Usage
Hydroxypropylmethylcellulose (HPMC), also known as hypromellose, is primarily prescribed for the treatment of dry eyes and eye irritation. It is also used as a lubricant for artificial eyes and hard contact lenses. Additionally, HPMC finds application as a surgical aid during certain ophthalmic procedures, especially anterior segment surgeries like cataract extraction. It acts as a viscoelastic, helping maintain a deep anterior chamber during surgery and protecting the corneal endothelium. It’s also used in some diagnostic procedures such as gonioscopy.
HPMC is classified as an ophthalmic lubricant and a viscoelastic agent.
Its mechanism of action involves forming a lubricating, transparent, and moistening film on the cornea. This protective layer retains moisture, prevents tear evaporation, and provides a soothing effect to relieve dryness and irritation caused by decreased tear flow. In surgical settings, it acts as a viscoelastic, maintaining space and protecting delicate ocular tissues.
Alternate Names
Hydroxypropyl methylcellulose is also known as hypromellose. Brand names include Lacrisert (ophthalmic insert), as well as various generic artificial tear solutions and gels. Many brand name artificial tears contain HPMC as the active ingredient. Brand names for surgical solutions containing HPMC include OcuCoat. It’s important to note that numerous brands use HPMC, so checking the active ingredient list is essential. Different concentrations and formulations are available for specific uses, such as dry eye treatment versus surgical application.
How It Works
Pharmacodynamics: HPMC exerts its therapeutic effect by forming a viscous, protective film over the ocular surface. This film mimics natural tears, lubricating and moisturizing the eye, thus alleviating dryness and irritation. It reduces friction caused by blinking, improving comfort. During surgical procedures, it maintains the shape of the anterior chamber, protects the cornea, and facilitates surgical maneuvers.
Pharmacokinetics: When administered as eye drops or gel, HPMC acts locally on the ocular surface and is not systemically absorbed in significant amounts. This minimizes the risk of systemic side effects. As a surgical aid, it is directly injected into the anterior chamber and is later removed through irrigation or aspiration after the procedure is completed.
Mode of Action: HPMC’s large macromolecules create a physical barrier on the ocular surface. This barrier traps moisture, reduces tear evaporation, and lubricates the eye, relieving dryness and irritation. The viscous nature of HPMC also helps to prolong the tear film break-up time, further contributing to ocular hydration.
Elimination: When used as an ophthalmic lubricant, any excess HPMC is typically eliminated through normal tear drainage. In surgical settings, it is physically removed from the anterior chamber by irrigation/aspiration after the procedure. There is minimal systemic absorption and therefore minimal systemic elimination when used topically.
Dosage
Standard Dosage
Adults: For dry eye or eye irritation, instill one or two drops of ophthalmic solution in the affected eye(s) three or four times a day, or as directed by a physician. For Lacrisert (ophthalmic insert), one insert is placed in the inferior cul-de-sac of the eye once daily.
Children: The dosage for children is generally the same as for adults, but always follow the physician’s specific recommendations.
Special Cases:
- Elderly Patients: Dosage adjustments are not typically required in elderly patients, but individual responses and coexisting conditions should be considered.
- Patients with Renal Impairment: No dose adjustments are necessary as HPMC is not systemically absorbed in clinically significant amounts.
- Patients with Hepatic Dysfunction: No dose adjustments are necessary.
- Patients with Comorbid Conditions: Consider underlying eye conditions and any other medications being used.
Clinical Use Cases
- Intubation: Not applicable for intubation.
- Surgical Procedures: As a viscoelastic agent in anterior segment eye surgery, the dose of HPMC used is determined by the surgeon based on the specific procedure and patient’s needs.
- Mechanical Ventilation: Not applicable.
- Intensive Care Unit (ICU) Use: May be used for ocular lubrication in ICU patients to prevent corneal dryness. Follow physician’s orders.
- Emergency Situations: Not typically used in systemic emergency situations.
Side Effects
Common Side Effects
Temporary blurred vision, mild eye irritation, burning or stinging, sticky eyelashes, and foreign body sensation.
Rare but Serious Side Effects
Severe eye pain, changes in vision, continued redness or irritation. Seek medical attention if these occur.
Long-Term Effects
No significant long-term side effects are generally associated with proper HPMC use.
Adverse Drug Reactions (ADR)
Allergic reactions (rare).
Contraindications
Hypersensitivity to HPMC or any component of the formulation. Severe eye infections or injuries.
Drug Interactions
Limited information on drug interactions is available. If using other ophthalmic medications, maintain a 5-15 minute interval between administrations.
Pregnancy and Breastfeeding
Considered generally safe for use during pregnancy and breastfeeding, but always consult a doctor for individualized advice. There is limited research regarding fetal risks or neonatal side effects.
Drug Profile Summary
- Mechanism of Action: Forms a lubricating and moisturizing film on the cornea. Acts as a viscoelastic in surgical procedures.
- Side Effects: Temporary blurred vision, eye irritation, burning/stinging.
- Contraindications: Hypersensitivity to HPMC.
- Drug Interactions: Limited information available; space out other ophthalmic medications.
- Pregnancy & Breastfeeding: Generally safe, but consult a doctor.
- Dosage: 1-2 drops 3-4 times daily for dry eyes. Surgical dose as needed.
- Monitoring Parameters: Eye comfort, vision changes, signs of irritation/infection.
Popular Combinations
HPMC is often combined with other lubricants in artificial tear formulations. In surgical settings, it may be used in combination with other ophthalmic solutions.
Precautions
- General Precautions: Discontinue use if eye irritation persists or worsens. Avoid touching the tip of the container to the eye.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Hydroxypropylmethylcellulose for dry eyes?
A: Typically, one or two drops in the affected eye(s) three or four times a day, or as directed by your doctor.
A: It depends on the specific product and type of contact lenses. Some HPMC solutions are compatible with contact lenses, while others require removal of the lenses before instillation. Consult the product instructions or your doctor for specific recommendations. It is generally advisable to remove lenses before using HPMC eye drops and wait for 15 minutes after instilling the drop to re-insert them.
Q3: What are the common side effects of HPMC?
A: Common side effects include temporary blurred vision, mild eye irritation, burning or stinging sensation.
Q4: Is HPMC safe to use during pregnancy?
A: HPMC is generally considered safe to use during pregnancy, but consulting a doctor is always recommended for personalized advice.
Q5: How does HPMC work in eye surgery?
A: HPMC acts as a viscoelastic agent during anterior segment surgery. It helps to maintain a deep anterior chamber, protects the corneal endothelium, and facilitates surgical maneuvers.
Q6: Can I use HPMC if I have glaucoma?
A: Patients with glaucoma should consult their ophthalmologist before using HPMC, especially for extended periods. The increased viscosity and potential rise in intraocular pressure warrant caution.
Q7: What should I do if I experience persistent eye irritation after using HPMC?
A: Discontinue use and consult your doctor. Persistent irritation could indicate an allergic reaction or underlying eye condition requiring further evaluation.
Q8: Are there any drug interactions I should be aware of with HPMC?
A: If using other ophthalmic medications, wait 5-15 minutes between applications. Consult with your doctor about any potential interactions.
Q9: How should I store HPMC eye drops?
A: Store HPMC eye drops as directed on the product packaging. Typically, this involves storing at room temperature and avoiding excessive heat or direct sunlight. Discard the solution after the expiration date or if it changes color or becomes cloudy.
