Hypromellose
Hypromellose is a cellulose-based, aqueous tear substitute used to replace the aqueous component of the trilaminar tear film. It acts as a lacrimomimetic agent to provide lubrication and relieve dryness in the eye. **Clinical Pearl:** It is frequently used in the management of keratoconjunctivitis sicca (KCS) or 'dry eye' in animals, often in conjunction with tear stimulants like topical cyclosporine or tacrolimus. Because it is an aqueous substitute, it requires frequent application compared to more viscous ointments or gels.
Mechanism: Hypromellose is a hydrophilic polymer that acts as a **lacrimomimetic**. It increases the viscosity of tears and prolongs corneal contact time. Cellulose-based polymer → binds to existing tears → stabilizes the aqueous layer of the trilaminar tear film → prevents rapid tear evaporation and provides mechanical lubrication to the cornea and conjunctiva.
Dosing by species
- Keratoconjunctivitis sicca (dry eye) / Ocular lubrication · 1-2 drops per affected eye · Topical (Ophthalmic) · q4h to q12h (or as frequently as needed) · Ongoing · Frequency depends on the severity of dry eye. May be used as often as every 1-2 hours in severe cases.
- Ocular lubrication (e.g., during anesthesia or for exophthalmos) · 1 drop per eye · Topical (Ophthalmic) · As needed · Ongoing · Useful to prevent corneal desiccation during anesthesia.
- Ocular lubrication · 1-2 drops per affected eye · Topical (Ophthalmic) · q4h to q12h (or as frequently as needed) · Ongoing · Frequency depends on the severity of dry eye.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Hypersensitivity to hypromellose or any component of the formulation (such as preservatives like benzalkonium chloride in multi-dose bottles)
Adverse effects
- Transient blurred vision immediately after application
- Mild ocular irritation or stinging (rare)
- Crusting on the eyelids from dried polymer
Drug interactions
- Other topical ophthalmic medications · May wash out other eye drops if administered simultaneously. Hypromellose can also act as a barrier if applied before other drugs. · minor
Monitoring
- Resolution of clinical signs of dry eye (e.g., redness, mucoid discharge, blepharospasm)
- Schirmer Tear Test (STT) if managing KCS
- Corneal staining (fluorescein) to monitor for corneal ulceration secondary to dry eye
Overdose
Overdosage is highly unlikely due to the topical route of administration and lack of systemic absorption. Excess drops will simply overflow from the eye.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.