Fate of Alkyl Polyglucosides in the Environment.

Alkyl polyglucosides (APGs) belong to the class of green or natural surfactants synthesized from fatty acids and sugars. Growing concerns on toxicity of sulfates and ethoxylates has led to their popularity in personal and home care products. Increasing usage has resulted in higher concentrations in discharge sites or wastewater treatment plants. Studies show that APGs are readily biodegradable in laboratory settings; however, limited data are available on their effects on the environment. In this focused review, we discuss their biodegradation profile and toxicity of the parent compounds and metabolites in aquatic systems.

Intravaginal ring eluting tenofovir disoproxil fumarate completely protects macaques from multiple vaginal simian-HIV challenges.

Topical preexposure prophylaxis interrupts HIV transmission at the site of mucosal exposure. Intermittently dosed vaginal gels containing the HIV-1 reverse transcriptase inhibitor tenofovir protected pigtailed macaques depending on the timing of viral challenge relative to gel application. However, modest or no protection was observed in clinical trials. Intravaginal rings (IVRs) may improve efficacy by providing long-term sustained drug delivery leading to constant mucosal antiretroviral concentrations and enhancing adherence. Although a few IVRs have entered the clinical pipeline, 100% efficacy in a repeated macaque vaginal challenge model has not been achieved. Here we describe a reservoir IVR technology that delivers the tenofovir prodrug tenofovir disoproxil fumarate (TDF) continuously over 28 d. With four monthly ring changes in this repeated challenge model, TDF IVRs generated reproducible and protective drug levels. All TDF IVR-treated macaques (n = 6) remained seronegative and simian-HIV RNA negative after 16 weekly vaginal exposures to 50 tissue culture infectious dose SHIV162p3. In contrast, 11/12 control macaques became infected, with a median of four exposures assuming an eclipse of 7 d from infection to virus RNA detection. Protection was associated with tenofovir levels in vaginal fluid [mean 1.8 × 10(5) ng/mL (range 1.1 × 10(4) to 6.6 × 10(5) ng/mL)] and ex vivo antiviral activity of cervicovaginal lavage samples. These observations support further advancement of TDF IVRs as well as the concept that extended duration drug delivery devices delivering topical antiretrovirals could be effective tools in preventing the sexual transmission of HIV in humans.

Intravaginal flux controlled pump for sustained release of macromolecules.

PURPOSE: To design a flux controlled pump (FCP) capable of 30-day, controlled release of macromolecules to the vaginal mucosa. METHODS: The FCP is composed of a single chamber fabricated from a rigid thermoplastic with orifices and encloses a pellet of water-swellable polymer containing the drug substance. We performed testing both in vitro and in rabbits. To ensure vaginal retention in the rabbit, we designed and attached an oval shape-memory polyether urethane retainer to the FCP allowing for long-term intravaginal evaluation of a solid dosage form without invasive surgical implantation. RESULTS: The orifices and swelling properties of the polymer pellet control water entry for polymer hydration and expansion, and subsequent extrusion of the drug-containing gel from the orifice. A FCP device containing a pellet composed of hydroxypropyl cellulose compounded with a model macromolecule, achieved controlled in vitro release for 30 days with an average release rate of 24 ± 2 µg/day (mean ± SD) and range of 16 to 42 µg/day. We observed a slightly lower average release rate in vivo of 20 ± 0.6 µg/day (mean ± SD). CONCLUSIONS: The size of the orifice and nature of the swelling polymer controls the hydration rate and thereby macromolecule release rate and duration from this FCP.

Novel preclinical models of topical PrEP pharmacodynamics provide rationale for combination of drugs with complementary properties.

