DDS Study Set: Lectures 13+14

Describe various otic dosage forms

What are the two types of intraocular administration?

Intravitreal (injections into the aqueous humor) and intracameral (injections into the anterior chamber)

When is intravitreal administration typically employed?

Intravitreal administration is employed for severe posterior segment diseases

What is a significant advantage of intravitreal administration?

It results in high bioavailability in the posterior segment

What are some disadvantages of intraocular administration?

• It is an invasive route of administration

• It can increase the risk of hemorrhage, especially while treating chronic diseases of the eye

When is periocular administration typically used?

Periocular administration is usually employed for treating anterior segment diseases when topical administration has failed

What are the two types of periocular administration?

Periocular administration may be either subconjunctival or sub-Tenon

How is injection administered in subconjunctival administration?

Injection is made underneath the conjunctiva in the case of subconjunctival administration

How do drugs administered via periocular route enter the eye?

By diffusing through the sclera, which has high permeability compared with the cornea

What is transscleral administration?

Transscleral administration is a viable alternative to deliver drugs to the posterior segment

Why is transscleral administration considered a viable alternative?

Due to the sclera's large surface area and high permeability characteristics

What type of therapeutics is transscleral administration suitable for?

Protein therapeutics

What are the advantages of topical ocular administration?

• Convenience

• Noninvasiveness

• Ease of self-administration

• Fewer systemic drug effects

What are the disadvantages of topical ocular administration?

• Low ocular bioavailability

• Ineffective in the treatment of posterior segment diseases

In the context of topical formulations, solutions sometimes have viscosity enhancers, why are they used?

Increase precorneal residence time to increase ocular bioavailability

What is a key characteristic of ophthalmic suspensions?

They provide slow dissolution and prolonged release of drugs

What are some characteristics of ophthalmic ointments and gels?

• Primarily used for nighttime therapy, in contrast to eye drops used during the day

• Provides longer contact time compared to solutions

• Ointments are suitable for moisture-sensitive drugs

What is an Ocusert® Device?

A polymer membrane that controls release rate…

• Increasing contact time

• Improving bioavailability

• Providing a prolonged drug release

_________ ____________ is the primary cause of blindness from contaminated ophthalmics.

Pseudomonas aeruginosa

What factors determine the method of sterilization for ophthalmic products?

Depends on the product

• Autoclaving for heat-stable drugs

• Membrane filtration (0.22 μm for heat-labile drugs or 0.5 μm for sterility).

What is buffer capacity?

It is a measure of the resistance to change in the pH of the solution

When do we use a low buffer capacity?

When we want to allow tear fluid to adjust pH to neutrality after application to the eye

What is the relationship between buffering and bioavailability?

More buffering = more bioavailability

Why do we want the eye solutions to be isotonic?

To reduce tearing and irritation (comfort)

What tonicity values can the eye tolerate without great discomfort?

0.5% to 1.6%

What value are sodium chloride and boric acid isotonic with tears?

• 0.9% sodium chloride

• 1.9% boric acid

What happens if we administer a hypertonic eye solution?

It can draw water toward the site of the topical application

What happens when we administer a hypotonic eye solution?

It will induce the passage of water from the site of an ophthalmic application through the tissues of the eye

What can be done to increase the viscosity of an eye solution?

Adjuvants such as emollients and demulcents can be added

What are the three otic dosage forms?

• Cerumen removing solutions

• Solutions for ear infections

• Anti-inflammatory and analgesic preparations

Why would we use direct pulmonary drug delivery for a local effect in the lungs?

• We need a small dose

• Lessen the systemic side effects

• Works faster

• Can do it yourself

Why would we use direct pulmonary drug delivery for a systemic effect?

• Avoids the first pass effect

• Increased drug absorption (large surface area of the lungs)

• Works faster than oral

Where are the respiratory and conducting airways?

See image

What is mucocilliary clearance and how does it work?

It is a significant barrier to pulmonary drug delivery and it moves deposited particles from the conducting airways to the oropharyngeal space

What is the primary factor impacting the deposition of a particle in the airway?

The size of the particle

What airway will deposition occur if the particles are large (5-10μm)?

Oropharnynx and upper airways through inertial impaction

What airway will deposition occur if the particles are smaller (1-5μm)?

Smaller bronchioles and the alveolar region through gravity sedimentation

What airway will deposition occur if the particles are less than 0.5μm?

Alveolar region though brownian diffusion

What is the mechanism of aerosolization for jet nebulizers?

Pressurized compressed air

What does a spacer do?

• Can slow the aerosol spray before it reaches the mouth

• Allows reduction of aerosol particle size before reaching the mouth

• Reduces oropharyngeal deposition of the medication particles

• Eliminates the need for coordination of inhalation and actuation

Why is the respiratory region an important site for drug absorption?

It is the largest region in the nasal cavity with rich blood supply

What kind of dose is needed for a local nasal effect, small or big?

Small

Identify the location of the nasal vestibule, the respiratory region, and the olfactory region.

See image