Population Pharmacokinetics of Dolutegravir in African Children: Results From the CHAPAS-4 Trial.

We characterized population pharmacokinetics in 42 African children receiving once-daily 25 mg (14 to <20 kg) or 50 mg (>20 kg) dolutegravir. Coadministration with emtricitabine and tenofovir alafenamide reduced dolutegravir bioavailability by 19.6% (95% confidence interval: 8.13%-30.8%) compared with zidovudine or abacavir with lamivudine. Nevertheless, concentrations remained above efficacy targets, confirming current dosing recommendations.

Endoplasmic reticulum transporter OAT2 regulates drug metabolism and interaction.

Xenobiotic metabolic reactions in the hepatocyte endoplasmic reticulum (ER) including UDP-glucuronosyltransferase and carboxylesterase play central roles in the detoxification of medical agents with small- and medium-sized molecules. Although the catalytic sites of these enzymes exist inside of ER, the molecular mechanism for membrane permeation in the ER remains enigmatic. Here, we investigated that organic anion transporter 2 (OAT2) regulates the detoxification reactions of xenobiotic agents including anti-cancer capecitabine and antiviral zidovudine, via the permeation process across the ER membrane in the liver. Pharmacokinetic studies in patients with colorectal cancer revealed that the half-lives of capecitabine in rs2270860 (1324C > T) variants was 1.4 times higher than that in the C/C variants. Moreover, the hydrolysis of capecitabine to 5'-deoxy-5-fluorocytidine in primary cultured human hepatocytes was reduced by OAT2 inhibitor ketoprofen, whereas capecitabine hydrolysis directly assessed in human liver microsomes were not affected. The immunostaining of OAT2 was merged with ER marker calnexin in human liver periportal zone. These results suggested that OAT2 is involved in distribution of capecitabine into ER. Furthermore, we clarified that OAT2 plays an essential role in drug-drug interactions between zidovudine and valproic acid, leading to the alteration in zidovudine exposure to the body. Our findings contribute to mechanistically understanding medical agent detoxification, shedding light on the ER membrane permeation process as xenobiotic metabolic machinery to improve chemical changes in hydrophilic compounds.

Bioequivalence and Pharmacokinetics Study of Two Zidovudine/Lamivudine Tablets in Chinese Healthy Volunteers.

Zidovudine/lamivudine tablets are nucleoside reverse transcriptase inhibitors that are used to treat human immunodeficiency virus. The objective of this study was to investigate the bioequivalence and pharmacokinetics (PKs) of test and reference preparations of zidovudine/lamivudine tablets in healthy Chinese subjects. We designed a randomized, open, single-center, single-dose, 2-crossover experiment with a 7-day washout period involving 20 healthy subjects. The subjects were given a single dose of the test or reference preparation after fasting overnight for 10 hours. Blood samples were subsequently collected at scheduled time points from 0 hour (preadministration) up to 24 hours postadministration. The plasma concentrations of zidovudine and lamivudine were determined by a validated ultra-performance liquid chromatography-tandem mass spectrometry method. Analysis of variance (ANOVA) was used to compare differences in the mean values of key PK parameters between the 2 preparations. Bioequivalence was evaluated by 2 one-sided t-tests and 90% confidence intervals (CIs) of the geometric mean ratio (GMR). In total, 19 of the 20 subjects completed the trial. Based on the analysis of PK parameters, the relative bioavailability of zidovudine and lamivudine was 101.1% ± 2.0% and 100.3% ± 1.5%, respectively. ANOVA found no significant difference in primary PK parameters when compared between the 2 formulations, and the 90% CIs of the GMR of the 2 formulations were within the bioequivalence margins of 80%-125%. No serious adverse events occurred. Thus, we confirmed that the 2 preparations were bioequivalent in healthy Chinese volunteers. Our analysis demonstrated that both products showed good tolerance in all subjects.

Potential of mucoadhesive chitosan glutamate microparticles as microbicide carriers - antiherpes activity and penetration behavior across the human vaginal epithelium.

