Astodrimer

Summary

Astodrimer (also known as astodrimer sodium, SPL7013, or VivaGel) is a synthetic, polyanionic carbosilane dendrimer formulated as a topical gel for the treatment of bacterial vaginosis (BV) and, more recently, as a nasal spray with antiviral intent. It is a prescription‑only product approved for vaginal use and is being investigated for respiratory virus prevention.

Mechanism of Action

The dendrimer carries multiple negative charges that bind to positively charged sites on bacterial surface proteins, blocking adhesion of pathogenic bacteria to the vaginal epithelium and disrupting established biofilms. In vitro, the same charge‑based interactions can inactivate enveloped viruses, including SARS‑CoV‑2, by binding to viral envelope proteins and preventing cell entry. The molecule is not absorbed systemically when applied topically.

What the Research Shows

Phase 2 and two Phase 3 double‑blind, placebo‑controlled trials in women with BV showed that astodrimer 1 % gel applied vaginally once daily for seven days achieved clinical cure rates of 46‑56 % versus 11‑21 % for placebo (P < 0.01). A systematic review and meta‑analysis of four RCTs (1,165 participants) confirmed superior clinical and microbiological cure, though vulvovaginal candidiasis occurred slightly more often with astodrimer. A separate exploratory trial of a 1 % nasal spray in 30 healthy volunteers demonstrated good tolerability, no serious adverse events, and no detectable systemic absorption, supporting further antiviral investigations.

Reported Benefits

Clinical trials consistently show that astodrimer gel improves BV cure rates and reduces patient‑reported symptoms such as discharge and odor, offering a non‑antibiotic alternative that does not promote systemic resistance. The formulation is well tolerated, with most adverse events being mild and self‑limited. Early nasal spray data suggest a safe, locally acting antiviral option that could complement infection‑control measures.

Limitations of the Evidence

Evidence of efficacy is currently limited to BV; antiviral benefits are based on in‑vitro activity and a small safety study, not on clinical infection outcomes. Recurrence reduction in BV was modest, and the rate of vulvovaginal candidiasis was higher than with placebo. Long‑term safety, comparative effectiveness against standard antibiotics, and real‑world use data remain sparse.

Safety Considerations

Astodrimer gel was associated with mild, self‑limiting adverse events; treatment‑related events occurred in about 15 % of users, most commonly vulvovaginal candidiasis (≈2‑3 %). The nasal spray study reported only mild nasal irritation, with no serious or systemic adverse events and no detectable systemic absorption. Users should be monitored for signs of candidiasis or allergic reaction.

How It Is Administered

For BV, the gel is supplied as a 5 g pre‑filled applicator to be inserted vaginally once daily for seven consecutive days. The nasal spray formulation (1 % solution) in trials was self‑administered as one spray per nostril, up to four times daily for 14 days; the product is a liquid spray, not a tablet or capsule.

Routes of Administration

Goals & Uses

• HPV preventionAnti Infective / PreventionLow
• HIV prevention (topical microbicide)Anti Infective / PreventionModerate
• HSV preventionAnti Infective / PreventionModerate
• COVID-19 prevention (nasal spray)Anti Infective / PreventionModerate
• Bacterial vaginosis treatmentAnti Infective / GynaecologyHigh

Contraindications

• Pregnancy (vaginal use)ReproductiveModerate
• Known hypersensitivity to astodrimer or formulation excipientsAllergyHigh

Adverse Effects

• HeadacheNeurologicUncommonPain in the head or upper neck
• Vaginal irritation/burningLocalCommon
• Vulvovaginal candidiasisGynaecologicalUncommon
• Vaginal dischargeLocalCommon
• Nasal irritation (nasal spray)LocalCommon

Drug Interactions

• Intravaginal medicationsLow
• Latex condoms/diaphragmsModerate

Population Constraints

• PregnancyReproductive SafetyRelative
• Pediatric patientsAgeAbsolute
• Immunocompromised individualsImmunologicalRelative

Regulatory Status

• AUApprovedApproved: Bacterial vaginosis (VivaGel vaginal gel 1%)Approved by the TGA (Therapeutic Goods Administration) in Australia.
• European UnionApprovedApproved: Bacterial vaginosis (VivaGel vaginal gel 1%)Approved by EMA in Europe for bacterial vaginosis.
• United StatesInvestigationalNot FDA-approved; investigational for BV and STI prevention; VivaGel BV not yet approved in the US.

Approved in Australia by the TGA as VivaGel (astodrimer sodium 1% vaginal gel) for bacterial vaginosis. Also approved in Europe (EMA) for the same indication. Investigational for HIV/STI prevention and COVID-19 nasal spray in various jurisdictions.

Evidence & Sources

• A phase 2, double-blind, multicenter, randomized, placebo-controlled, dose‑ranging study of the efficacy and safety of Astodrimer Gel for the treatment of bacterial vaginosis
  Journal ArticleModerateWaldbaum AS, et al.2020-01-01T00:00:00.000000Z
• Astodrimer gel for treatment of bacterial vaginosis: A systematic review and meta-analysis of randomized controlled trials
  Journal ArticleHighAbu-Zaid A, et al.2021-01-01T00:00:00.000000Z
• Astodrimer sodium antiviral nasal spray for reducing respiratory infections is safe and well tolerated in a randomized controlled trial
  Journal ArticleModerateCastellarnau A, et al.2022-01-01T00:00:00.000000Z
• Astodrimer sodium and bacterial vaginosis: a mini review
  Journal ArticleModerateMendling W, Holzgreve W2022-01-01T00:00:00.000000Z
• Advances in Dendrimer-Based Anti-Infective Systems: In Vivo Insights and Perspectives
  Journal ArticleModerateAparici C, et al.2026-01-01T00:00:00.000000Z
• Two phase 3, double-blind, placebo-controlled studies of the efficacy and safety of Astodrimer 1% Gel for the treatment of bacterial vaginosis
  Journal ArticleModerateChavoustie SE, et al.2020-01-01T00:00:00.000000Z

Frequently Asked Questions