Infectious Disease Drugs Flashcards by Grace Poole

what is an anti-viral drug

acyclovir

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what is the role of acyclovir

inhibits herpes-specific DNA polymerase

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what are 4 common side effects of antiviral drugs

Dizziness
GI disturbance
Headache
Skin rash

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what can IV infusion of acyclovir cause

Thrombophlebitis

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what can IV infusion of acyclovir also cause and why

High concentrations may precipitate in the kidney and lead to renal failure

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what are 3 macrolides

Clarithromycin
Erythromycin
Azithromycin

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what is first-line for chlamydia

One-off dose azithromycin

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what is the spectrum of activity of erythromycin

Broad: gram negative and positive

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what is the spectrum of activity of clarithromycin and azithromycin

Increasingly gram negative - particularly effective against H. Influenza

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what is used to treat infective exacerbation of COPD

Clarithromycin/ Amoxicillin or Doxycycline

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what is the MOA of macrolides

Bind to 50s subunit and prevent translocation = bacteriostatic

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which macrolide is associated with worst effects

erythromycin

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what gastric abnormalities can macrolides cause

antibiotic-associated colitis

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what liver abnormalities can macrolides cause

cholestatic jaundice

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what cardiac abnormalities can macrolides cause

Prolong QT interval - lead to tornadoes de pointes

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what side effect can macrolides cause affecting the ears

ototoxic

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when are macrolides useful

can be used in patients with penicillin allergies - as they have no similarity

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what do erythromycin and clarithromycin do to CYP450

inhibit it

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what does inhibiting CYP450 mean

increases serum concentration and hence SEs of drugs metabolised by CYP450

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what can clarithromycin and warfarin result in and why

clarithromycin inhibits CYP450 - increases warfarin can lead to bleeding

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what can clarithromycin and statins result in and why

clarithromycin inhibits CYP450 - increases statins = lead to rhabdomyolysis

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what drugs should macrolides not be prescribed with

other drugs that prolong CYP450

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name 5 drugs that prolong the QT interval

SSRI
Quinolones
Quinines
amiodarone
antipsychotics

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explain IV infusion of macrolides

dilute in large volume and inject into large proximal vein to avoid thrombophlebitis over 60-min to avoid QT prolongation

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what is metronidazole effective against

gram negative anaerobic bacteria

what is MOA of metronidazole

passively diffuses into cells and then is reduced to produce a nitro free-radical, which can bind to and degrade DNA leading to cell-death (bactericidal)

what is a common side effect of metronidazole

GI disturbance

if used for a prolonged time what may metronidazole cause

neurological disorders: - peripheral neuropathy - optic neuropathy - encephalopathy

what is the one absolute CI to metronidazole

alcohol

why is alcohol contraindicated in metronidazole

metronidazole inhibits acetaldehyde dehydrogenase, meaning if individual has alcohol there is an accumulation of acetaldehyde which can cause hangover like effects including flushing, headache, nausea and vomiting

what is the effect of metronidazole on CYP450

Inhibitor

what drug does metronidazole increase toxicity of

Lithium

what antibiotics may alcohol reduce effectiveness of

- Erythromycin | - Doxycycline

what is nitrofurantoin effective for

UTI

what is the MOA of nitrofurantoin

Enters cells and is reduce to nitrate free radical where it damages DNA

what is a common SE of nitrofurantoin

GI Upset

what can nitrofurantoin do to urine

Turns urine dark yellow or brown

what are 3 rare SEs of nitrofurantoin

- Pneumonitis - Hepatitis - Peripheral Neuropathy

when does the risk of hepatitis, pneumonitis and peripheral neuropathy with nitrofurantoin increase

Prolonged-used

if given in the third trimester what happens

nitrate free radicals damage DNA or RBC leading to haemolysis causing a haemolytic anaemia

what are 3 absolute CI to nitrofurantoin

- Third-trimester - First 3 months of neonatal life - Renal impairment

why should nitrofurantoin not be prescribed in renal impairment

leads to toxicity

name two narrow penicillins

benzylpenicillin | phenoxymethylpenicillin

what are narrow spectrum penicillins not effective against

gram negative rods

what is MOA of penicillins

inhibit cross-linking of peptidoglycan cell walls causing osmotic lysis

how can bacteria gain resistance to penicillins

B-lactamases break down penicillin

how does penicillin allergy usually manifest

Rash 7-10d after first exposure | Or, 1-2d after repeat exposure

what is penicillin allergy mediated by

IgG

what is anaphylactic reaction to penicillin caused by

IgE

how does anaphylaxis present clinically

- facial oedema - laryngeal oedema - hypotension

what can high doses of penicillin cause

neurological toxicity

what is an absolute CI to penicillin

penicillin allergy

if a patient has a history of penicillin allergy, what antibiotic should they also not be prescribed and why

take care prescribing cephalosporins - as they also have a B-lactam ring

what drug to penicillins reduce renal excretion of leading to toxicity

methotrexate

what is phenoxymethylpenicillin called

penicillin V

what is the spectrum of activity of vancomycin

gram-positive

what is the MOA of vancomycin

inhibits cross-linking peptidoglycan cell wall causing death by osmotic lysis

what is the most common SE of vancomycin

thrombophlebitis

what is thrombophlebitis

painful inflammation of veins

what happens if vancomycin is infused rapidly

red-man syndrome

what is red man syndrome

erythema over face, chest and arms

what causes red man syndrome

vancomycin degranulation of mast cells

what can IV vancomycin cause

- Ototoxicity - Nephrotoxocity - Neutropenia - Thrombocytopenia

when used with what drugs does vancomycin increase risk of ototoxicity and nephrotoxocity

- Ciclosporin - Aminoglycoside - Loop diuretics

name 3 anti-fungal drugs

- Nystatin - Fluconazole - Co-trimazole

what are the topical anti-fungal drugs

Nystatin Co-trimazole

what are the oral anti-fungal drugs

Fluconazole

what are 3 side effects of fluconazole

- Headache - Hypersensitivity - Hepatitis

what is a severe side effects of fluconazole

Sever liver impairment | Prolong QT

when should fluclonazole be prescribed with caution

Someone with liver disease - due to risk adverse effects

in what condition should fluconazole be completely avoided

Pregnancy - due to teratogenic

explain interaction of fluclonazole and CYP450

fluconazole inhibits CYP450