Block 5 Flashcards
What are the systemic effects of topically administered beta blockers?
May cause decrease in HR
Brochospasm
CNS depression
*risky for asthma, lung disease, or vessel spasm patients
Typically used for open-angle glaucoma (non selective b/c you want to block beta 2)
What are the systemic effects of topically administered Muscarinic blockers?
May cause increased HR
Dry mouth
Hallucinations
(The sympathetics)
Typically used for cycloplegia (ex. Atropine)
What are the systemic effects of topically administered alpha 2 agonists?
Fatigue, lethargy (low sympathetics)
Typically used for open angle glaucoma (ex. Methyldopa)
What is the pH of tears?
7.4 (same as blood)
What is the volume of the tear layer?
8-10 uL
What is the total volume that can be held for a brief time in the eye if the eyelids are not squeezed after dosing?
30 uL
What is the lowest volume of drug delivered by an eye drop?
25 uL
What is the normal tear flow rate and what happens to it with age?
Normal rate is 0.5-2.2 uL/min
It decreases with age
What does the flow rate have to do with dry eye?
Those whose flow rate is at the lower limit
A typical drop of medication is not diluted as much in a dry eye patient thus resulting in greater drug absorption
What 2 things influence drug absorption by the anterior segment of the eye?
Tear flow rate
Tear volume
Where is the major site of absorption for topically administered drugs?
Cornea
Where is the storage location (depot) for lipophilic drugs?
Corneal epithelium
Where is the storage location (depot) for hydrophilic drugs?
Corneal stroma
What is an example of a prodrug that is popular for glaucoma?
Latanoprost
It’s a PGF2 alpha agonist
When activated to latanprost acid, it concentrates in the aqueous humor and increases fluid drainage to lower IOP
In the eye it lasts 24 hours, systemically it only lasts 17 minutes
What is an example (drug) of an active metabolite? (The parent drug is active and that drug forms an active metabolite)
Loteprednol (parent drug is prednisolone)
Rapidly inactivated in the eye thus having fewer side effects than parent drug (less likely to increase IOP)
**this is the case where a shorter acting drug is more beneficial
What structures remove many drugs and metabolites from the vitreous humor and retina?
Retinal blood vessels
Which structures remove drugs from the iris and ciliary body?
Uveal blood vessels
What are ways to reduce systemic toxicity for topically administered drugs?
Store meds away from kids
Wipe excess solution or ointment from the lids and lashes
Use the lowest concentration and minimal dosage frequency
Consider the potential adverse effects of a drug compared to its benefit
Recognize adverse drug reactions
Drugs get into systemic circulation via the conj capillaries, nasal mucosa from lacrimal system, or after swallowing
What are the purpose of preservatives in ocular formulations?
Preservatives kill bacteria and fungi that may contaminate drug bottles, however they are harsh chemicals that can harm the cornea and conj epithelial cells
Chronic exposure can lead to dry eye due to poor production of tear film
Most commonly used in ophthalmic solutions is a detergent BAK - causes serious and irreversible side effects in the eye
2nd gen less toxic preservatives being used are oxidizing preservatives
Recently, ionic buffered preservatives are inactivated by the eye and thought to be least toxic
What is the purpose of vehicles in ocular formulations?
It is an agent other than the active drug that is added to the formulation to provide proper tonicity, buffering, and viscosity to complement the drug action
High molecular weight polymers increase viscosity and delay washout from the tear film which increases drug bioavailability
Polyionic molecules (oil based ointments) provide longer retention of drugs at the corneal surface
What are the various options for topical drug administration?
Solutions and suspensions (eye drops) Sprays Ointments Lid scrubs Gels
Which option of topical application tends to last the longest?
Ointments - it acts as a reservoir to enhance drug contact time
What are lid scrubs used for?
Blepharitis
What are the steps for instilling topical solutions or suspensions?
Tilt head back
Gently grasp lower lid and pull away from eye
Place dropper over eye by looking at it
Look up, apply drop
Look down for a few seconds after applying drop
Release lid
Gently close eyes for 2-3 minutes
What are disadvantages of topical solutions?
Short ocular contact
Imprecise/inconsistent delivery of drug
Contamination
Risk of injury by dropper tip
Identify periocular routes of administration?
Subconjunctival route - right in the conj
Retrobulbar route - right behind the eye but in the muscles
Peribulbar route - much lower behind the eye below the muscles
Intracameral - directly into anterior chamber
Intravitreal - directly into the vitreous
Identify all the parts of a prescription?
