Alternative Magnesium Sulfate Dosing Regimens for Women With Preeclampsia: A Population Pharmacokinetic Exposure-Response Modeling and Simulation Study

Magnesium sulfate is the anticonvulsant of choice for eclampsia prophylaxis and treatment; however, the recommended dosing regimens are costly and cumbersome and can be administered only by skilled health professionals. The objectives of this study were to develop a robust exposure-response model for the relationship between serum magnesium exposure and eclampsia using data from large studies of women with preeclampsia who received magnesium sulfate, and to predict eclampsia probabilities for standard and alternative (shorter treatment duration and/or fewer intramuscular injections) regimens. Exposure-response modeling and simulation were applied to existing data. A total of 10 280 women with preeclampsia who received magnesium sulfate or placebo were evaluated. An existing population pharmacokinetic model was used to estimate individual serum magnesium exposure. Logistic regression was applied to quantify the serum magnesium area under the curve-eclampsia rate relationship. Our exposure-response model-estimated eclampsia rates were comparable to observed rates. Several alternative regimens predicted magnesium peak concentration < 3.5 mmol/L (empiric safety threshold) and eclampsia rate ≤ 0.7% (observed response threshold), including 4 g intravenously plus 10 g intramuscularly followed by either 8 g intramuscularly every 6 hours × 3 doses or 10 g intramuscularly every 8 hours × 2 doses and 10 g intramuscularly every 8 hours × 3 doses. Several alternative magnesium sulfate regimens with comparable model-predicted efficacy and safety were identified that merit evaluation in confirmatory clinical trials

Safety, Tolerability, and Efficacy of Raltegravir in a Diverse Cohort of HIV-Infected Patients: 48-Week Results from the REALMRK Study

The racial diversity and gender distribution of HIV-infected patients make it essential to confirm the safety and efficacy of raltegravir in these populations. A multicenter, open-label, single-arm observational study was conducted in a diverse cohort of HIV-infected patients (goals: ≥25% women; ≥50% blacks in the United States), enrolling treatment-experienced patients failing or intolerant to current antiretroviral therapy (ART) and treatment-naive patients (limited to ≤20%). All patients received raltegravir 400 mg b.i.d. in a combination antiretroviral regimen for up to 48 weeks. A total of 206 patients received study treatment at 34 sites in the United States, Brazil, Dominican Republic, Jamaica, and South Africa: 97 (47%) were female and 153 (74%) were black [116 (56%) in the United States]. Of these, 185 patients were treatment experienced: 97 (47%) were failing and 88 (43%) were intolerant to current therapy; 21 patients (10%) were treatment naive. Among treatment-intolerant patients, 55 (63%) had HIV-1 RNA<50 copies/ml at baseline. Overall, 15% of patients discontinued: 13% of men, 18% of women, 14% of blacks, and 17% of nonblacks. At week 48, HIV RNA was <50 copies/ml in 60/94 (64%) patients failing prior therapy, 61/80 (76%) patients intolerant to prior therapy, and 16/21 (76%) treatment-naive patients. Response rates were similar for men vs. women and black vs. nonblack patients. Drug-related clinical adverse events were reported by 8% of men, 18% of women, 14% of blacks, and 9% of nonblacks. After 48 weeks of treatment in a diverse cohort of HIV-infected patients, raltegravir was generally safe and well tolerated with potent efficacy regardless of gender or race

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Effect of Tipranavir-Ritonavir on Pharmacokinetics of Raltegravir▿

Raltegravir (RAL) is a novel and potent human immunodeficiency virus type 1 integrase inhibitor that is predominantly metabolized via glucuronidation. The protease inhibitor combination tipranavir (TPV) at 500 mg and ritonavir (RTV) at 200 mg (TPV-RTV) has inhibitory and inductive effects on metabolic enzymes, which includes the potential to induce glucuronosyltransferase. Because RAL may be coadministered with TPV-RTV, there is the potential for the induction of RAL metabolism. Consequently, we assessed the effect of TPV-RTV on the pharmacokinetics of RAL and the safety and tolerability of this combination. Eighteen healthy adults were enrolled in this open-label study. The participants received RAL at 400 mg twice daily for 4 days (period 1) and TPV-RTV twice daily for 7 days (period 2), followed immediately by 400 mg RAL with TPV-RTV twice daily for 4 days (period 3). Under steady-state conditions, the RAL concentration at 12 h (C12) was decreased when RAL was administered with TPV-RTV (geometric mean ratio [GMR], 0.45; 90% confidence interval [CI] 0.31, 0.66; P = 0.0021); however, the area under the concentration-time curve from time zero to 12 h (GMR, 0.76; 90% CI, 0.49, 1.19; P = 0.2997) and the maximum concentration in serum (GMR, 0.82; 90% CI, 0.46, 1.46; P = 0.5506) were not substantially affected. There were no serious adverse experiences or discontinuations due to study drug-related adverse experiences, and RAL coadministered with TPV-RTV was generally well tolerated. Although the RAL C12 was decreased with TPV-RTV in this study, favorable efficacy data collected in phase III studies substantiate that TPV-RTV may be coadministered with RAL without dose adjustment

Minimal Pharmacokinetic Interaction between the Human Immunodeficiency Virus Nonnucleoside Reverse Transcriptase Inhibitor Etravirine and the Integrase Inhibitor Raltegravir in Healthy Subjects▿

