Antimicrobials 2 Flashcards
1
Q
What are bacteriocidal antibiotics?
A
they kill bacteria dead
2
Q
Give examples of bacteriocidal antibiotics
A
penicillin
cephalosporins
metronidazole
3
Q
What are bacteriostatic antibiotics?
A
they make bacteria stop working
bacteria are then cleared by the immune system
4
Q
Give examples of bacteriostatic antibiotics
A
macrolides
lincosamides
tetracyclines
fusidic acid
5
Q
How is the in-vitro antimicrobial activity of drugs assessed?
A
determining minimum inhibitory concentration (MIC) and minumum bactericidal concentration (MBC)
6
Q
What is the minimum inhibitory concentration?
A
the lowest concentration of a chemical that prevents visible growth (bacteriostatic)
7
Q
What is the minimum bactericidal concentration?
A
lowest concentration of a chemical that results in death (bactericidal)
8
Q
Practically, how is the antimicrobial activity of a chemical assessed?
A
overnight aerobic incubation of a standard size inoculum of bacteria in a low protein liquid medium at pH 7.2
9
Q
Why may the antimicrobial activity of a chemical differ in vivo?
A
conditions in vivo will be different from incubation conditions thus antimicrobial activity will change
10
Q
If a drugs has a MBC 4x greater than the MIC then the drug is classed as …
A
bactericidal
11
Q
What are broad spectrum antibiotics?
A
they act against both gram positive and gram negative bacteria
12
Q
When are broad spectrum antibiotics used?
A
prior to formal identification of the (specific) disease causing bacteria
13
Q
Give examples of broad spectrum antibiotics
A
amoxicillin
co-amoxiclav
tetracyclines
14
Q
What are narrow spectrum antibiotics?
A
they act against a specific family of bacteria
15
Q
When are narrow spectrum antibiotics used?
A
best when used with culture sensitivity and testing
16
Q
Give examples of narrow spectrum antibiotics
A
Macrolides
Clindamycin
17
Q
What is pharmacokinetics?
A
This is what the body does to the drug
ADME
18
Q
What does absorption refer to ?
A
bioavailability of the drug
19
Q
What does distribution refer to ?
A
the process by which a drug diffuses from intravascular fluid space to extravascular fluid spaces
20
Q
Elimination of the drug after administration usually occurs from …
A
liver or kidney
21
Q
What is pharmacodynamics?
A
this is what the drug does to the body
22
Q
Regarding pharmacodynamics, the antimicrobial effects of the drug at the site of infection is…
A
concentration dependent
time dependent
23
Q
What are the clinical functions of pharmacodynamics?
A
-used to predict drug efficacy in patients
-provide a rational basis for determining the optimal dosing regimens
24
Q
The pharmacodynamics of an antimicrobial drug relates its pharmacokinetics to the _________ of the antimicrobial effects at the site of action.
A
time course
25
What is the most common side effect of antibiotics ?
allergic reactions
26
How are allergic reactions to antibiotics typically avoided?
by avoiding the drug
27
What is an option for patients with an allergy to a specific antibiotic who have no other antibiotic options?
desensitisation
(may be possible)
28
What serious allergic reactions can arise from antibiotic use?
Stevens Johnson Syndrome (SJS)
Toxic Epidermal Necrolysis (TEN)
29
SJS and TEN can present as
serious skin and mucous membrane disorders
rashes, skin peeling and sores on mucous membranes
30
What antibiotics can be implicated in SJS and TEN?
penicillin
cephalosporins
31
Antibiotic associated colitis a side effect of antibiotic use due to ...
disruption of the normal balance of the gut flora
eradication of the normal gut flora by antibiotic which results in an overgrowth of other microbes which include clostridium difficile
32
____% of patients may develop anti-biotic associated diarrhoea
5-25%
33
What kind of antibiotics are often implicated in antibiotic-associated colitis ?
broad spectrum antibiotics
Clindamycin (this is a narrow spectrum antibiotic)
cephalosporin
coamoxiclav
amoxicillin (to a lesser extent?)
