A hot-melt extruded intravaginal ring for the sustained delivery of the antiretroviral microbicide UC781

Personalization of Intravaginal rings by droplet deposition modeling based 3D printing technology

Intravaginal rings (IVRs) are long-acting drug device systems designed for controlled drug release in the vagina. Commercially available IVRs employ a one-size-fits-all development approach, where all patients receive the same drug in similar doses and frequencies, allowing no space for dosage individualization for specific patients' needs. To allow flexibility for dosage individualization, this study explores the impact of infill-density on critical characteristics of personalized IVRs, manufactured using droplet deposition modeling three-dimensional (3D) printing technology. The model drug was dispersed on the surface of thermoplastic polyurethane pellets using an oil coating method. IVR infill-density ranged from 60 to 100 %. The compatibility of the drug and matrix was assessed using thermal and spectroscopic analyses. The IVRs were evaluated for weight, porosity, surface morphology, mechanical properties, and in vitro drug release. The results demonstrated high dimensional accuracy and uniformity of 3D-printed IVRs, indicating the robustness of the printing process. Increasing infill-density resulted in greater weight, storage modulus, Young's modulus, Shore hardness, and compression strength, while reducing the porosity of IVRs. All IVRs showed a controlled drug release pattern when tested under accelerated conditions of temperature for 25 days. Notably, greater infill-densities were associated with a decrease in the percentage of drug released. Overall, the study demonstrated that infill-density was an important parameter for personalizing the critical characteristics of the 3D-printed IVRs to fit individual patient needs.

Toward a new generation of vaginal pessaries via 3D-printing: concomitant mechanical support and drug delivery

To improve patient adherence, vaginal pessaries - polymeric structures providing mechanical support to treat stress urinary incontinence (SUI) - greatly benefit from 3D-printing through customization of their mechanics, e.g. infill modifications. However, currently only limited polymers provide both flawless printability and controlled drug release. The current study closes this gap by exploring 3D-printing, more specifically fused filament fabrication, of pharmaceutical grade thermoplastic polyurethanes (TPU) of different hardness and hydrophilicity into complex pessary structures. Next to the pessary mechanics, drug incorporation into such a device was addressed for the first time. Mechanically, the soft hydrophobic TPU was the most promising candidate for pessary customization, as pessaries made thereof covered a broad range of the key mechanical parameter, while allowing self-insertion. From the drug release point of view, the hydrophobic TPUs were superior over the hydrophilic one, as the release levels of the model drug acyclovir were closer to the target value. Summarizing, the fabrication of TPU-based pessaries via 3D-printing is an innovative strategy to create a customized pessary combination product that simultaneously provides mechanical support and pharmacological therapy.

Fused deposition modeling three-dimensional printing of flexible polyurethane intravaginal rings with controlled tunable release profiles for multiple active drugs

We designed and engineered novel intravaginal ring (IVR) medical devices via fused deposition modeling (FDM) three-dimensional (3D) printing for controlled delivery of hydroxychloroquine, IgG, gp120 fragment (encompassing the CD4 binding site), and coumarin 6 PLGA-PEG nanoparticles (C6NP). The hydrophilic polyurethanes were utilized to 3D-print reservoir-type IVRs containing a tunable release controlling membrane (RCM) with varying thickness and adaptable micro porous structures (by altering the printing patterns and interior fill densities) for controlled sustained drug delivery over 14 days. FDM 3D printing of IVRs were optimized and implemented using a lab-developed Cartesian 3D printer. The structures were investigated by scanning electron microscopy (SEM) imaging and in vitro release was performed using 5 mL of daily-replenished vaginal fluid simulant (pH 4.2). The release kinetics of the IVR segments were tunable with various RCM (outer diameter to inner diameter ratio ranging from 1.12 to 2.61) produced from FDM 3D printing by controlling the printing perimeter to provide daily zero-order release of HCQ ranging from 23.54 ± 3.54 to 261.09 ± 32.49 µg/mL/day. IgG, gp120 fragment, and C6NP release rates demonstrated pattern and in-fill density-dependent characteristics. The current study demonstrated the utility of FDM 3D printing to rapidly fabricate complex micro-structures for tunable and sustained delivery of a variety of compounds including HCQ, IgG, gp120 fragment, and C6NP from IVRs in a controlled manner.

