Pharmacology and Dry Eye Disease

Vocabulary flashcards related to pharmacology, ocular allergies, and dry eye disease.

Keratoconjunctivitis Sicca

Dry Eye Disease

Vehicles

Various combinations of all the components below

Allergic & Inflammatory Reactions (H-1 Receptors) Skin:

dilation and increased permeability (leakage) of capillaries

Allergic & Inflammatory Reactions (H-1 Receptors) Nerve endings:

itching

Allergic & Inflammatory Reactions (H-1 Receptors) Lungs:

Constriction of bronchioles (bronchoconstriction)

First-Generation Antihistamines (1st gen H1RAs) Indications:

allergies (allergic rhinitis), motion sickness, insomnia

Second-Generation Antihistamines (2nd gen H1RAs) Indications:

allergies (allergic rhinitis), conjunctivitis, urticaria

Diphenhydramine (Benadryl®)

allergies, insomnia, and motion sickness

Dimenhydrinate (Dramamine®)

motion sickness

Chlorpheniramine (Chlor-Trimeton®)

allergies, urticaria

Meclizine (Bonine®)

motion sickness

1st gen. antihistamines

Penetrate the CNS (cause sedation), have a low specificity, which means they block other receptors (muscarinic, α-adrenergic, and serotonin) which produces anticholinergic effects.

Loratadine (Claritin®, Alavert®)

allergic rhinitis, conjunctivitis

Desloratadine (Clarinex®)

allergic rhinitis, urticaria

Fexofenadine (Allegra®)

allergic rhinitis, upper respiratory

Cetirizine (Zyrtec®)

allergic rhinitis, urticaria

Levocetirizine (Xyzal®)

allergic rhinitis, urticaria

Ocular Allergy Overview

Ocular allergies result in swollen eyelids and red, chemotic watery eyes.

Type I Hypersensitivity Reactions

Known as an immediate allergic response or anaphylactic reaction and occurs when antigens are reintroduced after previous exposure.

Histamine

the main mediator in Type I allergic reactions

Histamine activates histamine-1 (H-1) receptors on blood vessels which results in:

vasodilation, leakage of fluid due to increased vascular permeability, and tissue swelling

Dry eye disease (DED)

also known as keratoconjunctivitis sicca, dry eye syndrome, and dysfunctional tear syndrome

Keratoconjunctivitis sicca

dryness of the conjunctiva (the membrane that lines the eyelids and covers the white of the eye) and cornea

Dry Eye Disease and Ocular Surface Disease (OSD)

Dry eye is part of a group of eye conditions called ocular surface disease which indicates damage to the surface layers of the eye, namely the cornea and conjunctiva.

Aqueous Deficient Dry Eye (ADDE)

reduced tear secretion

Evaporative Dry Eye (EDE)

excessive tear evaporation

Ocular surface staining:

identify areas of discontinuity in the corneal epithelium or devitalized epithelium in the cornea and conjunctiva

Tear break-up time:

determine tear film stability

Schirmer test:

quantify the number of tears produced

The goals of ocular surface disease treatment are to:

Relieve symptoms, heal the ocular surface, and prevent serious complications.

Dry eye treatment includes the following categories:

Tear Supplementation, Tear Conservation (evaporation/resorption), and Tear Stimulation/Reduce Inflammation

General Requirements of Artificial Tears

Maintain the clarity and aid in the formation of the aqueous layer, Maintain and do not alter lipid layer function, Maximize surface tension of the tear film, Mimic the actions of the mucin layer if it is absent.

Demulcents

Water soluble polymers that are used to protect and lubricate the ocular surface.

Emollients

Fat-based or oil-based products that seek to replicate the lipid layer of the eye

Preservatives

Prevent the growth of microorganisms

Viscosity-Increasing Agents

Prolong contact time by slowing drainage from the eye

Antioxidants

Prevent or delay deterioration by oxygen

Wetting Agents

Reduce surface tension, allowing the drug solution to spread across ocular surface

Buffers

Maintain ophthalmic products in the pH range of 6 to 8

Tonicity Agents

Maintain isotonicity with preocular tear film (0.6%-1.8%)

Detergents:

Quaternary ammoniums (detergent surfactants and disinfectants): BAK or BZAK, polyquaternium-1 (Polyquad), etc.

Mercurial derivatives:

thimerosal, phenylmercuric compounds

Biguanides or Amides:

polyhexamethylene biguanide (PHMB), chlorhexidine, polyaminopropyl biguanide (PAPB)

Alcohols:

chlorobutanol (detergent), benzyl alcohol, phenylethenol (phenyl ethyl alcohol)

Miscellaneous:

Sorbic Acid, Methylparaben and Propylparaben (Parabens), Disodium EDTA (ethylenediaminetetraacetic acid)

Sorbic Acid MOA:

Is an antioxidant

Methylparaben and Propylparaben (Parabens esters as a class) MOA:

Inhibits microbial metabolism

Disodium EDTA (ethylenediaminetetraacetic acid) MOA:

Has antioxidant properties and is also chelating agent that binds divalent cations (unique action) which disrupts cell membranes

MOA: Stabilized Oxychloro-Complex (Purite®) and Sodium Perborate (GenAqua®)

Oxidative preservative systems

MOA: SofZia®

Ionic buffered preservative system

polymers in artificial tear solutions or tear substitute solutions as viscosity increasing agents

Polysaccharides/Cellulose Ethers (Methylcellulose (MC), Carboxymethylcellulose (CMC), Hydroxypropyl methylcellulose (HPMC)) and Vinyl derivatives (water soluble polymers) (polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP or Povidone))