Osmolality - Clinical Research & Resources

Clinical studies compare personal intimacy lubricants with their impact on vaginal epithelium have pointed to a clear conclusion – that hyperosmolar lubricants can lead to measurable damage in the vaginal epithelium. Conversely, products that are iso-osmotic and that closely mimic the pH of natural vaginal secretions demonstrate no vaginal epithelial damage.

Hyperosmolal vaginal lubricants markedly reduce epithelial barrier properties in a three-dimensional vaginal epithelium model.
Seyoum Ayehuniea, Ying-YingWang, Timothy Landry, Stephanie Bogojevic, and Richard A. Cone. Toxicology Reports (2018).


The osmolality of healthy vaginal fluid is 370 ± 40 mOsm/Kg in women with Nugent scores 0–3, and that a well-characterized three-dimensional human vaginal epithelium tissue model demonstrated that vaginal lubricants with osmolality greater than 4 times that of vaginal fluid (>1500 mOsm/Kg) markedly reduce epithelial barrier properties and showed damage in tissue structure. Four out of four such lubricants caused disruption in the parabasal and basal layers of cells as observed by histological analysis and reduced barrier integrity as measured by trans-epithelial electrical resistance (TEER). No epithelial damage to these layers was observed for hypo- and iso-osmolal lubricants with osmolality of <400 mOsm/Kg. The results confirm extensive reports of safety concerns of hyperosmolal lubricants.


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Mucosal irritation potential of personal lubricants relates to product osmolality as detected by the slug mucosal irritation assay.
Els Adriaens and Jean Paul Remon. Journal of the American Sexually Transmitted Diseases Association (2008).


Five commercial lubricants with an osmolality range were evaluated using the previously validated slug mucosal irritation assay. Specifically, arion lusitanicus were treated with lubricants over 5 days to quantify mucus production and tissue damage, allowing assignment of each product into an irritation potency category (none, mild, moderate, or severe). Commonly used personal lubricants show a full range of mucosal irritation potential, which is related to product osmolality, with iso-osmotic lubrication products causing no change in vaginal mucous production or irritation.


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Treating vulvovaginal atrophy/genitourinary syndrome of menopause: how important is vaginal lubricant and moisturizer composition?
D. Edwards and N. Panay. Climacteric (2015).


Personal lubricants and moisturizers are effective treatment options in the management of vaginal dryness with a variety of causes. However, differences exist between commercially available products. Given that non-physiological pH and osmolality, and the presence of excipients such as parabens and microbicides, are associated with a variety of proven or potential detrimental effects, the recommended safe values for pH and osmolality should be carefully ensured when choosing or prescribing a personal lubricant. This provides a stimulus for both regulatory authorities and manufacturers to work together in reformulating preparations to be more patient-friendly.


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Global Consultation on Personal Lubricants
Meeting Summary


Lubricants are widely used for sexual intercourse by men, women, and transgender individuals around the world. Some reports suggest that personal lubricant used for rectal sex by men who have sex with men (MSM) is greater than 90% among MSM communities in the USA. Used in combination with condoms, personal lubricants help to reduce friction, improve comfort, and may help to reduce breakage in some situations, providing greater protection against unintended pregnancy, HIV, and other STIs. However, there are concerns about the safety of these products, as research has shown users are experiencing irritation, burning, and damaging effects to vaginal and rectal tissue. The Global Consultation on Personal Lubricants, held 8–10 November 2016 in Bangkok, Thailand, was convened to study these issues and examine ways to produce, procure, and distribute safer products for all. Hosted by the United Nations Population Fund (UNFPA), the United States Agency for International Development (USAID), the World Health Organization (WHO), and the International Planned Parenthood Federation (IPPF), the meeting brought together more than 80 manufacturers, researchers and technical experts, sexual health advocates and educators, and international organizations that procure lubricants for governments or local organizations.


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