Ocular Pharmacology pt 3 Flashcards
parasympatholytics are not used in what cases?
- we avoid using parasympatholytics in cases of glaucoma as the pupillary dilation and
relaxation of the ciliary body can increase the intraocular pressure in patients with glaucoma or at risk of glaucoma
mydriatics
dilate the pupil
cycloplegics
paralyze the pupillary sphincter and ciliary muscle
Phenylephrine
- what is it?
- use
- cats?
- adverse effect?
- direct acting alpha agonist sympathomimetic
- lesion localization in Horner’s syndrome
- will only dilate cats with a postganglionic lesion
> no effect on other cats - can increase blood pressure
Atropine
- what is it?
- duration
- use
- concentration
- parasympatholytic drug with both mydriatic and cycloplegic properties
- duration of action can last 4-5 days
- commonly used in patients with uveitis
- most common concentration used in practice is 1%
atropine adverse effects
- transient decrease in tear production
- hypersalivation if drainage through the nasolacrimal system enters the mouth
- tachycardia, decreased gastrointestinal motility and photophobia
<><>
Long-term topical administration of atropine in young cats can result in smaller resting pupils
following cessation of therapy
<><>
canine patients may react paradoxically to atropine (or tropicamide) topical administration with miosis
Tropicamide
- what is it?
- duration
- adverse effect
- parasympatholytic drug that is commonly used prior to examination of the fundus
- short duration (6-12h)
- weak cycloplegic
<><><><>
in young cats, IOP can significantly
increase to above the normal range
types of drugs used for glaucoma
- Prostaglandin analogues
- Carbonic anhydrase inhibitors
- Beta-adrenergic drugs
- Parasympathomimetics
- Diuretics
Prostaglandin analogues
- mechanism
- uses
- onset
- adverse effects
- effective topical anti-glaucoma drugs
- decrease IOP by increasing the uveal-scleral outflow in dogs
- NOT effective in cats
- canine primary glaucoma
- effects seen in 30-60 min
<><><><> - side effect: severe miosis lasting 12-18 hour
- patients at risk for lens luxation should not be prescribed this medication
- pateints with glaucoma secondary to severe uveitis should not be prescribed this medication (breaks down blood-aqueous barrier)
<><><><>
-prost
Carbonic anhydrase inhibitors
- mechanism
- use
- speed of effect
- decrease IOP by lowering the production of aqueous humour
- not as rapid as prostaglandin analogues or osmotic diuretics (~1-2 hours)
- adjunct therapy for primary and secondary glaucoma in both dogs and cats
<><><><>
-zolamide
Carbonic anhydrase inhibitors - disadvantages of systemic (ie. why we prefer topical)
- systemic acidosis
- vomiting
- diarrhea
- general malaise
- anorexia
- panting
- lameness due to paresthesia and ataxia (cats especially)
<><><><> - Long-term supplementation with potassium is also needed due to the diuresis that induces hypokalemia
Beta-adrenergic drugs
- mechanism
- synergy
- adverse effects
- decrease IOP by lowering the production of
aqueous humour - A positive additive effect is seen with combinations of beta-blockers and carbonic anhydrase inhibitors
<><><><> - Mild miosis
- bradycardia
- NOT to be used in cats with asthma
<><><><>
-olol
Parasympathomimetics
- mechanism
- use
- adverse effects
- decrease IOP by opening the aqueous outflow channels due to contraction of the ciliary body
- decrease IOP by causing a break in the blood aqueous barrier and therefore increasing vascular permeability
- replaced in practice by prostaglandin analogues
<><><><> - Conjunctival inflammation and miosis
Diuretics
- mechanism
- onset time
- contraindications
- lowering IOP by reducing the aqueous and vitreous volumes within the eye
- as early as 10 minutes
<><><><> - contraindicated in patients with congestive heart failure, systemic hypertension, renal
insufficiency, and diabetes mellitus
Tear stimulants and corneal lubricating formulations
- when are they needed?
- needed in cases of tear deficiency and poor tear quality
- Keratoconjunctivitis sicca in dogs
Cyclosporine use
- what it does
- schedule of application
- use with schirmer tear test
- onset of action
- caution
- Topical cyclosporine has been shown to be an effective treatment for canine KCS
- Increased lacrimation is seen in normal and most deficient dogs after application of cyclosporine, but not in cats
- 2x daily, life-long
- It is imperative that cyclosporine be given the morning of the recheck Schirmer Tear Test appointment to adequately evaluate response to treatment
- 2-3 months for onset
of action
<><><><>
Optimmune, 0.2% cyclosporine ointment, is the
only licensed veterinary product for canine KCS
<><><><> - handling of cyclosporine should be done with
gloves, as it is an immunosuppressive drug
Tacrolimus
- use
- adverse effects and instructions for use
- increase lacrimation
- alternative to topical cyclosporine
- potential link to cancer
- prescription of this medication in patients that are non-responsive to cyclosporine, use of gloves when manipulating the drug, and avoid contact with children
Pilocarpine
- use
- adverse effects
- time to onset
- Topical pilocarpine 1-2% can also be used orally to stimulate tear production in neurogenic
cases of KCS - toxicity can occur quickly > vomiting and
diarrhea - increase in schrimer tear test after 3 weeks
Artificial tear supplements
- use
important adjunct therapy for tear deficiencies
Sodium chloride 5% use for ophtho
- helps reduce corneal oedema
- endothelial dystrophy or degeneration, bullous keratopathy and superficial corneal ulceration may benefit
- oitment q 6 hours
Sodium fluorescein
- corneal ulcers
- nasolacrimal patency (Jones)
- tear break up time
- aqueous fluid leaks following corneal perforation (Seidel)
Topical anesthesia for the eye
- what drug
- adverse effects
- 0.5% proparacaine
- onset of action is rapid
<><><><> - toxicity to corneal and conjunctival epithelium
- decreased epithelial healing rates due to inhibited mitosis and cellular migration
<><><><> - collect culture samples prior to instillation
preferred germicide for prepping of
ophthalmic surgical patients
- adverse effects?
- Diluted povidone-iodine solution (1:50)
- bactericidal, virucidal and fungicidal
<><><><>
chemosis and conjunctivitis