BACKGROUND: The limited success of recent HIV topical pre-exposure prophylaxis clinical trials highlights the need for more predictive models of drug efficacy that better simulate what may happen during sexual exposure. To address this gap, we developed complementary in vitro models to evaluate the ability of drugs to retain anti-HIV activity if cells were washed with seminal plasma (simulating what may happen following exposure to ejaculate), and to protect drug-naive T cells (representing newly recruited immune cells) co-cultured with explants that had been pretreated with drug. We focused on tenofovir disoproxil fumarate (TDF), the non-nucleoside reverse transcriptase inhibitors dapivirine (DPV) and IQP-0528, and the entry inhibitors maraviroc (MVC) and the D-peptide chol-PIE-12 trimer (PIE12). Studies were extended to macaques and the ability of cervical biopsies obtained from animals treated with an intravaginal ring formulation of IQP-0528 to protect ex vivo co-cultured T cells was determined. The antiviral activity of cervicovaginal lavage samples against a primary Clade C isolate was also measured and correlated with drug levels. RESULTS: Cells exposed to TDF were equally protected from HIV whether or not the drug-treated cells were washed with medium or seminal plasma prior to challenge. In contrast, several-fold higher concentrations of NNRTIs and entry inhibitors were needed to attain similar levels of HIV inhibition following a wash with seminal plasma. Conversely, the NNRTIs and PIE12, but not TDF or MVC, were effectively transferred from ex vivo treated explants and protected co-cultured T cells. Biopsies obtained from IQP-0528 ring-treated macaques also protected co-cultured T cells with viral inhibition ranging from 42-72%. Antiviral activity correlated with the concentration of drug recovered. Combinations of TDF with IQP-0528 protected in both in vitro models. CONCLUSIONS: Together, these models suggest that intracellularly retained drugs such as TDF may protect resident immune cells following coitus but sustained delivery may be required to protect immune cells subsequently recruited into the genital tract. Sustained delivery may also be critical for NNRTIs, which are rapidly transported out of cells and could be lost following sexual intercourse. An ideal approach may be a combination of drugs with complementary bioavailability profiles formulated for sustained delivery.

Intravaginal ring delivery of tenofovir disoproxil fumarate for prevention of HIV and herpes simplex virus infection.

OBJECTIVES: A safe and effective topical prevention strategy will likely require sustained delivery of potent antiviral drugs and a delivery system that simultaneously maximizes drug distribution and overcomes the behavioural challenges related to adherence. Activity against HIV and herpes simplex virus (HSV) would be advantageous, given the epidemiological link between the two pathogens. We hypothesize that tenofovir disoproxil fumarate (tenofovir DF), a prodrug of tenofovir, may be more potent than tenofovir and ideal for sustained intravaginal ring (IVR) delivery. METHODS: The anti-HIV and anti-HSV activity of tenofovir and tenofovir DF were assessed in cell and explant models. Cumulative tenofovir DF release and stability from polyether urethane (PEU), ethylene-co-vinyl acetate (EVA) and silicone IVRs were compared, and the activity and safety of drug released were evaluated in cervical explants and in a polarized dual-chamber model. RESULTS: Tenofovir DF inhibited HIV and HSV at ≈ 100-fold lower concentrations than tenofovir and retained activity in the presence of semen. PEU rings delivered >1 mg/day of tenofovir DF for 30 days. Pre-treatment of cervical explants with 10 µg/mL tenofovir DF or eluants from PEU minirings resulted in >90% inhibition of HIV and reduced HSV-2 yields by 2.5 log. Tenofovir DF and eluants did not prevent cell growth or polarization, or have any deleterious effects on an epithelial barrier. CONCLUSIONS: The findings support the development of a PEU tenofovir DF ring, which may provide potent and sustained protection against HIV and HSV.

Electroporation of polymeric nanoparticles: an alternative technique for transdermal delivery of insulin.