Chitosan glutamate (gCS) spray-dried microparticles appear promising carriers to overcome challenges associated with vaginal microbicide delivery. This study aimed at elucidating the penetration and mucoadhesive behavior of developed gCS multiunit carriers with zidovudine (ZVD) as a model antiretroviral agent in contact with excised human vaginal epithelium followed with an examination of in vitro antiherpes activity in immortal human keratinocytes HaCaT and human vaginal epithelial cells VK2-E6/E7. Both ZVD dispersion and placebo microparticles served as controls. Microparticles displayed feasible (comparable to commercial vaginal product) mucoadhesive and mucoretention characteristics to isolated human vaginal tissue. Ex vivo penetration studies revealed that gCS increased the accumulation of active agent in the vaginal epithelium but surprisingly did not facilitate its penetration across human tissue. Finally, the obtained antiviral results demonstrated the potential of gCS as an antiherpes adjunctive, whose mode of action was related to blocking viral attachment.

Pharmacokinetics and Safety of Zidovudine, Lamivudine, and Lopinavir/Ritonavir in HIV-infected Children With Severe Acute Malnutrition in Sub-Saharan Africa: IMPAACT Protocol P1092.

BACKGROUND: Severe acute malnutrition (SAM) may alter the pharmacokinetics (PK), efficacy, and safety of antiretroviral therapy. The phase IV study, IMPAACT P1092, compared PK, safety, and tolerability of zidovudine (ZDV), lamivudine (3TC), and lopinavir/ritonavir (LPV/r) in children with and without SAM. MATERIALS AND METHODS: Children living with HIV 6 to <36 months of age with or without World Health Organization (WHO)-defined SAM received ZDV, 3TC, and LPV/r syrup for 48 weeks according to WHO weight band dosing. Intensive PK sampling was performed at weeks 1, 12, and 24. Plasma drug concentrations were measured using liquid chromatography tandem mass spectrometry. Steady-state mean area under the curve (AUC0-12h) and clearance (CL/F) for each drug were compared. Grade ≥3 adverse events were compared between cohorts. RESULTS: Fifty-two children were enrolled across 5 sites in Africa with 44% (23/52) female, median age 19 months (Q1, Q3: 13, 25). Twenty-five children had SAM with entry median weight-for-height Z-score (WHZ) -3.4 (IQR -4.0, -3.0) and 27 non-SAM had median WHZ -1.0 (IQR -1.8, -0.1). No significant differences in mean AUC0-12h or CL/F were observed (P ≥ 0.09) except for lower 3TC AUC0-12h (GMR, 0.60; 95% CI, 0.4-1.0; P = 0.047) at week 12, higher ZDV AUC0-12h (GMR, 1.52; 1.2-2.0; P = 0.003) at week 24 in the SAM cohort compared with non-SAM cohort. Treatment-related grade ≥3 events did not differ significantly between cohorts (24.0% vs. 25.9%). CONCLUSION: PK and safety findings for ZDV, 3TC, and LPV/r support current WHO weight band dosing of syrup formulations in children with SAM.

Construction and Verification of Physiologically Based Pharmacokinetic Models for Four Drugs Majorly Cleared by Glucuronidation: Lorazepam, Oxazepam, Naloxone, and Zidovudine.

Physiologically based pharmacokinetic (PBPK) modeling is less well established for substrates of UDP-glucuronosyltransferases (UGT) than for cytochrome P450 (CYP) metabolized drugs and more verification of simulations is necessary to increase confidence. To address specific challenges of UGT substrates, we developed PBPK models for four drugs cleared majorly via glucuronidation (lorazepam, oxazepam, naloxone, and zidovudine). In vitro to in vivo scaling of intrinsic clearance generated with co-cultured human hepatocytes was applied for hepatic metabolism and extra-hepatic clearance was extrapolated based on relative expression of UGT isoforms in the liver, kidney, and intestine. Non-metabolic clearance and the contributions of individual UGT isoforms to glucuronidation were based on in vitro and in vivo studies taken from the literature and simulations were verified and evaluated with a broad set of clinical pharmacokinetic data. Model evaluation showed systemic clearance predictions within 1.5-fold for all drugs and all simulated parameters were within 2-fold of observed. However, during the verification step, top-down model fitting was necessary to adjust for under-prediction of zidovudine VSS and renal clearance and over estimation of intestinal first pass for lorazepam, oxazepam, and zidovudine. The impact of UGT2B15 polymorphisms on the pharmacokinetics of oxazepam and lorazepam was simulated and glucuronide metabolites were also simulated for all four drugs. To increase confidence in predicting extra-hepatic clearance, improvement of enzyme phenotyping for UGT substrates and more quantitative tissue expression levels of UGT enzymes are both needed. Prediction of glucuronide disposition is also challenging when active transport processes play a major role.