34
What is pseudomembranous colitis ?
medical condition in which the colon gets inflamed in association with excessive intake of antibiotics
35
What are the symptoms of pseudomembranous colitis?
watery diarrhoea
abdominal pain along with cramping
fever
mucousy stools
nausea
dehydration
36
Another side effects of antibiotic induce/mediated flora change is _________.
opportunistic candidal infections which may occur in mouth or vagina
overgrowth of fungal species
Candida albicans may take over where there is limited competition from bacteria due to antibiotic treatment
37
What is the effect of antibacterial on typhoid vaccine?
antibacterials inactivate typhoid vaccine
38
Miconazole (antifungal) interacts with what drugs?
Alfacalcidol- miconazole reduces effects of alfacalcidol
Calcitriol- miconazole possibly reduces effects of calcitriol
ciclosporin- miconazole possibly inhibits metabolism of ciclosporin which increases its plasma concentration
Coumarins- miconazole enhances the anticoagulant effect of coumarins; avoid concomitant use if possible
(coumarins include warfarin)
39
Miconazole (antifungal) interacts with what drugs?
Alfacalcidol- miconazole reduces effects of alfacalcidol
Calcitriol- miconazole possibly reduces effects of calcitriol
ciclosporin- miconazole possibly inhibits metabolism of ciclosporin which increases its plasma concentration
Coumarins- miconazole enhances the anticoagulant effect of coumarins; avoid concomitant use if possible
(coumarins include warfarin)
40
MHRA (Medicines and healthcare products regulatory agency) employs the use of _________ and __________ to monitor adverse effects observed due to drugs/medication
Yellow card schemes
Medical alerts
41
In 2012, a medical alert for the potential reminder of hypersensitivity for which drug was announced by the MHRA?
chlorhexidine
42
In 2016, a medical alert for the potential reminder of serious interaction with warfarin for which drug was issued by the MHRA?
topical miconazole, including oral gel
43
What is the Yellow Card scheme used for ?
used to report suspected side effects or adverse drug reactions to any medicines, vaccines and even medical devices
medical devices e.g. implants
44
What are components of a typical bacterial cell?
cell wall
plasma membrane
chromosome
cytoplasm
ribosome
45
Whats is the MOA of penicillin?
beta-lactams present in penicilln interfere with the crosslinking of peptidoglycan protein in the bacterial cell wall
(bacterial cell wall- peptidoglycan crosslinks present)
Penicillin (beta lactam) binds to the transpeptidase enzyme which is responsible for peptidoglycan cross-links
this weakens the strength of the cell wall
46
Penicillin have a ______ dependent bactericidal action
time dependent
47
What adverse drug reaction is associated with penicillin?
allergy
48
What is a contraindication of penicillin use ?
methotrexate (immunomodulatory) - dihydrofolate reductase enzyme inhibitor
probencid (kidney disease)
49
What is the purpose of a beta-lactam ring
disrupt peptidoglycan cell wall- prevent cross-links from forming
50
What enzyme is responsible for the formation of the peptidoglycan crosslinks?
bacterial DD-transpeptidase enzyme
51
What is a requirement for penicillin to work?
the bacteria must be growing for it to work
52
Briefly compare the bioavailability of oral dose amoxicillin and penicillin V
amoxicillin has a greater oral bioavailability (74-92%) compared to penicillin v
53
How is penicillin G administered and why is this?
Penicillin G is administered intravenously
it is not acid stable thus cannot be delivered orally
54
Amoxicillin is equally well absorbed with food or in the fasting state. True or false
True
55
When is co-amoxiclav better taken (for better absorption)?
it is better taken at the start of a meal
56
When is penicillin V better taken (for better absorption)?
it is better absorbed in the fasting state
57
Is penicillin able to cross the BBB?
no it is not because it is poorly lipid soluble
58
How is penicillin eliminated after drug administration?
excreted unchanged by tubular secretion in the kidneys
59
Penicillin excretion/elimination can be blocked by...
probencid (used in kidney disease)
60
Penicillin excretion/elimination can be blocked by...