PURPOSE: The aim was to study transdermal electroporation of insulin-loaded nanocarriers as a methodology for delivering macromolecules. METHODS: The efficacy of electroporation of insulin as solution and nanoparticles was compared in vitro and in vivo. Histology and confocal laser scanning microscopy were used to assess the effects of electroporation on skin structure, whereas the latter also demonstrated the depth of permeation of the nanoparticles. In vivo studies were performed on streptozotocin-diabetic male Wistar rats and compared with subcutaneous administration. RESULTS: A linear increase in insulin flux was noted on increasing the applied voltage (R(2) = 0.9514), the number of pulses (R(2) = 0.8515), and the pulse length (R(2) = 0.9937). Electroporation of nanoparticles resulted in fourfold enhancement in insulin deposition in rat skin in contrast to solution. In vivo studies showed maximum reduction of 77 ± 5% (87.2 ± 6.4 mIU/mL, t = 2 hours) and 85 ± 8% (37.8 ± 10.2 mIU/mL, t = 4 hours) in blood glucose levels for solution and nanoparticles, respectively, with therapeutic levels maintained for 24 and 36 hours. CONCLUSION: Overall, electroporation of polymeric nanosystems proved to be an ideal alternative to injectable administration.

Investigation on the synergistic effect of a combination of chemical enhancers and modulated iontophoresis for transdermal delivery of insulin.

PURPOSE: The main objective of this study was to assess the flux enhancement of insulin transdermally by utilizing a complex of chemical enhancers in combination with modulated iontophoresis. METHODS: The experiments were performed on porcine epidermis model under three different circumstances, namely, (a) 1-hour modulated iontophoresis alone; (b) pretreatment with vehicle and chemical enhancer combinations and (c) combination of (a) and (b). The mechanism of action of the enhancers was studied using infra-red spectra by derivative and curve-fitting techniques and Confocal laser scanning microscopy. The efficacy of the optimized combination was tested in vivo in streptozocin-diabetic Wistar rats. RESULTS: A blend of 1,8 cineole, oleic acid and sodium deoxycholate in propylene glycol : ethanol (7:3) resulted in 45% enhancement, when permeation was performed in combination with iontophoresis as compared to the latter alone. In-depth analysis of infra-red spectra revealed that each of the enhancers acted differentially on lipid-protein domains of the stratum corneum thereby supporting the observed synergism. Movement of fluorescently labeled insulin depicted highlighted follicular regions and paracellular accumulation of the probe after iontophoresis and chemical enhancer treatment respectively. Presence of the fluorescent peptide in these regions 4 hour after treatment with the combination reinforced the results of the permeation studies. Finally the combination of modulated iontophoresis with chemical enhancer blend resulted in lowering of blood glucose for 8 hour in vivo. CONCLUSIONS: The study proved the applicability of modulated iontophoresis with chemical pretreatment in delivering insulin transdermally.

Particulate and vesicular drug carriers in the management of tuberculosis.

Although oral drug therapy for tuberculosis exists and is widely followed, its major drawbacks are lack of patient compliance and development of adverse effects like hepatotoxicity on long term use. Absence of new therapeutic agents and the above mentioned demerits have led to search for alternative methods for delivery of antitubercular agents. Colloidal drug carriers, a popularly utilized delivery system has been deeply explored for the cause. The article discusses the advances in the management of tuberculosis by the use of particulate and vesicular drug carriers by parenteral, inhalational and oral routes. Use of this delivery strategy has led to massive reduction in the dosage resulting in toxicity alleviation. As a number of studies have already been undertaken in experimental models, it will be a promising tool in the prevention of relapse and successful treatment of tuberculosis in patients.

Engineering and characterization of simplified vaginal and seminal fluid simulants.

