Tenofovir vaginal film as a potential MPT product against HIV-1 and HSV-2 acquisition: formulation development and preclinical assessment in non-human primates.

Tenofovir (TFV) is an adenosine nucleotide analog with activity against HIV and HSV-2. Secondary analyses of clinical trials evaluating TFV gel as pre-exposure prophylaxis (PrEP) for HIV have shown that gel formulations of TFV provide significant protection against both HIV and HSV-2 acquisition in women who had evidence of use. An alternate quick-dissolving polymeric thin film, to deliver TFV (20 and 40 mg) has been developed as a potential multipurpose technology (MPT) platform. Film formulation was developed based on excipient compatibility, stability, and ability to incorporate TFV doses. Placebo, low dose (20 mg), and high dose (40 mg) films were utilized in these studies. The developed film platform efficiently incorporated the high dose of TFV (40 mg/film), released more than 50% of drug in 15 min with no in vitro toxicity. Pharmacological activity was confirmed in an ex vivo HIV-1 challenge study, which showed a reduction in HIV-1 infection with TFV films. Films were stable at both doses for at least 2 years. These films were found to be safe in macaques with repeated exposure for 2 weeks as evidenced by minimal perturbation to tissues, microbiome, neutrophil influx, and pH. Macaque sized TFV film (11.2 mg) evaluated in a pigtail macaque model showed higher vaginal tissue concentrations of TFV and active TFV diphosphate compared to a 15 mg TFV loaded gel. These studies confirm that TFV films are stable, safe and efficiently deliver the drug in cervicovaginal compartments supporting their further clinical development.

Intracellular Islatravir-Triphosphate in Dried Blood Spots and Peripheral Blood Mononuclear Cells from Pig-Tailed Macaques.

The purpose of this study was to evaluate the relationship between intracellular islatravir-triphosphate (ISL-TP) in paired peripheral blood mononuclear cells (PBMCs) and dried blood spots (DBS). Three pig-tailed macaques (PMs) were dosed with a single intravaginal extended-release ISL-etonogestrel film for a period of 31 days. After extraction and quantification, repeated measures correlation (rrm) was assessed between log-transformed DBS and PBMC ISL-TP concentrations. Twenty-six paired PBMC/DBS samples were included. Peak ISL-TP concentrations in DBS ranged from 262 to 913 fmol/punches, PBMC Cmax ranged from 427 to 857 fmol/106 cells. Repeated measures correlation yielded an rrm value of 0.96 (95% confidence interval 0.92-0.98; p < .0001). Importantly, ISL-TP was quantifiable in DBS and its pharmacokinetics were similar to PBMC in PMs. Human studies should evaluate DBS applications in clinical pharmacokinetic studies to help define ISL's place in the antiretroviral drug armamentarium.

Development and Evaluation of Nanoparticles-in-Film Technology to Achieve Extended In Vivo Exposure of MK-2048 for HIV Prevention.

MK-2048 is a second-generation integrase inhibitor active against HIV, which has been applied vaginally using ring formulations. In this work, a nanoparticle-in-film technology was developed as a discrete pre-exposure prophylactic product option against HIV for an extended duration of use. A film platform loaded with poly (lactic-co-glycolic acid) nanoparticles (PNP) encapsulating MK-2048 was engineered. MK-2048 PNPs were loaded into films that were manufactured via the solvent casting method. Physicochemical and mechanical properties, in vitro efficacy, Lactobacillus compatibility, in vitro and ex vivo permeability, and in vivo pharmacokinetics in macaques were evaluated. PNPs with a mean diameter of 382.2 nm and −15.2 mV zeta potential were obtained with 95.2% drug encapsulation efficiency. PNP films showed comparable in vitro efficacy to free MK-2048 (IC50 0.46 vs. 0.54 nM) and were found to have no impact on Lactobacillus. MK-2048 encapsulated in PNPs showed an increase in permeability (>4-fold) compared to the free MK-2048 in MDCKII cell lines. Furthermore, PNPs had higher ectocervical tissue permeability (1.7-fold) compared to free MK-2048. PNP films showed sustained drug levels for at least 3 weeks in the macaque vaginal fluid. This work demonstrates the synergy of integrating nanomedicine and polymeric film technology to achieve sustained vaginal drug delivery.

Drug delivery strategies for management of women's health issues in the upper genital tract.

