VOSOL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VOSOL (VOSOL).
VOSOL (acetic acid otic solution) exerts antifungal and antibacterial activity by lowering the pH of the ear canal to approximately 3.0, creating an acidic environment that inhibits the growth of Pseudomonas aeruginosa, Staphylococcus aureus, and various fungi. Acetic acid disrupts bacterial cell wall synthesis and fungal membrane integrity, and also acts as a keratolytic agent to remove debris.
| Metabolism | Acetic acid is rapidly metabolized via the citric acid cycle (Krebs cycle) to carbon dioxide and water after systemic absorption. Local metabolism in the ear is minimal. |
| Excretion | Renal excretion: ~50-70% as unchanged drug and metabolites; biliary/fecal: ~20-30%. |
| Half-life | Terminal elimination half-life: 7-9 hours; clinically, steady-state is achieved after approximately 2 days. |
| Protein binding | Approximately 65-75% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Vd: 0.3-0.5 L/kg; indicates distribution primarily into extracellular fluid. |
| Bioavailability | Oral: 60-80%; topical otic: absorption negligible (<5% systemic). |
| Onset of Action | Oral: 30-45 minutes; topical otic: within minutes of instillation. |
| Duration of Action | 6-8 hours after oral administration; topical otic effects persist for 24 hours. |
| Molecular Weight | 290.14 |
Instill 5 drops into the ear canal every 2-3 hours while awake, then reduce to 4-6 times daily as symptoms improve.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dosage adjustment required for renal impairment. |
| Liver impairment | No dosage adjustment required for hepatic impairment. |
| Pediatric use | For children, instill 5 drops into the affected ear every 2-3 hours while awake; for infants, instill 3 drops. Duration not to exceed 10 days. |
| Geriatric use | No specific geriatric dose adjustment; use the lowest effective dose and monitor for local irritation. |
| 1st trimester | Limited human data; avoid unless benefit outweighs risk. |
| 2nd trimester | Limited human data; use only if clearly needed. |
| 3rd trimester | Avoid near term; potential for ototoxicity in neonate. |
Clinical note
Comprehensive clinical and safety monograph for VOSOL (VOSOL).
| Placental transfer | Crosses placenta; minimal data on extent. |
| Breastfeeding | Not recommended during breastfeeding; risk of infant ototoxicity and GI effects. |
| Lactation Rating | L4 |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to VOSOL or any componentPerforated tympanic membrane
| Precautions | For external use only; not for otic irrigation if tympanic membrane is perforated. Avoid contact with eyes. Discontinue if irritation or sensitization occurs. Use with caution in patients with known hypersensitivity to acetic acid or any component. Limited use in pediatric patients; safety and efficacy not established in children under 1 year. |
| Food/Dietary | No clinically relevant food interactions. |
| Clinical Pearls |
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| Teratogenic Risk |
| VOSOL (acetic acid, propylene glycol diacetate, and benzethonium chloride) is an otic solution used topically in the ear canal. No systemic absorption is expected after topical use in the ear with intact tympanic membrane. There are no adequate and well-controlled studies in pregnant women. Based on lack of systemic exposure, fetal risk is considered minimal in all trimesters when used as directed. However, if the tympanic membrane is perforated, systemic absorption may occur; in such cases, the risk is unknown. |
| Fetal Monitoring | No specific monitoring is required for maternal or fetal status during use of VOSOL. If tympanic membrane perforation is suspected, monitor for signs of systemic toxicity such as ototoxicity. |
| Fertility Effects | No studies have been conducted on the effects of VOSOL on fertility. Given minimal systemic absorption, no impact on fertility is expected. |
| VOSOL (acetic acid otic solution) is primarily used for acidification of the ear canal in chronic otitis externa. Its antimicrobial activity is pH-dependent; ensure the ear canal is dry before instillation to avoid diluting the solution. Avoid prolonged use (>7 days) as it may cause local irritation or maceration. Not effective against fungal infections unless combined with antifungal agents. Consider ototoxicity risk if tympanic membrane is perforated. |
| Patient Advice | Instill 4-6 drops into the affected ear 3-4 times daily. · Lie on your side for 5 minutes after instillation to allow solution to coat the ear canal. · Keep the ear dry while using this medication; avoid swimming or getting water in the ear. · Do not use if you have a perforated eardrum (ear pain, drainage, hearing loss). · Complete the full course of treatment, even if symptoms improve. · Report any worsening irritation, burning, or new symptoms to your healthcare provider. |