BACKGROUND: Reported vaginal and seminal fluid simulants have complex compositions with multiple preparatory steps that contribute to physical instability. We report the design and characterization of stable and simplified buffers that mimic the salient physical/chemical properties of the physiological fluids. STUDY DESIGN/METHODS: Human cervicovaginal and seminal fluid samples were collected and buffering capacity was determined. The major buffering species were identified from published compositions of reproductive tract fluids. These values were used to compute the composition of vaginal and seminal fluid simulants. Ionic strength, buffering capacities, pH and osmolalities were then calculated or experimentally determined. Finally, cytotoxicity was evaluated in HEC-1-A cells and 3D reconstructed EpiVaginal™ tissue (VEC-100-FT) using naïve cells/tissue and nonoxynol-9 as controls. RESULTS: The use of calculated amounts of conjugate acid and base for buffer development resulted in compositions that did not require endpoint pH adjustment and could be formulated as stable 10× concentrates. Furthermore, due to the absence of complex divalent salts, all our proposed simulants were stable at 4 °C for 1 month whereas precipitation and pH and osmolality changes were noted in reported buffers. Experimental determination of buffering capacities yielded similar values for undiluted cervicovaginal fluid (ß4.2-5.2=35.6 ± 12.3 mM, N=7) and human seminal fluid (ß7-6=37.5 ± 5 mM, N=3). All neat simulants showed significant cytotoxicity in HEC-1-A cells but were well tolerated by organotypic vaginal tissue. CONCLUSIONS: We report revised and improved compositions of buffers mimicking salient properties of vaginal and seminal fluid necessary for in vitro product evaluation. IMPLICATIONS: To support research in reproductive health and in particular drug delivery, we have designed and characterized stable new media to mimic these important fluids that can be used in a variety of in vitro studies.

Controlling the hydration rate of a hydrophilic matrix in the core of an intravaginal ring determines antiretroviral release.

Intravaginal ring technology is generally limited to releasing low molecular weight species that can diffuse through the ring elastomer. To increase the diversity of drugs that can be delivered from intravaginal rings, we designed an IVR that contains a drug matrix encapsulated in the core of the IVR whereby the mechanism of drug release is uncoupled from the interaction of the drug with the ring elastomer. We call the device a flux controlled pump, and it is comprised of compressed pellets of a mixture of drug and hydroxypropyl cellulose within the hollow core of the ring. The pump orifice size and chemistry of the polymer pellets control the rate of hydration and diffusion of the drug-containing hydroxypropyl cellulose gel from the device. A mechanistic model describing the hydration and diffusion of the hydroxypropyl cellulose matrix is presented. Good agreement between the quantitative model predictions and the experimental studies of drug release was obtained. We achieved controlled release rates of multiple antiretrovirals ranging from µg/d to mg/d by altering the orifice design, drug loading, and mass of pellets loaded in the device. This device could provide an adaptable platform for the vaginal drug delivery of many molecules.

Osmotic pump tablets for delivery of antiretrovirals to the vaginal mucosa.

Vaginal pre-exposure prophylaxis has focused heavily on gel formulations. Low adherence linked with frequent dosing and short therapeutic duration has emerged as the major reason for inconsistent efficacy outcomes with gels in clinical trials. Osmotic pumps can achieve versatile drug release profiles however, have not been explored for vaginal delivery. In this report, we describe an osmotic pump tablet (OPT) that can deliver antiretrovirals for several days. We also describe configuring the OPT for pH sensitive delivery where the drug delivery system consistently delivers an antiretroviral at vaginal pH and then gives a burst release triggered by a coitally associated pH increase. We have investigated the vaginal OPT for multiple day delivery of a potent antiretroviral, IQP-0528 in a sheep model. To effectively register spatial drug distribution we also engineered a tool to precisely collect multiple vaginal fluid samples. In a 10-day duration post single application, high micromolar mucosal levels were obtained with peak concentration more than 6 logs higher than the EC50 of IQP-0528. Overall, our results show successful implementation of the osmotic pump technology for vaginal antiretroviral delivery.

Evaluation of folate conjugated pegylated thermosensitive magnetic nanocomposites for tumor imaging and therapy.

