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28 Cards in this Set
- Front
- Back
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STERILITY
Autoclaving & filtration |
- during production, to avoid introducing pathogens to eye
1- under pressure at 121degC for 15 minutes - destroys all microorganisms - but some drugs decompose 2 -aseptic filtering through pre-sterilised containers - porous membranes fine enough to stop bacteria passage - 0.22um filter, bact 0.5um - does not remove viruses |
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STERILITY
Tests of sterility |
1.prepare suitable culture media
- anareobic bacteria - fluid thioglycollate - fungi and aerobic bacteria - soya-bean casein digest medium 2. Transfer contents to be tested to membrane, filter, transfer to culture medium and incubate for at least 14 days 3. At set intervals and conclusion examine for macroscopic evidence of microbial growth - no evidence - product complies withtest for sterility - evidence - does not comply |
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PRESERVATIVES
Requirement and problems |
- in all multi-use preparations to maintain sterility after opening
- corneal toxicity, allergic reactions, TF disruption - more frequent if used in eyes withTF abnormalities, or prolonged period - resolution on cessation or substitution for presrvative free prep |
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PRESERVATIVES
Ideal Criteria (6) |
- non-irritating but effective
- non-sensitising - AB and AF - and retain effect despite adverse factors - render sterility over reasonable period of time - chemically stable - doesn't interfere with main ingredient activity |
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PRESERVATIVES
Mechanism of Action |
- Bacteriostatic - inhibits bacterial growth (most preservatives)
- Fungistatic - inhibits fungal growth - Bactericidal - active destruction of bacteria - Fungicidal - active destruction of fungi |
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PRESERVATIVES
Rate of bacterial destruction factors (7) |
- preservative nature
- organism kind - organism degree of dispersion - amount of organic matter - temperature - pH, viscosity agent type, buffer - solution age |
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PRESERVATIVES
D value |
- preservative's ability to kill organisms
- time required to decrease number of organisms 1 log unit - kill 90% - lower D value = greater antimicrobial effect - bacteria killed more quickly than fungi |
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PRESERVATIVE TYPES
Surfactants |
- detergents - ionically charged molecules
- alter relationship of interfaces > disrupt plama membrane > improve drug penetration - usually barctericidal - 'toxicity' effect - disturbs tears and cornea - inactivated by organic matter - stable - CX, BAK |
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PRESERVATIVE TYPES
Chemical toxins |
- block cells normal processes
- non-selective action on all cells - allergy problems - no effect on tears - eg, TH, iodine, alcohols |
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PRESERVATIVE TYPES
Oxidative |
- penetrate cell walls/membranes > interfere with essential cell function
- eg. hydrogen peroxide |
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PRESERVATIVES
BAK - mechanism of action, uses, side effects |
Benzalkonium Chloride
- cationic detergent, acts on membrane permeability, extremely effective - antibacterial and antifungal - stable, long shelf life - eye drop preservation, instrument sterilisation, clean skin, improve corneal penetration - conc: 0.01% typical (.004-.02% range) - often EDTA combined - TF disruption, corneal toxicity - dose dependent reduction in cell viability - reduced ep thickness, nuclear condensation, vacuole formation - not for intraocular use |
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PRESERVATIVES
CX -mechanism of action, uses, side effects |
Chlorhexidine
- + charged molecule binds to - charged bact cell wall > ruptures cell membrane - broad spectrum - effective against Gram + and - - disinfectant used in skin/hand cleaners - Hibitane 5%, eye drops 0.02% - role in acanthamoeba keratitis role - not used in conjunction with sulfates of atropine neomycin - in some mouthwashes - less corneal ep effect than BAK - some people develop sensitivity - freq mouthwash use - damage healthy oral bacteria |
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PRESERVATIVES
Cetrimide - mechanism of action, uses, side effects |
- antiseptic