In Vitro Methods for Evaluating Drug Release of Vaginal Ring Formulations-A Critical Review

The vagina is a promising site for both local and systemic drug delivery and represents an interesting administration route for compounds with poor oral bioavailability. Whereas most of the currently marketed dosage forms were designed as immediate release formulations, intravaginal rings (IVRs) offer the possibility of a controlled vaginal drug delivery over several weeks or months. For a long time, the development of IVRs was limited to steroid-releasing formulations. Recently, IVRs have witnessed a surge of new interest as promising delivery systems for microbicides. Therefore, various novel IVR designs have been introduced. To ensure that only safe and effective IVRs will be administered to patients, it is important to properly distinguish between IVRs with desired and undesired release performance. In vitro methods for evaluating drug release of IVRs that present with sufficient predictive capacity for in vivo drug release, and discriminatory power with regard to IVRs quality, are an essential tool for this purpose. The objective of the present review article is to present the current status of in vitro drug release testing of IVRs and to critically discuss current compendial and non-official in vitro drug release methods with regard to their discriminatory power and in vivo predictivity.

In vitro release testing methods for drug-releasing vaginal rings

Drug-releasing vaginal rings are torus-shaped devices, generally fabricated from thermoplastic polymers or silicone elastomers, used to administer pharmaceutical drugs to the human vagina for periods typically ranging from three weeks to twelve months. One of the most important product performance tests for vaginal rings is the in vitro release test. Although it has been fifty years since a vaginal ring device was first described in the scientific literature, and despite seven drug-releasing vaginal rings having been approved for market, there is no universally accepted method for testing in vitro drug release, and only one non-compendial shaking incubator method (for the estradiol-releasing ring Estring®) is described in the US Food and Drug Administration's Dissolution Methods Database. Here, for the first time, we critically review the diverse range of test methods that have been described in the scientific literature for testing in vitro release of drug-releasing vaginal rings. Issues around in vitro-in vivo correlation and modelling of in vitro release data are also discussed.

The development of a silicone vaginal ring with a prostaglandin analogue for potential use in the treatment of canine reproductive disorders

In veterinary medicine, vaginal rings (VRs) are rarely used. However, there are diseases of female dogs' reproductive system which represent a suitable possibility for their usage. An example of such a disease is canine pyometra which can be treated by lipophilic prostaglandin drugs, unfortunately with harmful side effects after systemic administration. The aim of the study was to prove that the matrix VR based on silicone and channel-forming substance can be successfully used as a carrier for a three-day delivery of prostaglandin E₂ (PGE₂). Based on an in-vitro release study, an optimum channel-forming substance and its concentration were selected. The results were implemented during the construction of VR from the medical grade silicone DDU-4840 with PGE₂ (5 mg). Glucose anhydrous in the 30% concentration was chosen as the most functional channel-forming substance due to synergism of osmotic activity and solubility. The DDU-VR containing PGE₂ and 30% of glucose anhydrous exhibited excellent mechanical characteristics and ensured 29% drug release through water-filled channels in first-order kinetic manner. This is eight times higher than a sample without glucose where molecular diffusion through the silicone matrix was dominating the release mechanism. Moreover, drug-free VRs were tested for mechanical resistance and the design of removal thread.

Twin-screw extrusion of sustained-release oral dosage forms and medical implants

Most of published reviews of twin-screw extrusion focused on its application for enhancing the bioavailability of amorphous solid dispersions while few of them focused on its use for manufacturing sustained-release oral dosage forms and medical implants, despite the considerable interest and success this process has garnered both in academia and in the pharmaceutical industry. Compared to conventional batch processing, twin-screw extrusion offers the advantages of continuous processing and the ability to prepare oral dosage forms and medical implants that have unique physicochemical and drug release attributes. This review provides an in-depth analysis of the formulation composition and processing conditions of twin-screw extrusion and how these factors affect the drug release properties of sustained-release dosage forms. This review also illustrates the unique advantages of this process by presenting case studies of a wide variety of commercial sustained-release products manufactured using twin-screw extrusion.

Advanced Pharmaceutical Applications of Hot-Melt Extrusion Coupled with Fused Deposition Modelling (FDM) 3D Printing for Personalised Drug Delivery

Three-dimensional printing, also known as additive manufacturing, is a fabrication process whereby a 3D object is created layer-by-layer by depositing a feedstock material such as thermoplastic polymer. The 3D printing technology has been widely used for rapid prototyping and its interest as a fabrication method has grown significantly across many disciplines. The most common 3D printing technology is called the Fused Deposition Modelling (FDM) which utilises thermoplastic filaments as a starting material, then extrudes the material in sequential layers above its melting temperature to create a 3D object. These filaments can be fabricated using the Hot-Melt Extrusion (HME) technology. The advantage of using HME to manufacture polymer filaments for FDM printing is that a homogenous solid dispersion of two or more pharmaceutical excipients i.e., polymers can be made and a thermostable drug can even be introduced in the filament composition, which is otherwise impractical with any other techniques. By introducing HME techniques for 3D printing filament development can improve the bioavailability and solubility of drugs as well as sustain the drug release for a prolonged period of time. The latter is of particular interest when medical implants are considered via 3D printing. In recent years, there has been increasing interest in implementing a continuous manufacturing method on pharmaceutical products development and manufacture, in order to ensure high quality and efficacy with less batch-to-batch variations of the pharmaceutical products. The HME and FDM technology can be combined into one integrated continuous processing platform. This article reviews the working principle of Hot Melt Extrusion and Fused Deposition Modelling, and how these two technologies can be combined for the use of advanced pharmaceutical applications.