Superparamagnetic iron oxide nanoparticles (SPIONs) have been receiving great attention lately in biomedical applications, such as in magnetic resonance imaging and drug delivery. However, their systemic administration still remains a challenge due to their hydrophobic nature with instances of aggregation leading to fast reticuloendothelial system (RES) uptake. In this study, magnetic nanocomposites with thermosensitive polymer have been investigated. Random polymers of N-isopropylacrylamide (NIPAAM), acrylic acid (AA) and PEGMA have been coated on SPIONs followed by conjugation with folic acid. Particles of ∼200 nm and low polydispersity 0.1-0.2 having a critical temperature (T(c)) of 44 °C were formed. Thermogravimetric and powder X-ray diffraction studies showed that the nanocomposites were composed of 90% cubic face-centered magnetite. Nearly 76.5% doxorubicin was loaded onto the nanoparticles by diffusion method. Drug release was higher at the hyperthermia temperature (72.42 ± 5.25% in 48 h) proving the thermoresponsive nature of the polymer. Folate conjugated samples showed a magnetization value of 32 emu/g as well as high r1 and r2 relaxivities in magnetic resonance imaging. R2 weighted images of nanocomposites were darker than the control with 20 µg/mL as the darkest. At this concentration the magnetic composites showed nearly 95% viability in L929 fibroblast cells. These thermoresponsive nanosystems with pegylated surfaces and size of ∼200 nm are therefore highly suitable for in vivo imaging and hyperthermia based drug delivery.

Characterization and cell material interactions of PEGylated PNIPAAM nanoparticles.

The aim of this study was to investigate the haemocompatibility of poly(N-isopropylacrylamide)-co-poly(ethylene glycol), PNIPAAM-PEG based nanoparticles and the influence of poly(ethylene glycol), PEG on the interactions of nanoparticles with cells. To achieve this purpose, thermosensitive PNIPAAM-PEG nanoparticles were synthesized by free radical dispersion polymerization method. Optimized nanosystems had particle sizes less than 200 nm, low polydispersity and LCST of 40-41 degrees C. The nanoparticles also showed nearly 83% encapsulation efficiency for doxorubicin HCl with temperature dependent release. Presence of PEG resulted in reduced protein adsorption by more than 50% in comparison to non-PEG containing nanoparticles. Protein adsorption was noted to be dependent on PEG chain length and was the least with M(n)=4000. The particles up to a concentration of 2mg/ml did not show any toxicity on J774 and L929 cell lines. No interactions were observed when NIPAAM-PEG nanoparticles were incubated with blood cells viz. RBCs, neutrophils, platelets and the coagulation system suggesting their haemocompatibility.

Flexible polymerosomes--an alternative vehicle for topical delivery.

Self-assembled vesicles of poly(caprolactone)-poly(ethylene glycol)-poly(caprolactone) co-polymer of 122+/-20 nm were prepared by solvent evaporation method and analyzed morphologically by TEM and AFM. Transmission electron micrographs showed the presence of double-walled deformable structures with average wall thickness of 25 nm. AFM depicted somewhat flattened tops resembling a 'pancake' further confirming the flexibility of the nanocarriers. Permeation studies of fluorescently labelled vesicles in cadaver epidermis confirmed their presence across the stratum corneum within 2h of application and accumulation in the deeper layers thereafter. The flexible nature of these nanosystems makes them an efficient alternative to liposomes for targeting melanomas and basal cell carcinomas.

Evaluation of pharmacological efficacy of 'insulin-surfoplex' encapsulated polymer vesicles.

The present study has been designed to study whether formation of ion-pair complex or 'surfoplex' can enhance the pharmacological efficacy of protein-loaded PCL-PEG-based polymerosomes. Insulin was selected as the model protein and was complexed with sodium deoxycholate, a naturally occurring bile salt. The surfoplexes were characterized for extent and site of complexation, stability, mass and partition coefficient. The lipophilicity of insulin was enhanced 5-fold upon complexation resulting in an increase in entrapment efficiency by 10-50% for all formulations compared to free insulin. The release of insulin from the systems was also modulated with reduction in burst release by 30%. The surfoplex was found to be therapeutically active for 8h duration (C(max) serum insulin=64.15+/-13.28 mIU/mL) in diabetic rat model. However, pharmacological efficacy of the complex-loaded nanoparticles (Nps) did not show significant enhancement with respect to insulin-loaded systems. The study therefore suggests that while ion-pair complexes may improve the in vitro kinetics of protein-loaded carriers, their therapeutic potential is dependent on the intensity of interactions between the peptide chains and polymer matrix.