Population pharmacokinetics and dosing regimen optimisation of lopinavir in Chinese adults infected with HIV

Lopinavir (LPV) is a protease inhibitor (PI) for the treatment of human immunodeficiency virus (HIV) infections. Current studies on LPV are mainly focused on Caucasians, and none have investigated the population pharmacokinetics (PPK) of LPV in Chinese population. The present study aimed to develop a PPK model for oral LPV in Chinese adults who are HIV‐infected. A total of 460 LPV concentrations from 174 Chinese patients who received LPV/ritonavir (LPV/r) 400/100 mg orally every 12 hours (q12h) were analysed using the non‐linear mixed‐effects modelling approach. Simulations of the LPV concentration profile were performed with different dosing regimens. A one‐compartment model with first‐order absorption and elimination process described the data. The estimated apparent clearance (CL/F) and volume of distribution (V/F) (% relative standard error [RSE]) for oral LPV were 5.9 L/h (3%) and 117 L (8%), respectively. Body‐weight was identified as a covariate on CL/F. In patients who weighed between 45 and 115 kg and received the standard 400/100 mg q12h regimen, the probability of achieving target trough concentration (C_trough) of 1 mg/L was >98% for PI‐naïve patients and the probability of achieving target C_trough of 4 mg/L was <80% for PI‐pretreated patients. This is the first population pharmacokinetic study to characterise the PK of LPV in Chinese patients with HIV infection. There were no obvious ethnic differences in the PK of LPV between the Chinese population and Caucasian population. The simulations demonstrated that the standard dosing regimen of 400/100 mg q12h (LPV/r tablets) appears to be sufficient for PI‐naïve patients but suboptimal for PI‐pretreated patients. Therefore, the regimen of 800/200 mg q12h was recommended for PI‐pretreated patients. Further investigation of dosage recommendation could be helpful in optimising LPV therapy for HIV infections.     

Characterization of resistant HIV variants generated by in vitro passage with lopinavir/ritonavir

Lopinavir (LPV, formerly ABT-378) is an HIV protease inhibitor (PI) that is co-administered with a small amount of ritonavir (RTV), which greatly increases and sustains the plasma levels of LPV. Lopinavir/ritonavir (LPV/r) has shown potent antiviral activity in both therapy-nai;ve and PI-experienced patients. To assess the effect of pharmacologically relevant ratios of LPV/RTV (LPV/r) on the emergence of resistant HIV in vitro, HIV-1 pNL4-3 was passaged in the presence of increasing concentrations of LPV alone and LPV/r. Passages with fixed 5/1 and 15/1 concentration ratios of LPV/r initially selected I84V and I50V/M46I mutants, respectively. Selection with LPV alone also generated the same initial mutants (I50V/M46I) as the 15/1 LPV/r passage. Further passage produced other mutations previously found to be associated with PI-resistance. Phenotypic susceptibility to both LPV and RTV decreased with successive passages, irrespective of whether RTV was present in the selection experiment. Furthermore, in the two selection experiments that included RTV (at either 5/1 or 15/1 LPV/r ratio), the IC(50) of RTV at each passage evaluated was at least five-fold higher than the concentration of RTV employed at that passage, while the IC(50) of LPV toward the passaged virus was similar to the concentration of LPV used at that passage, indicating that the selective pressure was attributable to LPV and not RTV.     

