Ophthalmic Drug Delivery and Dosage Forms
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Questions and Answers

What should a patient do to minimize taste and drainage after instilling eye drops?

  • Use a cotton ball to absorb excess liquid.
  • Keep the eye open for as long as possible.
  • Apply pressure to the inner corner of the eye for 30 seconds. (correct)
  • Gently blow the nose immediately after application.

When administering eye drops and ointments, what is the recommended order and time interval?

  • Ointment first, followed by drops after 5 minutes.
  • Drops first, followed by ointment after 10 minutes. (correct)
  • Ointment should not be used if drops are applied.
  • Drops and ointments can be applied simultaneously.

What is a critical guideline for the storage of eye drop products?

  • Most products should be kept in direct sunlight.
  • Certain eye drops may require refrigeration as specified. (correct)
  • All eye drops must be stored in a freezer.
  • Eye drops should be stored at room temperature regardless of the product.

What is a major pathway for ophthalmic drug absorption into systemic circulation?

<p>Nasolacrimal drainage into the nasal cavity (A)</p> Signup and view all the answers

What action should be taken if multi-dose eye drops show signs of contamination?

<p>Dispose of the product within 30 days of opening. (D)</p> Signup and view all the answers

Which of the following is NOT recommended when administering eye ointment?

<p>Squeezing a ribbon of ointment directly into the eye. (B)</p> Signup and view all the answers

Which factor is NOT considered key in designing topical ophthalmic dosage forms?

<p>Bioavailability (D)</p> Signup and view all the answers

What is the consequence of contamination in ophthalmic products?

<p>Risk of serious complications including blindness (D)</p> Signup and view all the answers

Which preservative is most commonly used in multi-dose eye drops?

<p>Benzalkonium Chloride (BAK) (B)</p> Signup and view all the answers

Which statement about the GI tract absorption pathway for ophthalmic drugs is accurate?

<p>Drugs reaching the nasopharynx can be swallowed leading to GI absorption. (B)</p> Signup and view all the answers

Why do single-use eye drops not require preservatives?

<p>They are designed for immediate use and do not last long. (C)</p> Signup and view all the answers

What is a potential drawback of using Benzalkonium Chloride (BAK) as a preservative?

<p>Risk of corneal epithelium damage at high concentrations (B)</p> Signup and view all the answers

What percentage of an instilled ophthalmic dose can potentially be systemically absorbed?

<p>More than 50% (C)</p> Signup and view all the answers

Which preservative has seen a decline in use due to hypersensitivity concerns?

<p>Thimerosal (C)</p> Signup and view all the answers

What is the ideal pH range for an ophthalmic product to avoid eye irritation?

<p>6.6 - 7.8 (C)</p> Signup and view all the answers

What osmolarity is generally considered isotonic for ophthalmic formulations?

<p>300 mOsm/kg (C)</p> Signup and view all the answers

Which of the following viscosity modifiers is NOT commonly used in ophthalmic formulations?

<p>Ethanol (A)</p> Signup and view all the answers

What role do buffers play in ophthalmic formulations?

<p>Adjust pH for stability and patient comfort (B)</p> Signup and view all the answers

Which ingredient is intentionally hypertonic for treating corneal edema?

<p>Sodium chloride 5% (A)</p> Signup and view all the answers

What potential issue can arise from using excessive viscosity in ophthalmic formulations?

<p>Blurred vision (A)</p> Signup and view all the answers

What is the primary form of liquid ophthalmics?

<p>Solutions (D)</p> Signup and view all the answers

What is the function of tonicity modifiers in ophthalmic solutions?

<p>To adjust osmolarity for stability (C)</p> Signup and view all the answers

How are most solution formulations sterilized?

<p>Through heat or filtration (D)</p> Signup and view all the answers

What is the primary purpose of using finely micronized drug particles in suspensions?

<p>To promote rapid dissolution (C)</p> Signup and view all the answers

Why can't suspensions be filter sterilized?

<p>It would remove the drug particles from the formulation (D)</p> Signup and view all the answers

What roles do chelating agents, like EDTA sodium, serve in ophthalmic products?

<p>Enhancing the activity of preservatives (C)</p> Signup and view all the answers

Which component is frequently added to ointments to reduce their viscosity?

<p>Mineral oil (B)</p> Signup and view all the answers

What is the disadvantage associated with the use of ointments in ophthalmic applications?

