quinoloes in the treatment of respiratory tract

04/11/2023 amrhamdy MD FCCP 1

QUINOLONES IN THE TREATMENT OF RESPIRATORY TRACT INFECTIONS


AMR BADRELDIN HAMDY

MD, FCCPPROF OF PULMONARY MEDICINE

CAIRO EGYPT


PULMONARY MEDICINE CONSULTANT

IBN NAFEES MEDICAL CENTRE

ABU DHABI


The first consideration in selecting an antimicrobial agent is whether it is indicated.


Antibiotics are antibacterial substances produced by various species of microorganisms (bacterial, fungi, and actinomycetes) that suppress the growth of the microorganisms.


Common usage often exclude the term antibiotics to include synthetic antimicrobial agents, such as sulphonamides and quinolones.


Antibiotics have three general uses:• Empirical therapy• Definitive therapy• Prophylactic or preventive therapy.


When used as empirical or initial therapy, the antibiotic should cover all the likely pathogens because the infecting organism(s) has not yet been defined.


Optimal and judicious selection of antimicrobial agents for the therapy of infectious diseases requires clinical judgement and detailed knowledge of pharmacological and microbiological factors.


The quinolones are a family of synthetic broad –spectrum antibiotic drugs.


The first generation of the quinolones began with the introduction of nalidixic acid in 1962 for the treatment of urinary tract infections in humans.


• There are simple quinolones and fluoroquinolones.• FQs are quinolone antimicrobials

having one or more fluorine substituations.


The ‘first generation’ FQs was introduced in 1980’s.


In the 1990s, compounds with additional fluoro and other substitutions have been developed (2nd generation FQs)- further extending antimicrobial activity to gram +ve cocci and anaerobes, and/ conferring metabolic stability (long t1/2), and/ or conferring metabolic stability (longer t1/2).


Therapeutic uses of simple quinolones:

• Uncomplicated urinary tract infection.• Urinary antiseptic.• Diarrhea casued by Proteus, E. coli.

Salmonella, Shigella (ampicillin resistant).


Fluoroquinolones are the only class of antimicrobial agents in clinical use that are direct inhibitors of bacterial DNA synthesis.


They inhibit two bacterial enzymes, DNA gyrase and topoisomerase IV.


Fluoroquinolones are bactericidal agents.


FQ enter the host cells and are therefore active against intracellular pathogens, e.g. Mycoplasma spp, and Chlamydia spp.


Spectrum of ActivityThe greatest activity of FQs is against

aerobic gm-ve bacilli, particularly Enterobacteriaceae, and against Haemophilus spp and gm-ve cocci e.g. Neisseria spp and Moraxella catarrhalis, and also against non-enteric gm-ve bacilli such as Ps aeruginosa and against staphylococci.


Use in Pregnancy

• Not used during pregnancy.• Not used in lactating mothers as it is

secreted in breast milk.


Use in Children

Not recommended for routine use in children less than 18 years of age (arthropathy with erosions of the cartilage in weight-bearing joints).


Use in Children cont’d

• Used in cystic fibrosis?• Complicated urinary tract infections

and pyelonephritis?


Absorption

The quinolones are well absorbed from the upper gastrointestinal tract.


Concentration in prostate tissue, stool, bile, lung, and neutrophlis as well as macrophages usually exceed serum concentrations.


Resistance

• Resistance to FQs has been slow to develop.• Increasing resistance has been

reported among Salmonella, Pseudomonas, Staphylococci, Gonococci and Pneumococci.


Resistance cont’d

• The likelihood of developing quinolone resistance is thought to be related to the intensity and duration of therapy.• Resistance may occur via mutations

in chromosomal genes via mutations in plasmids


Resistance cont’d

• The use of the most potent FQ is a logical choice if resistance has to be avoided/ delayed.• Previous exposure to an FQ in the

recent past precludes the use of a member of this class for the empirical treatment of CAP.


Among “atypicals’, antibiotic resistance is rare and very seldom responsible for clinical failure.


Side Effects


Gastrointestinal

• Occurs in 3-17% of patients.• Anorexia, nausea, vomiting, and

diarrhea. • Abdominal discomfort.


Nervous System

• In 0.9 -11%.• Mild headache and dizziness.• Insomnia.• Alteration of mood.• Hallucinations, delirium, seizures.


Rash and other Allergic Manifestations

• In 0.4-2.2 %.• Photo toxicity.


Arthropathy• Arhtropathy with cartilage erosions

and non inflammatory effusions occurs in the weight-bearing joints (in animals).• Tendinopathy and tendon ruptures

have been reported, mainly the Achilles tendon, also rotator cuff, hand, biceps, and thumb.


Arrhythmia and QT Interval Prolongation

Moxifloxacin, levofloxacin and gemifloxacin should be avoided in patients with known QT interval prolongation and with hypokalemia, hypomagnesemia and use of anti arrhythmic drugs.


Contraindications


• Known allergy to the drug.• Epilepsy.• QT prolongation.• Pre-existing CNS lesions or

inflammation or stroke.• With benzodiazepines


In the USA, a “Black Box” warning of increased risk of developing tendonitis and tendon rupture in patients of all ages. This risk is further increased in individuals over 60 yrs, taking CS drugs, and have received kidney, heart or lung transplantations.


May exacerbate weakness in patients with myasthenia gravis due to their neuromuscular blocking activity.