Anti-HIV drugs,lopinavir/ritonavir and atazanavir,modulate innate immune response triggered by Leishmania in macrophages: The role of NF-κB and PPAR-γ

This study evaluated the influence of HIV protease inhibitors lopinavir/ritonavir (LPV/RTV) and atazanavir (ATV) on macrophage functions during their first interaction with Leishmania. Macrophages from BALB/c mice treated for 10 days with LPV/RTV and ATV, infected or not in vitro with L. (L.) amazonensis, were used to investigate the effects of these drugs on infection index, leishmanicidal capacity, cytokine production and PPAR-γ and RelB expression. LPV/RTV and ATV treatments significantly increased the infection index and the percentage of Leishmania-infected macrophages compared to untreated infected macrophages. There was no correlated increase in the production of NO and H₂O₂ leishmanicidal molecules. Promastigotes derived from Leishmania-infected macrophages from LPV/RTV and ATV-treated BALB/c mice had an in vitro growth 45.1% and 56.4% higher in groups treated with LPV/RTV and ATV than with PBS in culture. ATV treatment reduced IL-12p70 and IL-10 secretion in Leishmania-infected macrophages, but had no effect on IL-23 and TNF production. LPV reduced IL-10 and had no effect on IL-12p70, TNF and IL-23 secretion. ATV treatment decreased PPAR-γ expression in Leishmania-infected macrophages compared to untreated infected macrophages. In addition, LPV/RTV, but not ATV, reduced RelB cytoplasm-to-nucleus translocation in Leishmania-infected macrophages. Results showed that LPV/RTV and ATV HIV protease inhibitors were able to modulate innate defense mechanisms against Leishmania via different intracellular pathways. Although HIV protease inhibitors are highly efficient to control the Human Immunodeficiency Virus, these drugs might also influence the course of leishmaniasis in HIV-Leishmania-co-infected individuals.     

Simplification of therapeutic drug monitoring for twice-daily regimens of lopinavir/ritonavir for HIV infection

Cost and inconvenience limit the application of full 12-hour pharmacokinetic (PK) analysis for routine therapeutic drug monitoring of antiretroviral medications. We explore whether lopinavir (LPV) and ritonavir (RTV) exposures can be estimated with limited sampling for patients taking twice-daily LPV/RTV. One hundred and one PK profiles from 81 patients, most receiving salvage therapies including twice-daily LPV/RTV, were obtained for the analysis. After a minimum of 2 weeks on a stable regimen, blood was drawn immediately before and at 1, 2, 4, 6, 8, 10, and 12 hours after a timed medication dose. Plasma drug concentrations were determined by a validated HPLC-MS-MS assay. Peak concentrations, evening troughs, and AUC0-12 h were entered into linear and log10-log10 linear regression models to determine the best correlation with LPV and RTV plasma concentrations using a maximum of 2 time points. The accuracy and precision of PK parameter estimates of the resultant models were tested on data collected for an additional 25 patients. Twelve models using various combinations of 2 timed LPV concentrations afforded accurate (maximum % bias = -6.45) and precise (relative standard deviation < 15%) estimates for the LPV peak concentration or AUC0-12h. Four sets of 2 concentrations provided simultaneous estimates of both PK parameters, with the best estimates derived from data collected at 2 and 6 hours postdose. Evening trough concentrations were the best estimators of the daily nadir; however, no adequate substitute for collecting blood 12 hours postdose emerged from this analysis.     

Comparative Bioavailability of Two Formulations of Biopharmaceutical Classification System (BCS) Class IV Drugs: A Case Study of Lopinavir/Ritonavir

BackgroundLopinavir/ritonavir (LPV/r-A, Kaletra®), a fixed dose, co-formulated antiviral therapy for the treatment of HIV infection has been used worldwide for over two decades. Both active substances have low solubility in water and low membrane permeability. LPV/r-A tablets contain key excipients critical to ensuring acceptable bioavailability of lopinavir and ritonavir in humans. An established dog pharmacokinetic model demonstrated several generic LPV/r tablet formulations have significant oral bioavailability variability compared to LPV/r-A.MethodsAnalytical characterizations of LPV/r-B tablets were performed and a clinical study was conducted to assess the relative bioavailability of Kalidavir® (LPV/r-B) 400/100 mg tablets relative to Kaletra® (LPV/r-A) 400/100 mg tablets under fasting conditions.ResultsThe presence of active substances were confirmed in LPV/r-B tablets in an apparent amorphous state at essentially the labeled amounts, and dissolution profiles were generally similar to LPV/r-A tablets. Excipients in the tablet formulation were found to be variable and deviate from the labeled composition. Lopinavir and ritonavir exposures (AUC) following LPV/r-B administration were approximately 90% and 20% lower compared to that of LPV/r-A.ConclusionsLPV/r-B was not shown to be bioequivalent to LPV/r-A.     

