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Therapeutics > ophthalmic drugs: anti-infective drugs > Flashcards

ophthalmic drugs: anti-infective drugs Flashcards

1
Q

what are the 3 different therapeutic classes of anti-infective drugs

A 
- Antibacterials
Topical
Oral
- Antivirals
- Anti-protozoals
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2
Q

what 2 forms is antibacterial drugs available in

A
  • Topical

- Oral

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3
Q

even though anti infective drugs have a long shelf life, why do optometrists not stock them in practice

A

because they won’t use them enough for us to have a stock of them and some of them need to be refrigerated so its a hassle

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4
Q

how much % do anti infective drugs count for as prescription ophthalmic drugs in the UK

A

17%

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5
Q

why is 17% an under estimation of anti infective drugs supplied in the UK

A

because that counts for prescription only, and many anti infective drugs are available OTC or pharmacists can supply chloramphenicol

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6
Q

when will a pharmacist decide to supply a px with chloramphenicol

A

only if the px is suspected of having acute bacterial conjunctivitis (and not for anything else)

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7
Q

what can an optometrist supply chloramphenicol to a px for that a pharmacist can’t and how

A

as a POM drug which has a broader licence to treat post corneal abrasion
the optom will use a signed order where they write down the drug name and give it to the pharmacist

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8
Q

what do drugs exploit

A

the difference between human (eukaryotic) and bacterial (prokaryotic) cells

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9
Q

list 4 differences between bacterial cells and human cells

A
  • Bacterial cells have a unique cell wall
  • There are differences in their cell membrane
  • Bacterial cells show differences in the mechanism of DNA and protein synthesis
  • Bacterial cells have different biosynthetic pathways
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10
Q

what do the differences between human and bacterial cells form the basis for

A

the selective toxicity of anti-bacterial drugs

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11
Q

what are drugs that kill the cell called

A

bactericidal

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12
Q

what do bacteriostatic drugs do

A

inhibit growth of the bacteria

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13
Q

name 2 drugs which affect the cell wall synthesis

A
  • Penicillins

- Cephalosporins

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14
Q

name 2 drugs affecting the bacterial cell membrane

A
  • Polymyxin B

- Propamidine

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15
Q

name 4 drugs affecting bacterial protein synthesis

A
  • Aminoglycosides
  • Tetracyclines
  • Chloramphenicol
  • Fusidic acid
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16
Q

name a drug affecting bacterial DNA synthesis

A

Fluoroquinolones

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17
Q

name a drug affecting bacterial metabolism

A

Sulphonamides

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18
Q

what is the most common way that a anti bacterial drug works

A

affecting bacterial DNA synthesis

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19
Q

name 5 general considerations when selecting a antibiotic

A
  • Spectrum of cover e.g.
    Narrow vs broad
    Single vs combination
  • Penetration into appropriate tissue
  • Mode of action
  • Route of administration
  • Side effects e.g.
    Tolerability
    Pregnancy / Lactation
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20
Q

what 2 variations come under spectrum of cover when choosing an antibiotic

A

Narrow vs broad
or
Single vs combination

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21
Q

what 2 examples of side effects need to be considered when choosing an antibiotic

A
  • Tolerability

- Pregnancy / Lactation

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22
Q

what 2 examples of penetration into appropriate tissue needs to be considered when choosing an ophthalmic antibiotic

A
  • topical
    or
  • injected into eye
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23
Q

give 4 examples of routes of administrations of anti bionics

A
  • topical
  • orally
  • injection
  • slow release implant
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24
Q

what is the name of the test to check the sensitivity of antibiotics

A

Kirby-Bauer Antibiotic Sensitivity test

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25
Q

when can the Kirby-Bauer Antibiotic Sensitivity test be carried out on a bacteria

A

once its isolated

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26
Q

list the steps of how the Kirby-Bauer Antibiotic Sensitivity test is carried out

A
  • a colony of bacteria is picked off the agar plate
  • emulsified in a small volume of saline and then spread on a sensitivity test agar plate
  • a paper disc, which has been impregnated with various antibiotics, is placed on top of the culture
  • which is then incubated at 37C for 18 hours
  • zones of diameter are read around each antibiotic disc and compared with standard values to judge whether the zone size represents a sensitive, intermediate or resistant isolate
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27
Q

which condition is the Kirby-Bauer Antibiotic Sensitivity test the gold standard treatment for

A

bacterial keratitis

you take a biopsy of the ulcer to sample the bug that is growing

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28
Q

list the 3 antibiotics available to all registered optometrists

A
  • Chloramphenicol
  • Fusidic acid
  • Propamidine (P medicine bought OTC)
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29
Q

what is the antibiotic Polymyxin B available to optometrists as

A

Additional supply (by those who took additional qualifications)