The female upper genital tract (UGT) hosts important reproductive organs including the cervix, uterus, fallopian tubes, and ovaries. Several pathologies affect these organ systems such as infections, reproductive issues, structural abnormalities, cancer, and inflammatory diseases that could have significant impact on women's overall health. Effective disease management is constrained by the multifaceted nature of the UGT, complex anatomy and a dynamic physiological environment. Development of drug delivery strategies that can overcome mucosal and safety barriers are needed for effective disease management. This review introduces the anatomy, physiology, and mucosal properties of the UGT and describes drug delivery barriers, advances in drug delivery technologies, and opportunities available for new technologies that target the UGT.

Development, Characterization and In Vivo Pharmacokinetic Assessment of Rectal Suppositories Containing Combination Antiretroviral Drugs for HIV Prevention.

Receptive anal intercourse (RAI) contributes significantly to HIV acquisition underscoring the need to develop HIV prevention options for populations engaging in RAI practices. We explored the feasibility of formulating rectal suppositories with potent antiviral drugs for on-demand use. A fixed-dose combination of tenofovir (TFV) and elvitegravir (EVG) (40 mg each) was co-formulated in six different suppository bases (three fat- and three water-soluble). Fat-soluble witepsol H15 and water-soluble polyethylene glycol (PEG) based suppositories demonstrated favorable in vitro release and were advanced to assess in vivo pharmacokinetics following rectal administration in macaques. In vivo drug release profiles were similar for both suppository bases. Median concentrations of TFV and EVG detected in rectal fluids at 2 h were 1- and 2-logs higher than the in vitro IC50, respectively; TFV-diphosphate levels in rectal tissues met or exceeded those associated with high efficacy against rectal simian HIV (SHIV) exposure in macaques. Leveraging on these findings, a PEG-based suppository with a lower dose combination of tenofovir alafenamide (TAF) and EVG (8 mg each) was developed and found to achieve similar rectal drug exposures in macaques. This study establishes the utility of rectal suppositories as a promising on-demand strategy for HIV PrEP and supports their clinical development.

Biorelevant and screening dissolution methods for minocycline hydrochloride microspheres intended for periodontal administration.

Currently, there is no compendial-level method to assess dissolution of particulate systems administered in the periodontal pocket. This work seeks to develop dissolution methods for extended release poly(lactic-co-glycolic acid) (PLGA) microspheres applied in the periodontal pocket. Arestin®, PLGA microspheres containing minocycline hydrochloride (MIN), is indicated for reduction of pocket depth in adult periodontitis. Utilizing Arestin® as a model product, two dissolution methods were developed: a dialysis set-up using USP apparatus 4 and a novel apparatus fabricated to simulate in vivo environment of the periodontal pocket. In the biorelevant method, the microspheres were dispersed in 250 µL of simulated gingival crevicular fluid (sGCF) which was enclosed in a custom-made dialysis enclosure. sGCF was continuously delivered to the device at a biorelevant flow rate and was collected daily for drug content analysis using UPLC. Both methods could discriminate release characteristics of a panel of MIN-loaded PLGA microspheres that differed in composition and process conditions. A mechanistic model was developed, which satisfactorily explained the release profiles observed using both dissolution methods. The developed methods may have the potential to be used as routine quality control tools to ensure batch-to-batch consistency and to support evaluation of bioequivalence for periodontal microspheres.

Rational Design of a Multipurpose Bioadhesive Vaginal Film for Co-Delivery of Dapivirine and Levonorgestrel.

Human immunodeficiency virus (HIV) infection and unintended pregnancy, which can lead to life-threatening complications, are two major burdens for female reproductive health. To address these pressing health issues, multipurpose prevention technologies (MPTs) are proposed to deliver two or more drugs simultaneously. MPTs could offer several benefits for users such as improved convenience, increased effectiveness, reduced cost, and decreased environmental burden. Here, we report the development, and in vitro and in vivo assessment of a bioadhesive vaginal film as a coitally-independent MPT dosage form for delivering dapivirine (DPV) and levonorgestrel (LNG) to prevent HIV infection and unintended pregnancy, respectively. After confirming the feasibility of bioadhesive film use for weekly drug delivery in vivo through colpophotography and MRI evaluation, the pharmacokinetics (PK) of DPV/LNG single entity and combination bioadhesive films was investigated in pigtailed macaques (n = 5). Both drugs from single entity or combination films were able to provide sustained drug release in vivo. The combination film showed lower local tissue clearance for DPV and exhibited significantly increased plasma concentration for LNG as compared to the single entity film. This proof-of-concept study demonstrates the ability of this novel bioadhesive film platform to deliver LNG and DPV simultaneously as an MPT product for the prevention of HIV infection and unintended pregnancy.