Lopinavir/ritonavir (ABT-378/r)

Despite major advances in HIV research, eradication of HIV from the body is not yet possible. However, current antiretroviral (ARV) therapy can achieve disease control via viral suppression below the limits of detection of currently available assays. This has led to a marked decline in morbidity and mortality associated with the development of opportunistic infections and malignancies. Since viral suppression appears to be the most achievable goal of current therapy, there arises a need for new and more potent ARV agents in order to maintain viral suppression. Many of the currently available protease inhibitors (PIs) have a high protein-binding ability, short plasma half-life [1] and pharmacokinetic interactions with food or other drugs [2]. This can result in sub-optimal plasma drug concentrations, which may allow the virus to break through and replicate, leading to the development of resistant mutants [1]. Lopinavir/ritonavir (LPV/r; Kaletra^®, Abbott Laboratories) is a new PI consisting of a co-formulation of lopinavir and low-dose ritonavir. The sub-therapeutic dose of ritonavir (a potent cytochrome P450 [CYP] 3A4 inhibitor) inhibits the metabolism of lopinavir, resulting in higher lopinavir concentrations than when lopinavir is administered alone [3]. This pharmacokinetic interaction is associated with a high lopinavir trough level:wild type median effective concentration (EC₅₀) ratio and good general tolerability when compared with other currently licensed PIs [4]. The concept of pharmacokinetic enhancement – boosting – is not new as ritonavir has previously been utilised in this context with other PIs. The relationship between plasma and intracellular drug levels has yet to be clarified. What has been ascertained from pharmacokinetic studies thus far is the correlation between ARV trough plasma concentrations (C_min) and virological outcome [5,6]. LPV/r exemplifies how the pharmacokinetic profile of a drug can be modified to attain sufficient C_min to suppress pheno- and genotypically resistant viral strains, as well as provide a pharmacological barrier to the emergence of resistance [7]. LPV/r reduces pill-burden and aids compliance, as shown by encouraging results in the treatment of both ARV-naive and -experienced patients.     

Lopinavir/ritonavir pharmacokinetics in HIV/HCV-coinfected patients with or without cirrhosis

Liver disease may alter the pharmacokinetics of antiretrovirals and produce changes in plasma protein binding. The aim was to evaluate the pharmacokinetics of total and unbound lopinavir (LPV) in HIV-infected patients with and without hepatitis C virus (HCV) coinfection. Fifty-six HIV+ patients receiving lopinavir/ritonavir (LPV/r) (group I = 24 controls; II = 23 HIV/HCV-coinfected; III = 9 cirrhotic HIV/HCV-coinfected) were included.Total (n = 56) and unbound (n = 36) LPV pharmacokinetic parameters were determined at steady-state using validated high-performance liquid chromatography with ultraviolet detection and high-performance liquid chromatography-tandem mass spectrometry methods, respectively. Pharmacokinetic parameters (plasma concentration just before drug administration, peak concentrations in plasma, times to maximum plasma concentration, areas under the plasma concentration-time curve from 0 to 12 hours, and CL/F/kg) of both total and unbound LPV were calculated by standard noncompartmental methods and differences among groups evaluated (Kruskal-Wallis test).LPV apparent oral clearance normalized to body weight (median, interquartile range) was 55 (40-68), 59 (44-69), and 71 (53-78) mL/h/kg for groups I, II, and III, respectively (II vs. I, P = 0.52; III vs. I, P = 0.16). The areas under the plasma concentration-time curve from 0 to 12 hours were 110.4 (80.9-135.2), 103.4 (85.5-131.3), and 92.8 (87.4-116.3) microg h/mL for groups I, II, and III, respectively (II vs. I, P = 0.68; III vs. I, P = 0.71).Chronic liver impairment produced a slight, although not significant, decrease in plasma protein binding. The free-fraction of LPV increased ( approximately 21%) from 0.97% (0.80-1.06) in HIV+/HCV- patients to 1.18% (0.89-1.65) in HIV/HCV+ cirrhotic patients. The apparent oral clearance of unbound LPV (CLu/F/kg) in cirrhotic patients did not change significantly, supporting the concept that the clearance of unbound LPV in liver disease is not affected after being inhibited by low-dose ritonavir co-administration.LPV total and unbound pharmacokinetics were not affected by hepatic impairment, suggesting that no adjustment of LPV/r dose is required for HIV/HCV-coinfected patients with and without cirrhosis and moderate impairment of liver function.     

