A fluid medium was developed to simulate the fluid produced in the human vagina. The composition of the medium was based on an extensive review of the literature on constituents of human vaginal secretions. In choosing the ingredients for this medium, the goal was to emphasize properties that influence interactions of vaginal fluid with topical contraceptive, prophylactic, or therapeutic products. Among these properties, pH and osmolarity play a dominant role in physicochemical processes that govern drug release and distribution.
PIP: This article investigates a vaginal fluid simulant intended to model the fluid properties originating in the vagina--specifically the vaginal transudite found in healthy, nonpregnant premenopausal women. Methods of volume measurement of vaginal fluid fell into two categories: those that measured the quantity of vaginal fluid present at any one time and those that measured production over an extended interval. A volume of 0.75 ml vaginal fluid simulant was used. The proposed simulant was designed to incorporate information about chemical composition determined by previous researchers; this information emphasized pH modeling and the osmolarity of the material. Consequently, the specific "recipe" for 1 liter of this simulant given as compound and weight (g) was as follows: NaCl, 3.51; KOH, 1.40; Ca(OH)2, 0.222; borine serum albumin, 0.018; lactic acid, 2.00; acetic acid, 1.00; glycerol, 0.16; urea, 0.4; glucose, 5.0. The simulant was designed to have the same physical and chemical properties as those known to influence intravaginal gel efficacy. Further efforts by other researchers are needed if improved simulants are to be developed.