PROJECT
Clinical Studies: Carraguard®/Levonorgestrel 

There is an urgent need for a vaginal product that will not only protect against sexually transmitted infections but also prevent conception. The Population Council is developing just such a product, combining the candidate microbicide Carraguard (the main ingredient of which is the sulfated polysaccharide carrageenan) with the synthetic progestin levonorgestrel (LNg).

Carraguard has already shown its ability to deliver LNg into the systemic circulation at doses known to inhibit ovulation. Laboratory studies have also shown that Carraguard is highly effective in blocking HIV in vitro. In mice, it has effectively protected against vaginal and rectal infection by herpes simplex virus-2 (HSV-2) and has also prevented human papillomavirus infection in human tissue grafted into mice.

Carraguard was tested for safety and efficacy in preventing HIV transmission in a large Phase 3 trial in South Africa. Its physical properties make the agent an ideal vehicle to deliver a progestin in a microbicide/ contraceptive combination. The progestin LNg has a long history of safety when used in various contraceptives and has been approved for clinical use in various delivery systems.

Studies conducted to date indicate that this is a viable approach to dual protection for women; future studies include confirming the efficacy of a high dose of Carraguard/LNg to delay or prevent ovulation when used “on demand” before occasional intercourse; determining the lowest effective dose of LNg for daily use; and, once the effective dose is defined, testing longer-term use over three cycles in two different regimens.

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Population Council researchers

Régine Sitruk-Ware, Robin Maguire, David Phillips

Non-Council collaborators

Luis Bahamondes (Universidade Estadual de Campinas)

Vivian Brache (PROFAMILIA)

Horacio Croxatto (Instituto Chileno de Medicina Reproductiva)

Donor

National Institute of Child Health and Human Development

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