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48 Cards in this Set
- Front
- Back
3 ways to deliver opthalmic drugs
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1) topically applied to eye
2) surface or intraocular conditions 3) Infections, allergies ,inflammation, elevated IOP, dry eye |
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Can you use systemic effects opthalmically?
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No, local effects only
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3 ways to apply opthalmic drugs
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1) dropwise
2) thin ribbon on lower lid margin 3) insertion of device for continuous release of drug |
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General info on the capacity of the eye 4 things
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1) blinking and flushing effect of lachrymal fluid
2) tear fluid in cul-de-sac = 7-8 mcL 3) non-blinking 30 mcL X blinking 10 mcL 4) Blinking: 80% of 50 mcL dose lose after 5 min of admin. |
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Extended periods of therapy need increased contact time, occurs by what 5 processes?
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1) multiple-drop therapy with timer intervals
2) increased viscosity 3) suspensions, ointments, gels 4) inserts 5) oral or parenteral therapy if serious condition |
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Main pharmaceutical requirement for all opthalmics
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Sterility and Preservation
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4 main ways to gain sterility for opthalmics
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1) Autoclave 121 celsius for 15 min
2) Bacterial filtration: 0.2 mcm pore size 3) Sterilizing oven with petrolatum (similar) ointment bases with non heat sensitive drug --> melts but re-solidifies 4) Antibacterial agents --> especially in preparations for intact corneal membranes (multiple dose containers) |
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When are preservatives not used for opthalmics?
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For preparations used during surgery, for inserts, eye washes used in large quantities on burned or abnormal corneas, or any single dose preparations
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4 most common preservatives for opthalmics?
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1) Benzalkonium chloride
2) chlorobutanol 3) phenylmercuric acetate/nitrate 4) thimerosal Some agents are incompatible with drugs or other ingredients |
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Concentrations of preservatives tolerated by the are are ineffective against what?
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some strains of Pseudomonas Aeruginosa --> causes ulceration and blindness
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Mixtures of preservatives and other agents in opthalmics to make more preserved or more stable ore more effective for extended shelf life….
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Preservatives combined with:
1) Antibiotics (polymixin B) 2) Chelating agents (EDTA) Ex: Benzalkonium + polymixin B (or EDTA or ALL 3!) |
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Isotonicity of opthalmics have osmotic pressure similar to what?
What % can eye tolerate with tonicity? |
Lachrymal fluid = 0.9% NaCl (eye can tolerate NaCl concentrations from 0.6% to 2% --> causes discomfort b/c not isotonic)
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Why is isotonicity of opthalmics necessary?
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Needed for efficacy, safety and comfort
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A given volume of a solution of electrolyte will exert a ???? osmotic pressure than the same volume of a non-electrolyte solution?
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Greater
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If 2 liquids have same osmotic pressure they are called ????
But a liquid is ISOTONIC only when it has the same ???? |
1) Isosmotic
2) same osmotic pressure as body fluid |
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T or F
All solutes and agents contribute to the osmotic pressure? |
True!
Even non-electolytes Each agent of a combination of drugs contribute to tonicity |
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2 ways to calculate tonicity of opthalmic solutions?
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NaCl equivalent and freezing point depression
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USP provides pre-calibrated volumes of sterile water to be added to ????
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1g of some common opthalmic drugs to prepare isotonic solutions
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Hypertonic solutions cause what?
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If added to eye --> draws water out of cells causing shrinking
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Hypotonic solutions cause what?
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If added to eye --> water enters cells of eye and can cause bursting
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Buffering of Opthalmics help or reduce 3 things...
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1) helps maintain stability of drug b/c most drugs are weak acids or bases and need some buffer to remain stable
2) helps control therapeutic activity 3) reduces discomfort of the patient |
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pH of lachrymal fluid
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7.4 with some small buffering capacity but since it is almost neutral, if a drug needs to be buffered it needs to be provided in the preparation
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2 main USP buffer vehicles
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1) Boric Acid: 1.9% boric acid solution with pH of 5.0
2) Isotonic phosphate: mixture of mono basic and dibasic salts of phosphate with pH of 5.9 - 8.0 |
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Fast lachrymal drainage affects what?
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Liquids with low viscosity have little contact times with corneal membranes and may not reach therapeutic effect needed
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Thickening agents added to opthalmic solutions and suspensions do what 2 things?