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30
Q

what type of antibiotics are available to independent prescribing optometrists

A

All anti-infectives available for the treatment of diseases of the eye and surrounding tissues
(only restriction is injections)

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31
Q

what type of antibiotics is chloramphenicol

A
  • broad spectrum
  • Bacteriostatic (may be bacteriocidal for some species at high concentration)
  • resistance if fairly low
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32
Q

what is chloramphenicol not affective against

A

pseudomonas

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33
Q

what condition is linked with systemic use of chloramphenicol but very unlikely with topical chloramphenicol

A

aplastic anaemia and ‘Grey Baby Syndrome’

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34
Q

what is aplastic anaemia

A

a life threatening stem cell deficiency which will need a bone marrow transplant

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35
Q

what is grey baby syndrome

A

a condition which can occur if chloramphenicol is given intravenously to babies in high doses

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36
Q

what is the UKs first choice of drug for most ocular surface infections

A

topical chloramphenicol

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37
Q

what is chloramphenicol officially licensed for and give 3 examples

A

the treatment of superficial infections of the eye

e. g.
- bacterial conjunctivitis
- infective blepharitis
- prophylaxis following trauma

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38
Q

what is prophylaxis

A

a treatment of antibiotic given to px in order to avoid them getting a bacterial infection

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39
Q

what are the 2 different formulations and concentrations of POM chloramphenicol available in
what else are POM chloramphenicol available in addition to this

A
  • Redidrops, 0.5% POM
  • Chloromycetin Ophthalmic ointment, 1% POM
  • unit dose (minims)
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40
Q

how often should POM chloramphenicol be used

A

1-2 drops every 3-6 hours for 1 week

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41
Q

what happened to chloramphenicol eyedrops in 2005

A

it was reclassified from POM to P for the treatment of acute bacterial conjunctivitis

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42
Q

when was chloramphenicol ointment reclassified from POM to P

A

2007

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43
Q

what is the mode of action of chloramphenicol

A

The binding of chloramphenicol to peptidyl transferase on the 50S ribosomal subunit prevents the incorporation of new amino acids to the growing peptide chain

it works by inhibiting bacterial synthesis, the ribosomes goes along the messenger RNA and you have a growing peptide chain thats standard in all cells. The ribosomes used in bacteria are different to ribosomes used in human cells, so chloramphenicol binds to bacterial ribosomes and inhibits the growth of that peptide chain

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44
Q

list the 5 isolates associated with bacterial conjunctivitis

A
  • Stapha = Staph. aureus
  • Staphe = Staph epidermis
  • Haemop = Haemophilus species
  • Pseudo = Pseudomonas
  • Strep = Streptococcus species
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45
Q

what are the 2 bugs that are most common in bacterial conjunctivitis

A
  • Stapha = Staph. aureus

- Staphe = Staph epidermis

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46
Q

which bug is rarely a cause of bacterial conjunctivitis

A

Pseudo = Pseudomonas

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47
Q

which bug is the next most common after staph to cause bacterial conjunctivitis

A

Strep = Streptococcus species

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48
Q

which bug is the most likely to cause bacterial conjunctivitis in children than in adults

A

Haemop = Haemophilus species

49
Q

what did a randomised double blinded treatment of chloramphenicol in the treatment of bacterial conjunctivitis show

A

that people just get better without any treatment and shows no statistical difference between chloramphenicol and the placebo, so if you do nothing it is just as affective

50
Q

what is the POM Fusidic acid effective against

A

a broad range of gram +ve organisms (particularly Staph. Aureus)

51
Q

what type of antibiotic is fusidic acid

A

Bacteriostatic (may be bacteriocidal at high concentrations)

52
Q

what is the antibiotic fusidic acid licensed for

A

for the treatment of bacterial conjunctivitis

53
Q

why will fusidic acid be used instead of chloramphenicol

A

because you only need to put it in twice a day instead of 4x a day
is easy to use on children

54
Q

give a reason where fusidic acid is not an appropriate agent for acute bacterial conjunctivitis in children

A

because it is ineffective against Gram-negative H influenzae, the most common causative pathogen in this population

55
Q

name 2 off licence uses of fusidic acid

A
  • prophylaxis following corneal abrasion

- blepharitis

56
Q

what is the trade name of the only formulation of ophthalmic fusidic acid available