- Patient name and address
- Patient age and date
- Rx icon is the beginning of your instructions
- details of the drug - drug name, drug strength, and drug formulation NO ABBREVIATIONS
- Dispensing directions - write out numbers, bottle size, ointment tube size, or number of tablets
- Patient use instructions - when to take, how much, route, when to stop, list the diagnosis
- Any refills - NEVER leave blank also any special instructions (refrigerate or take with food)
- Prescriber’s info and signature
What is the duty to disclose risks for diagnostic and therapeutic agents?
In diagnostic agents - informed consent is not necessary unless you are dealing with the very small percent of the population that is at risk for condition (angle closure glaucoma, or allergies to dyes)
Therapeutic agents - ALWAYS inform patients of toxic side effects
Greatest risks for topical steroids, systemic steroids, beta blockers, M agonists for glaucoma, and oral CAIs
Due to the fact that we lack the control over the drug administration (these are the chronic ones)
Describe the categories of drug scheduling for drugs of abuse?
1 has the highest potential for abuse and currently no accepted medical use in the US
5 has the lowest potential for abuse
What are the drugs in schedule 1?
Ecstasy, LSD, heroin
What are the drugs in schedule 2?
Morphine
What are the drugs in schedule 3?
Codeine for pain
What are the drugs in schedule 4?
Benzodiazepines (anxiety, sleep aids, muscle relaxants)
What are the drugs in schedule 5?
Codeine for cough
How are mydriatics different from cycloplegic?
Cycloplegic dilate AND knock out accommodation
Why do we use the local anesthetic before instilling mydriatic drops?
It facilitates the drug’s effect by affecting the permeability of the epithelium
It does reduce the burning and stinging produced by the mydriatic
What do you have to do before giving dilation drops?
You need to warn and document the side effects
Light colored eyes dilate _____?
Faster and more completely than darkly pigmented eyes
The pigment sucks up the drug
What are the pupils with poorly controlled diabetes?
They have smaller pupils and are slower to dilate
How does age affect dilation?
Higher the age the smaller the pupil and a longer time to dilate
The sphincter and the dilator of the iris is under control of which system?
Autonomic nervous system
What is the pathway to the dilator?
Sympathetic pathway
Hypothalamus
Ciliospinal center of Budge
Superior cervical Ganglion
Dilator muscle
What is the pathway of the sphincter muscle of the iris?
Parasympathetic pathway
Pretectal nucleus
E-Westphal nucleus
Ciliary ganglion
Sphincter muscle
What is the MOA of the Anticholinergics/Antimuscarinics?
They bind to and inhibit the cholinergic receptors
Inhibit pupillary sphincter (mydriasis(dilate))
Inhibit ciliary body (cycloplegia)
What are the anticholinergics/antimuscarinics used for?
Cycloplegic refraction
Pupillary dilation
Management of uveitis
What are the drug names of the anticholinergics/Antimuscarinic?
STop ACH
*all have a red cap
Scopolamine Tropicamide Atropine Cyclopentolate Homatropine
What is the anticholinergic that lasts the longest?
Atropine
What is the anticholinergic that is the shortest?
Tropicamide
What is the use for scopolamine?
NOT usually used - only if patients are allergic to others
**remember it is used as a motion sickness patch, so if someone comes in with a patch on and a dilated eye, that is normal
What are the systemic side effects of scopolamine?
CNS toxicity!! It penetrates the BB barrier
***this is important! Always pick scopolamine for CNS toxicity
Watch in elderly, small children, and Down’s patients specifically
What is the drug of choice for routine mydriasis?
Tropicamide
Fastest onset and shortest duration
What are the side effects for tropicamide?
NONE
These one is very well tolerated
What is the most potent mydriatic and cycloplegic?
Atropine
Which drug should you use as an alternative to amblyopia occlusion?
Atropine
Very common b/c you only have to drop once a week or so
What are the side effects of atropine?
It is safe when the correct dosage is used, however never give to elderly, small children, or Down’s patients
6 cases of death
What is the drug of choice for cycloplegic refraction?
Cyclopentolate
Faster cycloplegia with less residual accommodation
What is the standard drug for treating anterior uveitis?
Homatropine
Also useful for pain and prevention of posterior synechiae
What is the MOA of phenylephrine?
Stimulates the alpha adrenergic receptors causing mydriasis only! Also vasoconstriction
NO cycloplegia!
What are uses for phenylephrine?
Dilation without cycloplegia
**differentiates scleritis and episcleritis
If redness goes away its episcleritis
Used to break posterior synechiae
What is posterior synechiae?
Attachment of iris to lens
What is anterior synechiae?
Attachment of iris to cornea
What are contraindications of phenylephrine?
Do not use in patients taking MAO inhibitors, tricyclics antidepressants, or methyldopa
Or patients with Graves’ disease
What is Paremyd?