Evaluation of the effect of synthetic compounds derived from azidothymidine on MDA-MB-231 type breast cancer cells.

The present study aimed to investigate the effect of AZT derivates containing tellurium (Te) on human breast cancer cell lines and the mechanisms underlying cell death. The inhibitory effect of AZT and its derivatives (7m and 7r) was determined by the MTT assay (6.25, 12.5, 25, 50 and 100 µM in 24 and 48 h time points), meanwhile the induction of apoptosis and the cell cycle phases was investigated by flow cytometry. The MTT assay showed that AZT derivatives decreased the rate of cell proliferation at concentrations of 12.5 µM, while commercial AZT showed low antitumor potential. In flow cytometric analysis, we demonstrate that the AZT derivatives do not induce apoptosis at the concentration tested and promote the cell cycle arrest in the S phase. Besides, predicted absorption, distribution, metabolization, excretion and toxicity analysis suggest that the compounds possess a good pharmacokinetic profile and possibly less toxicity when compared to conventional AZT. These compounds containing tellurium in their formulation are potential therapeutic agents for breast cancer.

Zidovudine and lamivudine reach higher concentrations in ventricular than in lumbar human cerebrospinal fluid.

OBJECTIVE: For the treatment of HIV-1-related brain disease and for the prevention of the brain becoming a viral reservoir, it is important that antiretroviral agents reach sufficient concentrations in the CNS. To date, human brain pharmacokinetic data are solely derived from lumbar cerebrospinal fluid (CSF) and mostly originate from single samples. DESIGN: We determined concentrations of antiretroviral drugs in serial samples of ventricular CSF and compared these to the concentrations in serum and lumbar CSF of these patients. METHODS: Two treatment-naïve HIV-1-infected patients received external ventricular drainage for obstructive hydrocephalus. Starting with a combination antiretroviral regimen (cART), ventricular CSF, and subsequently lumbar CSF, with parallel serum, was frequently collected. Drug concentrations were determined and CSF-to-serum ratios were calculated. RESULTS: High concentrations, resulting in high CSF-to-serum ratios, were found in the ventricular CSF of the three substances zidovudine, lamivudine and indinavir, whereas this was not observed for stavudine, ritonavir, saquinavir and efavirenz. Concentrations of zidovudine and lamivudine were up to four times greater in CSF from the ventricles than in lumbar CSF of the same patient. The zidovudine concentrations in the ventricular CSF exceeded serum concentrations by a factor of 1.4. CONCLUSION: Unexpectedly high concentrations of some antiretrovirals in the ventricular CSF, the site close to the brain parenchyma where HIV is located, should be considered when the cART regimen is aiming at CNS viral replication.

Nucleoside Reverse Transcriptase Inhibitor Interaction with Human Equilibrative Nucleoside Transporters 1 and 2.

Equilibrative nucleoside transporters (ENTs) transport nucleosides across the blood-testis barrier (BTB). ENTs are of interest to study the disposition of nucleoside reverse-transcriptase inhibitors (NRTIs) in the human male genital tract because of their similarity in structure to nucleosides. HeLa S3 cells express ENT1 and ENT2 and were used to compare relative interactions of these transporters with selected NRTIs. Inhibition of [3H]uridine uptake by NBMPR was biphasic, with IC50 values of 11.3 nM for ENT1 and 9.6 µM for ENT2. Uptake measured with 100 nM NBMPR represented ENT2-mediated transport; subtracting that from total uptake represented ENT1-mediated transport. The kinetics of ENT1- and ENT2-mediated [3H]uridine uptake revealed no difference in Jmax (16.53 and 30.40 pmol cm-2 min-1) and an eightfold difference in Kt (13.6 and 108.9 µM). The resulting fivefold difference in intrinsic clearance (Jmax/Kt) for ENT1- and ENT2 transport accounted for observed inhibition of [3H]uridine uptake by 100 nM NBMPR. Millimolar concentrations of the NRTIs emtricitabine, didanosine, lamivudine, stavudine, tenofovir disoproxil, and zalcitabine had no effect on ENT transport activity, whereas abacavir, entecavir, and zidovudine inhibited both transporters with IC50 values of ∼200 µM, 2.5 mM, and 2 mM, respectively. Using liquid chromatography-tandem mass spectrometry and [3H] compounds, the data suggest that entecavir is an ENT substrate, abacavir is an ENT inhibitor, and zidovudine uptake is carrier-mediated, although not an ENT substrate. These data show that HeLa S3 cells can be used to explore complex transporter selectivity and are an adequate model for studying ENTs present at the BTB. SIGNIFICANCE STATEMENT: This study characterizes an in vitro model using S-[(4-nitrophenyl)methyl]-6-thioinosine to differentiate between equilibrative nucleoside transporter (ENT) 1- and ENT2-mediated uridine transport in HeLa cells. This provides a method to assess the influence of nucleoside reverse-transcriptase inhibitors on natively expressed transporter function. Determining substrate selectivity of the ENTs in HeLa cells can be effectively translated into the activity of these transporters in Sertoli cells that comprise the blood-testis barrier, thereby assisting targeted drug development of compounds capable of circumventing the blood-testis barrier.