probencid (used in kidney disease)
61
Why is a dose reduction of penicillin necessary for patient with kidney disease on probencid?
this is because probencid can block tubular excretion of penicillin
62
Amoxicilling is a __________ spectrum antibiotic which can be used to treat ... (name the conditions)
broad
Dental abscesses
otitis media
bronchitis
pneumonia
urinary tract infections
gonorrheoa
63
Phenomethylpenicillin (Pen V) is a _______ spectrum antibiotic for use as amoxicillin. How is it dosed?
narrow spectrum
dosed QDS (4x daily) on an empty stomach
64
What is the benefit of co-amoxiclav?
(as amoxicillin)
reduced resistance due to clavulanic acid which inhibits beta-lactamase enzyme
((beta-lactamase enzyme developed to increase resistance to beta-lactam which interferes with cell wall synthesis)
65
Co amoxiclav side effects can include ...
pseudomembranous colitis?
risk of c. difficle
66
When should co-amoxiclav be used?
after consultation with secondary care
67
When antibiotics are under the antibiotic class "penicillins"
penicillin
amoxicillin
coamoxiclav
68
What are the most common side effects of penicillins?
rash
diarrhoea
abdominal pain
nausea/vomiting
drug fever
hypersensitivity
allergic reactions
69
When should you contact a health care provider immediately when using penicillins?
bloody stool
anaphylaxis
severe skin reaction
fever
70
What is the MOA of metronidazole (broad spectrum antibiotic)?
inhibits DNA synthesis once converted into an active form by anaerobic bacteria
71
Metronidazole is active against... (name the microorganisms)
anaerbobic bacteria
Protozoa
72
Metronidazole has _________ dependent bactericidal action
dose/concentration dependent
73
What adverse reactions are associated with metronidazole?
Di-sulfiram reaction where there is an acute sensitivity to alcohol
- immediate feeling of a hangover
should NOT be taken with alcohol.
74
What are the contraindications for metronidazole?
interacts with coumarin anticoagulants like warfarin
75
What is the clinical use of metronidazole?
dental abscess and NUG (necrotising ulcerative gingivitis)
also used to treat pseudomembranous colitis (C.difficile)
76
Briefly describe bioavailability of metronidazole?
excellent bioavailability after oral administration
food has no effect on bioavailability of metronidazole
77
Briefly describe distribution of metronidazole
lipid soluble drug thus has wide distribution throughout the body
78
When is the peak serum concentration of metronidazole reached?
after one hour of administration
79
How is metronidazole eliminated from the body?
eliminated unchanged in the urine
80
Disulfiram reaction associated with metronidazole is more unpleasant than serious. What must you warn you patients of?
NO alcohol
When it occurs- tachycardia and flushing can occur
81
Disulfiram reaction can occur up to _______ after stopping metronidazole
up to 72 hours after stopping metronidazole
82
What is the effect of metronidazole on warfarin (coumarin)?
the anticoagulant effects of warfarin increases
this has cause bleeding in some cases
83
What should you do if metronidazole is prescribed to a patient on warfarin?
monitor INR (international normalised ratio)
84
What are the most common side effects of metronidazole?
nausea/vomiting
dizziness
headache
vaginal candidiasis
metallic taste
85
Combined use of alcohol and metronidazoe may lead to...
cramps
nausea/vomiting
flushing
headache
red-brown urine discoloration
86
What is the MOA of macrolides (bacteriostatic)?
they inhibit protein synthesis by acting on bacterial ribosomes
87
Macrolides have the same site of action as ___________ antibiotics. Considering this, how should they be administered?
clindamycin
they should not be administered concurrently as they will compete for the same site of action
88
What are adverse reactions associated with macrolides?
