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Summer Final: Glaucoma > Medical Managemtn Of Glaucoma-3 > Flashcards

Medical Managemtn Of Glaucoma-3 Flashcards

1
Q

Osmotic drugs intro

A
  • infrequently used for reduction of IOP
  • more effective in short term treatments
  • preoperative preparation
  • initial treatments of acute and extreme elevation of IOP. Angle closure glaucoma, secondary glaucoma
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2
Q

MOA of osmotic agents

A

lower IOP by increasing osmotic gradiaent between blood and ocular fluids
-administration: blood osmalility increased by up to 20-30mOsm/L: loss of water from eye to hyperosmoistic plasma

Osmotic gradient between retina choroid and vitreous causes water transfer leading to reduction of vitreous volume

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3
Q

Factors affecting osmotic gradient

A
  1. Ocular penetration
  2. Distribution in body fluids
  3. Molecular weight and concentration
  4. Dosage
  5. Rate and route of administration
  6. Rare of systemic clearance
  7. Type of diuresis
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4
Q

Ocular penetration of osmotic agents

A
  • drugs entering eye rapidly produce less of an osmotic gradient than those that penetrate slowly or not at all
  • ethyl alcohol enters aqueous rapidly, but slow penetration in the avascuarl vitreous
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5
Q

Permeability of osmotic agents

A

Permeability is greatly increased with inflamamtion and congestion

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6
Q

Distribution of body fluids: osmotic agents

A
  • drugs restricted to extracellular fluid space (mannitol) have a greater effect on blood osmolarity
  • at same dose, blood osmolarity is less affected by drugs distributed in total body water (urea) Urea no longer utilized
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7
Q

Concentration issues and osmotic agents

A

Drugs with low solubility require larger volumes of solution

-ingestion of fluids after osmotic drug use decreases blood osmolarity

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8
Q

Dosage of osmotic agents

A

-change in blood osmolalitly depends on total dose admintered and weight of patient

Route and rate of administration
-IV bypasses GI absorption: more rapid and greater gradient compared with oral

Rate of systemic clearance

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9
Q

Indications for osmotic agents

A
  • short term treatment of acute and marked elevation of IOP
  • angle closure glaucoma
  • aqueous misdirection
  • certain secondary glaucoma
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10
Q

Contraindications of osmotic agents

A
  • Anuria
  • severe dehydration
  • frank or impending acute pulmonary edema
  • severe cardiac decompensation
  • hypersensitivity to any component of preparations
  • caution in: cardiac, retinal or hepatic diseases, CHF, hypervolemia, electrolyte imbalance, confused mental statues, dehydration
  • oral glycerol may cause blood glucose to rise in diabetic patients
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11
Q

Treatment regiment of osmotic agents

A

-flavoring and pairing glycerol solution over Ice improve palatabiltiy

Isosorbide

  • 45% wt/vol solution
  • 1-2 g/kg of body weight
  • osmotic effect persists up to 5-6 hours
  • 2-4 doses per day during the short term use
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12
Q

Treatment Regimen of mannitol (osmotic agents)

A
  • does may be lowered if IOP is not too high
  • terminate IV infusion when desired effect on IOP reached
  • stored at room temp
  • higher concentrations may require slight warming-crystals may form at temporatures below room temp
  • should include filter
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13
Q

Side effects of osmotic drugs

A
  • IOP rebound may be less common with glycerol and mannitol-have poor ocular penetration compared with other osmotic drugs
  • hyperglycemia in using glycerol
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14
Q

Side effects of osmotic drugs

A

Ocular

  • IOP rebound
  • intraocualr heme
  • increased GI activity
  • CNS problems
  • CHF, PE, and angina

-hyperglycemia
Hypersensitivity

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15
Q

Drug interactions of osmotic drugs

A

-drugs that’s may compromise renal or cardiovascular status hsould be used with caution in combintastion with osmotic drugs

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16
Q

Angle closure glaucoma and osmotic agents

A
  • therapy directed at lowering IOP and opening AC angle
  • osmotic drugs are mainstay in treatment
  • vitreous dehydration allows lens and iris to move posteriorly-deepening of AC chamber
  • iris sphincter often nonreactive due to relative ischemia when IOP elevated