Anti-HIV agent azidothymidine decreases Tet(X)-mediated bacterial resistance to tigecycline in Escherichia coli.

Recent emergence of high-level tigecycline resistance mediated by Tet(X3/X4) in Enterobacteriaceae undoubtably constitutes a serious threat for public health worldwide. Antibiotic adjuvant strategy makes antibiotic more effective against these resistant pathogens through interfering intrinsic resistance mechanisms or enhancing antibiotic actions. Herein, we screened a collection of drugs to identify compounds that are able to restore tigecycline activity against resistant pathogens. Encouragingly, we discovered that anti-HIV agent azidothymidine dramatically potentiates tigecycline activity against clinically resistant bacteria. Meanwhile, addition of azidothymidine prevents the evolution of tigecycline resistance in E. coli and the naturally occurring horizontal transfer of tet(X4). Evidence demonstrated that azidothymidine specifically inhibits DNA synthesis and suppresses resistance enzyme activity. Moreover, in in vivo infection models by Tet(X4)-expression E. coli, the combination of azidothymidine and tigecycline achieved remarkable treatment benefits including increased survival and decreased bacterial burden. These findings provide an effective regimen to treat infections caused by tigecycline-resistant Escherichia coli.

Influence of a herbal preparation on the pharmacokinetics of highly active antiretroviral therapy drugs in rats.

Shenlin Fuzheng Capsule (SLFZC) is a herbal preparation used for HIV/AIDS in Guangxi, China. This study was designed to evaluate the influence of SLFZC on the pharmacokinetics of highly active antiretroviral therapy (HAART) drugs, zidovudine (3'-azido-3'-deoythymidine, AZT), 2',3'-dideoxy-3'-thiacytidine (3TC) and efavirenz (EFV). Thirty-six male SD rats were divided into three groups. Group A was given a combination of AZT, 3TC and EFV (AZT/3TC/EFV). Group B rats were given AZT/3TC/EFV simultaneously with SLFZC. Group C rats were given AZT/3TC/EFV 2h prior to SLFZC. Blood samples were collected at fixed time intervals. Plasma concentration of each antiretroviral drug was tested for calculation of pharmacokinetic parameters. There was significant difference among groups with respect to t1/2 for AZT (F=3.371, P<0.05), but the Student-Newman-Keuls (SNK) pairwise multiple comparison procedure showed no statistical differences in all pairwise comparisons (P>0.05). There were no significant differences among groups in terms of Cmax, T max, AUC0-12h and CL for AZT, and t1/2, Cmax, Tmax, AUC0-12h and CL for 3TC and EFV, respectively. The results indicate that SLFZC has little impact on pharmacokinetic properties of AZT, 3TC and EFV.

Bile duct ligation enhances AZT CNS toxicity partly by impairing the expression and function of BCRP in rat brain.