Combination Therapy


1. For empirical therapy of an infection in which the cause is unknown.

2. For treatment of polymicrobial infections.

3. To enhance antimicrobial activity( i.e. synergism) for a specific infection.

4. To prevent the emergence of resistance.


Uses of FQs

• Upper respiratory tract infections.• Lower respiratory tract infections.• MD resistant TB.


Upper Respiratory Tract Infections


Guidelines from the IDSA ( Infection Disease Society of America) recommend the following options for empiric-second line treatment for ABRS:


• Amoxicillin-clavulanate 2000mg/125 mg b.i.d.• Levofloxacin 500mg/ day.• Moxifloxacin 400mg/ day.


If improvement is seen within 3-5 days of initiation of therapy, a total course duration of 7-10 days is recommended.


Lower Respiratory Tract Infections


Community-aquired LRTI is a very common cause of acute illness and probably the most common reason for lost working time in adults.


The spectrum of disease ranges from a mild mucosal colonization or infection, an acute bronchitis or AE/COPD to an overwhelming parenchyma infection with the patient presenting with a severe CAP.


It is an acute illness (present for 21 days or less), usually with cough as the main symptom, with at least one other LRT symptom (sputum, dyspnea, wheeze or chest discomfort/pain) and no alternative explanation (e.g. sinusitis or asthma).


Definitive CAP• Is an acute illness with cough and at

least one of new focal chest signs, fever more than 4 days or dyspnea/ tachypnea, and without an obvious cause. • Supported by chest radiograph

findings of lung shadowing that is likely to be new.


• CAP is a common and potentially serious illness.• It is associated with considerable

morbidity and mortality, particularly in elderly patients and those with significant co-morbidities.


• Pneumonia, which is most often a bacterial disease, should, in general, be treated with antibiotics.• A delay of more than 8 hours in

treatment is associated with increased mortality.


Older quinolones, such as ciprofloxacin and ofloxacin have rather poor anti-pneumococcal efficacy and are not recommended for the empirical treatment of CAP.


Advantages of Respiratory FQ

• They exhibit broad spectrum coverage including all common LRTI pathogens.

• They have a high bioavailability.• They have good penetration resulting in

high intra-celullar concentrations.• A long half-life permitting once or twice

daily dosing.• Are rapidly bactericidal.


Respiratory quinolones are more likely to result in treatment success than the combination of a beta-lactam plus a microlide for treatment of CAP.


AE/COPDAn event in the natural course of the

disease characterized by a worsening of the patient’s baseline dyspnea, cough and/or sputum beyond day-to-day variability sufficient to warrant a change in management (chest radiograph shadowing consistent with infection confirms CAP)


The newer FQs have excellent intrinsic activity against Str. Pneumonia, H. influenzae, Moraxella catarrhalis and the atypical respiratory pathogens.


• FQs may be used as mono-therapy to treat high risk patients with AE/COPD, for patients with CAP requiring hospitalization, but not admission to ICU.• The newer FQs often achieve clinical

cure rates in more than 90 % of these patients.


Key factors to consider when selecting Antibacterial Therapy for LRTIs


Modifying factors that Increase the Risk of Infection with Specific Pathogens


Risk Factors for MDR Pathogens Causing HAP, HCAP, and VAP


Treatment of MDR TB


• There appears to be an increase in multidrug- resistant TB.• It was estimated that in 2004 half a

million new cases of MDR-TB cases were diagnosed world wide.


Of the new compounds being tested for their efficacy in TB treatment, the FQ are the first novel drugs since the development of rifamycins to have been shown to have significant activity against M. tuberculosis.


• Multidrug-resistant TB (MDR-TB) is defined as TB resistant to at least isoniazid and rifampin.• Extensively drug-resistant TB (XDR-

TB) is caused by MDR strains that are also resistant to at least one FQ and one or more injectable agents.


• The anti-TB activity of FQs has been under investigation since the 1980s.• FQs are novel anti-TB drugs to be

used when a patient is infected with a MDR-TB strain.


Many are active in vitro but only a few, including oflaxicin, ciprofloxacin, levofloxacin, sparfloxacin, levofloxacin and lemofloxaxin, have been clinically assessed.


• The choice of FQ should be based not only on the in vitro activity, but also on the long-term tolerance.• The in vivo activity of FQs is

concentration dependent.


• The administration of FQ for CAP patients with TB has been associated with delay in diagnosis and increased resistance and poor outcomes.• Multiple FQs prescriptions for

undiagnosed TB were more likely to have FQ resistant M. TB.


According to a recent meta analysis of 11 randomized controlled trials comprising a total of 1,514 patients, no statistically significant difference was observed in relation to cure, treatment failure and clinical and radiological improvement when first-line drugs were replaced by a FQ (ciprofloxacin, oflaxacin or moxifloxacin).


Thus, there is currently no justification for the substitution of a FQ for first line drugs or the addition of a FQ to the standard regime.


Moxifloxacin at the recommended daily dose of 400mg is the most active FQ against TB, while ciprofloxacin is the least effective.


Warning

The broad spectrum activity and common use against many other infections is also concern, since widespread use of this class of antibiotics may lead to a rapid increase in already emerging resistance problems.


It is wise not to use respiratory FQs as a first-line therapy for LRTI, but to reserve these drugs for selected patients with CAP.


References


• Andriole VT: The Quinolones. Acadamic Press (1989).


THANK YOU

quinoloes in the treatment of respiratory tract

Health & Medicine