OptoP: Ocular Medications - Weeks 6 and 7 Flashcards
When an optometrist diagnoses glaucoma and starts anti-glaucoma therapy: within what time period should a referral be made to an ophthalmologist?
Within 4 months of starting treatment
referral can be for either: a second opinion or to consider a surgical option
What condition is the majority of optometry drug prescriptions for?
Glaucoma (45.4% of drug prescriptions)
What route of drug administration is best suited for a superficial eye condition?
Topical
What route of drug administration is best suited for a deep eye condition?
Oral or injection
Between topical vs oral and injection, which route of drug administration is more likely to produce adverse effects (AEs)?
Oral and injection route (because they are non-targeted)
Rate the timing of drug availability from fastest to slowest for 3 routes of admin: topical, oral and injection
injection>oral>topical
How do oral drugs enter the bloodstream?
by absorption over the GI tract. They are also subject to first-pass metabolism in the liver
How do topical drugs enter the bloodstream? (2)
by direct absorption across conjunctival blood vessels (~30% of the drug) and by draining via naso-lacrimal duct into nasal cavity and eventually gut (70%)
List the 3 modes of absorption for topical drugs
Nasal mucosa (rugae, very fast blood stream)
Cross membrane of olfactory nerve (direct access to CNS (fast). Very potent compared to injection) - e.g. cocaine snorting
Gut (slow)
When may drugs produce systemic effects when in the blood stream?
When they are unbound
What binds drugs in the bloodstream? (2) What does this do?
Binding is by blood cells and proteins. Binding inactivates drug for metabolic breakdown
What is the “Double-D” rule for minimising the systemic absorption of topical drugs
Don’t open eyes (1-2 mins) (minimise conjunctival flow)
Digital occlude puncta (reduce puncta access)
By how much does the Double-D rule reduce concentration of topical drug in the blood?
by 65-70%
What features of drugs are required to cross the corneal barrier? (2)
To cross the corneal barrier, drugs must be:
- Hydrophilic (to dissolve in tears)
- Lipophilic (to cross cellular membranes)
What is a drug formulary?
a list of prescription drugs
What is the best formulary for corneal absorption?
Acetate formulary (i.e. acetate formulation)
Describe the features of an acetate formulation in relation to corneal absorption (5) incl.
- rate of absorption
- degree of toxicity
- speed and duration of effect
rapid absorption borders on toxicity at a lower dose avoids toxicity (dotted line on graph) effect = fast but short lived good to load with multiple drops
Describe the features of a phosphate formulation in relation to corneal absorption (3) incl.
- speed of absorption
- duration of effect
- degree of toxicity
slower absorption than acetate
longer duration than acetate
non-toxic therapuetic
Describe the features of a phosphate OINTMENT formulation in relation to corneal absorption (2) incl.
- speed of release (in comparison to phosphate and acetate)
- therapeutic duration (in comparison to phosphate and acetate)
Slowest speed of release
Longest therapeutic duration
Describe the steroid potency, penetrance, and capacity to raise IOP of the following drugs in the eye:
- Hydrocortisone alcohol and Hydrocortisone acetate
Low
Describe the steroid potency, penetrance, and capacity to raise IOP of the following drugs in the eye:
- Fluorometholone alcohol and Prednisolone phosphate
Mid
Describe the steroid potency, penetrance, and capacity to raise IOP of the following drugs in the eye:
- Fluoromethalone acetate
High
Describe the steroid potency, penetrance, and capacity to raise IOP of the following drugs in the eye:
- Prednisolone acetate
Very High (highest penetrance of the group of steroids mentioned)
Describe the steroid potency, penetrance, and capacity to raise IOP of the following drugs in the eye:
- Dexamethasone alcohol
Very Very High (however penetrance only mid-high)