It is a mixture of hydroxyamphetamine and tropicamide
MOA: causes release of Norepinephrine from adrenergic nerve terminals and possibly inhibits its reuptake (indirect alpha adrenergic agonist)
Inhibits the response of iris sphincter and ciliary body muscles via acetylcholine receptors inhibit
What is the use for paremyd?
Dilation without cycloplegia
Conjunctival blanching
Utilized after cocaine or apraclonidine to determine lesion location in Horner’s syndrome
*acts on postganglion neuron to release NE and dilation will occur - if no dilation, that means postganglionic neuron is damaged
What are the contraindications of paremyd?
Do not give to patients taking MAO inhibitors, or antidepressants or with Grave’s disease
May be slightly safer than phenylephrine in high risk patients
What are the side effects of paremyd?
Less stinging than phenylephrine
Little or no elevation of IOP in glaucoma patients
What are the uses for ophthalmic anesthetics?
Minor eye trauma, removal of superificial foreign bodies, measuring IOP, nasalacrimal tract irrigation and probing, cataract surgery
Local anesthetic is used for _____% of cataract operations/
95%
When is general anesthetic most appraise in ocular surgery?
Children and younger cataract patients
Or people who have trouble keeping still due to tremor or confusion/distress
What is the MEC? Maximum effective concentration
Concentration where there is no further increase in activity
Which type are the most commonly used topical ocular anesthetics?
Esters
Why is there a contraindication of the combination of 2 or more local anesthetics?
There is an increased toxic risk
What are the commonly used topical anesthetics in ocular surgery?
Benoxinate hydrochloride with fluorescein sodium
Benoxinate hydrochloride with flourexon sodium
Proparacaine hydrochloride
Proparacaine hydrochloride with fluorescein sodium
What is the ophthalmic use of cocaine?
For otolaryngologist purpose in Horner’s syndrome (10% solution)
When is cocaine contraindicated?
It blocks reuptake of NE so it is contraindicated in patients with systemic hypertension or taking adrenergic agonists
What are the major ocular side effects of cocaine?
Visible grayish pits and irregularities
Loosening of the corneal epithelium resulting is large erosions
Systemic toxicity (10 drops of 4% soln) causes irregular pulse, dilated pupil, abdominal pain, delirium, convulsion
What is tetracaine?
Topical anesthetic which is an ester of PABA
Use for tonometry, cataract surgery, intraocular lens implantation
What are major ocular side effects of tetracaine?
Overdose if administered in higher doses than 1.5mg/kg of body weight
Structural damage to cell membrane
Loss of microviili and desquamtion of superficial epithelial cells
Produces moderate stinging or burning sensation after topical instillation
May develop local allergy
Cross sensitivity with proparacaine
Drug that is only available in combination of Na-fluorescein and Na-fluorexon(vital dye solution) aka flurasafe or fluress
Benoxinate
It does NOT stain hydrogel contact lenses
What is the use of benoxinate?
Applanation tonometry
Has significant antimicrobial properties
What are side effects of benoxinate?
Sensation of stinging or burning
Very low or rare allergic potential therefore replaces tetracaine
This drug is in 0.5% with or without Na-fluorescein and Na-fluorexon
Causes less pain or irritation compared to tetracaine
Proparacaine
What are the side effects of proparacaine?
Fewer side effects but may cause hypersensitivity reaction or allergic contact dermatitis on the fingertips
Upon administration, what is the comparison between proparacaine and tetracaine
Proparacaine stings less but tetracaine produces a better anesthesia
Warn the patient for brief stinging
What are side effects of anesthetic drops?
Stinging
Keratitis if overdosed
Specifically tetracaine inhibits corneal epithelial cell healing
Don’t use if know hypersensitive and use caution with hypertensive patients
What are common injected anesthetics?
Lidocaine hydrochloride (most common)
Bupivacaine
Cocaine
Where are anesthetics injected?
Subcutaneous Subconjuunctival Sub-tenon** safest Peribulbar Retrobulbar
(Last 2 have higher risk)
What are the the ocular side effects of injected anesthetics
Peribulbar and retrobulbar injections are trickier and can result in retrobulbar hemorrhage, globe puncture, optic nerve damage, muscle palsy, and 7th cranial nerve complications
Systemic side effects are rare but can occur if a very large dose is injected
What are the risks of local anesthetics?
Localized self limiting hemorrhage
Sight limiting complications are rare
Patients on anticoagulants or antiplatelet agents are as increased risk for minor complications
Drop LAs do not block muscular action - this can be an issue in procedures where movements of millimeter or less can have serious consequences
What are some agents added to LA and why?
