daily LPV/r monotherapy in HIV-HCV coinfected individuals offers a safe and effective approach to the management of the HIV infection, with a predictable pharmacokinetic profile.

Haplotype structure of CYP2B6 and association with plasma efavirenz concentrations in a Chilean HIV cohort.

OBJECTIVES: Efavirenz is extensively metabolized by CYP2B6, and associations between CYP2B6 polymorphisms and plasma efavirenz exposure have been reported. The objective of this study was to investigate CYP2B6 haplotype structure and functional consequences in a Latin American population. PATIENTS AND METHODS: Two hundred and nineteen patients were recruited at Fundación Arriarán, Chile, between September and December 2008. Plasma efavirenz concentrations were determined using liquid chromatography with mass spectrometry. Genotyping for 30 single nucleotide polymorphisms (SNPs) with a minor allele frequency of >0.05 in the HapMap CEU population at intervals of approximately 1 kb across the CYP2B6 locus was conducted using Sequenom iPLEX MALDI-TOF. RESULTS: Thirteen SNPs passed quality control and, of these, statistically significant associations (P < 0.001) with plasma efavirenz concentrations were observed for 11. Pairwise tagging SNP analysis (R(2) > 0.8) identified 3 SNPs (rs10403955, rs2279345 and rs8192719) representative of the 11 associated SNPs. A composite genetic model of these three alleles was constructed, and an association between carriers of four to six of these alleles and the risk of efavirenz plasma concentrations >4 microg/mL was identified with an odds ratio of 48.1 (95% confidence interval: 13.5-207.7). This represents a positive predictive value of 80.9% and a negative predictive value of 91.8%, with sensitivity of 57.9% and specificity of 97.2%. CONCLUSIONS: A composite genetic model of CYP2B6 SNPs in a Chilean HIV-positive cohort may have value in predicting concentrations of efavirenz associated with a higher likelihood of CNS toxicity. Further investigation of the functional basis of these associations is now required.

Atazanavir-associated choledocholithiasis leading to acute hepatitis in an HIV-infected adult.

OBJECTIVE: To report a case of atazanavir-associated choledocholithiasis in an HIV-infected individual. CASE SUMMARY: A 47-year-old treatment-naïve HIV-positive African female presented to the emergency department with a 3-day history of right epigastric pain. Six weeks prior to this episode, she began antiretroviral therapy with a regimen consisting of atazanavir 400 mg and abacavir/lamivudine 600/300 mg once daily. Alanine aminotransferase (766 U/L), aspartate aminotransferase (876 U/L), gamma-glutamyltransferase (588 U/L), alkaline phosphatase (348 U/L), and total bilirubin (3.9 mg/dL) levels were elevated. Abdominal ultrasound revealed obstructive choledocholithiasis as well as intra- and extrahepatic biliary dilatation. She underwent a laparoscopic cholecystectomy, which revealed approximately 50 small calculi present in the gallbladder. Since previous ultrasounds had also shown gallstones, an analysis of the extracted calculi was performed to determine the possible association with atazanavir use; low amounts of atazanavir were detected. DISCUSSION: Atazanavir is an inhibitor of the bilirubin-conjugating enzyme UGT1A1 and has been frequently linked to the occurrence of hyperbilirubinemia without complications. This individual experienced hyperbilirubinemia that peaked at hospital presentation after she developed choledocholithiasis and secondary acute hepatitis. Analysis of the extracted gallstones revealed that smaller stones contained a higher content of atazanavir than larger stones, which suggests that atazanavir precipitation may play a role in cholelithiasis, although the mechanism remains unknown. The low yield of atazanavir may be explained by the short, 6-week duration of drug exposure as well as the lack of assay for metabolites. The Naranjo probability scale implicated choledocholithiasis as a possible atazanavir-associated adverse event. This report provides the first published evidence that even short-term use of atazanavir may lead to hyperbilirubinemia with choledocholithiasis and secondary acute hepatitis in HIV-infected adults. CONCLUSIONS: Atazanavir should be considered a possible contributor in the development of cholelithiasis or choledocholithiasis, and people with HIV should receive adequate counseling in the recognition of symptoms associated with gallstones. The exact incidence and mechanism still need to be elucidated.

Interaction studies of tipranavir-ritonavir with clarithromycin, fluconazole, and rifabutin in healthy volunteers.