Delineating the effects of hot-melt extrusion on the performance of a polymeric film using artificial neural networks and an evolutionary algorithm.

The aim of this study was to utilize an artificial neural network (ANN) in conjunction with an evolutionary algorithm to investigate the relationship between hot melt extrusion (HME) process parameters and vaginal film performance. Investigated HME process parameters were: barrel temperature, screw speed, and feed rate. Investigated film performance attributes were: percent dissolution at 30 min, puncture strength, and drug content. An ANN model was successfully developed and validated with a root mean squared error of 0.043 and 0.098 for training and validation, respectively. Of all three assessed process parameters, the model revealed that barrel temperature has a significant impact on film performance. An increase in barrel temperature resulted in increased dissolution and punctures strength and decreased drug content. Additionally, a successful implementation of an evolutionary algorithm was carried out in order to demonstrate the potential applicability of the developed ANN model in film formulation optimization. In this analysis, the values predicted of film performance attributes were within 1% error of the experimental data. The findings of this study provide a quantitative framework to understand the relationship between HME parameters and film performance. This quantitative framework has the potential to be used for film formulation development and optimization.

Nanocrystal Formulation Improves Vaginal Delivery of CSIC for HIV Prevention.

5-Chloro-3-phenylsulfonylindole-2-carboxamide (CSIC) is a highly potent non-nucleoside reverse transcriptase inhibitor (NNRTI) with potential for use in topical prophylaxis against HIV transmission. However, the hydrophobic nature of CSIC limits its administration through vaginal route. In this study, we developed nanocrystals of CSIC to potentially improve the aqueous solubility and intracellular uptake of CSIC in vitro and in vivo. CSIC nanocrystals were manufactured and stabilized with Pluronic F98 and hydroxypropyl methylcellulose E5. Transmission electron microscopy showed CSIC nanocrystals to be needle-like. Dynamic light scattering measurements showed a hydrodynamic size of 243 nm (polydispersity index < 0.3) and near neutral surface charge (- 7.8 mV). Particle size was maintained for at least 7 days in the liquid state and for at least 5 months after lyophilization. Drug content in the CSIC nanocrystal formulation (nanosuspension) was 0.8 mg/mL, which is 1000 times higher than the aqueous solubility of CSIC. In vitro release study showed that over 90% of CSIC was released from the nanocrystal formulation in a linear fashion over a period of 4 days. Importantly, CSIC nanocrystals showed equivalent cell-based anti-HIV activity (EC50 ~ 1 nM) as that of non-formulated drug. In vitro studies demonstrated rapid macrophage uptake of CSIC nanocrystals via both energy-dependent (endocytosis) and independent processes. In vivo studies in Swiss Webster female mice showed that the nanocrystal formulation significantly improved CSIC delivery to mouse cervicovaginal tissues following intravaginal instillation. In summary, nanocrystals are a promising formulation approach for topical delivery of CSIC for protection against HIV sexual transmission.

Novel Application of Hot Melt Extrusion for the Manufacturing of Vaginal Films Containing Microbicide Candidate Dapivirine.

Polymeric films are safe and effective and can be used for vaginal administration of microbicide drug candidates. Dapivirine (DPV), an investigational and clinically advanced antiretroviral drug, was selected as a model compound for this study. We have previously developed and clinically tested a quick-dissolving DPV film using solvent cast (SC) manufacturing technique. As an alternative to current pharmaceutical film manufacturing techniques, we investigated hot melt extrusion (HME) process in this study because it has several benefits, including its capacity as a continuous manufacturing process, lack of solvents, smaller footprint, and ease of scalability. The goal of this work was to evaluate the feasibility of using HME for DPV vaginal film manufacturing and to develop a robust manufacturing process using HME by evaluating the effect of process parameters on film quality and performance. DPV was successfully incorporated into a vaginal film using HME and maintained acceptable characteristics. Three process parameters (zone temperature, screw speed, and feed rate) had an impact on film quality and performance. Of these, the zone temperature was found to most significantly affect weight, thickness, puncture strength, and dissolution of films. Additionally, film manufacturing using HME was highly reproducible. Finally, the DPV HME film was comparable to films manufactured using SC in terms of physicochemical, biological, and safety characteristics including in vitro drug release, mechanical strength, tissue permeability, compatibility with commensal vaginal Lactobacilli, and in vitro bioactivity. These results demonstrate that HME is an effective, robust, and viable manufacturing method to produce vaginal films.