Current State of Microbicide Development

Efforts in developing an effective vaccine for human immunodeficiency virus (HIV) has been challenging as HIV strains are highly variable and exhibit extraordinary mutability. Despite condom usage and pre-exposure prophylaxis as excellent prevention strategies, lack of accessibility in some developing countries and low adherence due to sociocultural factors continue to act as barriers in reducing the HIV epidemic. Microbicides are topical therapies developed to prevent HIV and other sexually transmitted infections during intercourse. Microbicides applied vaginally or rectally are intended to prevent HIV infection at the site of transmission by either inhibiting its entry into immune cells or prevent viral replication. This review will summarize some of the current state-of-the-art microbicide formulations that are in preclinical and clinical stages of development and discuss some of the challenges associated with microbicide development.

Sustained Release Drug Delivery Applications of Polyurethanes

Since their introduction over 50 years ago, polyurethanes have been applied to nearly every industry. This review describes applications of polyurethanes to the development of modified release drug delivery. Although drug delivery research leveraging polyurethanes has been ongoing for decades, there has been renewed and substantial interest in the field in recent years. The chemistry of polyurethanes and the mechanisms of drug release from sustained release dosage forms are briefly reviewed. Studies to assess the impact of intrinsic drug properties on release from polyurethane-based formulations are considered. The impact of hydrophilic water swelling polyurethanes on drug diffusivity and release rate is discussed. The role of pore formers in modulating drug release rate is examined. Finally, the value of assessing mechanical properties of the dosage form and approaches taken in the literature are described.

Smart and Biostable Polyurethanes for Long-Term Implants

This article reviews stimuli-responsive and biostable polyurethanes (PUs) and discusses biomedical applications of smart PUs with a particular focus on long-term implantable PU biomaterials such as PU generated artificial blood vessels, artificial intervertebral discs (IVDs), and intravaginal rings (IVRs). Recently, smart PUs have been actively researched to enhance bioactivity, biocompatibility, and reduce drug side effects. Although biodegradability is important in regenerative medicine, biostability of PU plays a key role for long-term implantable biomaterials. This article reviews recent publications of research and inventions of stimuli-responsive and biostable PUs. Applications of smart PUs in long-term implantable biomaterials are discussed and linked to the future outlook of smart biostable PU biomaterials.

Implant delivering hydroxychloroquine attenuates vaginal T lymphocyte activation and inflammation

Evidence suggests that women who are naturally resistant to HIV infection exhibit low baseline immune activation at the female genital tract (FGT). This "immune quiescent" state is associated with lower expression of T-cell activation markers, reduced levels of gene transcription and pro-inflammatory cytokine or chemokine production involved in HIV infection while maintaining an intact immune response against pathogens. Therefore, if this unique immune quiescent state can be pharmacologically induced locally, it will provide an excellent women-oriented strategy against HIV infection To our knowledge, this is the first research article evaluating in vivo, an innovative trackable implant that can provide controlled delivery of hydroxychloroquine (HCQ) to successfully attenuate vaginal T lymphocyte activation and inflammation in a rabbit model as a potential strategy to induce an "immune quiescent" state within the FGT for the prevention of HIV infection. This biocompatible implant can deliver HCQ above therapeutic concentrations in a controlled manner, reduce submucosal immune cell recruitment, improve mucosal epithelium integrity, decrease protein and gene expression of T-cell activation markers, and attenuate the induction of key pro-inflammatory mediators. Our results suggest that microbicides designed to maintain a low level of immune activation at the FGT may offer a promising new strategy for reducing HIV infection.

Solid crystal suspension of Efavirenz using hot melt extrusion: Exploring the role of crystalline polyols in improving solubility and dissolution rate

Poor aqueous solubility of drugs has emerged as a major issue for pharmaceutical scientists from many decades. The current study explores the manufacture and development of a thermodynamically stabilized solid crystal suspension (SCS) of poorly water soluble drug efavirenz via hot melt extrusion. Efavirenz is a non-nucleoside reverse transcriptase inhibitor and belongs to BCS class II. The SCS was prepared using pearlitol and xylitol as a crystalline carrier. The drug-excipient blend was processed by hot melt extrusion with up to 50% (w/w) drug loading. Physico-chemical characterization of the SCS conducted via a scanning electron microscopy, differential scanning calorimetry and hot stage microscopy confirmed that SCS are in crystalline state. Similarly, X-ray powder diffraction analysis revealed highly crystalline existence of pure drug, crystalline carriers and developed SCS. The FTIR chemical imaging analysis of SCS formulations showed a homogeneous drug distribution within respective crystalline carriers while an advanced chemical analysis via atomic force microscopy and Raman analysis complemented the foregoing findings. The developed SCS1 formulation showed up to 81 fold increase in the solubility and 4.1 fold increase in the dissolution rate of the drug compared to that of the bulk substance. Surprisingly, the developed SCS formulation remained stable for a period of more than one year at accelerated conditions inferred from dissolution studies. It can be concluded that the SCS approach can be used as an alternative contemporary technique to enhance the dissolution rates of many other poorly water-soluble drugs by means of thermal HME processing.

