[Code of Federal Regulations]
[Title 21 Volume 5]
[Revised as of April 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR349.3]

[Page 269-270]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED)
 
PART 349--OPHTHALMIC DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE--Table of Contents
 
                      Subpart A--General Provisions
 
Sec. 349.3  Definitions.

    As used in this part:
    (a) Ophthalmic drug product. A drug product, which should be sterile 
in accordance with Sec. 200.50, to be applied to the eyelid or instilled 
in the eye.
    (b) Astringent. A locally acting pharmacologic agent which, by 
precipitating protein, helps to clear mucus from the outer surface of 
the eye.
    (c) Buffering agent. A substance which stabilizes the pH of 
solutions against changes produced by introduction of acids or bases 
from such sources as drugs, body fluids, tears, etc.
    (d) Demulcent. An agent, usually a water-soluble polymer, which is 
applied topically to the eye to protect and lubricate mucous membrane 
surfaces and relieve dryness and irritation.
    (e) Emollient. An agent, usually a fat or oil, which is applied 
locally to eyelids to protect or soften tissues and to prevent drying 
and cracking.
    (f) Eyewash, eye lotion, irrigating solution. A sterile aqueous 
solution intended for washing, bathing, or flushing the eye.
    (g) Hypertonicity agent. An agent which exerts an osmotic gradient 
greater than that present in body tissues and fluids, so that water is 
drawn from the body tissues and fluids across semipermeable membranes. 
Applied topically to the eye, a hypertonicity agent creates an osmotic 
gradient which draws water out of the cornea.
    (h) Isotonicity. A state or quality in which the osmotic pressure in 
two fluids is equal.
    (i) Vasoconstrictor. A pharmacologic agent which, when applied 
topically to the mucous membranes of the eye,

[[Page 270]]

causes transient constriction of conjunctival blood vessels.