Breast cancer resistance protein (BCRP) is one of ATP-binding cassette (ABC) transporters in brain microvessel endothelial cells that transport their substrates from brain to blood, thus limiting substrates to crossing into brain through blood-brain barrier. Our previous works show that bile duct ligation (BDL) impairs expression and function of brain BCRP in rats. Since zidovudine (AZT) is BCRP substrate, we investigated whether impaired expression and function of BCRP increased brain distribution and toxicity of AZT in BDL-D7 rats. After administration of AZT (10 mg/kg, i.v.), BDL markedly increased brain AZT concentrations, compared with sham-operated (SO) rats. The ratio of AZT brain-to-plasma area under concentration curve (AUC) in BDL rats was increased to 1.6-folds of SO rats. After treatment with AZT (100 mg/kg every day, i.v.) for 7 days, BDL significantly impaired cognitive functions compared with SO rats, evidenced by the significantly decreased percentage of alternation in Y-maze test and prolonged escaped latency in two-way passive avoidance trial. Furthermore, AZT treatment caused significant decrease in copies of mitochondrial DNA and mitochondrial membrane potential in hippocampus of BDL rats. Moreover, AZT treatment caused a significant decrease of cortex microtubule-associated protein 2 and hippocampus synaptophysin levels in BDL rats. AZT-induced CNS adverse alterations in BDL rats were not observed in SO rats treated with AZT. In conclusion, BDL decreases the function and expression of brain BCRP in rats, leading to increased brain distribution of AZT, which in turn enhances AZT CNS toxicity, leading to mitochondrial dysfunction, neuronal damage, and ultimately cognitive dysfunction.

WB-PBPK approach in predicting zidovudine pharmacokinetics in preterm neonates.

Antiretroviral therapy has been the mainstay of treatment for neonates born to HIV infected mothers. Neonates born prematurely to HIV positive mothers are underdeveloped not only in anatomical terms but also in their physiological systems. Zidovudine, the first antiretroviral drug in clinical therapy for the treatment of HIV has been approved for use in preterm neonates both prophylactically and therapeutically. The present work describes the whole body physiologically based pharmacokinetic (WB-PBPK) model development for zidovudine in preterm neonates of varying gestational ages, to observe the pharmacokinetic behavior of the drug in this vulnerable group of the population. Along with the height, weight, post-natal, and gestational ages of the preterm neonates, metabolic enzymes CYP2A6, CYP2C8, etc. were incorporated for each neonate. The composition of the different organs in terms of water and lipid components, blood flow rates, etc. were specified during simulations according to the gestational ages of these neonates. The following PK parameters were estimated for preterm neonates using simulated plasma profiles: AUC 2686.41 ± 123.49 µmol min/L, Cmax 6.46 ± 0.74 µmol/L, half-life 8.98 ± 2.36 hr, mean residence time 12.23 ± 3.43 hr, and total plasma clearance 1.48 ± 0.19 ml/min/kg in comparison with the observed PK parameters of a clinical study by Mirochknic et al. in preterm neonates with AUC 2020.04 µmol/min/L, Cmax 6.10 µmol/L, and total plasma clearance 1.62 ml/min/kg. PBPK simulations provide an opportunity to visualize the possible impact of physiological maturity levels at varying gestational ages on the pharmacokinetic behavior of zidovudine in preterm neonates.

Application of a physiologically based pharmacokinetic model for the prediction of mirabegron plasma concentrations in a population with severe renal impairment.

We previously verified a physiologically based pharmacokinetic (PBPK) model for mirabegron in healthy subjects using the Simcyp Simulator by incorporating data on the inhibitory effect on cytochrome P450 (CYP) 2D6 and a multi-elimination pathway mediated by CYP3A4, uridine 5'-diphosphate-glucuronosyltransferase (UGT) 2B7 and butyrylcholinesterase (BChE). The aim of this study was to use this PBPK model to assess the magnitude of drug-drug interactions (DDIs) in an elderly population with severe renal impairment (sRI), which has not been evaluated in clinical trials. We first determined the system parameters, and meta-analyses of literature data suggested that the abundance of UGT2B7 and the BChE activity in an elderly population with sRI was almost equivalent to and 20% lower than that in healthy young subjects, respectively. Other parameters, such as the CYP3A4 abundance, for an sRI population were used according to those built into the Simcyp Simulator. Second, we confirmed that the PBPK model reproduced the plasma concentration-time profile for mirabegron in an sRI population (simulated area under the plasma concentration-time curve (AUC) was within 1.5-times that of the observed value). Finally, we applied the PBPK model to simulate DDIs in an sRI population. The PBPK model predicted that the AUC for mirabegron with itraconazole (a CYP3A4 inhibitor) was 4.12-times that in healthy elderly subjects administered mirabegron alone, and predicted that the proportional change in AUC for desipramine (a CYP2D6 substrate) with mirabegron was greater than that in healthy subjects. In conclusion, the PBPK model was verified for the purpose of DDI assessment in an elderly population with sRI.

