Qualaquin
Qualaquin
Generic Name
Qualaquin
Mechanism
- Inhibition of bacterial DNA synthesis:
- Binds to DNA gyrase (topoisomerase II) and topoisomerase IV, stabilizing the DNA–enzyme complex after DNA cleavage and preventing re-ligation.
- This leads to double‑strand breaks, halting replication and transcription.
- Broad Gram‑negative and Gram‑positive coverage with activity against *E. coli*, *Klebsiella*, *Pseudomonas*, *Streptococcus* spp., and *Staphylococcus aureus* (including MRSA when susceptible).
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Pharmacokinetics
- Absorption: Rapid, >90 % bioavailable orally; food does not significantly affect absorption.
- Dissemination: Widely distributed; penetrates well into lung, bone, synovial fluid, and tissues.
- Metabolism: Minimal hepatic metabolism; primarily excreted unchanged.
- Excretion: ~70 % renal (glomerular filtration and tubular secretion); ~30 % fecal.
- Half‑life: ~8 h in adults with normal renal function; prolonged in renal impairment.
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Indications
- Community‑acquired pneumonia (including cystic fibrosis–associated).
- Lower respiratory tract infections – bronchitis, exacerbations.
- Acute bacterial sinusitis (with confirmed or suspected resistance).
- Urinary tract infections – cystitis, pyelonephritis, prostatitis.
- Skin & soft‑tissue infections – cellulitis, abscesses, surgical prophylaxis.
- Intra‑abdominal infections (e.g., acute appendicitis, peritonitis) when broad coverage is required.
- Other: bone and joint infections, otitis media, and postoperative nosocomial infections in select settings.
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Contraindications
Contraindications
• Hypersensitivity to levofloxacin or any fluoroquinolone.
• Known hypersensitivity to *fluoroquinolone* moiety.
Warnings
• Tendonitis & tendon rupture – especially in patients >60 yrs, corticosteroid users, or after trauma.
• QT‑interval prolongation & arrhythmias – caution in patients with electrolyte disturbances, pre‑existing QT prolongation, or on QT‑prolonging drugs.
• Peripheral neuropathy – rare, may be exacerbated by high doses or prolonged therapy.
• Central nervous system effects – agitation, insomnia, hallucinations, seizures.
• Concomitant use with high‑dose calcium salts or antacids containing magnesium, aluminum, or calcium – may reduce absorption.
• Use in pregnancy – category C; weigh maternal benefit against fetal risk.
• Use in pediatric – generally avoided; caution in patients under 18 yrs due to potential musculoskeletal toxicity.
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Dosing
| Infection Type | Typical Dose | Administration |
| Adults (normal renal function) | 500 mg PO once daily (or 750 mg IV once daily) | Oral: 500 mg tablets; IV: 750 mg infusion over 1 h. |
| Urinary Tract Infection | 250 mg PO twice daily | Oral; dose adjustment for renal impairment. |
| Bacterial Pneumonia | 750 mg PO once daily (or IV) | Oral or IV; 1 h infusion. |
| Renal impairment | Reduce dose: 250 mg (CrCl 30‑50 mL/min) or 125 mg (CrCl 13 days. |
• Administration tips
• Do not take with antacids, soy products, multivitamins, iron salts, or dairy; separate by ≥2 h.
• For IV, dilute with normal saline; avoid infusion over less than 1 h to mitigate infusion reactions.
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Adverse Effects
| Adverse Effect | Frequency | Notes |
| Gastrointestinal (diarrhea, nausea, vomiting) | Common | May precipitate *Clostridium difficile* colitis. |
| Central nervous system (headache, insomnia, dizziness) | Common | Severe seizures/psychosis rare but reported. |
| Musculoskeletal (tendonitis, tendon rupture) | Rare | Highest risk in elderly, steroid users. |
| Dermatologic (rash, photosensitivity) | Rare | Severe cutaneous reactions (SJS/TEN) extremely infrequent. |
| Hepatotoxicity | <0.1 % | Monitor LFTs if prolonged therapy or baseline abnormality. |
| QT prolongation | <1 % | Avoid in patients with congenital long-QT, electrolyte imbalance. |
| Glucose dysregulation | Rare | Hyperglycemia or hypoglycemia observed in diabetic patients. |
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Monitoring
- Renal function (CrCl) before initiation, every 2–3 days for >14 days therapy.
- Hepatic panel if prolonged therapy or baseline elevation.
- QT interval (ECG) in high‑risk patients (QT > 440 ms).
- Blood glucose in diabetic patients or new hyper/hypoglycemia.
- Signs of tendinopathy – educate patients about early pain/tingling.
- Clostridium difficile symptoms (watery diarrhea, abdominal pain) – assess promptly.
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Clinical Pearls
- Avoid the “pediatric rule‑out.” Though primarily for adults, levofloxacin can be used in children ≥8 yrs for life‑threatening infections *when no alternatives exist*, but only for 7–10 days.
- Chelation alert: Antacids and multivitamins with calcium, magnesium, or aluminum *should be separated by 2 hrs* to maintain >90 % absorption.
- Renal dose titration is critical – a 1‑day error in a CrCl < 30 mL/min can lead to accumulation and serious toxicity.
- Combination with NSAIDs → GI bleeding risk – especially with chronic use or at high doses. Use PPIs if PPI‑protective co‑therapy is indicated.
- Caution in elderly with polypharmacy – the risk of tendon rupture rises sharply if a patient is on systemic corticosteroids, organ transplant immunosuppressants, or concurrent Q‑interval longers.
- Educate patients about early tendon symptoms – prompt reporting can prevent rupture.
- Pregnancy & lactation: While category C, maternal disease severity often outweighs risk; ensure nursing mother’s infant is not exposed via breast milk in the first 24 h post‑dose.
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• Key Takeaway: *Qualaquin (levofloxacin)* is a potent, broad‑spectrum fluoroquinolone effective against many resistant pathogens, but its use demands vigilant monitoring for musculoskeletal, cardiac, and CNS adverse events, especially in elderly, renal‑impaired, or poly‑pharmacy patients.