ACETIC ACID W/ HYDROCORTISONE
Clinical safety rating: avoid
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
Acetic acid exerts antibacterial and antifungal activity by lowering pH and disrupting microbial cell membranes. Hydrocortisone is a corticosteroid with anti-inflammatory, antipruritic, and vasoconstrictive properties.
| Metabolism | Acetic acid is metabolized via the Krebs cycle to carbon dioxide and water. Hydrocortisone is primarily metabolized in the liver. |
| Excretion | Acetic acid: minimal systemic absorption; hydrocortisone: hepatic metabolism, renal excretion of metabolites (<5% unchanged). Less than 10% of applied dose excreted in urine as metabolites; biliary/fecal excretion negligible. |
| Half-life | Acetic acid: not applicable; hydrocortisone: plasma half-life ~1.5 hours (biologic half-life 8–12 hours). Due to low systemic absorption from topical application, systemic half-life is clinically irrelevant. |
| Protein binding | Hydrocortisone: ~90% bound to corticosteroid-binding globulin (CBG) and albumin. Acetic acid: negligible binding. |
| Volume of Distribution | Hydrocortisone: Vd ~0.3–0.5 L/kg (systemic); topical application results in negligible systemic distribution. |
| Bioavailability | Topical: ~1–5% of hydrocortisone absorbed through intact skin; higher with inflamed skin or occlusion. Acetic acid: negligible systemic absorption. |
| Onset of Action | Topical: anti-inflammatory effect within hours (peak at 1–2 days); acetic acid: immediate acidification. |
| Duration of Action | Topical: anti-inflammatory effect persists for 12–24 hours following single application; requires twice-daily dosing for continuous effect. |
1 applicatorful (approximately 5 g) of the cream or ointment (containing 2% acetic acid and 1% hydrocortisone) inserted intravaginally once or twice daily for 7 days.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dose adjustment required for acetic acid. Hydrocortisone is minimally affected by renal impairment; no specific adjustment recommended. |
| Liver impairment | No dose adjustment required for acetic acid. For hydrocortisone, use with caution in severe hepatic impairment (Child-Pugh C) due to reduced metabolism; consider reducing frequency or dose, though no specific guidelines exist. |
| Pediatric use | Safety and efficacy not established in pediatric patients; use not recommended. |
| Geriatric use | No specific dose adjustment required. Use caution due to potential skin atrophy and systemic absorption; limit duration to minimum effective course. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
CYP3A4 inducers (eg phenytoin) may decrease efficacy and inhibitors may increase effects Can cause hyperglycemia and adrenal suppression with prolonged use.
| FDA category | Positive |
| Breastfeeding | Minimal systemic absorption of topical hydrocortisone and acetic acid; unlikely to affect the breastfed infant. Use on limited areas, avoid application to breast or nipple area. M/P ratio not established. |
| Teratogenic Risk | Topical corticosteroids are generally considered low risk in pregnancy. Hydrocortisone is a weak corticosteroid. No increased risk of congenital malformations has been observed with topical use. Systemic absorption is minimal with small-area application. Avoid prolonged use on large areas, occlusive dressings, or high-potency steroids. Acetic acid has no known teratogenic risk. |
■ FDA Black Box Warning
Not applicable.
| Common Effects | adrenal insufficiency |
| Serious Effects |
["Hypersensitivity to any component.","Viral or fungal infections of the external ear (e.g., herpes simplex, varicella).","Perforated tympanic membrane (risk of ototoxicity)."]
| Precautions | ["For otic use only; not for ophthalmic or systemic use.","Prolonged use may lead to fungal or bacterial superinfection.","Discontinue if irritation or sensitization develops."] |
| Food/Dietary | No clinically relevant food interactions. No specific dietary restrictions. |
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| Fetal Monitoring | Monitor for signs of local irritation or hypersensitivity. No specific fetal monitoring required. If prolonged or extensive use, monitor for maternal adrenal suppression (rare). |
| Fertility Effects | No known effects on fertility from topical acetic acid or hydrocortisone. |
| Clinical Pearls | Combination otic suspension for external otitis. Ensure tympanic membrane is intact before use; perforation risks ototoxicity. Shake well before instillation. Use for no longer than 10 days to avoid fungal overgrowth or adrenal suppression. Warm bottle in hands to avoid caloric vertigo. Contraindicated in viral or fungal infections of the ear canal. |
| Patient Advice | For ear use only. Do not swallow or put in eyes. · Lie on side with affected ear upward for 5 minutes after instillation. · Keep ear clean and dry while using the medication. · Complete full course even if symptoms improve. · Do not use if you have a perforated eardrum; seek medical evaluation first. · Shake the bottle well before each use. |