GI disturbances are common and unpleasant
89
Macrolides have a __________ post anti-biotic effect
prolonged
90
What are the clinical uses of macrolides?
used if a patient is allergic to penicillin and metronidazole
91
What are the members of the macrolide class of antibiotics ?
erythromycin
clarithromycin
azithromycin
92
What macrolide commonly has resistance against it?
erythromycin
93
Describe the bioavailability of macrolide antibiotics
Erythromycin and azithromycin have low bioavailability (40%); this is even lower in the presence of food
clarithromycin has good bioavailability, can be administered with or without food
94
Oral administration of erythromycin and azithromycin antibiotics must be done in a ________ state. Why is this ?
fasting state
this is because their bioavailability is even lower in the presence of food
95
What macrolides have a wide distribution?
erythromycin
clarithromycin
96
Briefly describe the distribution of azithromycin
sequestered within tissues by macrophages
not as widely distributed as the others
97
How are macrolides eliminated after administration?
erythromycin and azithromycin are excreted by the liver
98
Macrolides are contraindicated for use with what drug ?
domperidone (anti-sickness molecule)
99
Avoid using macrolide antibiotics with the following drugs...
salmeterol
simvastatin
100
What are the most common side effects of macrolide antibiotics?
abdominal pain
diarrhoea
anorexia
nausea/vomiting
101
Taste alteration is a common side effect of what macrolide antibiotic?
clarithromycin =
102
Macrolides have a high rate of GI side effects. What instructions are given to minimise these side effects?
do not crush, chew, break or open enteric coat or delayed release pill
103
What is the MOA of lincosamides?
they inhibit protein synthesis by acting on bacterial ribosomes
(same site of action on bacterial ribosomes as macrolides thus they will compete if give concurrently)
104
Lincosamides has a ___________ post antibiotic effect
prolonged
105
What adverse reactions are associated with lincosamides?
mild diarrhoea (common)
pseudomembranous colitis (rare but fatal)
106
What are the clinical uses of lincosamides?
effective at penetrating poorly vascularised bone and connective tissue; diabetics ? bone infections?
107
What are the members of the lincosamide class of antibiotics?
clindamycin
108
What is the clinical use of clindamycin?
currently being questioned whether it is appropriate as a pre-surgery dose before implants
109
Clindamycin is ________ absorbed
rapidly
110
Briefly describe the distribution of clindamycin
widely distributed throughout the body
may be actively transported into and out of host cells
111
How is clindamycin eliminated after administration?
excreted mainly by the liver
112
What are the most common side effects of clindamycin?
pseudomembranous colitis (may be severe)
diarrhoea
nausea/vomiting
rash
hypersensitivity
jaundice
113
When should a healthcare provider be consulted immediately with use of clindamycin?
if severe diarrhoea during treatment or for up to 8 weeks after treatment
may be pseudomembranous colitis
114
What is the mechanism of action of tetracycline antibiotics?
inhibits protein synthesis by binding to bacterial ribosomes
immunomodulatory, they can penetrate macrophages as well
has a different site of action to macrolides and lincosamides
115
Tetracyclines have bacteriostatic action and have _________ post antibiotic effect
prolonged
116
What are the adverse reactions associated with tetracycline use?
chelate calcium ions so are deposited in bones and teeth
117
Tetracyclines should not be prescribed to ...
pregnant/nursing mothers
children under 9 years old
118
What are the clinical uses of doxycyline (tetracycline member)
oro-antral communication
some advocate long courses for periodontitis
acne and rosacaea
119
Tetracyclines and oxytetracyclines are in the DPF but not included in various guidelines. True or false
true
120
Briefly describe absorption of tetracyclines
oral dose is rapidly absorbed
absorption of tetracyclines is reduced by the chelation with aluminium, magnesium and calcium ion
121
Briefly describe the distribution of tetracyclines
wide distribution throughout the body
122
Briefly state how tetracycline is eliminated after administration
excreted from the kidneys primarily by glomerular filtration
123
List the members of the antibiotic class "tetracyclines"
tetracycline
doxcycycline
124
What are the most common side effects of tetracycline?
nausea/vomiting
diarrhoea
anorexia
abdominal pain
tooth discoloration in children <8 years old
liver toxicity
125
What additional warnings come with tetracyclines and why?
avoid prolonged sunlight exposure, use sunscreen, wear protective clothing
Tetracyclines may cause the skin to be more sensitive to sunlight
This is because tetracycline chelates calcium which affects vitamin D absorption ????