Reversibly pH-responsive polyurethane membranes for on-demand intravaginal drug delivery

To provide better protection for women against sexually transmitted infections, on-demand intravaginal drug delivery was attempted by synthesizing reversibly pH-sensitive polyether-polyurethane copolymers using poly(ethylene glycol) (PEG) and 1,4-bis(2-hydroxyethyl)piperazine (HEP). Chemical structure and thermo-characteristics of the synthesized polyurethanes were confirmed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), ¹H-nuclear magnetic resonance (¹H-NMR), and melting point testing. Membranes were cast by solvent evaporation method using the prepared pH-sensitive polyurethanes. The impact of varying pH on membrane swelling and surface morphology was evaluated via swelling ratio change and scanning electron microscopy (SEM). The prepared pH-responsive membranes showed two times higher swelling ratio at pH 4 than pH 7 and pH-triggered switchable surface morphology change. The anionic anti-inflammatory drug diclofenac sodium (NaDF) was used as a model compound for release studies. The prepared pH-responsive polyurethane membranes allowed continuous NaDF release for 24h and around 20% release of total NaDF within 3h at pH 7 but little-to-no drug release at pH 4.5. NaDF permeation across the prepared membranes demonstrated a reversible pH-responsiveness. The pH-responsive polyurethane membranes did not show any noticeable negative impact on vaginal epithelial cell viability or induction of pro-inflammatory cytokine production compared to controls. Overall, the non-cytotoxic HEP-based pH-responsive polyurethane demonstrated its potential to be used in membrane-based implants such as intravaginal rings to achieve on-demand "on-and-off" intravaginal drug delivery.

STATEMENT OF SIGNIFICANCE

A reversible and sharp switch between "off" and "on" drug release is achieved for the first time through new pH-sensitive polyurethane membranes, which can serve as window membranes in reservoir-type intravaginal rings for on-demand drug delivery to prevent sexually transmitted infections (STIs). Close to zero drug release occurs at the normal vaginal pH (4.5) for minimal side effects. Drug release is only triggered by elevation of pH to 7 during heterosexual intercourse. The reversibly sharp and fast "on-and-off" switch arises from the creative incorporation of a pH-sensitive monomer in the soft segment of polyurethane. This polyurethane biomaterial holds great potential to better protect women who are generally at higher risk and are more vulnerable to STIs.

Advanced surface chemical analysis of continuously manufactured drug loaded composite pellets

The aim of the present study was to develop and characterise polymeric composite pellets by means of continuous melt extrusion techniques. Powder blends of a steroid hormone (SH) as a model drug and either ethyl cellulose (EC N10 and EC P7 grades) or hydroxypropyl methylcellulose (HPMC AS grade) as polymeric carrier were extruded using a Pharma 11mm twin screw extruder in a continuous mode of operation to manufacture extruded composite pellets of 1mm length. Molecular modelling study using commercial Gaussian 09 software outlined a possible drug-polymer interaction in the molecular level to develop solid dispersions of the drug in the pellets. Solid-state analysis conducted via a differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray powder diffraction (XRPD) analyses revealed the amorphous state of the drug in the polymer matrices. Surface analysis using SEM/energy dispersive X-ray (EDX) of the produced pellets arguably showed a homogenous distribution of the C and O atoms in the pellet matrices. Moreover, advanced chemical surface analysis conducted via atomic force microscopy (AFM) showed a homogenous phase system having the drug molecule dispersed onto the amorphous matrices while Raman mapping confirmed the homogenous single-phase drug distribution in the manufactured composite pellets. Such composite pellets are expected to deliver multidisciplinary applications in drug delivery and medical sciences by e.g. modifying drug solubility/dissolutions or stabilizing the unstable drug (e.g. hormone, protein) in the composite network.