Design of Poly(lactic-co-glycolic Acid) (PLGA) Nanoparticles for Vaginal Co-Delivery of Griffithsin and Dapivirine and Their Synergistic Effect for HIV Prophylaxis.

Long-acting topical products for pre-exposure prophylaxis (PrEP) that combine antiretrovirals (ARVs) inhibiting initial stages of infection are highly promising for prevention of HIV sexual transmission. We fabricated core-shell poly(lactide-co-glycolide) (PLGA) nanoparticles, loaded with two potent ARVs, griffithsin (GRFT) and dapivirine (DPV), having different physicochemical properties and specifically targeting the fusion and reverse transcription steps of HIV replication, as a potential long-acting microbicide product. The nanoparticles were evaluated for particle size and zeta potential, drug release, cytotoxicity, cellular uptake and in vitro bioactivity. PLGA nanoparticles, with diameter around 180-200 nm, successfully encapsulated GRFT (45% of initially added) and DPV (70%). Both drugs showed a biphasic release with initial burst phase followed by a sustained release phase. GRFT and DPV nanoparticles were non-toxic and maintained bioactivity (IC50 values of 0.5 nM and 4.7 nM, respectively) in a cell-based assay. The combination of drugs in both unformulated and encapsulated in nanoparticles showed strong synergistic drug activity at 1:1 ratio of IC50 values. This is the first study to co-deliver a protein (GRFT) and a hydrophobic small molecule (DPV) in PLGA nanoparticles as microbicides. Our findings demonstrate that the combination of GRFT and DPV in nanoparticles is highly potent and possess properties critical to the design of a sustained release microbicide.

On-demand microbicide products: design matters.

Sexual intercourse (vaginal and anal) is the predominant mode of human immunodeficiency virus (HIV) transmission. Topical microbicides used in an on-demand format (i.e., immediately before or after sex) can be part of an effective tool kit utilized to prevent sexual transmission of HIV. The effectiveness of prevention products is positively correlated with adherence, which is likely to depend on user acceptability of the product. The development of an efficacious and acceptable product is therefore paramount for the success of an on-demand product. Acceptability of on-demand products (e.g., gels, films, and tablets) and their attributes is influenced by a multitude of user-specific factors that span behavioral, lifestyle, socio-economic, and cultural aspects. In addition, physicochemical properties of the drug, anatomical and physiological aspects of anorectal and vaginal compartments, issues relating to large-scale production, and cost can impact product development. These factors together with user preferences determine the design space of an effective, acceptable, and feasible on-demand product. In this review, we summarize the interacting factors that together determine product choice and its target product profile.

Utilization of Near-Infrared Fluorescent Imaging for Pharmaceutically Relevant Applications.

Optical imaging can be utilized for several pharmaceutical applications involving near-infrared fluorescent (NIRF) dyes or NIRF moiety-containing products. Especially during the early phases of product development, NIRF dyes can be used as surrogates for drugs and optical imaging methods can be utilized to optimize the pharmaceutical product properties based on dye entrapment efficiency, in vitro dye release, cellular uptake, and in vivo biodistribution. Based on in vivo accumulation, product efficacy and toxicity can be evaluated in the early development stage. Compared to visible fluorescent dyes, NIRF offers advantages such as low background from formulation excipients as well as biological components.In this chapter, the utility of NIRF imaging methods for in vitro characterization (in vitro release and cellular uptake) and in vivo/ex vivo applicability of pharmaceutically relevant products is presented in detail. Specifically, the application of fluorescence imaging to characterize perfluorocarbon-based formulations for dye loading, in vitro release, cellular uptake, and in vivo imaging to assess target accumulation and biodistribution is discussed. These methods are widely applicable to other nanoparticle-based products involved in inflammation/cancer imaging and therapy. Overall, NIRF-based techniques are indispensible because they are relatively easy, fast, and cost effective to characterize and optimize pharmaceutical products at different stages of product development.