Rapid reduction of IOP by osmotic drugs may relieve this ischemia-sphincter function, iosis, opening of AC angle

17
Q

Which is easier to administer for angle closure glaucoma in the office for osmotic agents

A

Oral isosorbide or glycerol

18
Q

Benefit of isosorbide for angle closure vs glycerol

A

Less nausea and vomiting and not metabolized to glucose

-however nears already present in pateitns with angle closure and may not be able to retain oral medications

19
Q

Osmotic drugs used for secondary glaucoma

A
  • highly elevated IOP
  • glaucoma rewriting control of IOP until underling problem corrected
  • use of isosorbide avoids large calorie load intake ingested with glycerol therapy
  • uveitis and post traumatic glaucoma
  • preoperatiely in eye with extremely high IOP that require glaucoma surgery

Aqueous misdirection
-osmotic drugs temporarily dehydrate the vitreous

20
Q

Glycerol onset of action

A

10-30m

21
Q

Max effect: oral glycerol

A

45-120m

22
Q

Duration of action of oral glycerol

A

4-5 hours

23
Q

Metabolism of oral glycerol

A

80% in liver, 10-20% occurs in kidney

24
Q

Oral glycerol and diabetics

A

Produces 4.34cal/g

Diabetics may develop hyperglycemia and ketosis

25
Q

Problems with oral glycerol

A

Nausea and vomiting following ingestion-problem in therapy of acute glaucoma and perioperative use

26
Q

Oral isosorbide

A
  • similar to glycerol in onset of action, time to max effect and duration of effect
  • no caloric load
  • less likely than glycerol to produce nausea and vomittin-more likely to produce diarrhea
27
Q

Which osmotic agent has a caloric load

A

Oral glycerol

28
Q

Oral ethyl alcohol

A
  • oral dose for lowering IOP 2-3mL/kg of body weight of a 40-50% solution
  • rapidly absorbed
  • distribution in total body water and rapid penetration of eye limit degree and duration of osmotic gradient
  • alcohol induces hypotonic diuresis-prolong and increased osmotic gradient
  • increased caloric load
  • dehydration
  • CNS effects
29
Q

IV mannitol

A
  • drug of choice when IV osmotic drugreuwired for lowering IOP
  • onset 10-30m
  • peak effect 30-60m
  • duration of action 4-6 hours
  • distribution in extracellular water
  • poor ocular penetration
  • large volume of IV fluid required due to limited solubility
  • cardiac or renal disease require caution
30
Q

Does generic work as well as brand name

A

In theory yet but it actually depends

31
Q

Issues with generics

A
  • drop size-may not be equivalent
  • variability of active ingredient
  • environmental exposure such as heat
  • reaction with plastic containers
32
Q

Heat stress test

A

Latanaprost
-significant decreased compared to brand name in active ingredient

Dorzolamide/timolol
-resistant to heat changes

BAK concentrations at 50C was decreased

33
Q

Particulate matter and heat: generic vs brand name

A
  • at 25C, particulate matter increased in generic

- at 50X, both generic and brand name showed increased inarticulate matter

34
Q

Loss of efficacy of brand name vs generic

A

Baseline drop

  • 38.6% with Dalmatian
  • 22.7% with generic latanaprost
  1. 86% loss of efficacy change from Dalmatian to latanaprost
  2. 3% increase efficacy change from generic to brand name
35
Q

Summary of generic vs brand name

A
  • brand name offers more tighter control of the drug related issues
  • some drug is better than no drug and generics are here to stay
36
Q

Medications and glaucoma: chronic drug use and preservatives

A
  • chronic drug uses and its effect on future surgical outcomes?
  • chronic combination therapies-significant risk factor for failure of trabeculectomy

Preservative effect?
Inflamamtion leading to failure of future procedures

37
Q

Summary of preservatives

A
  • preservative free better solution given the understanding we have
  • non BAK preservatives may be a good trade off although not totally problem free
  • PGs dont need preservatives for drug penetrations
  • some drug is better than no drug, preserves medications have a role to play in glaucoma maagnentms

Summer Final: Glaucoma (15 decks)

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