Microbicide vaginal rings: Technological challenges and clinical development

Vaginal rings (VRs) are flexible, torus-shaped, polymeric devices designed to sustain delivery of pharmaceutical drugs to the vagina for clinical benefit. Following first report in a 1970 patent application, several steroid-releasing VR products have since been marketed for use in hormone replacement therapy and contraception. Since 2002, there has been growing interest in the use of VR technology for delivery of drugs that can reduce the risk of sexual acquisition of human immunodeficiency virus type 1 (HIV-1), the causative agent of acquired immunodeficiency syndrome (AIDS). Although no vaginally-administered product has yet been approved for HIV reduction/prevention, extensive research efforts are continuing and a number of VR devices offering sustained release of so-called 'HIV microbicide' compounds are currently being evaluated in late-stage clinical studies. This review article provides an overview of the published scientific literature within this important field of research, focusing primarily on articles published within peer-reviewed journal publications. Many important aspects of microbicide-releasing VR technology are discussed, with a particular emphasis on the technological, manufacturing and clinical challenges that have emerged in recent years.

Polyurethane types, synthesis and applications – a review

Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure–property relationships.

Impact of Hydroxychloroquine-Loaded Polyurethane Intravaginal Rings on Lactobacilli

The use of polymeric devices for controlled sustained delivery of drugs is a promising approach for the prevention of HIV-1 infection. Unfortunately, certain microbicides, when topically applied vaginally, may be cytotoxic to vaginal epithelial cells and the protective microflora present within the female genital tract. In this study, we evaluated the impact of hydroxychloroquine (HCQ)-loaded, reservoir-type, polyurethane intravaginal rings (IVRs) on the growth of Lactobacillus crispatus and Lactobacillus jensenii and on the viability of vaginal and ectocervical epithelial cells. The IVRs were fabricated using hot-melt injection molding and were capable of providing controlled release of HCQ for 24 days, with mean daily release rates of 17.01 ± 3.6 μg/ml in sodium acetate buffer (pH 4) and 29.45 ± 4.84 μg/ml in MRS broth (pH 6.2). Drug-free IVRs and the released HCQ had no significant effects on bacterial growth or the viability of vaginal or ectocervical epithelial cells. Furthermore, there was no significant impact on the integrity of vaginal epithelial cell monolayers, in comparison with controls, as measured by transepithelial electrical resistance. Overall, this is the first study to evaluate the effects of HCQ-loaded IVRs on the growth of vaginal flora and the integrity of vaginal epithelial cell monolayers.

Recent advances on anti-HIV vaginal delivery systems development

A review of the recent outcomes regarding technologies to prevent vaginal transmission of HIV, mainly by using antiretroviral (ARV) drugs formulated as microbicides. An introduction about the HIV transmission mechanisms by the vaginal route is included, together with the recent challenges faced for development of successful microbicide products. The outcomes of clinical evaluations are mentioned, and the different formulation strategies studied to-date, with the requirements, advantages, disadvantages and limitations of each dosage-form type, are presented. Finally, the recent attempts to apply various types of nanotechnologies in order to develop advanced microbicide-products and overcome existing limitations, are discussed.

An Intravaginal Ring for the Simultaneous Delivery of an HIV-1 Maturation Inhibitor and Reverse-Transcriptase Inhibitor for Prophylaxis of HIV Transmission

Nucleocapsid 7 (NCp7) inhibitors have been investigated extensively for their role in impeding the function of HIV-1 replication machinery and their ability to directly inactivate the virus. A class of NCp7 zinc finger inhibitors, S-acyl-2-mercaptobenzamide thioesters (SAMTs), was investigated for topical drug delivery. SAMTs are inherently unstable because of their hydrolytically labile thioester bond, thus requiring formulation approaches that can lend stability. We describe the delivery of N-[2-(3,4,5-trimethoxybenzoylthio)benzoyl]-β-alaninamide (SAMT-10), as a single agent antiretroviral (ARV) therapeutic and in combination with the HIV-1 reverse-transcriptase inhibitor pyrimidinedione IQP-0528, from a hydrophobic polyether urethane (PEU) intravaginal ring (IVR) for a month. The physicochemical stability of the ARV-loaded IVRs was confirmed after 3 months at 40°C/75% relative humidity. In vitro, 25 ± 3 mg/IVR of SAMT-10 and 86 ± 13 mg/IVR of IQP-0528 were released. No degradation of the hydrolytically labile SAMT-10 was observed within the matrix. The combination of ARVs had synergistic antiviral activity when tested in in vitro cell-based assays. Toxicological evaluations performed on an organotypic EpiVaginal(™) tissue model demonstrated a lack of formulation toxicity. Overall, SAMT-10 and IQP-0528 were formulated in a stable PEU IVR for sustained release. Our findings support the need for further preclinical evaluation. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3426-3439, 2015.

Pharmacokinetic evaluation of tenofovir disoproxil fumarate released from an intravaginal ring in pigtailed macaques after 6 months of continuous use

BACKGROUND AND METHODS

A reservoir intravaginal ring (IVR) eluting tenofovir disoproxil fumarate (TDF) was evaluated for 6 months of continuous use in normally cycling female pigtailed macaques with monthly IVR exchanges to define pharmacokinetics and safety.