126
What is the MOA of cepalosporins ?
Similar to penicillin
betalactam ?
prevents crosslinks of peptidoglycan from forming
127
What antibiotic has the highest levels of resistance in the UK?
cephalosporins
128
Cephalexin and cephradine are both in the DPF but there are no dental indications in the current UK guidelines. True or false
True
129
Briefly describe the absorption of cephalosporins
The are acid stable so they can be absorbed orally
they have high bioavailability (80-95%)
food can lower the bioavailability of cephaosporins but not those in the DPF
130
How are cephalosporins eliminated after administration?
they are excreted from the kidneys primarily by glomerular filtration
131
List the members of the antibiotic class of cephalosporins
cephhalexin
cephradine
132
What are the common side effects of cephalosporins ?
rash
diarrhoea
nausea/vomiting (rare)
hypersensitivity (allergic) reactions
serum sickness vaginal candidiasis
133
What is a concern for patients with a penicillin allergy for prescription of cephalosporins?
cross-sensitivity may occur in patients with documented penicillin allergy
keep in mind when prescribing cephalosporins
134
What is the MOA of fusidic acid?
inhibits protein synthesis
135
Fusidic acid is a ___________ spectrum antibiotic
narrow
136
What are the clinical uses of fusidic acid?
good against staphylococcus aureus
topical sodium fusidate cream can be used for angular chelitis (if antifungal has not worked)
137
Chlorhexidine is a ___________ which means that there are 2 positive charges at its polar ends
bisguanide
138
Chlorhexidine is highly active against _______ and ________ but not _______________.
bacteria and candida
but not M.tuberculosis
139
0.4% solution of chlorhexidine can be used for...
hibiscrub- surgical scrub
140
0.2% aqueous solution of chlorhexidine can be used for...
anti-plaque mouthwash
141
2% chlorhexidine can be used for...
denture disinfectant
142
What is the effect of fluoride on bacterial metabolism?
fluoride inhibits enolase enzyme of glycolysis
thus it inhibits bacterial metabolism
Enolase
143
What is the problem with under-dosage of antibiotics?
if the concentrations are not sufficient to kill them, the bacteria may develop resistance
144
Who discovered penicillin and where? (Briefly state how)
Alexander Fleming
1928
Mould juice inhibited staphlycoccus
145
In 2017, WHO released a list of antibiotic resistant "priority bacteria"; this lists includes bacteria that pose the greatest threat to human health. What is the purpose of this list ?
It is intended to guide and promote research and development of new antibiotics in an effort to address global resistance to antimicrobial medicines
146
Give examples of "critical" WHO superbugs
-acinetobacter baumannii (chest and blood infections)
-pseudomonas geruginosa (chest and blood infections)
-enterobacteriaceae inlcuding klebsiella, E.coli, proteus, Serratia
147
Give examples of "high priority" WHO superbugs
-Enterococcus faecium
-Staphylococcus aureus
-Helicobacter pylori
-Campylobacter spp
-Salmonellae
-Neisseria gonorrhoeae
148
Enterobacter faecium is ___________ resistant
vancomycin
149
Staphlococcus aureus is ____________ resistant
methicillin (hence MRSA)
Vancomycin intermediate and resistant
150
Helicobacter pylori is _____________ resistant
clarithromycin
151
Campylobacter spp is _____________ resistant
fluroquinolone resistant
152
Neisseria gonorrhoeae is ___________ and ___________ resistant
cephalosporin
fluoroquinolone
153
Acinetobacter baumanni is ___________ resistant
carbapenem
154
Pseudomonas geruginosa is _____________ resistant
carbapenem
155
Enterobacteriaceae are ____________ resistant
carbapene, ESBL producing strains
156
List "medium priority" WHO superbugs
-streptococcus pneumoniae
-Haemphilus influenzae
-Shigella spp.
