2. Quinolones

Question 1

Examples of fluroquinolones

Answer 1

Ciprofloxacin, Levofloxacin, Moxifloxacin

Question 2

Quinolones mechanism of action

Answer 2

Inhibits nucleic acid, such as DNA synthesis and are thus bactericidal

Question 3

Quinolone resistance

Answer 3

Should be avoided in infections caused by MRSA. As they are resistant. Should not be prescribed for non-severe or self-limiting infections (e.g lower UTI).

Question 4

Ciprofloxacin spectrum of activity

Answer 4

Broad-spectrum

Ciprofloxacin is active against gram-negative and moderate activity against gram-positive organisms

Question 5

Ciprofloxacin typically treats

Answer 5

Respiratory tract infections, infections of the GI system (such as typhoid fever), bone and joint infections, gonorrhoea and septicaemia. Additionally, urinary tract infections.

Question 6

Quinolones should NOT be used to treat

Answer 6

staphylococcal infections and MRSA infections

Question 7

Quinolones cautions and Side effects

Answer 7

Quinolones may lower seizure threshold and induce convulsions, in patients with or without a history of convulsions.

Peripheral neuroapthy.
Patients with persistent pins and needles numbers, burning sensation MUST REPORT

Quinolones risk tendon damage within 48 hours of treatment. Risk is increased with concomitant use of steroids.
Patients with tendon/joint and skin swelling MUST REPORT

Risk of aneurysms In inhalation of fluoroquinolones and an increased risk of heart valve regurgitation.
Patients MUST REPORT sudden severe, chest or back pain.

Quinolones also prolong QT interval, which can lead to dangerous ventricular arrthymias such as torsades de pointes. Moxifloxacin has the highest risk for this. Hypokalaemia and drugs that prolong the QT interval will also interact with quinolones.

Quinolones can cause severe hypersensitivity reactions and psychiatric interactions.

Question 8

Fluoroquinolone warning signs

Answer 8

Patients should stop treatment at first sign of muscle pain, tendon rupture, muscle weakness, joint pain and must immediately contact their doctor

Question 9

Quinolones common side effects

Answer 9

diarrhoea, reduced appetite, eye discomfort, constipation

Question 10

Apropriateness of quinolones in pregnancy

Answer 10

Quinolones are unsuitable in pregnancy

Question 11

Quinolones contraindications

Answer 11

Pregnancy, Patients under 12/growing adolescents as it may cause joint diseases (arthropathy).

Question 12

Quinolone label/counselling

Answer 12

REDUCED ABSORPTION:
Indigestion remedies containing iron or zinc should be avoided 2 hours before or after taking this medicine

ADDITIONALLY for ciprofloxacin: do not take milk 2 hours before or after taking this medicine.

AVOID SUNLIGHT:
specifically for ofloxacin: protect your skin from sunlight even on a cloudy day, do not use sunbeds.

Patients should be provided with a MHRA advice sheet describing the serious side effects of quinolones

Question 13

Quinolones interactions

Answer 13

Substrates of P450 enzymes as ciprofloxacin is an enzyme inhibitor

Drugs that prolong QT interval (antipsychotics, ani-arrhythmics, SSRI’s like, escitalopram and citalopram clarithromcyin, erthyromcyin, lithium, methadone, 5HT3 antagonists, clomipramine, domperidone, hydroxyzine). Hypokalaemia is a risk factor for prolonged QT interval

When you combine drugs that cause hypokalaemia at the same time as a drug that prolongs the QT interval, it increases the risk of a life-threatening ventricular arrhythmia called torsades de pointes. Example of this includes beta agonists + loop/thiazide diuretics.