Fluoroquinolones (Abx)

Question 1

What is the general action of fluoroquinolones?

Answer 1

Bactericidal

Directly inhibit bacterial DNA synthesis which prevents replication and ultimately causes cell death

Question 2

Name some common fluoroquinolones

Answer 2

Ciprofloxacin

Ofloxacin

Levofloxacin

Moxifloxacin

Delafloxacin

Norfloxacin

Question 3

What are the oral bioavailability of the different fluoroquinolones?

Answer 3

Ciprofloxacin = 70%

Moxifloxacin = 86%

Ofloxacin = > 95%

Delafloxacin = 70%

Norfloxacin = 30-40%

Question 4

Which of the common fluoroquinolones is only available as an oral formulation?

Answer 4

Norfloxacin

Question 5

Describe the pharmacokinetics of ciprofloxacin

Answer 5

Oral bioavailability = 50-85%

Protein binding =

Half-life = 3-5 hours

Metabolism = hepatic (inhibits CYP1A2)

Excretion for oral administration = 30-50% kidneys, 15% metabolised, 30% presystemic clearance (hepatobilliary and faecal)

Excretion for IV administration = 70% kidneys, 10% metabolised

Question 6

Describe the pharmacokinetics of levofloxacin

Answer 6

Oral bioavailability = 99%

Protein binding =

Half-life = 6-8 hours

Metabolism = Does not undergo CYP450 metabolism + does not inhibit/induce CYP450 enzymes

Excretion (for oral/IV administration) = 87% kidneys, < 1% metabolised, < 4% faeces

Question 7

Describe the pharmacokinetics of ofloxacin

Answer 7

Oral bioavailability = > 90%

Protein binding =

Half-life = 5-7.5 hours (prolonged in renal impairment)

Metabolism = Does not undergo CYP450 metabolism + does not inhibit/induce CYP450 enzymes

Excretion (oral/IV administration) = 80% kidneys, 4% metabolised, 4-8% faeces

Question 8

Which substances should be avoided when taking fluoroquinolones?

Answer 8

Antacids

Mineral supplements

Certain oral medications

Can reduce the bioavailability by 90% in some cases

Question 9

Are fluoroquinolones broad or narrow spectrum?

Answer 9

Broad

Potent activity against aerobic, enteric gram-negative bacilli and many common respiratory pathogens

Question 10

A 80-year-old diabetic male patient presents with very painful venous ulcers on his left gaiter area. O/E the ulcers were weepy, with a greenish film over them. Which organism is responsible for the superimposed infection and what Tx will you give him?

Answer 10

Pseudomonas

Ciprofloxacin (1st line)

Question 11

Which disease can fluoroquinolones make an individual at higher risk of getting?

Answer 11

C. difficile-associated disease

Question 12

What is the typical dosing of ciprofloxacin?

Answer 12

500-750mg PO BD

400mg IV 8-12 hours (given over 60 minutes)

Eye drops QDS

Question 13

What is the typical dosing of levofloxacin?

Answer 13

500mg PO/IV OD/BD

Question 14

What is the typical dosing of ofloxacin?

Answer 14

200-400mg PO/IV BD

Question 15

What are the indications for ciprofloxacin?

Answer 15

Superficial bacterial eye infection (inc. severe)

Corneal ulcer

Acute otitis externa

Moderate/severe diabetic foot infection

Fistulating Crohn’s disease

Acute diverticulitis (used in combo with metronidazole)

Respiratory tract infections

Pseudomonal lower respiratory tract infection in CF

UTIs

Acute prostatitis

Uncomplicated gonorrhoea/disseminated gonococcal infection

Surgical prophylaxis

Anthrax (Tx + pre-exposure prophylaxis)

Prevention of secondary case of meningococcal meningitis

Acute pyelonephritis, UTI (catheter related)

Question 16

What are the indications for levofloxacin?

Answer 16

Local Tx of eye infections

Acute sinusitis

Acute exacerbation of COPD

Acute exacerbation of bronchiectasis

CAP

HAP

UTIs/complicated UTIs

Prostatitis

Complicated skin infections/soft tissue infections

Inhalation of anthrax

Chronic pulmonary infections due to Pseudomonas aeruginosa in CF

H. pylori eradication (in combo with other drugs)

Question 17

What are the indications for ofloxacin?

Answer 17

Local Tx of infections

UTIs/complicated UTIs

Acute pyelonephritis

LRTI

Prostatitis

Complicated skin and soft-tissue infections

Uncomplicated gonorrhoea/disseminated gonococcal infection

Uncomplicated genital chlamydial infection

Non-gonococcal urethritis and cervicitis

PID

Question 18

What is a contraindication to the use of fluoroquinolones?

Answer 18

Hx of tendon disorders related to quinolone use

Question 19

What are the very common/common side effects of fluoroquinolones in general?

Answer 19

Decreased appetite

N + V

Arthralgia, myalgia

Asthenia (i.e., abnormal physical weakness or lack of energy)

GI symptoms e.g., diarrhoea

QT interval prolongation

Eye discomfort/disorders

Altered taste

Tinnitus

Sleep disorders

Skin reactions

Headache

Fungal infection

Fever

Question 20

What are the uncommon side effects of fluoroquinolones in general?

Answer 20

Altered smell

Anaemia

Anxiety

Arrhythmias

Chest pain

Confusion

Cough

Depression

Drowsiness

Dry eye

Eosinophilia

Hepatic disorders

Stomatitis

Tendon disorders

Thrombocytopenia

Tremor

Vertigo

Question 21

What are the rare/very rare side effects of fluoroquinolones in general?

Answer 21

Agranulocytosis

Angioedema

Arthritis

Abnormal coordination

Abnormal gait

Haemolytic anaemia

Idiopathic intercranial HTN

Aggravated myasthenia gravis

Photosensitivity reaction

Question 22

TRUE OR FALSE

Fluroquinolones must be avoided in pregnancy but can be used safely in breastfeeding

Answer 22

FALSE

Fluoroquinolones should be avoided in BOTH pregnancy and breastfeeding