indication

For the treatment of sinus and lung infections such as sinusitis, pneumonia, and secondary infections in chronic bronchitis. Also for the treatment of bacterial conjunctivitis (pinkeye).

pharmacology

Moxifloxacin is a quinolone/fluoroquinolone antibiotic. Moxifloxacin can be used to treat infections caused by the following bacteria: Aerobic Gram-positive microorganisms: Corynebacterium species, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus warneri, Streptococcus pneumoniae, and Streptococcus viridans group. Aerobic Gram-negative microorganisms: Acinetobacter lwoffii, Haemophilus influenzae, and Haemophilus parainfluenzae. Other microorganisms: Chlamydia trachomatis.
Moxifloxacin is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase, which allows the untwisting required to replicate one DNA double helix into two. Notably the drug has 100 times higher affinity for bacterial DNA gyrase than for mammalian. Moxifloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria.

mechanism of action

The bactericidal action of moxifloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV. DNA gyrase is an essential enzyme that is involved in the replication, transcription and repair of bacterial DNA. Topoisomerase IV is an enzyme known to play a key role in the partitioning of the chromosomal DNA during bacterial cell division.

toxicity

Symptoms of overdose include CNS and gastrointestinal effects such as decreased activity, somnolence, tremor, convulsions, vomiting, and diarrhea. The minimal lethal intravenous dose in mice and rats is 100 mg/kg.

biotransformation

Approximately 52% or oral or intravenous dose is metabolized via glucuronide and sulphate conjugation. The cytochrome P450 system is not involved in metabolism. The sulphate conjugate accounts for 38% of the dose, and the glucuronide conjugate accounts for 14% of the dose.

absorption

Well absorbed from the gastrointestinal tract. Absolute oral bioavailability is approximately 90%. Food has little effect on absorption.

half life

11.5-15.6 hours (single dose, oral)

route of elimination

Approximately 45% of an oral or intravenous dose of moxifloxacin is excreted as unchanged drug (~20% in urine and ~25% in feces).

drug interactions

Acenocoumarol: The quinolone antibiotic, moxifloxacin, may increase the anticoagulant effect of acenocoumarol.

Aluminium: Formation of non-absorbable complexes

Amiodarone: Increased risk of cardiotoxicity and arrhythmias

Anisindione: The quinolone antibiotic, moxifloxacin, may increase the anticoagulant effect of anisindione.

Artemether: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Bepridil: Increased risk of cardiotoxicity and arrhythmias

Bretylium: Increased risk of cardiotoxicity and arrhythmias

Calcium: Formation of non-absorbable complexes

Dicumarol: The quinolone antibiotic, moxifloxacin, may increase the anticoagulant effect of dicumarol.

Dihydroquinidine barbiturate: Increased risk of cardiotoxicity and arrhythmias

Disopyramide: Increased risk of cardiotoxicity and arrhythmias

Erythromycin: Increased risk of cardiotoxicity and arrhythmias

Iron: Formation of non-absorbable complexes

Iron Dextran: Formation of non-absorbable complexes

Josamycin: Increased risk of cardiotoxicity and arrhythmias

Lumefantrine: Additive QTc-prolongation may occur. Concomitant therapy should be avoided.

Magnesium: Formation of non-absorbable complexes

Magnesium oxide: Formation of non-absorbable complexes

Quinidine: Increased risk of cardiotoxicity and arrhythmias

Quinidine barbiturate: Increased risk of cardiotoxicity and arrhythmias

Quinupristin: This combination presents an increased risk of toxicity

Sotalol: Increased risk of cardiotoxicity and arrhythmias

Sucralfate: Formation of non-absorbable complexes

Tacrolimus: Additive QTc-prolongation may occur increasing the risk of serious ventricular arrhythmias. Concomitant therapy should be used with caution.

Thiothixene: May cause additive QTc-prolonging effects. Increased risk of ventricular arrhythmias. Consider alternate therapy. Thorough risk:benefit assessment is required prior to co-administration.

Tizanidine: Moxifloxacin may decrease the metabolism and clearance of Tizanidine. Consider alternate therapy or use caution during co-administration.

Toremifene: Additive QTc-prolongation may occur, increasing the risk of serious ventricular arrhythmias. Consider alternate therapy. A thorough risk:benefit assessment is required prior to co-administration.

Trimipramine: Additive QTc-prolongation may occur, increasing the risk of serious ventricular arrhythmias. Concomitant therapy should be used with caution.

Voriconazole: Additive QTc prolongation may occur. Consider alternate therapy or monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).

Vorinostat: Additive QTc prolongation may occur. Consider alternate therapy or monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).

Warfarin: The quinolone antibiotic, moxifloxacin, may increase the anticoagulant effect of warfarin.

Zinc: Formation of non-absorbable complexes

Ziprasidone: Additive QTc-prolonging effects may increase the risk of severe arrhythmias. Concomitant therapy is contraindicated.

Zuclopenthixol: Additive QTc prolongation may occur. Consider alternate therapy or use caution and monitor for QTc prolongation as this can lead to Torsade de Pointes (TdP).