Three separate controlled, two-period studies with healthy volunteers assessed the pharmacokinetic interactions between tipranavir-ritonavir (TPV/r) in a 500/200-mg dose and 500 mg of clarithromycin (CLR), 100 mg of fluconazole (FCZ), or 150 mg of rifabutin (RFB). The CLR study was conducted with 24 subjects. The geometric mean ratios (GMR) and 90% confidence intervals (90% CI; given in parentheses) of the areas under the concentration-time curve (AUC), the maximum concentrations of the drugs in serum (C(max)), and the concentrations in serum at 12 h postdose (Cp12h) for multiple-dose TPV/r and multiple-dose CLR, indicating the effect of TPV/r on the CLR parameters, were 1.19 (1.04-1.37), 0.95 (0.83-1.09), and 1.68 (1.42-1.98), respectively. The formation of the metabolite 14-OH-CLR was decreased by 95% in the presence of TPV, and the TPV AUC increased 66% compared to that for human immunodeficiency virus (HIV)-negative historical controls. The FCZ study was conducted with 20 subjects. The GMR (and 90% CI) of the AUC, C(max), and Cp24h, indicating the effect of multiple-dose TPV/r on the multiple-dose FCZ parameters, were 0.92 (0.88-0.95), 0.94 (0.91-0.98), and 0.89 (0.85-0.92), respectively. The TPV AUC increased by 50% compared to that for HIV-negative historical controls. The RFB study was conducted with 24 subjects. The GMR (and 90% CI) of the AUC, C(max), and Cp12h for multiple-dose TPV/r and single-dose RFB, indicating the effect of TPV/r on the RFB parameters, were 2.90 (2.59-3.26), 1.70 (1.49-1.94), and 2.14 (1.90-2.41), respectively. The GMR (and 90% CI) of the AUC, C(max), and Cp12h of TPV/r and RFB with 25-O-desacetyl-RFB were 4.33 (3.86-4.86), 1.86 (1.63-2.12), and 2.76 (2.44-3.12), respectively. Coadministration of TPV with a single dose of RFB resulted in a 16% increase in the TPV Cp12h compared to that for TPV alone. In the general population, no dose adjustments are necessary for the combination of TPV/r and CLR or FCZ. Combining TPV/r with RFB should be done with caution, while toxicity and RFB drug levels should be monitored. Study medications were generally well-tolerated in these studies.

Pharmacokinetics and tolerability of once- versus twice-daily lopinavir/ritonavir treatment in HIV-1-infected children.

BACKGROUND: Once-daily lopinavir/ritonavir (LPV/r) is not approved for treatment of HIV paediatric patients. Once daily treatment in children might serve the same goals of patient comfort and adherence as in adults. METHODS: HIV type-1-infected children aged 6 months to 18 years, who were virologically suppressed on an LPV/r-containing regimen, were eligible. Treatment 1 consisted of once-daily LPV/r 460/115 mg/m(2), plus two nucleoside reverse transcriptase inhibitors (NRTIs). Treatment 2 consisted of twice-daily LPV/r 230/57.5 mg/m(2) plus two NRTIs. Patients were randomized either to start with treatment 1 followed by treatment 2 or vice versa. Full pharmacokinetic profiles were analysed for lopinavir and ritonavir with a validated HPLC tandem mass spectrometry assay. RESULTS: Seven patients (five girls and two boys) were included in the study. Median age was 9.8 years (range 5.8-15.5). For the once-daily treatment, the median (range) lopinavir 24 h area under the plasma -concentration-time curve (AUC(24 h)), maximum plasma concentration (C(max)) and 24 h plasma concentration (C(24 h)) were 214.6 h*mg/l (114.2-289.2), 13.5 mg/l (8.3-17.5) and 3.4 mg/l (0.6-7.4), respectively. For the twice-daily treatment the median (range) lopinavir 12 h area under the plasma concentration-time curve (AUC(12 h)), C(max) and 12 h plasma concentration (C(12 h)) were 80.9 h*mg/l (23.3-135.9), 9.8 mg/l (3.4-15.2) and 5.7 mg/l (1.7-9.7), respectively. CONCLUSIONS: This study suggests that the pharmacokinetics of lopinavir after twice-daily and once-daily dosing are similar, with no observable difference in tolerability, in this group of patients between 5 and 15 years old.

Pharmacokinetics and Safety of Darunavir/Ritonavir in HIV-Infected Pregnant Women.

The dosage of darunavir/ritonavir is 800/100 mg once daily for treatment-naive patients or treatment-experienced patients with no prior darunavir resistance associated mutations, and 600/100 mg twice daily for treatment-experienced patients with one or more darunavir resistance associated mutations. Results from the five available pharmacokinetic studies show reductions in total darunavir plasma concentrations of between 20-50% during the third trimester of pregnancy. The unbound darunavir concentrations have been measured only in subsets of patients in two of the five pharmacokinetic studies. The unbound concentrations were 11% higher during pregnancy in one study of the 600/100 mg twice-daily dosage, and 13-38% lower during pregnancy for the 800/100 mg once-daily dosage. Ratios of darunavir concentration in cord blood compared to maternal plasma are in the range of 0.11-0.18, suggesting that darunavir does not have high trans-placental penetration. Despite the decrease in exposure, the darunavir/ritonavir 800/100 mg once-daily regimen in HIV-positive pregnant women in combination with background antiretroviral therapy has been effective in preventing mother-to-child transmission in the studies included in this review. Among the 137 infants born across the five studies, there was one case of mother-to-child transmission, which was in a mother taking the 600/100 mg twice-daily dose but who had documented poor adherence to treatment.