Fluorescein - dye combined with lidocaine or proparacaine drops to enable visualization of corneal epithelial defectes
Adrenaline (epinephrine) - diminishes blood flow, so it decreases systemic absorption and prolongs local effect (very low concentrations are used)
-when epi is subjected to heat it loses its potency, used specifically for injected LAs and not added to eye drops
Hyaluronidase - added to increase tissue permeability to injected fluid, usual concentration of 15 units/mL
Most LAs are what?
Bactericidal
Compare benoxinate, proparacaine, tetracaine, cocaine
Benoxinate - 1-20 minutes - only combined with vital dye
Minor irritation and side effects
Rare allergies
Proparacaine - 1-20 minutes - stand alone or combined with vital dye
Discoloration
Tetracaine - 10-30 minutes - significant corneal toxicity
Moderate stinging
More allergic reaction
Cocaine - 20+ minutes - significant corneal toxicity
Abuse potential
What are some ophthalmic NSAIDs used?
Bromfenac Diclofenac sodium Flurbiprofen sodium Ketorolac 0.5% Ketorolac 0.4% Ketorolac 0.5% PF Nepafenac
This drug is used for temporary relief of pain and photophobia in patients
Diclofenac sodium
Which drug is used for ocular itching, ,seasonal allergic conjunctivitis
Treatment of post op inflammation in cataract extraction patient
Ketorolac 0.5%
Drug used for reduction of ocular pain, burning, stinging after surgery
Ketorolac 0.4%
Drug for reduction of photophobia, pain associated with surgery
Ketorolac 0.5% PF
What do prostaglandins in the eye cause?
Increased IOP
Miosis (pupil constriction)
Increased vascular permeability
What is the MOA of ophthalmic NSAIDs?
Inhibits COX1 and COX2 which limits prostaglandin production and provides both analgesic and anti inflammatory activity
Topical ophthalmic NSAIDs are preferred over systemic NSAIDs b/c they produce higher ocular drug concentrations while avoiding some of the systemic adverse events
This drug inhibits the adherence of Stapp. Epidermidids to the soft lens material
Diclofenac
Drug with its greatest advantage being less initial stinging on instillation?
Bromfenac
This drug is combined with cyclosporine A for treatment of chronic dry eye disease
Ketorolac
This drug is a prodrug, it penetrates the cornea and is converted by ocular tissue hydrolases to its active form amfenac
This allows it to reach higher intraocular concentrations than other topical NSAIDs and provides longer lasting inhibition of PG synthesis
Nepafenac
What are some inflammatory complications that occur after cataract surgery that are treated with NSAIDs?
Posterior synechiae Chronic uveitis Secondary glaucoma Cystoid macular edema Pain
What is Cystoid macular edema? CME
Appears as multiple cyst like areas of accumulated fluid in the macula causing retinal swelling or edema
Can present as blurred or impaired central vision
It is the most common cause of reduced vision after cataract surgery
What are the side effects of ketorolac 0.5%?
<40 burning/stinging
Ocular irritation
Corneal edema
Slight vision change
What are the side effects of ketorolac 0.4%?
30-40 burning/stinging
Ocular irritation
Corneal edema
No vision change
What ar the side effects of ketorolac 0.5% PF?
20 burning/stinging
Ocular irritation
Corneal edema
Vision changes
What is the side effects of nepafenac 0.1%?
Vision changes
What are the complications of NSAIDs?
Bromfenac - contains sodium sulphite and is contraindicated in patients with sulphite hypersensitivity
Cross hypersensitivity in patients with aspirin and other NSAIDs - prolonged bleeding times and healing
May cause keratitis - epithelial breakdown, corneal thinning, erosion, and ulceration
Impaired healing if in combo with ophthalmic steroids
What are the side effects of topical antibiotics?
Stinging, burning, redness, blurry vision
Which is the only antibiotic that does not treat pseudomonas?
Neomycin
What is the drug of choice for pseudomonas?
Ciprofloxacin
Which topical antibacterial drop is yellow?
Moxifloxacin
Moxeza or Vigamox
When is betadine most useful?
When treating epidemic keratoconjunctivitis during the acute, red state
What is the dosage for oral acyclovir?
HSV = 400mg 5x per day 14-21 days HZV = 800mg 5x per day 7-10 days
What is the dosage for oral valacyclovir?
HSV 500mg TID 14-21 days
HZV 1000mg TID 7 days
What is the dosage for oral Famciclovir?
HSV 250mg BID 14-21 days
HZV 500mg TID 7 days
When is the oral drugs for herpes simplex and zoster the most effective?
Within 72 hours of the rash
What did the HEDS-1 study find?
Stromal diseases are best managed by topical steroids
Oral acyclovir didn’t do anything
What did the HEDS-2 study find?
Recurrent keratitis can be reduced by 45% with lifetime treatment of acyclovir 400 mg BID, famciclovir 250mg QD, or valacyclovir 500mg QD