RESULTS AND CONCLUSIONS

Tenofovir levels in vaginal secretions and tissue remained consistent for 6 months with no adverse safety concerns.

Assessing the potential of the Woman's Condom for vaginal drug delivery

BACKGROUND

The Woman's Condom is a new female condom that uses a dissolvable polyvinyl alcohol capsule to simplify vaginal insertion. This preclinical study assessed the feasibility to incorporate an antiviral drug, UC781, into the Woman's Condom capsule, offering a unique drug delivery platform.

STUDY DESIGN

UC781 capsules were fabricated using methods from the development of the Woman's Condom capsules as well as those used in vaginal film development. Capsules were characterized to evaluate physical/chemical attributes, Lactobacillus compatibility, in vitro safety and bioactivity, and condom compatibility.

RESULTS

Two UC781 capsule platforms were assessed. Capsule masses (mg; mean±SD) for platforms 1 and 2 were 116.50±18.22 and 93.80±8.49, respectively. Thicknesses were 0.0034±0.0004 in and 0.0033±0.0004 in. Disintegration times were 11±3 s and 5±1 s. Puncture strengths were 21.72±3.30 N and 4.02±0.83 N. Water content measured 6.98±1.17% and 7.04±1.92%. UC781 content was 0.59±0.05 mg and 0.77±0.11 mg. Both platforms retained in vitro bioactivity and were nontoxic to TZM-bl cells and Lactobacillus. Short-term storage of UC781 capsules with the Woman's Condom pouch did not decrease condom mechanical integrity.

CONCLUSIONS

UC781 was loaded into a polymeric capsule similar to that of the Woman's Condom product. This study highlights the potential use of the Woman's Condom as a platform for vaginal delivery of drugs relevant to sexual/reproductive health, including those for short- or long-acting HIV prevention.

IMPLICATIONS

We determined the proof-of-concept feasibility of incorporation of an HIV-preventative microbicide into the Woman's Condom capsule. This study highlights various in vitro physical and chemical evaluations as well as bioactivity and safety assessments necessary for vaginal product development related to female sexual and reproductive health.

Release characteristics of polyurethane tablets containing dicarboxylic acids as release modifiers - a case study with diprophylline

The influence of several dicarboxylic acids on the release characteristics of polyurethane tablets with a high drug load was investigated. Mixtures of diprophylline (Dyph) and thermoplastic polyurethane (TPUR) (ratio: 50/50, 65/35 and 75/25 wt.%) were hot-melt extruded and injection molded with the addition of 1, 2.5, 5 and 10% wt.% dicarboxylic acid as release modifier. Incorporating malonic, succinic, maleic and glutaric acid in the TPUR matrices enhanced drug release, proportional to the dicarboxylic acid concentration in the formulation. No correlation was found between the water solubility, melting point, logP and pKa of the acids and their drug release modifying capacity. Succinic and maleic acid had the highest drug release modifying capacity which was linked to more intense molecular interactions with Dyph. A structural fit between the primary and secondary alcohol of Dyph and both carboxylic groups of the acids was at the origin of this enhanced interaction.

Development of polyether urethane intravaginal rings for the sustained delivery of hydroxychloroquine

Hydroxychloroquine (HCQ) has been shown to demonstrate anti-inflammatory properties and direct anti-HIV activity. In this study, we describe for the first time the fabrication and in vitro evaluation of two types of intravaginal ring (IVR) devices (a surfaced-modified matrix IVR and a reservoir segmental IVR) for achieving sustained delivery (>14 days) of HCQ as a strategy for preventing male-to-female transmission of HIV. Both IVRs were fabricated by hot-melt injection molding. Surface-modified matrix IVRs with polyvinylpyrrolidone or poly(vinyl alcohol) coatings exhibited significantly reduced burst release on the first day (6.45% and 15.72% reduction, respectively). Reservoir IVR segments designed to release lower amounts of HCQ displayed near-zero-order release kinetics with an average release rate of 28.38 μg/mL per day for IVRs loaded with aqueous HCQ and 32.23 μg/mL per day for IVRs loaded with HCQ mixed with a rate-controlling excipient. Stability studies demonstrated that HCQ was stable in coated or noncoated IVRs for 30 days. The IVR segments had no significant effect on cell viability, pro-inflammatory cytokine production, or colony formation of vaginal and ectocervical epithelial cells. Both IVR systems may be suitable for the prevention of HIV transmission and other sexually transmitted infections.

"Set it and forget it": women's perceptions and opinions of long-acting topical vaginal gels

Women's initial understandings and anticipated acceptability of long-acting vaginal gels as potential anti-HIV microbicides was investigated by exploring the perceptibility variables associated with prototype formulations. Four focus groups with 29 women, aged 18-45, were conducted to consider gel prototypes with varied physicochemical and rheological properties. Participants responded favorably to the concept of long-acting vaginal gels as microbicides. Distinctions in understandings and stated needs regarding product dosing, characteristics, and effectiveness offer valuable insights into product design. Long-acting vaginal gels capable of protecting against HIV/STIs will be a viable option among potential users, with dosing frequency being an important factor in willingness to use.