Urinary bactericidal activity of colistin and azidothymidine combinations against mcr-1-positive colistin-resistant Escherichia coli.

A phase 1 clinical study was performed to assess the pharmacokinetics and safety of intravenous (i.v.) administration of colistin methanesulfonate (CMS) and azidothymidine (AZT) alone and in combination. Seven healthy subjects received three (every 12 h) 1-h i.v. infusions of 4, 2 and 2 million international units (MIU) of CMS co-administered with 200, 100 and 100 mg of AZT, respectively. In an ex vivo study, urinary bactericidal titres (UBTs) and time-kill curve determinations were performed in artificial urine spiked with colistin sulfate and AZT according to median and minimum peak concentrations in urine measured after the first and third dose using four mcr-1-positive colistin-resistant and five colistin-susceptible Gram-negative isolates. Reciprocal UBTs for the different colistin concentrations obtained in urine ranged from 1-128 and 0-2 for colistin-susceptible and colistin-resistant isolates, respectively. Combination with AZT could increase UBTs up to two dilution steps each for the Enterobacteriaceae and Acinetobacter strains tested. In contrast, the combination had no activity against Pseudomonas strains. In time-kill curves, the combination showed bactericidal activity against colistin-resistant strains even when the substances alone were not bactericidal. Thus, combination of CMS with AZT shows promising synergistic activity against Gram-negative uropathogens, including colistin-resistant Enterobacteriaceae. According to the urinary bactericidal activity, a maintenance dosage of 2 MIU of CMS combined with 100 mg of AZT twice daily may be sufficient for the treatment of urinary tract infections (UTIs) caused by colistin-susceptible strains. However, the dosage requires optimisation for efficient treatment of UTIs caused by colistin-resistant strains.

Capillary electrophoresis study of systemin peptides spreading in tomato plant.

Systemin (Sys) is an 18-aa plant peptide hormone involved in the regulation of plant's defensive response. Sys is considered as a fast-spreading systemic wound signal. We developed a simple and rapid CE method to monitor the spreading of Sys peptides through tomato plant. A 1,2,3-triazole-linked AZT-systemin conjugate was designed as a model to study the possibility of translocating small cargo molecules 3'-Azido-2',3'-dideoxythymidine by systemin. The Sys peptides (Sys, N-propiolyl Sys, and AZT-systemin conjugate) were injected into the stem and leaves of mature tomato plant. Its transportation throughout the plant tissue was traced by CE. The peptides were clearly visible in the crude tomato exudates and an optimum separation was achieved in 25 mM phosphate "buffer" at pH 2.5 and a voltage of 20 kV using uncoated fused silica capillary. CE analysis showed that Sys peptides are well separated from tomato plant exudates ingredients and are stable in tomato stem and leaf exudates for up to 24 h. CE study revealed that the Sys peptides are effectively spreading throughout tomato stem and leaves and the peptides could be directly detected in the crude plant matrixes. The translocation was strongly inhibited by sodium azide. The results showed that the established CE method can be used to characterize plant peptides spreading under plant physiological conditions.

Antiretroviral Drug Concentrations in Breastmilk, Maternal HIV Viral Load, and HIV Transmission to the Infant: Results From the BAN Study.

BACKGROUND: Concentration of antiretroviral (ARV) drug found in plasma, and amounts of drug excreted into breastmilk, may affect HIV viral load and potentially perinatal HIV transmission. METHODS: In this cohort study with 2-phase sampling, we included mothers randomized to postpartum maternal ARVs or daily infant nevirapine during 28 weeks of breastfeeding in the Breastfeeding, Antiretrovirals, and Nutrition study. Among these, we included all mothers who transmitted HIV to their infants between 2 and 28 weeks and 15% of mothers who did not (n = 27 and 227, respectively). Spearman correlation coefficients (r) were used to assess the correlation between maternal plasma and breastmilk ARV concentration. Associations between the median effective drug concentration (EC50) and detectable maternal viral load (plasma: >40 copies per milliliter, breastmilk: >56 copies per milliliter) were assessed using mixed-effects models. Cox models were used to estimate the association between maternal or infant plasma drug concentration and breastmilk HIV transmission from 2 to 28 weeks. RESULTS: All ARV compounds exhibited substantial correlations between maternal plasma and breastmilk concentrations (r: 0.85-0.98, P-value <0.0001). Having plasma drug concentration above the EC50 was associated with lower odds of having detectable HIV RNA [maternal plasma odds ratio (OR) 0.64, 95% confidence interval (CI): 0.45 to 0.91; breastmilk OR 0.22, 95% CI: 0.14 to 0.35] and a reduced rate of breastmilk HIV transmission (hazard ratio 0.40, 95% CI: 0.18 to 0.93). Having breastmilk drug concentration above the EC50 was also associated with lower odds of having detectable maternal HIV RNA (plasma OR 0.62, 95% CI: 0.45 to 0.85; breastmilk OR 0.42, 95% CI: 0.29 to 0.59). CONCLUSIONS: Ensuring adequate drug concentration is important for viral suppression and preventing breastmilk HIV transmission.

