indication

For the treatment of infections (respiratory tract, kidney, skin, soft tissue, UTI), urethral and cervical gonorrhoea.

pharmacology

Ofloxacin is a quinolone/fluoroquinolone antibiotic. Ofloxacin 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. Ofloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria.

mechanism of action

Ofloxacin acts on DNA gyrase and toposiomerase IV, enzymes which, like human topoisomerase, prevents the excessive supercoiling of DNA during replication or transcription. By inhibiting their function, the drug thereby inhibits normal cell division.

toxicity

LD₅₀=5450 mg/kg (orally in mice)

biotransformation

Hepatic

absorption

Bioavailability of ofloxacin in the tablet formulation is approximately 98%

half life

9 hours

route of elimination

Elimination is mainly by renal excretion. Between 65% and 80% of an administered oral dose of ofloxacin is excreted unchanged via the kidneys within 48 hours of dosing. Four to eight percent of an ofloxacin dose is excreted in the feces. This indicates a small degree of biliary excretion of ofloxacin.

drug interactions

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

Aluminium: Formation of non-absorbable complexes

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

Calcium: Formation of non-absorbable complexes

Calcium Acetate: Calcium salts such as calcium acetate may decrease the absorption of quinolone antibiotics such as ofloxacin. Of concern only with oral administration of both agents. Interactions can be minimized by administering oral quinolone at least 2 hours before, or 6 hours after, the dose of an oral calcium supplement. Monitor for decreased therapeutic effects of oral quinolones if administered with oral calcium supplements.

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

Dihydroquinidine barbiturate: Increased risk of cardiotoxicity and arrhythmias

Foscarnet: Increased risk of convulsions

Iron: Formation of non-absorbable complexes

Iron Dextran: Formation of non-absorbable complexes

Magnesium: Formation of non-absorbable complexes

Magnesium oxide: Formation of non-absorbable complexes

Procainamide: Ofloxacin may increase the effect of procainamide.

Quinidine: Increased risk of cardiotoxicity and arrhythmias

Quinidine barbiturate: Increased risk of cardiotoxicity and arrhythmias

Sucralfate: Formation of non-absorbable complexes

Tacrine: The metabolism of Tacrine, a CYP1A2 substrate, may be reduced by strong CYP1A2 inhibitors such as Ofloxacin. Consider modifying therapy to avoid Tacrine toxicity. Monitor the efficacy and toxicity of Tacrine if Ofloxacin is initiated, discontinued or if the dose is changed.

Thiothixene: The strong CYP1A2 inhibitor, Ofloxacin, may decrease the metabolism and clearance of Thiothixene, a CYP1A2 substrate. Consider alternate therapy or monitor for changes in Thiothixene therapeutic and adverse effects if Ofloxacin is initiated, discontinued or dose changed.

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

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

Zinc: Formation of non-absorbable complexes