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1) help drug remain in cul-de-sac of eye
2) enhance therapeutic effect |
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Most common opthalmic thickening agent used to increase viscosity
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Methylcellulose and cellulose derivatives
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Bioavailability of opthalmics affected by 4 things
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1) protein binding
2) Drug metabolism 3) lachrymal drainage 4) product formulation |
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Protein binding affects bioavailability how?
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Proteins in tears: 0.6 - 2% make drug unavailable for absorption and therefore when binds it makes drug ineffective
Certain diseases can increase ocular protein levels |
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What is uveitis?
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Inflammation of uveal tract of the eye may lead to visual impairment and blindness
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Drug metabolism affects bioavailability how?
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Lysozymes in lachrymal fluid may destroy drug before absorption occurs
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Lachrymal drainage affects bioavailability how?
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Fast removal of drug causes too brief contact with tissues
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Product formulation affects bioavailability how?
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Un-ionizied drugs (doesn't look like water or act like water) permeate cornea easier (greater lipid solubility)
Ionized drugs look and act like water and become hydrated and get absorbed less |
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4 main characteristics of opthalmic solutions (eye drops/ CL products)
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1) sterile
2) isotonic 3) aqueous 4) free of particulate matter |
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Opthalmic suspensions 3 main things
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1) used less than solutions but sometimes only way drug can be used opthalmically
2) extended corneal contact for improved drug action 3) particle size of suspension: very small and non-irritating to eye (no agglomeration/not gritty upon storage) |
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Opthalmic ointments 4 main things (includes 2 disadvantages and 1 main advantage)
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1) manufacture from sterile ingredients or sterilized after preparation by dry heat/sterilized oven
--> ointment melts and is sterile then re-solidifiys and can use dry powders to be sterilized then added to ointment 2) Provide increased ocular contact time comported to liquid forms --> advantage 3) blurred vision disadvantage --> disadvantage 4) cannot be used with CL --> disadvantage |
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Opthalmic gels designed for what?
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Extended drug action but is washed away faster than ointments because they are water soluble
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Disadvantages of opthalmic gels?
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Similar to opthalmic ointments
1) cannot be used with CL 2) blurred vision occurs |
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2 examples of opthalmic gels
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1) Pilocarpine HS gel --> carbopol 949 (high MW cross-linked polymer of acrylic acid)
2) Timoptic XE: contains gellan gum which forms gel uptown contact with pre-corneal tear film |
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Opthalmic inserts: structure (4 things)
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1) flexible, multilayered structure similar principle as TDDS (trans dermal delivery systems)
2) drug-controlling core: reservoir 3) rate-controlling copolymer membranes on each side 4) drug diffusion at constant rate |
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Pilocarpine Insert "Ocusert"
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Type of opthalmic insert in treatment of glaucoma with either 1 week or 1 month dose
Pilocarpine placed on cul-de-sac and is sandwiched between 2 ethylene vinyl acetate membrane and alginic acid (seaweed carb) is carrier for drug |
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Lacrisert
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Rod-shaped water-soluble hydroxypropyl cellulose insert for dry eyes
Q.d or b.i.d |
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Nasal preparations applied how?
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1) through nasal pathway for systemic effects (inhalation)
2) into nasal passage for local effects |
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3 main types of nasal preparations
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1) solution: drops, sprays, inhalants
2) suspension 3) jellies |
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5 usual active ingredients
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1) Adrenergic agents as decongestants for rhinitis and sinusitis but can become desensitized to tissues
2) Anti-inflammatory agents for internal effects 3) anti-allergic agents 4) synthetic oxytocin (hormone) for breast feeding 5) insulin (inconsistent absorption so hardly used), growth hormones, other |
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What occurs when adrenergic agents/decongestants are used too often?
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Should be only used 4-5 days max as rhinitis medicaments (rebound congestion) can occur and relief to congestion becomes addictive
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Types of dosage preparations for Otic/Aural/Ear preparations
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1) solutions
2) suspensions 3) ointments All placed in ear canal for local effect ONLY |
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Treatment of what types of issues?
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Inflammation, infections, pain: antibiotics, analgesics, anesthetics can be used
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Removal of excessive cerumen (ear wax) uses what ( "3" main things)
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Cerumenolytic surfactants --> triethanolamine polypeptide oleate-condensate or carbamide perioxide
Or can use light mineral oil, vegetable oil, hydrogen peroxide all dissolve cerumen Hygroscopic co-solvents: anhydrous glycerin and PEG reduce moisture and bacterial growth and inflammation secretions |