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)
What is the rule of thumb for steroid eye drops potency, penetrance, and capacity to raise IOP?
Acetate > Alcohol»_space; Phosphate
Name the 6 drug classes for optometrists
Allergy
Anti-inflammatory
Analgesics
Anti-biotics
Anti-virals
Anti-glaucoma
What 3 classes of response occur in response to mast cell degranulation (i.e. allergic respones)? What do each of these responses result in? (2, 3, 1)
Histamine response: results in red, itchy eye
Cytokine response: results in chemosis, swelling and mucous production in the eye
Cellular response: results in inflammation
When does the cellular response occur after mast cell degranulation?
Occurs after the histamine and cytokine response once the allergic response has been going on for some time
What does the cellular response to mast cell degranulation involve? (2)
Eosinophils and Neutrophils undergo chemotaxis to the site of degranulation via Eosinophil Chemotactic Factor (ECF) and Neutrophil Chemotactic Factor (NCF) respectively
Once there, they cause inflammation
Name 3 cytokines involved in the cytokine response to mast cell degranulation and state what they do
Heparin: anti-coagulant
Tryptase: COX-2, PG production + fibroblast proliferation
Chymase: increases vascular permeability via angiotensin II
Which cytokine in response to mast cell degranulation is responsible for mucous production?
Tryptase
Which cytokine in response to mast cell degranulation is responsible for chemosis?
All 3 of them
How long once the allergic response has begun does the cellular response take to kick in/start?
usually about a week
How can we manage the cellular response to mast cell degranulation? (4)
Use anti-metabolites: cyclosporin and tacrolimus
Also can use steroids (affects early in cellular response)
How long do anti-metabolites take to act to manage allergic response? Why is this?
a long time. At least 2 or 3 months before they have an effect. This is because they affect the cellular response which itself takes a while to start (although that only takes 1 week)
How can we manage the histamine response to mast cell degranulation? (2)
Lubricants
Antihistamines
How can we manage the cytokine response to mast cell degranulation? (2)
Steroids (for all cytokines)
NSAIDs (for use against tryptase)
How can we manage allergic response by acting on the mast cell?
Mast cell stabilizer.
When should you use a mast cell stabilizer? Why might this be an issue?
Before it degranulates. This is an issue because generally the patient won’t come in to treat allergies before it degranulates (instead they come in when they already have symptoms)
How are mast cell stabilizers suggested to be used to patients?
If patient has hayfever, start using the mast cell stabilizer one month before hayfever season starts
What condition is cyclosporin particularly useful for?
dry eye disease (for the cellular responses in dry eye disease)
Name 8 kinds of anti-allergy medications
Ocular lubricants
Vasoconstrictors
Astringents
Anti-histamines
Mast cell stabilisers (MCS + AH)
NSAIDS
Corticosteroids
Anti-metabolites
What can you use ocular lubricants for? (4)
Mild ocular surface irritation (incl. SPK)
Dry eye
Neurotrophic keratitis
Adjunct in severe inflammation
What allergic conditions are vasoconstrictors used for? (2)
Mild allergic conjunctivitis
Other mild non-specific hyperaemia
What type of agents are anti-allergy vasoconstrictors?
Alpha adrenergic agents
What is the role of astringents in anti-allergy treatment?
Reduce mucoid discharge in allergic surface disease
Name 1 chemical compound that astringents contain
Zinc sulphate
Which histamine receptor are anti-histamines selective for?
H1 receptor
Are mast cell stabilisers H1 selective?
Yes. So they also have an anti-histamine effect
What is the mechanism of NSAIDs?
Inhibit COX, which decreases prostaglandin synthesis and prostaglandin-mediated inflammation
What is the mechanism of corticosteroids? (3)
Intracellular receptor-mediated inhibition of inflammatory cascade, fibroblast and keratocyte activity
What type of drug administration may be required if inflammation is deeper than the iris? (4)
Either:
Oral, or
Intraocular/sub-conj./sub-Tenon’s injection may be required
What is the sub-tenon’s space?
A space between the capsule and the sclera
What effect does injection of NSAIDs into the eye have on the hypothalamic axis?
Suppresses it
Do NSAIDs perform inhibition on the anterior or posterior eye?
Anterior. They inhibit Cox anteriorly
How does topical use of NSAIDs affect the posterior pole?
Reduce overall ocular PG load at posterior pole
What is the typical dose of an oral steroid?
40mg po bd, 2d to 7d then taper over 2-4wks
Name 3 side effects of topical steroid treatment
Promotes microbial activity
Masks clinical signs
Delays wound healing