Evaluation of super-boosted lopinavir/ritonavir in combination with rifampicin in HIV-1-infected patients with tuberculosis

Rifampicin induces the metabolism of many drugs. To overcome the reduction in serum concentrations of lopinavir/ritonavir (LPV/r) when used in combination with rifampicin, 800/200 mg or 400/400 mg doses are used. This study evaluated super-boosted LPV/r (400/400 mg) in HIV/TB co-infected patients for adequate concentrations as well as short-term safety, tolerability and clinical response to therapy. This was an open-label, non-randomised pharmacokinetic (PK) study in HIV/TB patients. The primary objective was to determine the PK profile of super-boosted LPV/r when given with a rifampicin-based TB regimen. Secondary objectives were short-term safety, tolerability and clinical response. Primary endpoints were a lopinavir trough concentration (C_min) >1.0 µg/mL and a rifampicin maximum concentration (C_max) of 8–24 µg/mL. Secondary PK endpoints were a rifampicin area under the concentration–time curve from 0–24 h (AUC_0–24) of 44–70 µg·h/mL, a lopinavir C_max of 6–14 µg/mL and a lopinavir AUC_0–12 of 56–130 µg·h/mL. Eleven patients (10 male, age 25–43 years) were enrolled. Two patients were discontinued due to non-compliance. A lopinavir C_min of >1.0 µg/mL was achieved in a least one of the PK samplings in all nine subjects who completed treatment. All patients met lopinavir C_max and AUC_0–12 targets. Five patients achieved the primary endpoint of rifampicin C_max (≥8 µg/mL) in at least one of the PK samplings, and five achieved the minimum rifampicin AUC_0–24 (≥44 µg·h/mL). One grade 3 adverse event was reported. Super-boosted LPV/r was safe and effective in HIV/TB patients. [ClinicalTrials.gov ID NCT01700790.]     

CYP3A4-mediated lopinavir bioactivation and its inhibition by ritonavir

The combination of lopinavir (LPV) and ritonavir (RTV) is one of the preferred regimens for the treatment of HIV infection with confirmed efficacy and relatively low toxicity. LPV alone suffers the poor bioavailability due to its rapid and extensive metabolism. RTV boosts the plasma concentration of LPV by suppressing its metabolism and thus increasing LPV efficacy. In the current study, we found that RTV also inhibits LPV bioactivation. LPV bioactivation was investigated in human liver microsomes and cDNA-expressed human cytochromes P450. Twelve GSH-trapped reactive metabolites of LPV were identified by using a metabolomic approach. Semicarbazide-trapped reactive metabolites of LPV were also detected. RTV effectively suppressed all pathways of LPV bioactivation via CYP3A4 inhibition. Our data together with previous reports suggest that LPV plus RTV is an ideal combination because RTV not only boosts LPV plasma concentration, but it decreases LPV bioactivation.     

