Final - Osmotics

Question 1

Osmotics

• use
• effectiveness
• preparation

Answer 1

Infrequently for reduction in IOP
-initial tx of acute/extreme IOP elev (angle-closure, secondary)

Most effective in short-term tx

Pre-operative

Question 2

Osmotics

-MOA (2)

Answer 2

Lower IOP: incr osmotic gradient b/w blood and ocular fluids
-blood osmolality incr by ~20-30mOsm/L -> loss of water from eye to hyperosmostic plasma

Osmostic gradient b/w retina-choroid and vitreous causes water transfer -> reduction of vitreous volume

Question 3

Osmotics ocular penetration

• drugs that enter the eye rapidly
• ethyl alcohols
• permeability

Answer 3

Produce less of an osmotic gradient than those that penetrate slowly/not at all

Enter aqueous rapidly, but slow penetration in avascular vitreous

Greatly incr with inflammation, congestion

Question 4

Osmotics

-distribution in body fluids

Answer 4

Drugs restricted to ECF space (mannitol) have greater effect on blood osmolality

Less affected by drugs distributed in total body water (urea)

Question 5

Osmotics concentration issues

• drugs with low solubility
• ingestion of fluids after use

Answer 5

Require larger volumes of solution

Decr blood osmolality

Question 6

Osmotics dosage:

• change in blood osmolality dependent on
• route/rate of transmission

Answer 6

Total dose administered, weight of pt

IV bypasses GI tract = more rapid, greater osmotic gradient vs oral

Question 7

Osmotics

-indications

Answer 7

Short-term acute IOP
Angle-closure
Aqueous misdirection
Certain secondary glaucs

Question 8

Osmotics

-contraindications

Answer 8

Anuria
Severe dehydration
Acute pulmonary edema
Severe cardiac decompensation

Question 9

Osmotics tx regimen

• glycerol
• isosorbide
• mannitol

Answer 9

Flavoring, over ice

1-2 g/kg of body weight
Effect lasts 5-6 hrs
2-4 doses/day during short term use

Terminate IV when desired effect on IOP is reached
Store at room temp, higher [] may require slight warming
-crystals form
Should include filter

Question 10

Osmotics

-SE

Answer 10

IOP rebound may be less common with glycerol and mannitol
-poor ocular penetration

Hyperglycemia with glycerol

Question 11

Osmotics

-drug interactions

Answer 11

May compromise renal/CV status

-caution