GEMIFLOXACIN MESYLATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for GEMIFLOXACIN MESYLATE (GEMIFLOXACIN MESYLATE).
Inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, blocking DNA replication and transcription.
| Metabolism | Minimal hepatic metabolism; primarily excreted unchanged in urine via glomerular filtration and tubular secretion. |
| Excretion | Renal: ~61% as unchanged drug, ~7% as glucuronide; Fecal/biliary: ~28% as unchanged drug and metabolites. |
| Half-life | Terminal elimination half-life 7–9 hours (mean 8.2 h) in healthy adults; prolonged in renal impairment (e.g., 15–22 h in severe renal impairment). |
| Protein binding | ~60% bound to serum proteins (primarily albumin). |
| Volume of Distribution | Apparent Vd 4–5 L/kg (mean 4.7 L/kg), indicating extensive tissue penetration (e.g., lung, sinuses, urine). |
| Bioavailability | Oral: ~71% absolute bioavailability; absorption unaffected by food. |
| Onset of Action | Oral: Clinical effect within 1–2 hours after absorption. |
| Duration of Action | Dosing interval of 24 hours due to concentration-dependent bactericidal activity; post-antibiotic effect (PAE) of 2–6 hours for Gram-positive and Gram-negative organisms. |
| Molecular Weight | 485.51 |
320 mg orally once daily for 7-14 days
| Dosage form | TABLET |
| Renal impairment | CrCl 40-60 mL/min: 320 mg daily; CrCl <40 mL/min: 160 mg daily; hemodialysis: 160 mg daily after dialysis |
| Liver impairment | No adjustment required for mild-moderate hepatic impairment; safety in severe impairment not established |
| Pediatric use | Not recommended for use in patients <18 years of age |
| Geriatric use | Caution due to increased risk of tendonitis and tendon rupture; monitor renal function; no specific dose adjustment except based on renal function |
| 1st trimester | Avoid. Fluoroquinolones are associated with arthropathy in immature animals and limited human data; potential risk of fetal cartilage damage. |
| 2nd trimester | Avoid. Use only if no safer alternatives are available and infection is severe. Risk of fetal cartilage toxicity. |
| 3rd trimester | Avoid. Same risks as earlier trimesters; potential for neonatal adverse effects. |
Clinical note
Comprehensive clinical and safety monograph for GEMIFLOXACIN MESYLATE (GEMIFLOXACIN MESYLATE).
| Placental transfer | Gemifloxacin crosses the placenta in animal studies; limited human data suggest placental transfer occurs. |
| Breastfeeding | Gemifloxacin is excreted into breast milk in small amounts. Use caution; potential for infant gastrointestinal disturbance and cartilage toxicity. Only use if benefits outweigh risks. |
■ FDA Black Box Warning
Increased risk of tendinitis and tendon rupture, particularly in patients over 60, those on corticosteroids, and organ transplant recipients. Fluoroquinolones may exacerbate muscle weakness in myasthenia gravis patients. Risk of peripheral neuropathy, CNS effects (including seizures), and phototoxicity.
| Serious Effects |
Hypersensitivity to gemifloxacin or any fluoroquinoloneHistory of tendon disorder related to fluoroquinolone usePregnancy (except in severe infection where no alternatives)Lactation (unless benefits outweigh risks)Children and adolescents (<18 years) except special circumstances
| Precautions | Tendon damage, peripheral neuropathy, CNS effects (dizziness, seizures), QT prolongation, photosensitivity, hypersensitivity reactions, Clostridioides difficile-associated diarrhea, blood glucose disturbances in diabetics, renal impairment requires dose adjustment. |
| Food/Dietary | Absorption is reduced by divalent and trivalent cations. Avoid concomitant ingestion of dairy products (milk, yogurt, ice cream), calcium-fortified juices, sucralfate, antacids containing magnesium or aluminum, iron supplements, and multivitamins with zinc. Separate administration by at least 2 hours before or 6 hours after these products. No other significant food interactions. |
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| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Teratogenic risk in humans is not fully established due to limited data. In animal studies, gemifloxacin did not show teratogenicity at doses up to 4 times the human exposure. However, fluoroquinolones are generally avoided in pregnancy due to potential arthropathy in juvenile animals. In first trimester, caution warranted due to risk of spontaneous abortion associated with some fluoroquinolones; in second and third trimesters, potential for fetal cartilage damage cannot be excluded. |
| Fetal Monitoring | Monitor for maternal adverse effects including gastrointestinal disturbances, headache, dizziness, and rare tendonitis or tendon rupture. No specific fetal monitoring required, but ultrasound may be considered if fluoroquinolone exposure occurs during pregnancy to assess fetal development. |
| Fertility Effects | In animal studies, gemifloxacin did not impair fertility in rats at doses up to 300 mg/kg/day. No human data on fertility effects; however, fluoroquinolones are not known to significantly affect fertility. Theoretical concern for spermatotoxicity based on some animal studies with other quinolones, but not confirmed. |
| Clinical Pearls | Gemifloxacin is a respiratory fluoroquinolone with enhanced activity against Streptococcus pneumoniae, including penicillin- and macrolide-resistant strains. It has a low propensity for QT prolongation compared to moxifloxacin, but risk still exists. Monitor for tendonitis and tendon rupture, especially in patients over 60, those on corticosteroids, or with renal impairment. Avoid in myasthenia gravis due to risk of exacerbation. |
| Patient Advice | Take exactly as prescribed; do not skip doses or double up on missed doses. · Complete the full course of therapy even if you feel better. · Avoid taking with dairy products (milk, yogurt) or calcium-fortified juices; take 2 hours before or 6 hours after these products. · Stay well hydrated to prevent crystalluria. · Watch for signs of tendon pain or swelling; stop the drug and contact your doctor immediately. · Avoid sun exposure and use sunscreen; this medication can increase sensitivity to sunlight. · Report any unusual sensations like tingling, numbness, or weakness in limbs. · Do not drive if you experience dizziness or vision changes. · Notify your doctor if you have a history of seizures, QT prolongation, or low potassium/magnesium levels. |