157
Streptociccus pneumoniae _____________ non-susceptible
penicillin
158
Haemophilus influenzae is ___________ resistant
ampicillin
159
Shigella spp are _________________ resistant
fluoroquinolone
160
The most vulnerable immuno-compromised patients include those undergoing treatment for... (name the treatments)
cancer
transplants
161
Antibiotics select for ...
resistant bacteria
only bacteria that are resistant to that particular antibiotic will survive
162
Antibiotic resistance facilitates ____________. (Name the process)
natural selection
163
How is bacteria able to resist antibiotics?
Degradation- enzymes break them down
Alteration- enzymes deactivate the antibiotic
Efflux- protein pumps them out
164
New proteins in bacteria can confer resistance. How are new proteins developed in bacteria?
Mutations in genes give rise to new, structurally different proteins
Proteins can be acquired from another bacteria
165
What are the mechanisms by which bacteria can become resistant to antibiotics?
Mutation
Conjugation
Transformation
Transduction
166
Resistant genes are often expressed on __________ of DNA
plasmid
167
What is a plasmid ?
small ring of bacterial DNA
168
Name a single, important characteristic of plasmid DNA
they can move easily between bacteria
169
Briefly describe conjugation
this is where the plasmid passes directly from one bacterium to another
(direct contact between bacterial cells)
170
What are the three mechanisms of horizontal gene transfer ?
conjugation
transformation
transduction
171
Briefly describe transformation
DNA from dead bacteria can be taken up from the environment
the DNA taken up may include the resistant gene
172
Briefly describe transduction
certain viruses can pick up DNA from one bacteria and pass it to another
173
The process of transduction has been exploited by scientists as a laboratory technique referred to as ... (name the technique)
targeted gene insertion
174
Resistant strains of bacteria do no usually cause problems for healthy people. True or false
True
cause problems for the immunocompromised
175
MRSA stands for ...
methicillin resistant staphlococcus aureus
176
MRSA can be found on ...
the skin and nose
177
MRSA can cause ...
poor wound healing
septicaemia
endocarditis
178
What are some reasons why MRSA is associated with hospital care?
point of entry through skin
High density of at risk population (immunocompromised)
elderly and immunocompromised
179
Where is clostridium difficile found?
GI tract
180
What does Clostridium difficle cause?
colitis (inflammation of colon)
181
Clostridium difficile over-growth is associated with the use of which antibiotics?
4 C's
Co-amoxiclav
clindamycin
cephalosporin
ciprofloxacin
182
What is CPE?
Carbapenamase producing enterobacteriaceae
(gives resistance to carbapenem antibiotic)
183
What is an obligate anaerobe?
unable to grow in contact with oxygen
184
Many pathogenic bacteria will not grow in culture at all. True or false
True
185
When should microbial culture be undertaken?
when resistance is suspected
186
Why is a microbial culture from the mouth problematic?
rich in microbial diversity
some bacteria grow more readily in culture than others - many pathogenic bacteria will not grow in culture
187
Many hospitals require microbial cultures before prescribing following antibiotics? (State the antibiotics)
co-amoxiclav
clindamycin (lincosamide)
cephalosporins
188
Give examples of specimens that can be collected for microbial cultures
pus sample aspirate
Nasal swab for MRSA testing before surgery
189
A clinical required form for microbial culture should contain :
clinical condition
recent/current treatment details
patient details
reason for test being requested
190
What must you consider when transporting specimens for microbial testing ?
timescale
transport medium- should be compatible with organism e.g. anaerobes
safe robust containers
appropriate labelling of specimen and clinical request form
191
What is the purpose of clinical MIC breakpoints ?
Identify whether a bacterium is
-susceptible
-intermediate
-resistant
192
What agar is used for the disc diffusion method for staphylococci?
Mueller-Hinton agar
193
What agar is used for the disc diffusion method for streptococci?
mueller-hinton agar + 5% defibrinated horse blood
194
The MIC and zone diameter of inhibition (for disc diffusion method) are inversely related. What does this mean?
