Which antifungal drug used for vaginal candidiasis is classified as WHO MEC Category 4 (unacceptable risk) when combined with the levonorgestrel-releasing IUS (Mirena) due to risk of device failure?

• A Systemic fluconazole is WHO MEC Category 4 with LNG-IUS
• B Itraconazole inhibits levonorgestrel metabolism, potentially decreasing contraceptive efficacy
• C Topical clotrimazole can degrade the silicone reservoir of the LNG-IUS reducing levonorgestrel release
• D None — no antifungal drug is contraindicated with levonorgestrel IUS ✓

Explanation

No antifungal agent (topical or systemic) is classified as WHO MEC Category 4 with the LNG-IUS. Topical azoles (clotrimazole, miconazole) do not degrade the silicone matrix of the LNG-IUS at clinical concentrations and are safe to use for vaginal candidiasis in women with LNG-IUS. While systemic azoles (fluconazole, itraconazole) do interact with levonorgestrel metabolism via CYP3A4, the local hormonal delivery from the IUS is not clinically significantly affected. This distinction is important: systemic enzyme interactions affect pill contraceptive efficacy more significantly than IUS efficacy because IUS works primarily by local endometrial effects with very low systemic levonorgestrel levels.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.