Polyethylene glycol-based hydrogels for controlled release of the antimicrobial subtilosin for prophylaxis of bacterial vaginosis

Current treatment options for bacterial vaginosis (BV) have been shown to be inadequate at preventing recurrence and do not provide protection against associated infections, such as that with HIV. This study examines the feasibility of incorporating the antimicrobial peptide subtilosin within covalently cross-linked polyethylene glycol (PEG)-based hydrogels for vaginal administration. The PEG-based hydrogels (4% and 6% [wt/vol]) provided a two-phase release of subtilosin, with an initial rapid release rate of 4.0 μg/h (0 to 12 h) followed by a slow, sustained release rate of 0.26 μg/h (12 to 120 h). The subtilosin-containing hydrogels inhibited the growth of the major BV-associated pathogen Gardnerella vaginalis with a reduction of 8 log10 CFU/ml with hydrogels containing ≥15 μg entrapped subtilosin. In addition, the growth of four common species of vaginal lactobacilli was not significantly inhibited in the presence of the subtilosin-containing hydrogels. The above findings demonstrate the potential application of vaginal subtilosin-containing hydrogels for prophylaxis of BV.

Engineering a segmented dual-reservoir polyurethane intravaginal ring for simultaneous prevention of HIV transmission and unwanted pregnancy

The HIV/AIDS pandemic and its impact on women prompt the investigation of prevention strategies to interrupt sexual transmission of HIV. Long-acting drug delivery systems that simultaneously protect womenfrom sexual transmission of HIV and unwanted pregnancy could be important tools in combating the pandemic. We describe the design, in silico, in vitro and in vivo evaluation of a dual-reservoir intravaginal ring that delivers the HIV-1 reverse transcriptase inhibitor tenofovir and the contraceptive levonorgestrel for 90 days. Two polyether urethanes with two different hard segment volume fractions were used to make coaxial extruded reservoir segments with a 100 µm thick rate controlling membrane and a diameter of 5.5 mm that contain 1.3 wt% levonorgestrel. A new mechanistic diffusion model accurately described the levonorgestrel burst release in early time points and pseudo-steady state behavior at later time points. As previously described, tenofovir was formulated as a glycerol paste and filled into a hydrophilic polyurethane, hollow tube reservoir that was melt-sealed by induction welding. These tenofovir-eluting segments and 2 cm long coaxially extruded levonorgestrel eluting segments were joined by induction welding to form rings that released an average of 7.5 mg tenofovir and 21 µg levonorgestrel per day in vitro for 90 days. Levonorgestrel segments placed intravaginally in rabbits resulted in sustained, dose-dependent levels of levonorgestrel in plasma and cervical tissue for 90 days. Polyurethane caps placed between segments successfully prevented diffusion of levonorgestrel into the tenofovir-releasing segment during storage.Hydrated rings endured between 152 N and 354 N tensile load before failure during uniaxial extension testing. In summary, this system represents a significant advance in vaginal drug delivery technology, and is the first in a new class of long-acting multipurpose prevention drug delivery systems.

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.

Evaluation of hot-melt extrusion technique in the preparation of HPC matrices for prolonged release

The aim of the work was to explore the potential of hot-melt extrusion (HME) for preparing hydroxypropyl cellulose (HPC)-based prolonged-release matrices intended for oral administration. For this purpose, compressed and extruded systems, either composed of polymer only or containing different amounts of a model drug (theophylline or ketoprofen), were compared. The overall morphological/physical changes of the systems following interaction with water indicated that the manufacturing process would not exert a major influence on the swelling behavior of the polymeric matrices. On the other hand, the release rate was generally higher from HME systems probably due to an increase of the drug dissolution rate, which is in agreement with the relevant DSC data (loss of drug cristallinity). However, the technological characteristics of the matrices and the maximum drug load were demonstrated to depend on the mode of interaction of the active ingredient with the molten polymer. In this respect, the formation of a composite material from ketoprofen and HPC, when mixed in specific ratios, was supposed to explain the differences observed between compressed and extruded systems in terms of morphological characteristics, hydration/swelling and release. The obtained results support the possibility of exploiting the advantages offered by HME technique, above all the potential for continuous manufacturing, in the preparation of prolonged-release swellable matrices based on a cellulose derivative.

