In vivo evaluation of the release of zidovudine and polystyrene sulfonate from a dual intravaginal bioadhesive polymeric device in the pig model

A quantum mechanical investigation of nanocone oxide as a drug carrier for zidovudine: AIDS drug

Traditionally, nanocones as a drug delivery material allow controlled drug delivery close to the target area while reducing the toxicity and generic accumulation associated with traditional intravenous injection methods. In the current study, density functional theory (DFT) is employed to investigate the therapeutic potential of carbon nanocone oxide (ONC) as a carrier with zidovudine drug for the treatment of human immunodeficiency virus (HIV). The electronic ground state and excited state were studied to evaluate the drug carrier potential of ONC and Zidovudine-ONC complex. The Frontier Molecular Orbitals (FMOs) and Molecular Electrostatic Potential (MEPs) revealed that the ONC carrier acts as a donor and zidovudine as an acceptor. The FMOs confirmed the interaction between drug and carrier stabilization energy by calculating chemical hardness, material softness, electronegativity, Ionization energy and electron affinity. The natural bond analysis (NBO), non-covalent interaction (NCI) and electron localization function (ELF) revealed the charge transfer between zidovudine and ONC. The density of state (DOS) and Charge Deposition analysis (CDA) provided the charge transfer. To study the excited state of zidovudine, transition density matrix (TDM), UV(Ultra-visible), IR (infrared), Raman, and NMR (Nuclear Magnetic Resonance) spectra of ONC and zidovudine-ONC complex have been plotted. The spectra showed a significant red shift in the zidovudine-ONC complex. Photoinduced electron studies (PET) showed fluorescence quenching because of the interaction between the drug and the carrier and provided a graphical explanation of the distinct excited state. All the results show that the ONC carrier has therapeutic potential as a zidovudine carrier for the treatment of Human Immunodeficiency Virus (HIV).

In silico analytico-mathematical interpretation of biopolymeric assemblies: Quantification of energy surfaces and molecular attributes via atomistic simulations

Static-lattice atomistic simulations, in vacuum and solvent phase, have been recently employed to quantify the "in vitro-in vivo-in silico" performance-correlation profile of various drug delivery systems and biomaterial scaffolds. The reactional profile of biopolymers was elucidated by exploring the spatial disposition of the molecular components with respect to the formulation conditions and the final release medium. This manuscript provides a brief overview of recently completed and published studies related to molecular tectonics of: (a) the nanoformation and solvation properties of the surfactant-emulsified polymeric systems; (b) the formation and chemistry of polyelectrolyte complexes; (c) the effect of a plasticizer and/or drug on the physicomechanical properties of biomedical archetypes; (d) the molecular modeling templates to predict stimuli- and environmentally esponsive systems; and (e) the polymer-mucopeptide complexes and intermacromolecular networks. Furthermore, this report provides a detailed account of the role of molecular mechanics energy relationships toward the interpretation and understanding of the mechanisms that control the formation, fabrication, selection, design, performance, complexation, interaction, stereospecificity, and preference of various biopolymeric systems for biomedical applications.

Submicron Matrices Embedded in a Polymeric Caplet for Extended Intravaginal Delivery of Zidovudine

In this study, an intravaginal delivery system able to deliver an anti-HIV-1 agent for the purpose of potentially reducing HIV-1 transmission acting over an extended duration was successfully formulated. This delivery system was a composite polymeric caplet comprising zidovudine-loaded polyethylene glycol enclatherated pectin-mucin submicron matrices embedded within a poly (D,L-lactide), magnesium stearate, Kollidon® SR, and Carbopol® 974P NF-based polymeric caplet matrix. A three-factor and three-level Box-Behnken statistical design was utilized to optimize the polymeric caplet. The optimized directly compressed composite polymeric caplet hardness was 22.1 ± 0.3 N and the matrix resilience was 62.4 ± 0.6%. The swelling- and diffusion-controlled fractional zidovudine (AZT) release from the optimized caplet was 0.74 ± 0.01 in simulated vaginal fluid (SVF), which increased to 0.81 ± 0.21 in phosphate-buffered saline (PBS) simulating seminal fluid, over 30 days. Caplet matrix swelling was directly related to the percentage Carbopol 974P NF composition. An intravaginal system for AZT delivery was tested in the pig model over 28 days. X-ray analysis depicted delivery system swelling with matrix contrast fading over time as vaginal fluid permeated the matrix core. Plasma, vaginal fluid swab eluates, and tissue AZT concentrations were measured by gradient ultra-performance liquid chromatography (UPLC)-tandem photodiode array detection. Vaginal tissue and vaginal fluid swab eluate AZT concentrations remained above effective levels over 28 days and were higher than plasma AZT concentrations, availing a system with reduced systemic toxicity and more effective inhibition of viral replication at the site of entry.