Drug transporters in tissues and cells relevant to sexual transmission of HIV: Implications for drug delivery.

Efflux and uptake transporters of drugs are key regulators of the pharmacokinetics of many antiretroviral drugs. A growing body of literature has revealed the expression and functionality of multiple transporters in female genital tract (FGT), colorectal tissue, and immune cells. Drug transporters could play a significant role in the efficacy of preventative strategies for HIV-1 acquisition. Pre-exposure prophylaxis (PrEP) is a promising strategy, which utilizes topically (vaginally or rectally), orally or other systemically administered antiretroviral drugs to prevent the sexual transmission of HIV to receptive partners. The drug concentration in the receptive mucosal tissues and target immune cells for HIV is critical for PrEP effectiveness. Hence, there is an emerging interest in utilizing transporter information to explain tissue disposition patterns of PrEP drugs, to interpret inter-individual variability in PrEP drug pharmacokinetics and effectiveness, and to improve tissue drug exposure through modulation of the cervicovaginal, colorectal, or immune cell transporters. In this review, the existing literature on transporter expression, functionality and regulation in the transmission-related tissues and cells is summarized. In addition, the relevance of transporter function for drug delivery and strategies that could exploit transporters for increased drug concentration at target locales is discussed. The overall goal is to facilitate an understanding of drug transporters for PrEP optimization.

Theranostic nanoemulsions for macrophage COX-2 inhibition in a murine inflammation model.

Targeting macrophages for therapeutic and diagnostic purposes is an attractive approach applicable to multiple diseases. Here, we present a theranostic nanoemulsion platform for simultaneous delivery of an anti-inflammatory drug (celecoxib) to macrophages and monitoring of macrophage migration patterns by optical imaging, as measurement of changes in inflammation. The anti-inflammatory effect of the theranostic nanoemulsions was evaluated in a mouse inflammation model induced with complete Freund's adjuvant (CFA). Nanoemulsions showed greater accumulation in the inflamed vs. control paw, with histology confirming their specific localization in CD68 positive macrophages expressing cyclooxygenase-2 (COX-2) compared to neutrophils. With a single dose administration of the celecoxib-loaded theranostic, we observed a reduction in fluorescence in the paw with time, corresponding to a reduction in macrophage infiltration. Our data strongly suggest that delivery of select agents to infiltrating macrophages can potentially lead to new treatments of inflammatory diseases where macrophage behavior changes are monitored in vivo.

Macrophage targeted theranostics as personalized nanomedicine strategies for inflammatory diseases.

Inflammatory disease management poses challenges due to the complexity of inflammation and inherent patient variability, thereby necessitating patient-specific therapeutic interventions. Theranostics, which integrate therapeutic and imaging functionalities, can be used for simultaneous imaging and treatment of inflammatory diseases. Theranostics could facilitate assessment of safety, toxicity and real-time therapeutic efficacy leading to personalized treatment strategies. Macrophages are an important cellular component of inflammatory diseases, participating in varied roles of disease exacerbation and resolution. The inherent phagocytic nature, abundance and disease homing properties of macrophages can be targeted for imaging and therapeutic purposes. This review discusses the utility of theranostics in macrophage ablation, phenotype modulation and inhibition of their inflammatory activity leading to resolution of inflammation in several diseases.

Imaging neuroinflammation in vivo in a neuropathic pain rat model with near-infrared fluorescence and ¹9F magnetic resonance.

Chronic neuropathic pain following surgery represents a serious worldwide health problem leading to life-long treatment and the possibility of significant disability. In this study, neuropathic pain was modeled using the chronic constriction injury (CCI). The CCI rats exhibit mechanical hypersensitivity (typical neuropathic pain symptom) to mechanical stimulation of the affected paw 11 days post surgery, at a time when sham surgery animals do not exhibit hypersensitivity. Following a similar time course, TRPV1 gene expression appears to rise with the hypersensitivity to mechanical stimulation. Recent studies have shown that immune cells play a role in the development of neuropathic pain. To further explore the relationship between neuropathic pain and immune cells, we hypothesize that the infiltration of immune cells into the affected sciatic nerve can be monitored in vivo by molecular imaging. To test this hypothesis, an intravenous injection of a novel perfluorocarbon (PFC) nanoemulsion, which is phagocytosed by inflammatory cells (e.g. monocytes and macrophages), was used in a rat CCI model. The nanoemulsion carries two distinct imaging agents, a near-infrared (NIR) lipophilic fluorescence reporter (DiR) and a ¹9F MRI (magnetic resonance imaging) tracer, PFC. We demonstrate that in live rats, NIR fluorescence is concentrated in the area of the affected sciatic nerve. Furthermore, the ¹9FF MRI signal was observed on the sciatic nerve. Histological examination of the CCI sciatic nerve reveals significant infiltration of CD68 positive macrophages. These results demonstrate that the infiltration of immune cells into the sciatic nerve can be visualized in live animals using these methods.

