Macrolides and fluoroquinolones are classes of antibiotics. Macrolides like erythromycin, clarithromycin and azithromycin are bacteriostatic and inhibit bacterial protein synthesis. Fluoroquinolones like ciprofloxacin are bactericidal and inhibit bacterial DNA gyrase. They have activity against both gram-positive and gram-negative bacteria. Common uses include respiratory infections, skin infections, and UTIs. Adverse effects can include nausea, rash and joint pain.

1. 2.4 Antimicrobial Agents
Macrolides and Fluroquinolones
Dr. Saroj K. Suwal

2. E. Macrolides
 are a class of antibiotics which
contain macrocyclic lactone ring
 Bacteriostatic
 Against gram +ve and Gram –ve
cocci
 Erythromycin, clarithromycin,
azithromycin, telithromycin

3. MOA Macrolides
entering
microbial
cells
Attach or
bind to
50S
ribosomes
inhibit
microbial
protein
synthesis
• inhibiting protein synthesis of
bacteria
• Bacteriostatic or bactericidal
• Reversely bind to 50 s ribosomal
subunit →inhibit RNA dependent
protein synthesis
• also inhibit cell wall synthesis
Low concentration bacteriostatic and high concentration
bactericidal

4. Uses
 Pharyngitis, tonsillitis, sinusitis, chronic bronchitis,
pneumonia, uncomplicated skin infections
 Azithromycin and clarithromycin more potent than
erythromycin
 alternative to Penicillin drug

5. Pharmacokinetics
Route of Administration:
 Oral & parenteral.
Absorption:
 poorly absorbed from GIT due to acid sensitivity.
 Clarithromycin & azithromycin are well absorbed from GIT.
Distribution:
 Rapidly distributed into systemic circulation.
 cross placenta but can’t cross BBB.
 Metabolism: Via liver.
 Excretion: Through bile mainly, but clarithromycin is excreted through urine too.

6. Erythromycin
 1st macrolide obtained from streptomyces erytherus in 1952.
 Active against G(+) bacteria. ( bactericidal and bacteriostatic
 Plasma half life: 2hrs.
 Dose: adult(250-500mg 6-hourly).
 Structural derivative→ Clarithromycin and Azithromycin

7. Problems with erythromycin
Acid labile
 Narrow spectrum
 Poor GI tolerance
Short half-life

8. Clarithromycin
 derived from erythromycin by addition
of methyl group.
 Active against both G(+) & G(-) bacteria.
 stable in stomach acid.
 Plasma Half-life: 6 hrs
 Dose: 250-500mg twice daily for 7 days.

9. Azithromycin
 derived from erythromycin by addition of
methylated nitrogen into the lactone ring.
 Best activity against G(-) bacteria.
 Slowly released from tissue.
 Plasma half life >2days.
 Dose: 250-500 mg once daily for 5-7 days.
 Higher efficiency & lesser side effect.

10. Mechanism of Action
 reversibly bind to 50S ribosomal subunit → Inhibits protein
synthesis
 Suppress RNA-dependent protein synthesis by inhibition of
translocation of mRNA
 Typically→ bacteriostatic activity
 Bactericidal →at high concentrations

11. Macrolides Spectrum
Gram-Positive Aerobes
(Clarithro>Erythro>Azithro)
Gram-Negative Aerobes
(Azithro>Clarithro>Erythro)
Anaerobes – Upper airway anaerobes
Atypical Bacteria – All have excellent activity
Legionella pneumophila - DOC

12. Nursing Managements
 Avoid food immediately before or drug on erythromycin
 Should avoid prolong use→ cholestatic jaundice
 w/f Rash, puritis, lyrangeal edma, wheezing
 Azithro→ take one hr before or 2 hrs after meal( best
absorption)
 Shake well before administration if suspension

13. f. Fluroquinolones
 Bactericidal
 Inhibit DNA gyrase in organism→ interfere bacterial
DNA replication and repair
 For wide range of gram positive and negative organism

14. Common drugs→Classifications
 Ciprofloxacin,
moxifloxacin,
Norfloxacin,
Ofloxacin,

16. Ciprofloxacin
 LRTI,Skin, Enteric fever
 UTI
 Prostatitis
 Septicimia
 STD→Gonorrhea
 ENT infection
 Bone and joint infections

17. Preparations
 Tablets
 250mg, 500mg, 750mg
 Oral suspension→250mg/5ml
 Injection→ 200mg /100ml
 EYE/EAR drop /ointment
 Dose
 Typhoid →500 to 750mg BD X 10 days
 Bone and joint infections→ 500 to
750mg BD X 14days
 Infection diarrhea→500mg BDx 5-7 days
 UTI →200 to 400 mg x BD

18. CI
 Hypersensitivity
 Dizziness, headache, epigastric distress, joint pain,
abdominal pain, convulsion, jaundice, vasculitis,
arthropathy

19. Norfloxacin
 MOA : Same as Cipro (
inhibit DNA Gyrase)
 100mg, 200mg, 400mg
 Suspension: 100mg/5ml

20. Levofloxacin
 Effective against
 streptococcus pneumoniae, H. Influenza, Styphylococcus aureus, Hemophilus parainflunzea,
klebsiella, mycoplasma pneumonia, streptococcus pyogenese, ecoli, Enterobacter
 PReprations
 Injections→ 500mg
 Tabs→ 250mg, 500mg

21. Indications:
Acute sinusitis
Acute and chronic bronchitis
Pneumonia
Uncomplicated skin infections
UTI
Pyelonephritis and cystitis

22. Dose
 Acute sinusitis
500mg OD for 10-14 days
 Pneumonia
500mg OD x7-14 days
 UTI
250mg OD x10 days
• Contraindications
• Lactations
• Caution
• Oral dose one hr before or 2 hr
after antacids

23. Ofloxacin
 Tab→200mg, 400mg
 Suspension : 50mg/5ml, 200mg/100ml
 Dose
 200-400mg BD or 15mg/kg/day BD
 Infusion→200mg BD

24. CI and AE
 Hypersensitivity
 Epilepsy
AE
 Nausea, vomiting, epigastric distress
 Pseudomembranous colitis
 Rash,arthalgia,
 bone marrow depression,
 myalgia,
 G6PD deficiency