<p>Prolonged blurred vision (D)</p> Signup and view all the answers

How do emulsions primarily differ from suspensions in terms of drug formulation?

<p>Emulsions utilize surfactants for stabilization (C)</p> Signup and view all the answers

What is the primary advantage of using gelling agents like carbomers in ophthalmic gels?

<p>They facilitate once-daily dosing (A)</p> Signup and view all the answers

What type of ophthalmic product is commonly packaged in dropper bottles?

<p>Suspensions (D)</p> Signup and view all the answers

Which of the following is a common surfactant used in ophthalmic products?

<p>Tyloxapol (C)</p> Signup and view all the answers

What is the primary use of suspensions in ophthalmology?

<p>To allow for prolonged drug release (C)</p> Signup and view all the answers

Flashcards

Ophthalmic Drug Delivery Goal

Treat the eye, avoiding systemic absorption as much as possible.

Systemic Absorption Pathways (Eyes)

Nasolacrimal drainage, nasal/nasopharyngeal absorption, GI tract (swallowing), conjunctival absorption, trabecular meshwork drainage.

Nasolacrimal Drainage

A pathway where eye drops drain into the nose.

Ophthalmic Drug First-Pass Effect

Drugs absorbed in the eye bypass the liver's initial filtering process.

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Ophthalmic Drug Sterility

Essential to prevent eye infections, critical for safety like injectable drugs.

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Pseudomonas aeruginosa

Dangerous bacteria that can cause corneal ulcers, potential blindness.

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Ophthalmic Preservative

Needed for multi-dose eye drops to stop bacterial growth.

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Benzalkonium Chloride (BAK)

A common preservative in eye drops effective against Pseudomonas aeruginosa; but high concentrations can potentially damage the cornea

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Eye Drop Administration

Wash hands, shake suspensions, tilt head, instill one drop, close eye 30 seconds, avoid blinking.

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Timing eye drops

Wait 5 minutes between drops. Apply fast-acting before long-acting. Apply eye drops before ointments.

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Contact Lenses

Remove contact lenses before instilling eye drops, unless otherwise directed.

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Eye Ointment Application

Clean hands, tilt head, pull down eyelid, apply ointment, close eye 1-2 minutes, rotate eyes, remove excess, replace cap.

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Storage and Disposal of Eye Drops

Store eye drops according to manufacturer's instructions. Discard multi-dose after 30 days.

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Ophthalmic Product pH

The ideal pH for ophthalmic products should match the tear film's pH (approximately 6.6-7.8).

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Ophthalmic Buffer

Buffers adjust pH for stability, solubility, and patient comfort in ophthalmic formulations.

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Ophthalmic Isotonicity

Ophthalmic solutions should have an osmolarity similar to tears (approximately 300 mOsm/kg) for patient comfort.

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Hypertonic Ophthalmic Solutions

Some ophthalmic solutions are intentionally hypertonic to treat conditions like corneal edema.

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Tonicity Modifiers

Substances like sodium chloride, mannitol, and dextrose adjust the osmolarity of ophthalmic solutions.

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Viscosity in Ophthalmics

Viscosity influences drug residence time and diffusion, impacting bioavailability.

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Viscosity Modifiers

Substances like glycerin, cellulose derivatives, polyvinyl alcohol, and PEGs adjust the viscosity of ophthalmic solutions.

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Common Ophthalmic Form

Liquid ophthalmics, primarily solutions, are the most prevalent form.

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Ophthalmic Solution Sterilization

Sterilization of ophthalmic solutions involves heat or filtration through a 0.2-micron filter.

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Alternative Preservatives

Alternatives to benzalkonium chloride (BAK) include Polyquad (polyquaternium-1), thimerosal, and oxidizing agents like sodium perborate.

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Ophthalmic Suspensions

Finely divided drug particles suspended in a liquid vehicle; used for poorly soluble drugs and enhanced stability.

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Suspensions Sterilization

Suspensions cannot be filter sterilized because it would remove drug particles; sterile drug crystals are mixed with a sterile vehicle.

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Ophthalmic Emulsions

Drug dissolved in oil phase, stabilized with surfactants. Used for lipophilic drugs.

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Ophthalmic Antioxidants

Chemicals like sodium metabisulfite preventing drug oxidation, but consider potential patient sensitivity.