Two-color fluorescent (near-infrared and visible) triphasic perfluorocarbon nanoemuslions.

Design and development of a new formulation as a unique assembly of distinct fluorescent reporters with nonoverlapping fluorescence spectra and a F19 magnetic resonance imaging agent into colloidally and optically stable triphasic nanoemulsion are reported. Specifically, a cyanine dye-perfluorocarbon (PFC) conjugate was introduced into the PFC phase of the nanoemulsion and a near-infrared dye was introduced into the hydrocarbon (HC) layer. To the best of our knowledge, this is the first report of a triphasic nanoemulsion system where each oil phase, HC, and PFC are fluorescently labeled and formulated into an optically and colloidally stable nanosystem. Having, each oil phase separately labeled by a fluorescent dye allows for improved correlation between in vivo imaging and histological data. Further, dual fluorescent labeling can improve intracellular tracking of the nanodroplets and help assess the fate of the nanoemulsion in biologically relevant media. The nanoemulsions were produced by high shear processing (microfluidization) and stabilized with biocompatible nonionic surfactants resulting in mono-modal size distribution with average droplet size less than 200 nm. Nanoemulsions demonstrate excellent colloidal stability and only moderate changes in the fluorescence signal for both dyes. Confocal fluorescence microscopy of macrophages exposed to nanoemulsions shows the presence of both fluorescence agents in the cytoplasm.

Cyclooxgenase-2 inhibiting perfluoropoly (ethylene glycol) ether theranostic nanoemulsions-in vitro study.

Cylcooxgenase-2 (COX-2) expressing macrophages, constituting a major portion of tumor mass, are involved in several pro-tumorigenic mechanisms. In addition, macrophages are actively recruited by the tumor and represent a viable target for anticancer therapy. COX-2 specific inhibitor, celecoxib, apart from its anticancer properties was shown to switch macrophage phenotype from tumor promoting to tumor suppressing. Celecoxib has low aqueous solubility, which may limit its tumor inhibiting effect. As opposed to oral administration, we propose that maximum anticancer effect may be achieved by nanoemulsion mediated intravenous delivery. Here we report multifunctional celecoxib nanoemulsions that can be imaged by both near-infrared fluorescence (NIRF) and (19)F magnetic resonance. Celecoxib loaded nanoemulsions showed a dose dependent uptake in mouse macrophages as measured by (19)F NMR and NIRF signal intensities of labeled cells. Dramatic inhibition of intracellular COX-2 enzyme was observed in activated macrophages upon nanoemulsion uptake. COX-2 enzyme inhibition was statistically equivalent between free drug and drug loaded nanoemulsion. However, nanoemulsion mediated drug delivery may be advantageous, helping to avoid systemic exposure to celecoxib and related side effects. Dual molecular imaging signatures of the presented nanoemulsions allow for future in vivo monitoring of the labeled macrophages and may help in examining the role of macrophage COX-2 inhibition in inflammation-cancer interactions. These features strongly support the future use of the presented nanoemulsions as anti-COX-2 theranostic nanomedicine with possible anticancer applications.

Haloenol pyranones and morpholinones as antineoplastic agents of prostate cancer.

Haloenol pyran-2-ones and morpholin-2-ones were synthesized and evaluated as inhibitors of cell growth in two different prostate human cancer cell lines (PC-3 and LNCaP). Analogs derived from L- and D-phenylglycine were found to be the most effective antagonists of LNCaP and PC-3 cell growth. Additional studies reveal that the inhibitors induced G2/M arrest and the (S)-enantiomer of the phenylglycine-based derivatives was a more potent inhibitor of cytosolic iPLA(2)ß.