HIV (human immunodeficiency virus) is a virus that
damages the cells in the immune system and weakens a person’s ability to
fight everyday infections and disease. While AIDS cannot be transmitted from one person to another, the HIV virus can. There is currently no cure for HIV, but there are very effective drug treatments that enable most people with the virus to live a long and healthy life.
In the three decades since the first cases of AIDS were reported, investments in basic, biomedical, behavioural, and social science research have led to numerous HIV prevention interventions and life-saving treatments. Texture Analysis has an important role in this research, specifically in the improvement of drug delivery systems. This blog post contains some examples of Texture Analysis in HIV research in recent years.
HIV (human immunodeficiency virus) is a virus that damages the cells in the immune system and weakens a person’s ability to fight everyday infections and disease. While AIDS cannot be transmitted from one person to another, the HIV virus can. There is currently no cure for HIV, but there are very effective drug treatments that enable most people with the virus to live a long and healthy life.
In the three decades since the first cases of AIDS were reported, investments in basic, biomedical, behavioural, and social science research have led to numerous HIV prevention interventions and life-saving treatments. Texture Analysis has an important role in this research, specifically in the improvement of drug delivery systems. This blog post contains some examples of Texture Analysis in HIV research in recent years.
Researchers from Queen’s University Belfast have been investigating mechanical testing methods for drug-releasing vaginal rings. Vaginal rings (VRs) are currently marketed for contraceptive or hormone regulation purposes, and investigationally have been widely reported for delivery of antiretrovirals to reduce HIV transmission. To date, there is no national or international standard for the mechanical testing and minimum performance characteristics of any VR based products. This study describes a series of mechanical tests examining the durometer hardness, static and dynamic compression response, tensile properties and twist resistance of vaginal rings.
They used their TA.XTplus Texture Analyser to perform 1000 cycle compression tests on multiple samples in a purpose-built holder as well as twisting measurements. The final test protocols included assessment of cross sectional and outer diameters, durometer hardness testing of a ring laid flat in the horizontal plane, compression of the ring to 25% of its original diameter either statically for 28 days or dynamically for one thousand cycles, destructive tensile testing and recording of the angular twist during compression of the VR. Read more
Meanwhile, at Complutense University of Madrid, scientists have been undertaking a large amount of research into mucoadhesive vaginal drug delivery systems, including films, tablets and gels. Researchers have been investigating mucoadhesive vaginal films based on HMPC and zein as novel formulations to prevent sexual transmission of HIV. Although vaginal films were initially developed for a fast release of the drug, with a suitable formulation they can also be useful for sustained release. The latest strategies for the prevention of the sexual transmission of HIV have moved towards sustained-release dosage forms, so films may be an effective strategy that could also improve the patient’s comfort.
In this study, a hydrophilic polymer (hydroxypropylmethyl cellulose) and an amphiphilic polymer (zein) have been evaluated for the development of Tenofovir sustained-release vaginal films. They used their TA.XTplus Texture Analyser to measure the resistance and elasticity of the films. The film formulation developed here proved not only to have excellent mechanical properties, but was also able to release TFV in a sustained manner for 120 hours and remain attached to biological tissues throughout this time. This film could be an interesting option for the prevention of sexual transmission of HIV. Read more
Complutense University of Madrid researchers have also been investigating dapivirine bioadhesive vaginal tablets based on natural polymers for the prevention of sexual transmission of HIV. Young sub-Saharan women are a group that is vulnerable to the sexual transmission of HIV. Pre-exposure prophylaxis through vaginal microbicides could provide them an option for self-protection. Dapivirine has been demonstrated to have topical inhibitory effects in HIV, and to provide protection against the sexual transmission of this virus. This paper reports on the studies into swelling behaviour, bioadhesion and release carried out on dapivirine tablets based on chitosan, locust bean gum and pectin, to select the most suitable formulation.
They used their TA.XTplus Texture Analyser to measure the bioadhesion of gel samples. The modified simulated vaginal fluid led to a high solubility of dapivirine and allowed the dapivirine release profiles to be characterised in sink conditions; this aqueous medium is an alternative to organic solvents, which are not a realistic option when evaluating systems whose behaviour varies in aqueous and organic media.
Of the formulations evaluated, dapivirine/pectin tablets containing 290 mg of polymer and 30 mg of dapivirine present the most moderate swelling, making them the most comfortable dosage forms. Their high bioadhesive capacity would also allow the formulation to remain in the action zone and release the drug in a sustained manner, pointing to this formulation as the most promising candidate for future evaluations of vaginal microbicides for the prevention of HIV. Find out more
Researchers from the same group have been investigating chitosan-based mucoadhesive vaginal tablets for controlled release of the anti-HIV drug tenofovir. Vaginal microbicides have the potential to give women at high risk of contracting HIV the option of self-protection by preventing the sexual transmission of the virus. In this paper, mucoadhesive vaginal tablets based on chitosan, alone and in combination with pectin and locust bean gum, were developed for the sustained release of tenofovir (an antiretroviral drug). The formulations were placed in simulant vaginal fluid (SVF) to swell, and Hg porosity and SEM microscopy were used for the microstructural characterization of the swelling witnesses.