- Certimide + CX - increased effectiveness (Savlon) - in eye drops 0.005%-0.02% concs (UK) - may induce toxic epiliopathy after prolonged use |
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PRESERVATIVES
Polyquad - mechanism, uses, side effects |
Polyquaternium-1
- antimicrobial detergent-type preservative - derived from BAK - Bact cells attract PQ, ep cell repel > less toxicoty - does not concentrate in CLs - affect mucous production by decreasing conjunctival goblet cells - |
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PRESERVATIVES
Chlorobutanol - formation, mechanism, uses side effects |
- formed by nucleophilc addition of chloroform and acetone alcohol based chemical toxin
- action - cell lysis - disruption of microbial cell membrane lipid congiguration - bacteriostatic (Gram + & -), fungistatic - 0.03-0.5% concs - +BAK - both compounds actions engances - relatively non-irritating cf BAK - volatile compound - diffuses through plastic with prolonged storage - unstable at room temp |
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PRESERVATIVES
Thimerosal - type, uses, side effects |
- Chemical toxin
- once popular in CL solutions - 0.005% conc - banned to decrease mercury exposure - allergic reactions - red irritated eyes, ep changes, photophobia, lacrimation - delayed HS follicular reaction in 25-50% - inc IgG tear antibodies - not as effective as other preservatives - CX, chlorobutanol |
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PRESERVATIVES
Stabilised oxychloro complex - |
Purite
- oxydative preservative - Cl-O compound - converts to water and NaCl - neutralised by human cells and doesnt accumulate - effective against microorganisms - even low concs - in alphaganP - glaucoma med - reduced toxicity, improved tolerabilty profile - well tolerated with frequent dosage |
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PRESERVATIVES
Sodium Perborate |
- oxidative preservative
- against broad spectrum bacteria and aspergillus - converts to hydrogen peroxide when combined with water - decomposed to water and oxygen in eye - in genteal lubricant drops |
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PRESERVATIVES
SofZia |
- recently developed
- ionic buffer containing borate, sorbitol, zinc, propylene glycol - inactivatated ny TF cations - less surface cytotoxicity - in travoprost glaucoma med (used to be BAK) |
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PRESERVATIVES
Sorbate |
Sorbic Acid
- limited antimicrobial activity - inhibits cell growth by acidification - waste cells energy stores - safe for sensitive eyes and CL wearers |
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PRESERVATIVES
EDTA - action, uses, side effects |
Edetate disodium
- chelating agent - binds metals (to treat Ca deposits in eye) - assists action of many preservatives - thimerosal and BAK - in many glaucoma meds - non-toxic - aids detoxification - may cause contact dermatitis |
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DRUG EFFECTS ON CORNEAL EP
No damage |
- atropine
- chloromycetin - gentamicin - methylcellulose - polyvinyl alcohol - saline |
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DRUG EFFECTS ON CORNEAL EP
Moderate Damage |
- pilocarpine
- fluorescein - rose bengal stain |
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DRUG EFFECTS ON CORNEAL EP
Important Damage |
- BAK
- topical anaesthetics |
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Should preservatives be used in:
Dry eye productS? |
No
- TF and ocular surface compromised already - preservatives exacerbate - use unit dose products - dont need preservatives |
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Should preservatives be used in:
Ocular inflammatory agents? |
No
- inflamed eye more susceptible to to surface damage - need to prevent microbes colonising meds |
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Should preservatives be used in:
Glaucoma meds? |
- no symptoms at initial stages of long-term therapy
- discontinuation of Tx if ocular irritation - but drug required in posterior segment and BAK increases absorption |
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Would you use/Why
1 Unpreserved fluorescein 2 Unpreserved saline 3 Unit doses & minims 4 Tap water |
1. liquid form - pseudomonas use fluorescein as energy source (now supplied on dry filter paper)
2. introduction of bacteria by touching tip 3. preservatives not required, elimination of toxicity - expensive 4. Contains acanthamoeba - causes severe corneal ulceration - dont use to rinse CLs or cases |
