Glycerol monolaurate does not alter rhesus macaque (Macaca mulatta) vaginal lactobacilli and is safe for chronic use.
Glycerol monolaurate (GML) is a fatty acid monoester that inhibits growth and exotoxin production of vaginal pathogens and cytokine production by vaginal epithelial cells. Because of these activities, and because of the importance of cytokine-mediated immune activation in human immunodeficiency virus type 1 (HIV-1) transmission to women, our laboratories are performing studies on the potential efficacy of GML as a topical microbicide to interfere with HIV-1 transmission in the simian immunodeficiency virus-rhesus macaque model. While GML is generally recognized as safe by the FDA for topical use, its safety for chronic use and effects on normal vaginal microflora in this animal model have not been evaluated. GML was therefore tested both in vitro for its effects on vaginal flora lactobacilli and in vivo as a 5% gel administered vaginally to monkeys. In vitro studies demonstrated that lactobacilli are not killed by GML; GML blocks the loss of their viability in stationary phase and does not interfere with lactic acid production. GML (5% gel) does not quantitatively alter monkey aerobic vaginal microflora compared to vehicle control gel. Lactobacilli and coagulase-negative staphylococci are the dominant vaginal aerobic microflora, with beta-hemolytic streptococci, Staphylococcus aureus, and yeasts sporadically present; gram-negative rods are not part of their vaginal flora. Colposcopy and biopsy studies indicate that GML does not alter normal mucosal integrity and does not induce inflammation; instead, GML reduces epithelial cell production of interleukin 8. The studies suggest that GML is safe for chronic use in monkeys when applied vaginally; it does not alter either mucosal microflora or integrity.
Schlievert
Patrick M
PM
Department of Microbiology, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN 55455, USA. schli001@umn.edu
Strandberg
Kristi L
KL
Brosnahan
Amanda J
AJ
Peterson
Marnie L
ML
Pambuccian
Stefan E
SE
Nephew
Karla R
KR
Brunner
Kevin G
KG
Schultz-Darken
Nancy J
NJ
Haase
Ashley T
AT
D000282:Administration, Intravaginal; D000818:Animals; D005260:Female; D006801:Humans; D007778:Lactobacillus / Q000187:drug effects* / Q000254:growth & development; D007848:Laurates / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D008253:Macaca mulatta; D023421:Models, Animal; D050178:Monoglycerides / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D013501:Surface-Active Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D014621:Vagina / Q000187:drug effects / Q000382:microbiology; D014622:Vaginal Creams, Foams, and Jellies / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology
D007848:Laurates; D050178:Monoglycerides; D013501:Surface-Active Agents; D014622:Vaginal Creams, Foams, and Jellies; C020777:monolaurin