A

Fucithalmic, POM

57
Q

what does it mean when a drug isn’t licensed for that purpose but it still used

A

the drug company never ran clinical trials on these patients

58
Q

how often should Fucithalmic, POM be applied

A

twice daily application

59
Q

what form does fusidic acid come in and what advantage does this have

A

comes as a gel

so stays on the ocular surface much longer than eye drops

60
Q

what makes fusidic acid a good ocular surface agent

A

it doesn’t penetrate the ocular tissues and does not get as far as the aqueous

61
Q

which bacterial bug does fusidic acid have good efficacy against

A

staphylococcus

62
Q

what is the age group for chloramphenicol POM

A

> 1 month old

63
Q

what is the age group for chloramphenicol P

A

> 2 years old

64
Q

what is the instructed dose intake of chloramphenicol

A
  • Put one drop into the affected eye(s) every 2 hours for 2 days, and then three times a day for 5 days.
  • Ointment at bedtime
65
Q

what is the age group of Fusidic acid 1% eye drops

Fucithalmic (POM)

A

> 1 month

66
Q

what is the instructed dose intake of Fusidic acid 1% eye drops Fucithalmic (POM)

A

1 drop 2x per day for 7 days

67
Q

why is the age group of the OTC/P chloramphenicol > 2 years old

A

because of the theoretical risk of grey baby syndrome

68
Q

which drug was discontinued in October 2012 and what properties did it have

A
  • POM Polymyxin B
  • where chloramphenicol was not good against game -ve bugs, this drug was
  • it attaches to and interferes with the functioning of the cell membrane of aerobic Gram-negative bacteria, and bacitracin inhibits the synthesis of the cell wall of Gram-positive bacteria.
69
Q

which bacterial bug was the POM Polymyxin B active against

A

P aeruginosa

70
Q

which drug is active against gram +ve bacteria but less active against gram -ve bacteria, and also has anti fungal and anti amoebic properties
what treatment is it used for

A

OTC Propamidine
used topically for the treatment of minor eye infections such as conjunctivitis and blepharitis
it is an Aromatic diamidine disinfectant

71
Q

OTC Propamidine is not an antibiotic, but is an

A

Aromatic diamidine disinfectant

72
Q

how does OTC Propamidine work

A

by acting on the bacterial cell membrane, it increases it’s cell permeability and is bacteriostatic

73
Q

what is OTC Propamidine used by ophthalmologists for

A

patients who come into A&E with acanthamoeba keratitis

74
Q

what are the 2 different formulations of (P) propamidine available

A
  • Brolene

- Golden eye ointment

75
Q

what is (P) propamidine licensed for

A

treatment of superficial infections of the eye

e.g. bacterial conjunctivitis and infective blepharitis

76
Q

what is the instructed dose intake of (P) propamidine

A

1-2 drops up to 4x daily

77
Q

what did pharmacists used prior to chloramphenicol as an anti-infective agent

A

(P) propamidine

78
Q

list 4 other anti-bacterials that are used in ophthalmology

A
  • Quinolones
  • Aminoglycosides
  • Tetracylines
  • Azithromycin
79
Q

how does the ophthalmological anti bacterial Quinolones work

A

Inhibit DNA gyrate

they’re broad spectrum drugs

80
Q

list 4 examples of Quinolones

A
  • Ofloxacin
  • Ciprofloxacin
  • Levofloxacin
  • Moxifloxacin
81
Q

name the 2 newer generation Quinolones anti bacterials and why are there newer generation ones out

A
  • Levofloxacin
    and
  • Moxifloxacin

newer ones are added all the time because the old ones become useless as so many bacteria become resistant to them, therefore companies have to develop new ones to stay one step ahead of the bacteria

82
Q

how does the ophthalmological anti bacterial Aminoglycosides work

A

Inhibits protein synthesis
is bactericidal

they’re broad spectrum drugs

83
Q

what is a disadvantage of the ophthalmological anti bacterial Aminoglycosides

A

they are toxic to the ocular surface especially thick corneas

84
Q

name 2 examples of the ophthalmological anti bacterial Aminoglycosides

A
  • Gentamicin

- Tobramycin

85
Q

how does the ophthalmological anti bacterial drug Tetracylines work

A

Inhibit bacteria protein synthesis by blocking the attachment of the transfer RNA-amino acid to the ribosome

they’re broad spectrum drugs

86
Q

what is the ophthalmological anti bacterial drug Tetracylines used to treat

A

lid margin disease

87
Q

name 2 examples of the ophthalmological anti bacterial drug Tetracylines

A
  • Doxycycline

- Minocycline

88
Q

how is the ophthalmological anti bacterial drug Tetracylines administered

A

orally

instead of topically

89
Q

what 2 things is the ophthalmological anti bacterial drug Azithromycin licensed for