A review of hot-melt extrusion: process technology to pharmaceutical products

Over the last three decades industrial adaptability has allowed hot-melt extrusion (HME) to gain wide acceptance and has already established its place in the broad spectrum of manufacturing operations and pharmaceutical research developments. HME has already been demonstrated as a robust, novel technique to make solid dispersions in order to provide time controlled, modified, extended, and targeted drug delivery resulting in improved bioavailability as well as taste masking of bitter active pharmaceutical ingredients (APIs). This paper reviews the innumerable benefits of HME, based on a holistic perspective of the equipment, processing technologies to the materials, novel formulation design and developments, and its varied applications in oral drug delivery systems.

Vaginal rings for delivery of HIV microbicides

Following the successful development of long-acting steroid-releasing vaginal ring devices for the treatment of menopausal symptoms and contraception, there is now considerable interest in applying similar devices to the controlled release of microbicides against HIV. In this review article, the vaginal ring concept is first considered within the wider context of the early advances in controlled-release technology, before describing the various types of ring device available today. The remainder of the article highlights the key developments in HIV microbicide-releasing vaginal rings, with a particular focus on the dapivirine ring that is presently in late-stage clinical testing.

Quantitative evaluation of a hydrophilic matrix intravaginal ring for the sustained delivery of tenofovir

In vitro testing and quantitative analysis of a matrix, hydrophilic polyether urethane (HPEU) intravaginal ring (IVR) for sustained delivery of the anti-HIV agent tenofovir (TFV) are described. To aid in device design, we employed a pseudo-steady-state diffusion model to describe drug release, as well as an elastic mechanical model for ring compression to predict mechanical properties. TFV-HPEU IVRs of varying sizes and drug loadings were fabricated by hot-melt extrusion and injection molding. In vitro release rates of TFV were measured at 37 °C and pH 4.2 for 30 or 90 days, during which times IVR mechanical properties and swelling kinetics were monitored. Experimental data for drug release and mechanical properties were compared to model predictions. IVRs loaded with 21% TFV (w/w) released greater than 2mg TFV per day for 90 days. The diffusion model predicted 90 day release data by extrapolating forward from the first 7 days of data. Mechanical properties of IVRs were similar to NuvaRing, although the matrix elastic modulus decreased up to three-fold following hydration. This is the first vaginal dosage form to provide sustained delivery of milligram quantities of TFV for 90 days. Drug release and mechanical properties were approximated by analytical models, which may prove useful for the continuing development of IVRs for HIV prevention or other women's health indications.

An intravaginal ring that releases the NNRTI MIV-150 reduces SHIV transmission in macaques

Microbicides may prevent HIV and sexually transmitted infections (STIs) in women; however, determining the optimal means of delivery of active pharmaceutical ingredients remains a major challenge. We previously demonstrated that a vaginal gel containing the non-nucleoside reverse transcriptase inhibitor MIV-150 partially protected macaques from SHIV-RT (simian/HIV reverse transcriptase) infection, and the addition of zinc acetate rendered the gel significantly protective. We test the activity of MIV-150 without the addition of zinc acetate when delivered from either ethylene vinyl acetate (EVA) or silicone intravaginal rings (IVRs). MIV-150 was successfully delivered, because it was detected in vaginal fluids and tissues by radioimmunoassay in pharmacokinetic studies. Moreover, EVA IVRs significantly protected macaques from SHIV-RT infection. Our results demonstrate that MIV-150-containing IVRs have the potential to prevent HIV infection and highlight the possible use of IVRs for delivering drugs that block HIV and other STIs.

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.

Drug delivery in multiple indication (multipurpose) prevention technologies: systems to prevent HIV-1 transmission and unintended pregnancies or HSV-2 transmission

INTRODUCTION

The development of multiple indication (multipurpose) prevention technologies (MIPTs) is driven by overlapping relationships in the area of female reproductive health.

AREAS COVERED

In this review, the basis for MIPTs is detailed. The current state of the field for the use of drug delivery in novel MIPTs is covered. Of particular interest is the application of intravaginal rings (IVRs) for the delivery of two drugs simultaneously, to prevent one STI and pregnancy, or two STIs. IVRs are currently available commercially for contraception and have been developed for release of microbicides to prevent sexual transmission of HIV-1. Novel IVRs capable of releasing relatively large amounts of drugs such as tenofovir are discussed, along with those that contain independent delivery elements, such as pods, that can be used to release drugs at independent rates. The vaginal administration of macromolecules (antibodies and vaccines) is also reviewed in the context of MIPTs.

EXPERT OPINION

The field of MIPTs remains one of potential. There is yet to be a proven microbicide effective at preventing sexual transmission of HIV-1. Development of MIPTs in the near term will proceed under the assumption that one or more antiretroviral (ARV) drugs will eventually be proven successful. IVRs have already demonstrated success in the area of contraception. Prevention of sexual transmission of HIV-1 and herpes simplex virus-2 (HSV-2) (or suppression of recurrence) remains an attractive MIPT target. In the long term, development of MIPTs will require validation of surrogate end points, particularly for prevention of HIV-1 transmission.