Quinolones Flashcards
Quinolones
What are examples of quinolones?
Ciprofloxacin
Levofloxacin
Ofloxacin
Moxifloxacin
Quinolones
What are common indications?
UTI (gram negative)
Severe gastroenteritis
Infective exacerbation of COPD And pneumonia
Quinolones
What is their spectrum of activity?
Broad spectrum
Mainly against gram negative
Ciprofloxacin-significant activity against pseudomonas aeruginosa
Moxiflaxacin and levofloxacin-
Enhanced activity against gram-positive organism (so preferred over Cipro for treatment of lower RTI)
Quinolones
What is the mechanism of action?
Bacteriacidal
Inhibit DNA synthesis
Quinolones
What is bacteria mechanism of resistance?
accumulation of the drug by reducing permeability and/or increasing efflux
develop protective mutations in target enzymes
Quinolone resistance genes are spread horizontally between bacteria by plasmids, accelerating acquisition of resistance
Quinolones
What are important adverse effects?
GI upset
Hypersensitivity
C.diff (commonly associated quinolones and cephalosporins)
Quinolones
What are classic specific side effects?
Neurological-convulsions, peripheral neuropathy
Muscoskeletal- tendon damage and rupture
Cardiovascular- QT prolongation, valvular regurgitation, and aortic aneurysm/dissection
Quinolones
Who should be prescribed with caution?
Caution;
Pregnancy,children and young adults- risk of arthopathy
Adults >60 yrs -risk of tendon damage
Renal impairment
Neurological
Cardiovascular morbidity
Quinolones
What are important interactions?
Drugs containing divalent cations
Calcium,iron and zinc and antacids as they reduce absorption and efficacy
Ciprofloxacin inhibits certain CY-450 enzymes increasing risk of toxicity from some drugs notably theophylline
Co-prescriptions of NSAIDS increase risk of seizures
Prednisolone increases risk of tendon rupture
Prolongs QT interval and also when taken with other QT prolongation drugs
Quinolones
Why should IV be reserved for people unable to take drugs orally or absorb them from the GI tract?
Quinolones are rapidly and extensively absorbed from the GI tract so high plasma concentration is achieved via oral administration
Quinolones
What are typical dosages and why?
Ciprofloxacin ;250mg-750mg BD
Levofloxacin 500mg oral/IV OD
Moxifloxacin oral/IV OD
Eliminated by kidneys and Have a long half life so given 12 hourly-24 hourly
Quinolones
What are counselling notes for patients?
Advise that ciprofloxacin should not be taken with dairy products.
It must be separated from calcium/iron supplements and antacids by at least 2hours, as these interfere with absorption, making the antibiotic less
Quinolones
What are other indications for quinolones
Eye and ear drops for superficial bacterial infections
by inhalation of nebulised solution (levofloxacin) for infections due to p.aeruginosa in cystic fibrosis
