Final - Osmotics Flashcards
Osmotics
- use
- effectiveness
- preparation
Infrequently for reduction in IOP
-initial tx of acute/extreme IOP elev (angle-closure, secondary)
Most effective in short-term tx
Pre-operative
Osmotics
-MOA (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
Osmotics ocular penetration
- drugs that enter the eye rapidly
- ethyl alcohols
- permeability
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
Osmotics
-distribution in body fluids
Drugs restricted to ECF space (mannitol) have greater effect on blood osmolality
Less affected by drugs distributed in total body water (urea)
Osmotics concentration issues
- drugs with low solubility
- ingestion of fluids after use
Require larger volumes of solution
Decr blood osmolality
Osmotics dosage:
- change in blood osmolality dependent on
- route/rate of transmission
Total dose administered, weight of pt
IV bypasses GI tract = more rapid, greater osmotic gradient vs oral
Osmotics
-indications
Short-term acute IOP
Angle-closure
Aqueous misdirection
Certain secondary glaucs
Osmotics
-contraindications
Anuria
Severe dehydration
Acute pulmonary edema
Severe cardiac decompensation
Osmotics tx regimen
- glycerol
- isosorbide
- mannitol
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
Osmotics
-SE
IOP rebound may be less common with glycerol and mannitol
-poor ocular penetration
Hyperglycemia with glycerol
Osmotics
-drug interactions
May compromise renal/CV status
-caution