Etravirine, a next-generation nonnucleoside reverse transcriptase inhibitor, and raltegravir, an integrase strand transfer inhibitor, have separately demonstrated potent activity in treatment-experienced, human immunodeficiency virus (HIV)-infected patients. An open-label, sequential, three-period study with healthy, HIV-seronegative subjects was conducted to assess the two-way interaction between etravirine and raltegravir for potential coadministration to HIV-infected patients. In period 1, 19 subjects were administered 400 mg raltegravir every 12 h (q12 h) for 4 days, followed by a 4-day washout; in period 2, subjects were administered 200 mg etravirine q12 h for 8 days; and in period 3, subjects were coadministered 400 mg raltegravir and 200 mg etravirine q12 h for 4 days. There was no washout between periods 2 and 3. Doses were administered with a moderate-fat meal. Etravirine had only modest effects on the pharmacokinetics of raltegravir, while raltegravir had no clinically meaningful effect on the pharmacokinetics of etravirine. For raltegravir coadministered with etravirine relative to raltegravir alone, the geometric mean ratio (GMR) and 90% confidence interval (CI) were 0.90 and 0.68 to 1.18, respectively, for the area under the concentration curve from 0 to 12 h (AUC0-12), 0.89 and 0.68 to 1.15, respectively, for the maximum concentration of drug in serum (Cmax), and 0.66 and 0.34 to 1.26, respectively, for the trough drug concentration (C12); the GMR (90% CI) for etravirine coadministered with raltegravir relative to etravirine alone was 1.10 (1.03, 1.16) for AUC0-12, 1.04 (0.97, 1.12) for Cmax, and 1.17 (1.10, 1.26) for C12. All drug-related adverse clinical experiences were mild and generally transient in nature. No grade 3 or 4 adverse experiences or discontinuations due to adverse experiences occurred. Coadministration of etravirine and raltegravir was generally well tolerated; the data suggest that no dose adjustment for either drug is necessary

Lack of a Significant Drug Interaction between Raltegravir and Tenofovir▿

Raltegravir is a novel human immunodeficiency virus type 1 (HIV-1) integrase inhibitor with potent in vitro activity (95% inhibitory concentration of 31 nM in 50% human serum). This article reports the results of an open-label, sequential, three-period study of healthy subjects. Period 1 involved raltegravir at 400 mg twice daily for 4 days, period 2 involved tenofovir disoproxil fumarate (TDF) at 300 mg once daily for 7 days, and period 3 involved raltegravir at 400 mg twice daily plus TDF at 300 mg once daily for 4 days. Pharmacokinetic profiles were also determined in HIV-1-infected patients dosed with raltegravir monotherapy versus raltegravir in combination with TDF and lamivudine. There was no clinically significant effect of TDF on raltegravir. The raltegravir area under the concentration time curve from 0 to 12 h (AUC0-12) and peak plasma drug concentration (Cmax) were modestly increased in healthy subjects (geometric mean ratios [GMRs], 1.49 and 1.64, respectively). There was no substantial effect of TDF on raltegravir concentration at 12 h postdose (C12) in healthy subjects (GMR [TDF plus raltegravir-raltegravir alone], 1.03; 90% confidence interval [CI], 0.73 to 1.45), while a modest increase (GMR, 1.42; 90% CI, 0.89 to 2.28) was seen in HIV-1-infected patients. Raltegravir had no substantial effect on tenofovir pharmacokinetics: C24, AUC, and Cmax GMRs were 0.87, 0.90, and 0.77, respectively. Coadministration of raltegravir and TDF does not change the pharmacokinetics of either drug to a clinically meaningful degree. Raltegravir and TDF may be coadministered without dose adjustments

Lack of a Clinically Important Effect of Moderate Hepatic Insufficiency and Severe Renal Insufficiency on Raltegravir Pharmacokinetics▿ †

Raltegravir is a human immunodeficiency virus type 1 integrase strand transfer inhibitor with potent activity in vitro and in vivo. Raltegravir is primarily cleared by hepatic metabolism via glucuronidation (via UDP glucuronosyltransferase 1A1), with a minor component of elimination occurring via the renal pathway. Since the potential exists for raltegravir to be administered to patients with hepatic or renal insufficiency, two studies were conducted to evaluate the influence of moderate hepatic insufficiency (assessed by using the Child-Pugh criteria) and severe renal insufficiency (creatinine clearance, <30 ml/min/1.73 m2) on the pharmacokinetics of raltegravir. Study I evaluated the pharmacokinetics of 400 mg raltegravir in eight patients with moderate hepatic insufficiency and eight healthy, matched control subjects. Study II evaluated the pharmacokinetics of 400 mg raltegravir in 10 patients with severe renal insufficiency and 10 healthy, matched control subjects. All participants received a single 400-mg dose of raltegravir in the fasted state. In study I, the geometric mean ratios (GMR; mean value for the group with moderate hepatic insufficiency/mean value for the healthy controls) and 90% confidence intervals (CIs) for the area under the concentration-time curve from time zero to infinity (AUC0-∞), the maximum concentration of drug in plasma (Cmax), and the concentration at 12 h (C12) were 0.86 (90% CI, 0.41, 1.77), 0.63 (90% CI, 0.23, 1.70), and 1.26 (90% CI, 0.65, 2.43), respectively. In study II, the GMRs (mean value for the group with renal insufficiency/mean value for the healthy controls) and 90% CIs for AUC0-∞, Cmax, and C12 were 0.85 (90% CI, 0.49, 1.49), 0.68 (90% CI, 0.35, 1.32), and 1.28 (90% CI, 0.79, 2.06), respectively. Raltegravir was generally well tolerated by patients with moderate hepatic or severe renal insufficiency, and there was no clinically important effect of moderate hepatic or severe renal insufficiency on the pharmacokinetics of raltegravir. No adjustment in the dose of raltegravir is required for patients with mild or moderate hepatic or renal insufficiency