Studies and methodologies on vaginal drug permeation

The vagina stands as an important alternative to the oral route for those systemic drugs that are poorly absorbed orally or are rapidly metabolized by the liver. Drug permeation through the vaginal tissue can be estimated by using in vitro, ex vivo and in vivo models. The latter ones, although more realistic, assume ethical and biological limitations due to animal handling. Therefore, in vitro and ex vivo models have been developed to predict drug absorption through the vagina while allowing for simultaneous toxicity and pathogenesis studies. This review focuses on available methodologies to study vaginal drug permeation discussing their advantages and drawbacks. The technical complexity, costs and the ethical issues of an available model, along with its accuracy and reproducibility will determine if it is valid and applicable. Therefore every model shall be evaluated, validated and standardized in order to allow for extrapolations and results presumption, and so improving vaginal drug research and stressing its benefits.

Antiretroviral bioanalysis methods of tissues and body biofluids

Research in the many areas of HIV treatment, eradication and prevention has necessitated measurement of antiretroviral (ARV) concentrations in nontraditional specimen types. To determine the knowledgebase of critical details for accurate bioanalysis, a review of the literature was performed and summarized. Bioanalytical assays for 31 ARVs, including metabolites, were identified in 205 publications measuring various tissues and biofluids. 18 and 30% of tissue or biofluid methods, respectively, analyzed more than one specimen type; 35-37% of the tissue or biofluid methods quantitated more than one ARV. 20 and 76% of tissue or biofluid methods, respectively, were used for the analysis of human specimens. HPLC methods with UV detection predominated, but chronologically MS detection began to surpass. 40% of the assays provided complete intra- and inter-assay validation data, but only 9% of publications provided any stability data with even less for the prevalent ARV in treatments.

Preformulation studies of EFdA, a novel nucleoside reverse transcriptase inhibitor for HIV prevention

4'-Ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a novel nucleoside analog of great interest because of its superior activity against wild-type and multidrug-resistant HIV-1 strains, and favorable safety profiles in vitro and in vivo. The aim of this work was to provide preformulation information of EFdA important for delivery system development. A simple, accurate and specific reverse-phase high performance liquid chromatographic (RP-HPLC) method with UV detection was developed for quantification of EFdA. In addition, physicochemical characterizations including pH solubility profile, octanol/water partition coefficient (Log Po/w), DSC analysis, field emission scanning electron microscopy, and stability studies under various conditions were conducted. EFdA existed in planar or flake shape, with a melting point of ∼130 °C, and had a pH dependent solubility. The log Po/w value of EFdA was -1.19. The compound was stable upon exposure to pH levels from 3 to 9 and showed good stability at elevated temperature (65 °C). In vitro cytotoxicity assessments were performed in two different epithelial cell lines. In cell-based studies, the EFdA selectivity index (50% cytotoxic concentration [CC50] values/50% effective concentration [EC50]) was found to be greater than 1 × 10(3). Permeability studies using cell- and tissue-based models showed that EFdA had an apparent permeability coefficient (Papp) <1 × 10(-6)cm/s and that the paracelluar pathway was the dominant transport route for EFdA. Overall, EFdA possesses favorable characteristics for further formulation development.