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Ophthalmic Chelating Agents

EDTA sodium, chelates metal ions to prevent oxidation, and improves drug activity against certain bacteria.

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Surfactants (Ophthalmics)

Polysorbate 80 and tyloxapol; improve drug spreading and mixing for suspensions/emulsions.

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Ophthalmic Ointment

Petrolatum-based, viscous preparations providing sustained contact time; slow clearance rate (0.5%/min).

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Ophthalmic Ointment Sterilization

Sterilization method using heat or sterile filtration for the base of the ointment.

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Ophthalmic Gels

Gels like carbomer and cellulose derivatives provide prolonged contact time for once-daily dosing.

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Ophthalmic Packaging

Liquid ophthalmics usually in dropper bottles; semisolid are ointments or gels.

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Study Notes

Ophthalmic Drug Delivery

  • The primary goal of ophthalmic drugs is local treatment, not systemic absorption. Absorption's significance depends on drug potency and strength.

  • Systemic absorption pathways include:

    • Nasolacrimal drainage: Drops drain through the nasal cavity.
    • Nasal structures: Absorption in the nasal cavity, nasopharynx, and lacrimal sac is possible, including absorption through mixing with saliva.
    • Gastrointestinal tract: Swallowed drugs are absorbed.
    • Conjunctival absorption: Rich blood supply allows for more permeable absorption.
    • Trabecular meshwork: Drainage through this meshwork allows drugs to enter the bloodstream.

  • Over 50% of ophthalmic drugs can be systemically absorbed. Drugs absorbed via the GI tract bypass the hepatic first-pass effect.

Dosage Form Considerations

  • Sterility: Crucial for ophthalmic products, similar to injectable drugs. Contamination can lead to serious consequences, including blindness.
  • Pseudomonas aeruginosa is a significant corneal ulcer-causing organism.
  • Sterility testing is mandated for commercially manufactured ophthalmic medications.
  • Antimicrobial preservatives are necessary in multi-dose eye drops for sterility maintenance; single-use drops typically don't need these preservatives.

Preservatives

  • Benzalkonium Chloride (BAK): Is the most commonly used preservative, effective against Pseudomonas aeruginosa, but can damage corneal epithelium at high concentrations.
  • Alternatives include polyquad (polyquaternium 1), which is less sensitizing, and thimerosal.
  • Oxidizing agents like sodium perborate are newer and act via oxidation of microbes.

pH and Osmolarity

  • Ideal pH for ophthalmic products is around 6.6-7.8, matching tear film pH.
  • Buffers (acetate, phosphate, citrate, borate) help maintain product pH stability, solubility, and patient comfort.
  • Maintaining isotonicity (300mOsm/kg) like tears is crucial for patient comfort, although some products are intentionally hypertonic. (eg 5% NaCl)
  • Viscosity Modifiers: Viscosity affects residence time and drug diffusion; increased viscosity can cause blurred vision, while prolonged contact and reduced drainage are benefits. (eg glycerin, cellulose derivatives, polyvinyl alcohol, polyethylene glycols (PEGs))

Ophthalmic Formulations

  • Solutions: Most common form, involving dissolving the drug and excipients, followed by sterilization (heat or 0.2 micron membrane filtration).
  • Suspensions: Finely micronized particles for minimized irritation and improved dissolution. Used for poorly soluble drugs or to enhance drug stability.
  • Emulsions: Less common, employ lipophilic drugs dissolved in oil phase and emulsifiers for stabilization.
  • Ointments/Gels: Prolonged contact time, commonly petrolatum-based ointments that can be sterilized. Gels use gelling agents like carbomers and cellulose derivatives to achieve extended contact.

Administration

  • Wash hands, tilt head back, and pull down lower eyelid to create a pouch.
  • Instill one drop precisely into the conjunctival sac and keep eye closed for 30 seconds.
  • Avoid rubbing, wiping, or squeezing the eye. Replace the dropper tip cap without touching it.
  • Consider waiting at least five minutes between consecutive drops.

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Related Documents

Ophthalmic Drug Delivery Study Guide PDF

Description

Explore the essential aspects of ophthalmic drug delivery, focusing on local treatment methods and systemic absorption pathways. Understand key considerations for dosage forms, including sterility and potential absorption routes, to ensure effective and safe ocular therapies.

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