Lopinavir/ritonavir (ABT-378/r)

Despite major advances in HIV research, eradication of HIV from the body is not yet possible. However, current antiretroviral (ARV) therapy can achieve disease control via viral suppression below the limits of detection of currently available assays. This has led to a marked decline in morbidity and mortality associated with the development of opportunistic infections and malignancies. Since viral suppression appears to be the most achievable goal of current therapy, there arises a need for new and more potent ARV agents in order to maintain viral suppression. Many of the currently available protease inhibitors (PIs) have a high protein-binding ability, short plasma half-life [1] and pharmacokinetic interactions with food or other drugs [2]. This can result in sub-optimal plasma drug concentrations, which may allow the virus to break through and replicate, leading to the development of resistant mutants [1]. Lopinavir/ritonavir (LPV/r; Kaletra, Abbott Laboratories) is a new PI consisting of a co-formulation of lopinavir and low-dose ritonavir. The sub-therapeutic dose of ritonavir (a potent cytochrome P450 [CYP] 3A4 inhibitor) inhibits the metabolism of lopinavir, resulting in higher lopinavir concentrations than when lopinavir is administered alone [3]. This pharmacokinetic interaction is associated with a high lopinavir trough level:wild type median effective concentration (EC(50)) ratio and good general tolerability when compared with other currently licensed PIs [4]. The concept of pharmacokinetic enhancement - boosting - is not new as ritonavir has previously been utilised in this context with other PIs. The relationship between plasma and intracellular drug levels has yet to be clarified. What has been ascertained from pharmacokinetic studies thus far is the correlation between ARV trough plasma concentrations (C(min)) and virological outcome [5,6]. LPV/r exemplifies how the pharmacokinetic profile of a drug can be modified to attain sufficient C(min) to suppress pheno- and genotypically resistant viral strains, as well as provide a pharmacological barrier to the emergence of resistance [7]. LPV/r reduces pill-burden and aids compliance, as shown by encouraging results in the treatment of both ARV-naive and -experienced patients.     

Influence of body weight on achieving indinavir concentrations within its therapeutic window in HIV-infected Thai patients receiving indinavir boosted with ritonavir

Indinavir boosted with ritonavir (IDV/r) dosing with 400/100 mg, twice daily, is preferred in Thai adults, but this dose can lead to concentrations close to the boundaries of its therapeutic window. The objectives of this analysis were to validate a population pharmacokinetic model to describe IDV/r concentrations in HIV-infected Thai patients and to investigate the impact of patient characteristics on achieving adequate IDV concentrations. IDV/r concentration data from 513 plasma samples were available. Population means and variances of pharmacokinetic parameters were estimated using a nonlinear mixed effects regression model (NONMEM Version VI). Monte Carlo simulations were performed to estimate the probability of achieving IDV concentrations within its therapeutic window. IDV/r pharmacokinetics were best described by a one-compartment model coupled with a single transit compartment absorption model. Body weight influenced indinavir apparent oral clearance and volume of distribution and allometric scaling significantly reduced the interindividual variability. Final population estimates (interindividual variability in percentage) of indinavir apparent oral clearance and volume of distribution were 21.3 L/h/70 kg (30%) and 90.7 L/70 kg (22%), respectively. Based on model simulations, the probability of achieving an IDV trough concentration greater than 0.1 mg/L was greater than 99% for 600/100 mg and greater than 98% for 400/100 mg, twice daily, in patients weighing 40 to 80 kg. However, the probability of achieving IDV concentrations associated with an increased risk of drug toxicity (greater than 10.0 mg/L) increased from 1% to 10% with 600/100 mg compared with less than 1% with 400/100 mg when body weight decreased from 80 to 40 kg. The validated model developed predicts that 400/100 mg of IDV/r, twice daily, provides indinavir concentrations within the recommended therapeutic window for the majority of patients. The risk of toxic drug concentrations increases rapidly with IDV/r dose of 600/100 mg for patients less than 50 kg and therapeutic drug monitoring of IDV concentrations would help to reduce the risk of IDV-induced nephrotoxicity.     