Versatile iron-catechol-based nanoscale coordination polymers with antiretroviral ligand functionalization and their use as efficient carriers in HIV/AIDS therapy.

A novel chemical approach integrating the benefits of nanoparticles with versatility of coordination chemistry is reported herein to increase the effectiveness of well-known HIV antiretroviral drugs. The novelty of our approach is illustrated using a catechol ligand tethered to the known antiretroviral azidothymidine (AZT) as a constitutive building block of the nanoparticles. The resulting nanoscale coordination polymers (NCPs) ensure good encapsulation yields and equivalent antiretroviral activity while significantly diminishing its cytotoxicity. Moreover, this novel family of nanoparticles also offers (i) long-lasting drug release that is dissimilar inside and outside the cells depending on pH, (ii) triggered release in the presence of esterases, activating the antiviral activity in an on-off manner due to a proper chemical design of the ligand and (iii) improved colloidal stabilities and cellular uptakes (up to 50-fold increase). The presence of iron nodes also adds multifunctionality as possible contrast agents. The present study demonstrates the suitability of NCPs bearing pharmacologically active ligands as an alternative to conventional antiretroviral treatments.

Novel core-shell dextran hybrid nanosystem for anti-viral drug delivery.

Zidovudine (AZT) is an antiviral drug extensively used for combating the global pandemic- HIV/AIDS. However, its uses are overshadowed by its short half -life, poor aqueous solubility and inability to cross physiological barriers. This study highlights a nanosystem consisting of dextran and stearic acid for AZT delivery. This hybrid nanoparticle was prepared by double emulsion solvent evaporation method. The morphological analysis of the prepared nanoparticles was carried out by transmission electron microscopy (TEM) and structural analysis through FTIR spectroscopy. Haemolysis, blood cell aggregation and cytotoxicity evaluations were also performed. These biological evaluations indicated that the nanoparticles were compatible and fluorescence microscopy studies demonstrated increased cellular internalization of drug loaded hybrid nanoparticles when compared with free drug molecules. The experimental outcomes indicate that the prepared nanoparticles are highly biocompatible haemocompatible and effective in getting internalized into cells of neural origin. These results highlight the feasibility and efficacy of the hybrid nanoparticles for effective delivery of zidovudine.

Third-Generation Transdermal Delivery Systems Containing Zidovudine: Effect of the Combination of Different Chemical Enhancers and a Microemulsion System.

This study aimed to examine the influence of the combination of chemical enhancers and a microemulsion on the transdermal permeation of zidovudine (AZT). Ethanol, 1,8-cineole, and geraniol were incorporated in a microemulsion. The droplet size, zeta potential, rheology, and SAXS analysis were performed. The permeation enhancer effect was evaluated using pig ear skin. Snake skin (Boa constrictor) treated with the formulations was also used as a stratum corneum model and studied by attenuated total reflectance-infrared spectroscopy. As a result, it was observed that the incorporation of the chemical enhancers promoted a decrease of the droplet size and some rheological modifications. The 1,8-cineole associated with the microemulsion significantly increased the permeated amount of AZT. Conversely, ethanol significantly increased the quantity of the drug retained in the skin. The probable mechanism for the cineole and ethanol effects was respectively: fluidization and increasing of the diffusion coefficient, and increasing of the partition coefficient. Surprising, geraniol + microemulsion drastically decreased both the permeated and the retained amount of AZT into the skin. Thus, the adequate association of microemulsion and chemical enhancers showed to be a crucial step to enable the topical or transdermal use of drugs.