They used their TA.XTplus Texture Analyser to measure the hardness of tablet samples. The results show that the association of pectin and chitosan generated polyelectrolyte complexes and produced a robust system able to maintain its structure during the swelling process, when small pores are formed. Drug release and bovine vaginal mucoadhesion studies were performed in SVF showing that tenofovir-controlled dissolution profiles and adhesion to the mucosa were conditioned by the swelling processes of the polymer/s in each formulation.
Tablets based on chitosan/pectin have the most homogeneous tenofovir dissolution profiles and last up to 96 h, remaining attached to the vaginal mucosa for the same period. These formulations can therefore be considered a good option for the self-protection of women from the sexual transmission of HIV. Read more
Lastly from Complutense University of Madrid, scientists have been researching smart freeze-dried bi-gels for the prevention of the sexual transmission of HIV by accelerating the vaginal release of tenofovir during intercourse. Sub-Saharan African women are still at risk from the human immunodeficiency virus (HIV), and sex with men is the main route of transmission. Vaginal formulations containing antiretroviral drugs are promising tools to give women the power to protect themselves. The aim of this work was to obtain freeze-dried bigels containing pectin, chitosan, or hypromellose for the vaginal controlled release of Tenofovir, which is accelerated in the presence of semen.
Nine batches of bigels were formulated using different proportions of these polymers in the hydrogel (1, 2, and 3% w/w). The bigels obtained were freeze-dried and then underwent hardness and deformability, mucoadhesion, swelling, and drug release tests, the last two in simulated vaginal fluid (SVF) and SVF/simulated seminal fluid (SSF) mixture. They used their TA.XTplus Texture Analyser to perform mechanical tests on gel samples.
The formulation containing 3% pectin (fd3P) has the highest values for hardness, resistance to deformation, and good mucoadhesivity. Its swelling is conditioned by the pH of the medium, which is responsive to the controlled release of Tenofovir in SVF, with the fastest release in the SVF/SSF mixture. fd3P would be an interesting smart microbicidal system to allow faster release of Tenofovir in the presence of semen, and thus increase women’s ability to protect themselves from the sexual transmission of HIV. Find out more
Scientists from the Girijananda Chowdhury Institute of Pharmaceutical Science (India) have also been researching mucoadhesive vaginal gels. They have been looking at the development and evaluation of mucoadhesive nanogels of nevirapine for vaginal application, for the treatment of HIV infection. Mucoadhesive nanogels have gained greater attention as an alternative to conventional gels in the last decade. They are easier to handle and administer due to their lower viscosity at room temperature.
However, the high viscosity of the nanogels at room temperature can minimise the chance of gel leakage. Consequently, developing a mucoadhesive nanogel of nevirapine may increase the residence time of the formulation. They used their TA.XTplus Texture Analyser to perform mucoadhesion tests on different gels. The study successfully prepared this mucoadhesive gel using salting out followed by a homogenisation technique. Find out more
In an entirely different approach, researchers from Mercer University (Georgia, US) have been developing a transdermal delivery system for tenofovir alafenamide, a prodrug of tenofovir with potent antiviral activity against HIV and HBV. Tenofovir alafenamide (TAF) is an effective nucleotide reverse transcriptase inhibitor that is used in the treatment of HIV-1 and HBV. Currently, it is being investigated for HIV prophylaxis. Oral TAF regimens require daily intake, which hampers adherence and increases the possibility of viral resistance. Long-acting formulations would significantly reduce this problem. Therefore, the aim of this study was to develop a transdermal patch containing TAF and investigate its performance in vitro through human epidermis.
Two types of TAF patches were manufactured. Transparent patches were prepared using acrylate adhesive, and suspension patches were prepared using silicone and polyisobutylene adhesives. In vitro permeation studies were performed while using vertical Franz diffusion cells for seven days. An optimised silicone-based patch was characterised for its adhesive properties and tested for skin irritation.
They used their TA.XTplus Texture Analyser to perform adhesion tests. The silicone-based patch comprising of 15% w/w TAF showed the highest permeation. This study demonstrates the feasibility of developing silicone-based transdermal patches that can deliver a therapeutically relevant dose of TAF for the control of HIV and HBV infections. Find out more
To find out more about Texture Analysis of pharmaceutical products, contact Stable Micro Systems today.
For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.
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