Population pharmacokinetics and dosing of amoxicillin in (pre)term neonates

Amoxicillin plasma concentrations, pharmacokinetic parameters, and the influence of demographic, anthropometric, and clinical covariates were investigated in 150 neonates. Gestational age (GA) ranged from 25 to 42 weeks and mean postnatal age (PNA) was 0.8 days. Amoxicillin concentrations were measured with reversed-phase HPLC in surplus plasma from routine assays of coadministered gentamicin. Mean total body clearance corrected for body weight (CL/W) was 0.096 +/- 0.036 L/kg(-1)h(-1), mean elimination half-life (t(1/2)) was 5.2 +/- 1.9 hours, and mean volume of distribution corrected for body weight (V/W) was 0.65 +/- 0.13 L/kg. Multiple regression equations were calculated for the prediction of CL/W amoxicillin. CL/W gentamicin, V/W gentamicin, and GA were significant predictors of CL/W amoxicillin. Amoxicillin peak and trough concentrations after the second dose and the time the concentration exceeds the minimum inhibitory concentration (T>MIC), reached with the current dosage regimen, were evaluated. Toxic plasma concentrations were reached in several patients. Therefore, the authors have proposed a lower dosage regimen, based on GA, population pharmacokinetic parameters, bacterial susceptibility (T>MIC), and possible toxicity: 15 mg/kg per 8 hours and 20 mg/kg per 8 hours for neonates with GA < or = 34 and GA>34 weeks, respectively. Simulation with this new dosage regimen indicated that satisfactory plasma concentrations were reached in all 150 neonates. Therefore, use of therapeutic drug monitoring and pharmacokinetic calculations for dosage adjustment is generally not necessary.     

The effects of ritonavir and lopinavir/ritonavir on the pharmacokinetics of a novel CCR5 antagonist, aplaviroc, in healthy subjects

AIMS: This study assessed the effects of the CYP3A inhibitors lopinavir/ritonavir (LPV/r) on the steady-state pharmacokinetics (PK) of aplaviroc (APL), a CYP3A4 substrate, in healthy subjects. METHODS: In Part 1, APL PK was determined in eight subjects who received a single oral 50-mg APL test dose with/without a single dose of 100 mg ritonavir (RTV). Part 2 was conducted as an open-label, single-sequence, three-period repeat dose study in a cohort of 24 subjects. Subjects received APL 400 mg every 12 h (b.i.d.) for 7 days (Period 1), LPV/r 400/100 mg b.i.d. for 14 days (Period 2) and APL 400 mg + LPV/r 400/100 mg b.i.d. for 7 days (Period 3). All doses were administered with a moderate fat meal. PK sampling occurred on day 7 of Periods 1 and 3 and day 14 of Period 2. RESULTS: In Part 1, a single RTV dose increased the APL AUC(0-infinity) by 2.1-fold [90% confidence interval (CI) 1.9, 2.4]. Repeat dose coadministration of APL with LPV/r increased APL exposures to a greater extent with the geometric least squares mean ratios (90% CI) being 7.7 (6.4, 9.3), 6.2 (4.8, 8.1) and 7.1 (5.6, 9.0) for the APL AUC, C(max), and C(min), respectively. No change in LPV AUC or C(max) and a small increase in RTV AUC and C(max) (28% and 32%) were observed. The combination of APL and LPV/r was well tolerated and adverse events were mild in severity with self-limiting gastrointestinal complaints most commonly reported. CONCLUSIONS: Coadministration of APL and LPV/r was well tolerated and resulted in significantly increased APL plasma concentrations.     

