Update on nonoxynol-9 as vaginal spermicide

Abstract

Nonoxynol-9 (N-9) is a typical surfactant. For more than 30 years that very property of N-9 has been successfully exploited for its spermicidal action. It is available as an over-the-counter, locally acting vaginal spermicide. The suitability of N-9 as a spermicide is elaborated in this article. The reasons why N-9 may fail as a contraceptive are discussed. In spite of many drawbacks, which are mentioned in the article, N-9 is still often resorted to as a locally acting contraceptive. The review ends with suggestions to alter the molecular structure of N-9 and to adjust the dosages.

Detection of the Spermicide Nonoxynol-9 Via GC-MS

“…The chromatographic profiles observed are in agreement with industrial manufacture of nonoxynol-9, which results in a distribution of ethylene oxide repeat units, with the lowest detectable components being those corresponding to N 3 (reflecting the presence of three ethylene oxide repeats). Our results confirm a literature report that the industrial synthesis of nonoxynol-9 results in a Poisson distribution of compounds, with only trace levels of N 0 , N 1 , and N 2 being detected in the commercial product [15]. As such, the chromatograms of nonoxynol-9 show clusters of peaks centering on each poly(ethylene oxide) subunit, beginning at N 3 ( Figure 2).…”

“…Because its structure is both hydrophobic and hydrophilic, nonoxynol-9 forms micelles, which complicates its solubility [15]. Additionally, the long hydrocarbon side chains are engaged in intermolecular van der Waals interactions that negatively impact transfer of molecules into the gas phase.…”

“…The data presented herein provide direct insight into the complexity of the spermicide nonoxynol-9, and for the first time, establish the detailed signature of the substance via GC-MS [14,15]. The instrumentation employed is common to crime laboratories where electron impact ionization is routinely used, and the chromatograms and mass spectra of each isomer can be visualized in a manner not possible with softer ionization techniques.…”

“…The resulting product, a complex mixture of predominately para-substituted nonylphenols, is then subjected to a polymerization reaction with ethylene oxide. This reaction engages the phenol hydroxyl group, resulting in repeating ethylene oxide units of varying length, with the largest fraction of poly(ethylene oxide) repeats being nine (hence the name nonoxynol-9) [14,15]. The compositional complexity of nonoxynol-9, coupled with its surfactant-like properties and non-volatility have hindered both its detection via GC-MS and its detailed characterization of its mass spectral signature.…”

Microbicide Dosage Forms

“…The rate and extent of drug absorption and blood drug concentration after intravaginal administration are dependent on formulation factors, vaginal physiology, age, and menstrual cycle. Most drugs in vaginal formulations are indicated for the treatment of topical conditions such as vaginitis and other vaginal infections, and include antimicrobials (Bradshaw et al 2012), labor inducers (Seeras 1995;Seeras et al 1995), spermicides (Iyer and Poddar 2008), and sexual hormones for postmenopausal symptoms (Rad et al 2006). Vaginal preparations are traditionally used for local treatment, however, systemic effects via the vaginal route can also be achieved (Alexander et al 2004;Song et al 2004).…”