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Antimicrobials Antimicrobials - Quinolones & Fluoroquinolones - Quinolones & Fluoroquinolones Pharmacology -1 Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Dr/ Abdulaziz Saeedan Pharmacy College Pharmacy College 1

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Fluoroquinolones - Antimicrobial Spectrum Fluoroquinolones are broad-spectrum antibiotics. ► They are effective against many different types of bacteria, both Gram-negative including pseudomonas and Gram-positive.  Pharmacokinetics: 1- Absorption 1- Absorption. Well absorbed after oral administration (50% to >95%). ► This degree of absorption result in high blood levels comparable to their intravenous preparations. ► Thus, oral preparations should be used if the patient is able to take oral medications. 3

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Page 1: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

AntimicrobialsAntimicrobials- Quinolones & Fluoroquinolones- Quinolones & Fluoroquinolones

Pharmacology -1Pharmacology -1 DSX 215DSX 215

Dr/ Abdulaziz SaeedanDr/ Abdulaziz Saeedan Pharmacy CollegePharmacy College

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Page 2: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Quinolones and FluoroquinolonesQuinolones and Fluoroquinolones• The quinolones are a family of synthetic antibiotics.• The parent of this group is nalidixic acidnalidixic acid.• Nalidixic acid Nalidixic acid is a synthetic narrow spectrum antibiotic. ► Active against gram-negative bacteria except pseudomonaspseudomonas species.

• The addition of fluorine atom to the original quinolone antibiotics produced a new class of drugs, the fluoroquinolonesthe fluoroquinolones

• Fluoroquinolones are synthetic broad-spectrum antibiotics.

► Active against gram-negative bacteria, especially pseudomonaspseudomonas species in addition to gram-positive bacteria.

• Due to the excellent activity and safety of fluoroquinolones, they become alternatives to penicillin in the treatment of various infections.

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Page 3: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Fluoroquinolones - Antimicrobial SpectrumFluoroquinolones - Antimicrobial Spectrum

• Fluoroquinolones are broad-spectrum antibiotics.► They are effective against many different types of bacteria, both Gram-negative

including pseudomonas and Gram-positive.

Pharmacokinetics:Pharmacokinetics:1- Absorption1- Absorption.• Well absorbed after oral administration (50% to >95%). ► This degree of absorption result in high blood levels comparable to their

intravenous preparations. ► Thus, oral preparations should be used if the patient is able to take oral

medications.

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Page 4: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

2- Distribution2- Distribution.•Distributed into urine, kidney, prostate tissue, lung, stool, skin. ► So fluoroquinolones are very useful for treatment of infections in these areas of the body.

3- Elimination3- Elimination.•The kidneys are an important route of elimination.

Fluoroquinolones – AdvantagesFluoroquinolones – Advantages•Ease of administration•Excellent oral absorption•Prolonged half-lives ► daily or twice daily dosing •Excellent tissue penetration ► widely distributed

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Page 5: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Fluoroquinolones - ClassificationFluoroquinolones - Classification First Generation. ► Nalidixic acid• Antimicrobial Spectrum: Antimicrobial Spectrum: Gram-negative bacteria (but not Pseudomonas species)• Used only for uncomplicated urinary tract infections.• Nalidixic acid require more frequent dosing than the newer quinolones.

Second Generation. ► Norfloxacin, Lomefloxacin, Ciprofloxacin, Ofloxacin• Ciprofloxacin and ofloxacin are the most widely used second-generation quinolones

because of their availability in oral and intravenous formulations• Antimicrobial Spectrum: Antimicrobial Spectrum: Gram-negative bacteria (including Pseudomonas species),

some gram-positive bacteria (including Staphylococcus aureus but not Streptococcus pneumoniae).

• Ciprofloxacin is the most potent fluoroquinolone against Pseudomonas . • Used for uncomplicated and complicated urinary tract infections, pyelonephritis,

prostatitis, skin and soft tissue infections.

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Page 6: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Third Generation. ► Levofloxacin, Gatifloxacin, Sparfloxacin, Moxifloxacin.• Antimicrobial Spectrum: Antimicrobial Spectrum: The same as second-generation agents plus expanded

activity against gram-positive bacteria (Streptococcus pneumoniae).• Used for bronchitis and pneumonia

Fourth Generation. ► Trovafloxacin• Antimicrobial Spectrum: Antimicrobial Spectrum: Same as for third-generation agents plus anaerobic

bacteria.• The same uses of first-, second- and third-generation agents.

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Page 7: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Fluoroquinolones– Action & Mechanism of ActionFluoroquinolones– Action & Mechanism of Action

Action:Quinolones and fluoroquinolones are bacteriocidal drugs, meaning that they kill

bacteria.

MOA:• Quinolones and fluoroquinolones inhibit bacterial DNA-gyrase enzyme which

is necessary for supercoiling and replication of DNA .• This action results in damage of bacterial DNA and bacterial cell death. Thus,

fluoroquinolones are bactericidal agents.

NOTE:• Fluoroquinolones are the only class of antimicrobial agents that are direct

inhibitors of bacterial DNA synthesis. • Gyrase is an essential enzyme in prokaryotes but it is not found in eukaryotes,

So fluoroquinolones do not interfere with human DNA.. 7

Page 8: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Fluoroquinolones - Side Effects/PrecautionsFluoroquinolones - Side Effects/Precautions

1- The most common adverse effects of fluoroquinolones are nausea, vomiting and diarrhea, which occur in 3 -6 % of patients.

2- Other more serious but less common side effects are CNS effects (headache, confusion and dizziness).

3- Fluoroquinolones are not recommended for use in patients younger than 18 years.► They can affect the growth of bones, teeth, and cartilage.

4- Fluoroquinolones are not recommended for pregnant or feeding women. ► They have the potential to cause embryocidal effects. ► These agents are also excreted in breast milk.

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Page 9: Antimicrobials - Quinolones & Fluoroquinolones Antimicrobials - Quinolones & Fluoroquinolones Pharmacology -1 DSX 215 DSX 215 Dr/ Abdulaziz Saeedan Pharmacy

Fluoroquinolones -Fluoroquinolones - indicationsindications

• All of the fluoroquinolones are effective in treating urinary tract infections caused by susceptible organisms.

• Prostatitis ► They are the first-line treatment of uncomplicated or complicated cystitis.• Lower respiratory tract infections ► bronchitis, pneumonia • Acute sinusitis • Diarrhoea due to E.coli, Salmonellosis, Shiegellae,• Skin and soft tissue infections

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