Monosept (Cethexonium Bromide)

Cethexonium bromide is an ocular antiseptic used to control microbial contamination in various eye‑related conditions.

• Bacterial conjunctivitis: Reduces bacterial load on the conjunctival surface, aiding resolution of infection.
• Pre‑operative ocular antisepsis: Decontaminates the ocular surface before surgery to lower postoperative infection risk.
• Post‑operative infection prophylaxis: Applied after eye surgery to prevent bacterial colonisation and promote healing.

• Cethexonium bromide exerts its antiseptic effect by binding to microbial cell membranes and disrupting their lipid bilayer. This interaction leads to loss of membrane integrity, leakage of intracellular contents, and rapid cell death. The compound displays broad‑spectrum activity against Gram‑positive and Gram‑negative bacteria, certain fungi and enveloped viruses, making it suitable for ocular surface decontamination. The rapid bactericidal action helps limit the development of resistance when used appropriately.

Cethexonium bromide may cause local ocular reactions, ranging from mild irritation to rare severe events.

Common Side Effects

• Stinging or burning sensation: Transient discomfort upon instillation.
• Redness of the conjunctiva: Mild irritation that usually resolves quickly.
• Blurred vision: Temporary visual disturbance that clears after the solution is cleared.
• Tearing: Increased lacrimation as a reflex response.

Serious or Rare Side Effects

• Corneal ulceration: Deep corneal injury requiring immediate medical attention.
• Severe allergic reaction: Anaphylaxis or angioedema affecting the eye or surrounding tissues.

When using Cethexonium bromide ophthalmic solution, several precautions should be observed to ensure safety and efficacy.

• Hypersensitivity: Avoid use in patients with known allergy to quaternary ammonium compounds.
• Corneal integrity: Do not apply to compromised corneal epithelium unless directed by a specialist.
• Contact lenses: Remove contact lenses before instillation and re‑insert only after the recommended interval.
• Concomitant medications: Monitor for increased irritation when used with other ophthalmic solutions containing preservatives.
• Pediatric use: Use only under professional supervision in children.
• Store at room temperature: Keep in the original container, protect from light and moisture.

Cethexonium bromide can interact with other ophthalmic agents; awareness of these interactions helps prevent adverse outcomes.

Major Interactions (Avoid)

• Simultaneous use with other ocular antiseptics: May increase corneal irritation and toxicity.
• Application with contact lenses: Can cause lens discoloration and reduced comfort; lenses should be removed.

Moderate Interactions (Monitor Closely)

• Co‑administration with topical antibiotics: Monitor for additive irritation or synergistic effects.
• Use with ocular steroids: May mask signs of infection, requiring careful observation.
• Systemic antihistamines: May exacerbate dry‑eye symptoms when combined with the antiseptic.