Lopinavir protein binding in vivo through the 12-hour dosing interval

Most protease inhibitors available for the treatment of human immunodeficiency virus (HIV) infection are highly bound to plasma proteins, mainly alpha-1 acid glycoprotein. Therapeutic drug monitoring (TDM) of total protease inhibitor (PI) concentrations has been increasing in the past few years; however, the pharmacological activity of the PIs is dependent on unbound drug entering cells harboring HIV. There is little information available on unbound drug concentrations of these drugs in vivo. The aim of the study was to measure unbound plasma concentrations of lopinavir (LPV) and to relate them to the total plasma concentrations to establish the unbound percentage in vivo during a full dosage interval. A pharmacokinetic study was performed in HIV-infected subjects (n = 23; median CD4 cell count = 290 x 10(6) cells x L(-1); viral load < 50 copies x mL(-1)) treated with a LPV/ritonavir (RTV)-containing regimen. Ultrafiltration was used to separate unbound LPV in all plasma samples (n = 115). Equilibrium dialysis was also used to compare with ultrafiltration measurements in 10/23 patients at baseline and 2 hours after drug intake. Total and unbound LPV concentrations were measured by a fully validated method using high-performance liquid chromatography-mass spectometry (HPLC-MS/MS). Based on a comparison of AUC(unbound)AUC(total), the mean (+/- SD) unbound percentage of LPV from all the samples studied (n = 115) was 0.92% (+/- 0.22) when measured with ultrafiltration and 1.32% (+/- 0.44) when equilibrium dialysis was used (n = 20), showing a higher drug recovery (P = 0.048). The unbound percentage of LPV was found to be significantly higher after 2 h than at baseline (P < 0.05 with both methods), suggesting a concentration-dependent binding of LPV that has not been observed in vitro. However, the clinical significance of such phenomena is still unclear.     

丙戊酸钠对卡马西平药代动力学的影响

目的：考察丙戊酸钠对卡马西平药代动力学的影响。方法：6名健康志愿分别口服单剂量卡马西平片以及卡马西平和丙戊酸钠片，采用荧光偏振免疫法测定卡马西平血药浓度，经3p97程序处理，计算卡马西平的药代动力学参数以及丙戊酸钠对卡马西平药代动力学参数的影响。结果：合用丙戊酸钠后，卡马西平的Ke,CL/F明显增加，而T1/2Ke,AUC0-1明显减小（P＜0．05）。结论：丙戊酸钠可加速卡马西平的排泄，使卡马西平的半衰期缩短，生物利用度减小。     

Reduced indinavir exposure during pregnancy

Aim

To describe the pharmacokinetics and safety of indinavir boosted with ritonavir (IDV/r) during the second and third trimesters of pregnancy and in the post-partum period.

Methods

IMPAACT P1026s is an on-going, prospective, non-blinded study of antiretroviral pharmacokinetics (PK) in HIV-infected pregnant women with a Thai cohort receiving IDV/r 400/100 mg twice daily during pregnancy through to 6–12 weeks post-partum as part of clinical care. Steady-state PK profiles were performed during the second (optional) and third trimesters and at 6–12 weeks post-partum. PK targets were the estimated 10^th percentile IDV AUC (12.9 μg ml⁻¹ h) in non-pregnant historical Thai adults and a trough concentration of 0.1 μg ml⁻¹, the suggested minimum target.

Results

Twenty-six pregnant women were enrolled; thirteen entered during the second trimester. Median (range) age was 29.8 (18.9–40.8) years and weight 60.5 (50.0–85.0) kg at the third trimester PK visit. The 90% confidence limits for the geometric mean ratio of the indinavir AUC(0,12 h) and C_max during the second trimester and post-partum (ante : post ratios) were 0.58 (0.49, 0.68) and 0.73 (0.59, 0.91), respectively; third trimester/post-partum AUC(0,12 h) and C_max ratios were 0.60 (0.53, 0.68) and 0.63 (0.55, 0.72), respectively. IDV/r was well tolerated and 21/26 women had a HIV-1 viral load < 40 copies ml⁻¹ at delivery. All 26 infants were confirmed HIV negative.