Pharmacokinetics of once-daily lopinavir/ritonavir and the influence of dose modifications.

We studied the pharmacokinetics of lopinavir/ritonavir dosed at 800/200 mg a day in 20 HIV-1-infected patients, and evaluated the effect of dose modifications in the case of trough concentration (Ctrough) levels less than 1.0 mg/l. Ctrough levels after the daily administration of lopinavir/ritonavir were lower than with twice daily administration. Dose modifications in four patients with Ctrough levels less than 1.0 mg/l succeeded in only one patient. Therapeutic drug monitoring can identify patients with lower-than-expected lopinavir exposure in a larger study.

Reporting Guidelines for Clinical Pharmacokinetic Studies: The ClinPK Statement.

BACKGROUND AND OBJECTIVE: Transparent reporting of all research is essential for assessing the validity of any study. Reporting guidelines are available and endorsed for many types of research but are lacking for clinical pharmacokinetic studies. Such tools promote the consistent reporting of a minimal set of information for end users, and facilitate knowledge translation of research. The objective of this study was to create a guideline to assist in the transparent and complete reporting of clinical pharmacokinetic studies. METHODS: Preliminary content to be considered was identified from a systematic search of the literature and regulatory documents. Stakeholders were identified to participate in a modified Delphi exercise and a virtual meeting to generate consensus for items considered essential in the reporting of clinical pharmacokinetic studies. The proposed checklist was pilot tested on 100 recently published clinical pharmacokinetic studies. Overall and itemized compliance with the proposed guidance was determined for each study. RESULTS: Sixty-eight stakeholders from nine countries consented to participate. Four rounds of a modified Delphi survey and a series of small virtual meetings were required to generate consensus for a 24-item checklist considered to be essential to the reporting of clinical pharmacokinetic studies. When applied to the 100 most recently published clinical pharmacokinetic studies, 45 were determined to be compliant with at least 80 % of the checklist items. Explanatory text was prepared using examples of compliant reporting from these and other relevant studies. CONCLUSIONS: The reader's ability to judge the validity of pharmacokinetic research can be greatly compromised by the incomplete reporting of study information. Using consensus methods, we have developed a tool to guide transparent and accurate reporting of clinical pharmacokinetic studies. Endorsement and implementation of these guidelines by researchers, clinicians and journals would promote more consistent reporting of these studies and allow for better assessment of utility for clinical applications.

Lopinavir/ritonavir plus saquinavir in salvage therapy; pharmacokinetics, tolerability and efficacy.

Patients receiving a lopinavir/ritonavir and saquinavir dual protease inhibitor-based antiretroviral salvage regimen were studied to evaluate the pharmacokinetics, tolerability and efficacy of the regimen. Pharmacokinetic curves were obtained for lopinavir and saquinavir. Patient records were studied for adverse events and efficacy data. The pharmacokinetics of lopinavir and saquinavir were comparable with literature data, except for the saquinavir 0-12 h area under the curve and maximum concentration. The tolerability of the regimen was good and efficacy was encouraging.

Comparison of two reduced-dose regimens of indinavir (600 mg vs 400 mg twice daily) and ritonavir (100 mg twice daily) in healthy volunteers (COREDIR).

OBJECTIVE: To assess the pharmacokinetics and tolerability of reduced dosages of twice daily indinavir (IDV) boosted by low-dose ritonavir (RTV) in healthy volunteers. METHODS: Pharmacokinetics and tolerability of IDV/RTV twice daily (600/100 mg and 400/100 mg) were assessed in a randomized crossover design in 16 healthy volunteers. Each dosage was taken twice daily for 2 weeks before 12 h pharmacokinetics were obtained. RESULTS: Sixteen subjects were included, with a mean age +/- SD of 30 +/- 4 years; seven female, nine male. Fifteen subjects completed the study. After dose reduction of IDV AUC, Cmax and Cmin decreased significantly. In the 400 mg group three out of 15 subjects had IDV levels below 0.10 mg/l vs none in the 600 mg group. All subjects reported mild to moderate side effects throughout the study period, which were more severe in the 600 mg group (mostly renal, dry skin/lips, paresthesias/oral discomfort). In the 600 mg group four subjects reported dysuria and one subject discontinued because of flank pain, whereas two subjects reported dysuria and no subject discontinued in the 400 mg group, respectively. Eight subjects developed crystalluria without a significant difference between both groups. No significant change in serum creatinine was observed. CONCLUSIONS: IDV/RTV 400/100 mg twice daily resulted in significant lower IDV exposure, with three out of 15 subjects revealing Cmin values below the recommended threshold for wild-type virus of 0.10 mg/l. Tolerability, however, was lower in the 600 mg IDV group. Therapeutic drug monitoring in the individual patient appears to be necessary to guarantee appropriate drug levels and simultaneously minimize toxicity.

