Quinolones

Question 1

How does quinolones work ?

Answer 1

Inhbit DNA synthesis

broad spectrum + bactericidal

Question 2

Name all quinolones available ?

Answer 2

• ciprofloxacin
• levofloxacin
• moxifloxacin (QT prolongation, life threatening hepatotoxocicity)
• nalidixic acid ( 1st gen, avoid if eGFR less than 20)
• norfloxacin
• ofloxacin

Question 3

What are the side effects of quinolones ?

Answer 3

seizures
tendon damage
QT prolongation (especially moxifloxacin)
Arthropathy
Psychiatric, neurological and hypersensitivity reactions ( severe rash ) (discontinue if occurs)

Question 4

Why caution should be used if patient has myasthenia gravis, takes steroids and is put on quinolone antibiotics ?

Answer 4

tendon damage is increased by the concomitant use of corticosteroids

Question 5

Quinolones have the potential to lead to QT prolongation, what are the risk factors for QT prolongation ?

Answer 5

• hypokalaemia, hypomagnesaemia and more rarely hypocalcaemia
• Heart failure with reduced LVEF
• Acute MI
• bradycardia
• symtpomatic arryhtmias
• concomitant drugs that prolong QT interval

Question 6

Explain interaction between ciprofloxacin and theophylline ?

Answer 6

Ciprofloxacin is enzyme inhibitor and causes theophylline toxicity. Plus both drugs have convulsions as side effects.

Question 7

Which drugs given with quinolones would potentially lead to QT prolongation ?

Answer 7

SSRI, quinine, amiodarone, antipsychotics, macrolides

Question 8

What counselling should you provide to someone taking ciprofloxacin ?

Answer 8

• exposure to excessive sunlight and UV radiation should be avoided during treatment and for 48 hours after stopping treatment;
• stop treatment at the first signs of a serious adverse reaction, such as tendinitis or tendon rupture, muscle pain, muscle weakness, joint pain, joint swelling, peripheral neuropathy, and CNS effects, and to contact their doctor immediately.
• Patients (particularly those at risk) and their carers should be informed about rare events of aortic aneurysm and dissection, and advised to seek immediate medical attention if sudden-onset severe abdominal, chest, or back pain develops.
• Avoid milk
• Leave 2 hours before or after taking antacids and zinc/iron
• can impair driving; its effects enhance by alcohol