This means that the more susceptible the microorganism is, the lower the MIC and the larger the zone of inhibition
(less of antimicrobial concentration required to cause inhibition of growth)
195
Broth dilution tests involve...
broth dilutions with different concentrations of the antibiotic (hence dilutions)
196
What is the MBC ?
this is the lowest concentration of antibacterial agent that reduces the viability of the bacterial inoculum by >99.9%
197
There are genotypic methods that can be used to detect resistance genes. Give an example of this
DNA based assay
MRSA has MecA gener which confers resistance to methicillin and flucloxacillin
198
Give an advantage of genotypic methods of antimicrobial susceptibility testing
quicker
199
Give disadvantages of genotypic methods of antimicrobial susceptibility testing
expensive
thus not routinely used
200
Why are there only a few efficacious antivirals?
this is because it is difficult to interfere with viral activity without damaging the host cell
201
What is the only antiviral drug in the DPF?
aciclovir
202
When is the only time aciclovir is effective?
on an actively replicating virus
203
When is aciclovir ineffective?
in latent viruses in cells e.g. herpes labialis
204
What kind of patients benefit from active antiviral therapy?
immunocompromised patients
205
What is the mechanism of action of aciclovir ?
aciclovir triphosphate blocks herpes viral DNA polymerase
aciclovir is initially converted by viral thymidine kinase to aciclovir monophosphate
Aciclovir monophosphate is converted by host kinases to aciclovir monophosphate
206
What is the active form of aciclovir ?
aciclovir triphosphate
207
State the clinical use of aciclovir
primary and secondary herpes infections e.g. herpetic stomatitis and labialis
208
Ideally, aciclovir be started in the __________ phase of herpes infection.
prodromal phase
209
?What is the consequence of a later start of aciclovir in herpes infection?
will reduce discomfort, length and viral shedding period
210
What form of aciclovir is used to treat recurrent herpetic ulcers?
topical 5% cream
211
What form of aciclovir is used to treat severe herpetic stomatitis an herpes zoster ?
oral tablet/suspension
212
What forms of aciclovir can be used to treat primary gingivostomatitis ?
Topical 5% cream
oral tablet/suspension
213
Selective toxicity is difficult to achieve in antifungals. Why is this?
this is because both fungal and host cells are eukaryotic
214
What are the types of antifungals?
Azoles- miconazole, fluconazole
Polyenes- Nystatin
215
What is the MOA of azole antifungals ?
affect cell membrane synthesis
inhibit ergosterol synthesis
216
Aside from its anti-fungal function, miconazole is also bacteriostatic against what bacterial species?
Staphylococcus aureus
217
What is the clinical use of miconazole oromucosal gel?
angular cheilitis
218
What is the clinical use of fluconazole tablets?
prevention of candidal infections in HIV patienst
219
What is the dose of fluconazole tablets and why?
1x daily
this is because they have a long half-life
220
What is the MOA of polyene antifungals?
binds to the sterols in fungal cytoplasmic membrane
alters cell wall permeability- causes leakage of cell contents and death
221
What is the clinical use of nystatin?
used to prevent mucosal candidiasis
222
Nystatin is too toxic for systemic use. True or false
True
223
Nystatin is absorbed by the alimentary canal. True or false
False
224
What are drug interactions of fluconazole?
avoid use with clopidogrel
Possible interactions with - carbamazepine (anticonvulsant), citalopram (SSRI), diazepam (BZD), ibuprofen(NSAID), midazolam (BZD), simvastatin, warfarin
225
What are the drug interactions of miconazole?
avoid use with warfarin {[warfarin binds to albumin, miconazole competition for albumin binding increases free warfarin and increases risk of bleeding???}}
possible interactions with atorvastatin, carbamazepine, vitamin D substances
226
What are the interactions of Nystatin ?
no major interactions with commonly used drugs
227
What are the interactions with aciclovir?
no major interactions with commonly known drugs
228
Briefly describe absorption of fluconazole
rapidly absorbed
>90% bioavailability
229
How is fluconazole eliminated after administration?
excreted from kidneys primarily through glomerular filtration
80% excreted unchanged