Conclusion

Indinavir exposure during the second and third trimesters was significantly reduced compared with post-partum and ∼30% of women failed to achieve a target trough concentration. Increasing the dose of IDV/r during pregnancy to 600/100 mg twice daily may be preferable to ensure adequate drug concentrations.     

Effects of berberine on the blood concentration of cyclosporin A in renal transplanted recipients: clinical and pharmacokinetic study

Objective To study the effects of berberine (BBR) on the blood concentration and pharmacokinetics of cyclosporin A (CsA) in renal-transplant recipients.Methods In a randomized and controlled clinical trial, 52 renal-transplant recipients were treated with CsA and 0.2 g BBR three times daily for 3 months, while another 52 subjects received CsA without BBR co-administration. Blood trough concentration of CsA and biochemistry indexes for hepatic and renal functions were determined. For the pharmacokinetic study, six renal-transplant recipients were included with a 3-mg/kg dosage of CsA twice daily before and after oral co-administration of 0.2 g BBR three times daily for 12 days.Results The trough blood concentrations and the ratios of concentration/dose of CsA in the BBR-treated group increased by 88.9% and 98.4%, respectively, compared with those at baseline (P<0.05). As for the BBR-free group, they rose by 64.5% and 69.4%, respectively, relative to those at baseline (P<0.01). Nevertheless, the final blood concentrations and the ratios of concentration/dose of CsA in BBR-treated patients were still 29.3% and 27.8%, respectively, higher than those in BBR-free patients (P<0.05). No significant effects on liver or renal functions were observed under coadministration of BBR. After co-administration of BBR in six patients for 12 days, the mean AUC of CsA was increased by 34.5% (P<0.05). The mean time taken to reach the peak blood concentration (t_max) and the mean half-life (t_1/2) of CsA were increased by 1.7 h and 2.7 h, respectively (P<0.05). The average percentage increases in the steady-state drug concentration (C_ss) and minimum blood concentration (C_min) were 34.5% and 88.3%, respectively (P<0.05). In addition, the average percentage decrease in CL/F was 40.4% (P<0.05) and the peak-to-through fluctuation index was significantly reduced (P<0.01).Conclusion The BBR can markedly elevate the blood concentration of CsA in renal-transplant recipients in both clinical and pharmacokinetic studies. This combination may allow a reduction of the CsA dosage. The mechanism for this interaction is most likely explained by inhibition of CYP3A4 by BBR in the liver and/or small intestine.     

Prescribing issues in elderly individuals living with HIV

ABSTRACT

Introduction: Combined antiretroviral therapy has transformed HIV infection into a chronic disease thus people living with HIV (PLWH) live longer. As a result, the management of HIV infection is becoming more challenging as elderly experience age-related comorbidities leading to complex polypharmacy and a higher risk for drug-drug or drug–disease interactions. Furthermore, age-related physiological changes affect pharmacokinetics and pharmacodynamics thereby predisposing elderly PLWH to incorrect dosing or inappropriate prescribing and consequently to adverse drug reactions and the subsequent risk of starting a prescribing cascade.

Areas covered: This review discusses the demographics of the aging HIV population, physiological changes and their impact on drug response as well as comorbidities. Particular emphasis is placed on common prescribing issues in elderly PLWH including drug–drug interactions with antiretroviral drugs. A PubMed search was used to compile relevant publications until February 2019.

Expert opinion: Prescribing issues are highly prevalent in elderly PLWH thus highlighting the need for education on geriatric prescribing principles. Adverse health outcomes potentially associated with polypharmacy and inappropriate prescribing should promote interventions to prevent harm including medication reconciliation, medication review, and medication prioritization according to the risks/benefits for a given patient. A multidisciplinary team approach is recommended for the care of elderly PLWH.