Natamycin
| Evidence Level: L2 | Predicted Indications: 10 |
Table of Contents
Natamycin: From Mycotic Corneal Ulcer to Vulvovaginal Candidiasis
One-Sentence Summary
Natamycin is a polyene antifungal originally used for fungal (mycotic) corneal ulcer. The TxGNN model predicts it may be effective for vulvovaginal candidiasis, with 1 completed Phase 3 clinical trial and 14 publications currently supporting this direction.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Mycotic corneal ulcer |
| Predicted New Indication | Vulvovaginal candidiasis |
| TxGNN Prediction Score | 99.97% |
| Evidence Level | L2 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 1 |
| Recommended Decision | Proceed with Guardrails |
Note on evidence level: the only Phase 3 trial tests a natamycin + lactulose combination, so the effect of natamycin alone cannot be isolated. This report therefore grades the evidence conservatively as L2 (one completed Phase 3 RCT) rather than L1 (two or more).
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available for this drug. Based on the known polyene class mechanism, natamycin binds ergosterol in fungal cell membranes and disrupts membrane function.
Natamycin's approved use is topical treatment of fungal eye infections (the Singapore product is a 5% ophthalmic suspension). Candida species are also ergosterol-containing fungi, so activity against vulvovaginal candidiasis is mechanistically consistent. Natamycin vaginal tablets and pessaries (e.g. Pimafucin) have long been used for vaginal yeast infections in other countries, and the literature includes several older clinical studies with cure rates of roughly 76–94%.
The same logic explains why related predictions (candidiasis, vulvitis, vulvovaginitis, vaginitis) are plausible only where Candida is the cause. Predictions with no fungal link, such as postmenopausal atrophic vaginitis and vulvar neoplasm, are not supported by any evidence.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT06411314 | Phase 3 | Completed | 218 | Randomized superiority trial of natamycin 100 mg + lactulose 300 mg vaginal suppositories vs. natamycin 100 mg (Pimafucin) or lactulose 300 mg alone in non-pregnant adult women with vulvovaginal candidiasis. It is a combination product, so natamycin's own contribution cannot be separated. |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 39979898 | 2025 | RCT | BMC Women's Health | Efficacy and safety of natamycin + lactulose vaginal suppositories in adult women with vulvovaginal candidiasis |
| 4561566 | 1972 | Comparative clinical trial | Med J Aust | Amphotericin B (Fungilin) vs. natamycin (Pimafucin) pessaries in vaginal candidiasis |
| 6760652 | 1982 | Clinical study | Acta Obstet Gynecol Scand | 33 patients on natamycin vaginal tablets for 10 days; cure rate 94% with partner treated vs. 88% with placebo cream, not significantly different |
| 4584444 | 1973 | Clinical study | The Practitioner | Natamycin for vaginal candidiasis in pregnancy |
| 6966774 | 1980 | Clinical study | N Z Med J | 50 women given Pimafucin vaginal tablets for 10 days; 76% cure rate at two weeks, maintained at four weeks |
| 159686 | 1979 | Controlled trial | Aust N Z J Obstet Gynaecol | 120 patients with monilial vulvovaginitis; adding Elase to natamycin improved symptom relief and organism eradication vs. natamycin alone |
| 11048415 | 1999 | Review | Ceska Gynekol | Diagnosis of chronic vaginal candidiasis; natamycin compared with clotrimazole |
| 1082689 | 1975 | Clinical study | Zentralbl Gynakol | Oral metronidazole plus vaginal natamycin; vaginal candidiasis cured clinically in 89% after the first course |
| 12849848 | 2003 | Case-control | Reprod Toxicol | Teratology study of vaginal natamycin in pregnancy (supporting safety data) |
| 18288724 | 2008 | Formulation/preclinical | J Pharm Sci | Natamycin–γ-cyclodextrin vaginal mucoadhesive tablets; MIC90 below 0.0313 µg/mL |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN06719P | NATACYN 5% Sterile Ophthalmic Suspension (Alcon Research LLC) | Solution | Not stated in the data compiled for this report |
The only registered product is an ophthalmic suspension. No vaginal natamycin formulation is registered in Singapore, so using it for vulvovaginal candidiasis would need a suitable dosage form and route.
Safety Considerations
Safety data for natamycin are limited in the data compiled for this report. No drug-interaction records were found, and no contraindicated diseases were identified from the knowledge graph. A case-control study of vaginal natamycin use in pregnancy (PMID 12849848) provides some supporting reassurance. Please refer to the package insert for full safety information.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: A completed Phase 3 RCT (n=218) and several older clinical studies support natamycin for vulvovaginal candidiasis, and the antifungal mechanism fits. However, the Phase 3 trial used a natamycin + lactulose combination, and Singapore currently has only an ophthalmic product.
To proceed, the following is needed:
- Obtain and review the HSA package insert for warnings and contraindications
- Confirm the mechanism of action from DrugBank
- Review the full results of NCT06411314 and PMID 39979898, especially the natamycin-alone arm
- Evaluate the availability of a vaginal formulation and route in Singapore
- Limit the scope to candidal infections; the predictions for trichomonal vulvovaginitis, atrophic vaginitis, vulvar ulceration, vulvar neoplasm and tinea nigra lack supporting evidence and should be held
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.