Ophthalamic Drugs and Diabetes Insipidus (Ex2) Flashcards
What are the general indications of Ophthalamic drugs?
- dilate or constrict the pupils
- decrease aqueous fluid production or IOP
- increase tear production
- decrease inflammation
- treat infection
- topical anesthetics
What are the parasympathetic actions on the eye?
- miosis: contraction of the iris sphincter muscle
- contraction of ciliary body: near vision, increases aqueous outflow
What are the sympathetic actions on the eye?
- mydriasis: contraction of the iris dilator muscle
- relaxation of the ciliary body: far vision
- aqueous humor formation
Pilocarpine (Pilostat)
classification, uses
- direct acting parasympathomimetic (miotic)
- causes miosis lasting 2-6 hours
- diagnosis of parasympathetic lesions
- uncommonly used for glaucoma trtmt or KCS (keratoconjunctivitis sicca)
Atropine (Atrophate)
classification, uses
- direct acting parasympatholytic (mydriatic)
- causes mydriasis (onset 1 hr, dur 120+ hrs)
- causes cycloplegia (blurred vision)
- to reduce pain associated with uveitis
- can break up synechiae in uveitis
Atropine Cautions
- do not use in primary glaucoma
- generally minimal systemic absorption
- cycloplegia can cause horses to panic
- very bitter taste (cats froth at mouth)
Tropicamide (Mydricacyl)
classification, uses
- direct acting parasympatholytic
- causes mydriasis and cycloplegia (faster onset, shorter duration than Atropine)
- dilate pupil for exam
- prevent adhesions after cataract surgery
Tropicamide Cautions
- less effective pain control than atropine
- less bitter, but still can cause cats to hypersalivate
- avoid in glaucoma
- may alter Shirmer’s tear test
Phenylephrine
classification, uses, cautions
- direct acting sympathomimetic, alpha 1 agonist
- causes mydriasis
- perioperative use in cataract surgery
- help in diagnosis and trtmt of Horner’s
- cats and horses: need to combine with another agent to cause mydriasis
- can cause cardiovascular side effects
What types of drugs reduce aqueous humor formation and/or improve aqueous outflow?
- alpha agonists
- beta antagonists
- carbonic anhydrase inhibitors
- protaglandin analogs
Timolol (Timoptic)
classification, uses
- ophthalamic nonselective beta antagonist
- used in glaucoma management: prevent glaucoma in contralateral eye, decrease aqueous formation, may cause miosis
What is Cosopt?
Timolol + Dorzolamide
a carbonic anhydrase inhibitor
Dorzolamide (Trusopt)
What is it?
What is its ophthalamic use?
- topical carbonic anhydrase inhibitor
- decreases aqueous humor resulting in lower IOP
Latanoprost (Xalatan)
classification, uses
- topical prostaglandin analog
- increases uveoscleral outflow by stimulating FP receptors in the eye
- used topically to treat glaucoma and reduce IOP in dogs
- not effective in cats or horses
- often used in emergency
Cyclosporine (Optimmune)
classification, use
- topical immunomodulator/lacrimogenic agent
- used to treat canine KCS
- BID topical application required
- increases tear production and provides local immunosuppression
Topical Glucocorticoids
(use, administration, contraindications)
Name 2 drugs
- used to manage inflammatory and immune-mediated conditions
- some systemic absorption with local administration
- systemic needed to treat back of the eye
- contraindicated if corneal ulcer, infection, or diabetes
- Dexamethasone and Prednisolone
Topical NSAIDs
(use, contraindications)
Name 2 drugs
- similar to glucocorticoids, but used when a higher local concentration and lower systemic concentration is desired
- used in management of uveitis and some keratitis
- used to manage inflammation associate with cataracts
- contraindicated if corneal ulceration, glaucoma, or coagulopathies
- Flurbiprofen and Diclofenac
What is Gancyclovir?
topical antiviral agent
What is Natamycin?
antifungal agent
- human labeled product
Proparacaine (Alcaine)
classification, uses, MOA
- ophthalamic topical anesthetic
- used to decrease corneal sensation to allow diagnostic evaluation
- blocks Na channels to prevent axonal depolarization
Describe the stimulation of secretion of ADH
- volume contraction causes increased ECF osmolality
- this stimulates the osmoreceptors in the hypothalamus, which stimulates ADH secretion
- Also: hypotension stimulates volume receptors, which stimulates ADH secretion
What are the actions of ADH?
- stimulates reabsorption of water in distal tubules and collecting duct
- this results in increased water in ECF, and decreased ECF osmolality
How is ADH used?
natural ADH is administered IM or IV over 1 hour in lactated ringers or 5% dextrose for diagnosis of diabetes insipidus
What are the types of Diabetes Insipidus?
How are they caused?
- Central: caused by ADH deficiency
- Nephrogenic: caused by impaired responsiveness of the kidney to ADH