A
  • trachomatous conjunctivitis caused by Chlamydia trachoma’s

- acute bacterial conjunctivitis

90
Q

what is the off license use for the ophthalmological anti bacterial drug Azithromycin

A

to treat blepharitis

91
Q

what are viruses and how do they work

A
  • intracellular parasites
  • they need to take over cells in order to divert that cells machinery for producing proteins and DNA into synthesising and assembling new viruses
  • so an single virus infects and then sheds multiple viruses which go on to infect other cells = how the virus propagates
92
Q

what is the most common virus of the eye and what does it cause

A
  • herpes simplex HSV

- same virus that causes the chickenpox can be reactivated and cause cold sores and herpes simplex keratitis

93
Q

why is the herpes simplex HSV a problem

A

because following primary infection e.g. chicken pox, you don’t completely eradicate the virus and it tends to become latent where it travels down the sensory nerves and sits within the trigeminal ganglion, to be subsequently reactivated

94
Q

which type of patients are most likely to re-contract the herpes simplex virus HSV

A

the immunocompromised e.g HIV +ve or on steroids

95
Q

what type of virus are herpes virus

A

DNA viruses

96
Q

name 3 examples of the herpes virus

A
  • Herpes Simplex
  • Varicella zoster
  • Cytomegalovirus
97
Q

name 3 properties of HSV

A
  • Primary
  • Recurrent
  • Congenital
98
Q

which type of HSV is most common

A

HSV-1

99
Q

what do 60% of children have and by when

A

HSV by 5 years

100
Q

which type of HSV is most congenital

A

HSV-1

80%

101
Q

what ocular signs are recurrent in HSV

A
  • Thin dendritic ulcers

- Contain live virus

102
Q

what ocular signs is found with Varicella zoster VSV

A

Ophthalmic shingles

103
Q

how many Varicella zoster VSV patients with periocular shingles have eye involvement

A

50-72%

104
Q

which type of patients can the Cytomegalovirus CMV infections occur in

A

immunocompromised individuals e.g. AIDS, post-transplant

105
Q

what does the Cytomegalovirus CMV present as in the eye

A

a viral necrotizing retinitis

which is sight threatening

106
Q

which herpes virus infects the back of the eye rather than the front

A

Cytomegalovirus CMV

107
Q

which antiviral drug treats herpes simplex keratitis

A

aciclovir

108
Q

how does the drug acyclovir which treats herpes simplex keratitis work and what is the mechanism for this

A

by inhibiting viral DNA synthesis

-Aciclovir enters the cell and is
converted to aciclovir monophosphate by the herpes simplex virus enzyme thymidine kinase (TK).
- Enzymes add two more phosphates to form the active drug aciclovir triphosphate.
- The aciclovir triphosphate competes with 2- deoxyguanosine triphosphate (dGTP) as a substrate for viral DNA polymerase.

in other words:

  • the process assembles nucleotides to produce DNA
  • but when the aciclovir gets inside the cell its phosphorylated and so binds to one of the virus’s enzymes. - the phosphate is added and turns into aciclovir triphosphate and then the cell thinks that the aciclovir triphosphate is one of the DNA precursors, so it tries to incorporate it into the DNA synthesis and therefore it inhibits the process of synthesis
109
Q

what drug is used to treat the sight threatening viral necrotising retinitis caused by the Cytomegalovirus CMV

A

ganciclovir

110
Q

what is ganciclovir and how is it administered

A
  • Slow-release ocular implant

- inserted into the eye surgically

111
Q

what is the epidemiology of acanthamoeba

A

a free living amoeba found in water / Soil

112
Q

what are the 2 life cycles of acanthamoeba

A
  • Mobile trophozoites
    and
  • Dormant cysts
113
Q

what 3 things is acanthamoeba resistant to

A
  • freezing
  • drying
  • chlorine
114
Q

what is acanthamoeba cultured as

A

Specialised, Non-nutrient agar / E. coli

115
Q

what are the choices of drug and concentration for treating acanthamoeba

A
  • Propamidine 0.1% and Polyhexamethylene biguanide (PHMB) 0.02%
  • Chlorhexidine 0.02%
116
Q

how often should the drugs to treat acanthamoeba be administered

A

hourly day and night for 2 days then reduce as condition improves

117
Q

which drugs to treat acanthamoeba have activity against the cyst form

A
  • Polyhexamethylene biguanide (PHMB)
    and
  • Chlorhexidine
118
Q

what stage of acanthamoeba keratitis will no drug be effective and what will be the only thing to treat it

A
  • ring infiltrate

- will need corneal transplant

Therapeutics (19 decks)

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