Amiodarone and concurrent antiretroviral therapy: a case report and review of the literature.

Therapy for HIV often can make pharmacologic management of comorbidities challenging since many antiretroviral agents significantly modulate drug metabolism pathways. Amiodarone is commonly used to control cardiac arrhythmias; however, it is recognized as having a narrow therapeutic window with potential for significant drug toxicity. Amiodarone is metabolized by CYP3A4, CYP2C8 and CYP1A1 to an active metabolite and therefore may be affected by comedications that modulate these isoenzymes. Since amiodarone is frequently associated with toxicity, the Heart Rhythm Society (formerly the North American Society of Pacing and Electrophysiology) developed guidelines to minimize the potential for adverse events. However, recommendations for the management of situations where amiodarone must be given with a drug that significantly affects its metabolism are lacking. This paper will discuss our experience with a case of concurrent amiodarone and antiretroviral therapy, as well as provide a review of interactions that may lead to toxicity or potential treatment failure with amiodarone. Primary literature was identified through Medline (1946 to May 2013) and Embase (1980 to May 2013), using the following terms: amiodarone, antiretroviral, HIV, cytochrome P450 and drug interaction. Case reports, studies of xenobiotic interactions with amiodarone in healthy volunteers, and in vitro studies that investigated metabolic pathways of amiodarone were reviewed. Although clinical data was limited, several cases support the finding that potent inhibitors or inducers of cytochrome P450 may lead to amiodarone toxicity or lack of therapeutic effect, respectively. As well, several case reports, in vitro data and clinical investigations have associated some of the antiretrovirals with QT prolongation, which may result in additive cardiotoxicity in patients also receiving amiodarone. Therefore, to manage situations where amiodarone must be used with concurrent interacting antiretrovirals, we recommend a monitoring plan that follows the Heart Rhythm Society guidelines, however with the addition of serial therapeutic drug level monitoring and frequent electrocardiography to minimize potential toxicity and successfully manage both conditions.

Pharmacokinetics of raltegravir in the semen of HIV-infected men.

BACKGROUND: We sought to determine the pharmacokinetic disposition of raltegravir in the blood and seminal plasma of HIV-infected men. METHODS: We conducted a pharmacokinetic study using a staggered sampling approach. A total of 16 HIV-infected men receiving raltegravir-based therapy were recruited into the study. Each participant provided six blood plasma and six seminal plasma samples for quantification of drug concentrations in both compartments. Blood and semen samples were obtained within 1 h of each other and were collected prior to the morning dose and at 1, 2, 4, 8 and 12 h post-ingestion. Drug concentrations were determined by liquid chromatography tandem mass spectrometry. RESULTS: A total of 96 semen samples and 96 blood samples were obtained from all participants during the study period. The median age and baseline CD4(+) T-cell count of the study participants were 48 years (IQR 42-53) and 450 cells/mm(3) (IQR 289-585). Virological suppression to <50 copies/ml had been maintained for a median of 21 months (IQR 7-35) at the time of study enrolment. The median seminal plasma-to-blood plasma ratios and AUC0-12 h seminal plasma-to-blood plasma ratios of raltegravir were 3.25 (IQR 1.46-5.37) and 2.26 (IQR 1.05-4.45), respectively. CONCLUSIONS: Concentrations of raltegravir in seminal plasma are several fold higher than those attained in blood plasma and those required to inhibit viral replication in this compartment. Further research examining the therapeutic and prophylactic implications of these findings is warranted.

Effect of resveratrol on exercise capacity: a randomized placebo-controlled crossover pilot study.

To assess the effect on exercise capacity and tolerability of resveratrol, 13 healthy, sedentary adult volunteers were enrolled in a randomized crossover study comparing resveratrol and placebo over two 4-week periods, with a 2-week time between periods when subjects received no treatment. No significant changes in exercise duration or aerobic capacity (peak oxygen uptake) were observed. Gastrointestinal side effects were more common during resveratrol treatment (77% vs. 15%, p = 0.0048). A small reduction in fasting glucose and small but statistically significant increases in liver enzymes, total cholesterol, and triglycerides were observed, although mean results remained within normal limits. There was no change in complete blood count, inflammatory markers, renal function, or other measures of liver function.