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
What can be used to treat central diabetes insipidus?
Desmopressin
Thiazide diuretics
Chlorpropamide
Restricted sodium chloride uptake
What can be used to treat nephrogenic dibetes insipidus?
Thiazide diuretics are drug of choice
Restricted sodium chloride uptake
Desmopressin
classification, actions, pharmacokinetics
- a synthetic ADH analog
- more potent and longer duration that natural ADH
- minimal vasconstrictor action
- parenterally and nasal drops in eye
- drug of choice for CDI in dogs and cats
Chlorpropamide
classification, pharmacokinetics
- an oral hypoglycemic sulfonylurea durg
- requires presence of some endogenous ADH to act
- not very effective for trtmt of CDI in dogs and cats
