Penetrex - General Information

A broad-spectrum 6-fluoronaphthyridinone antibacterial agent (fluoroquinolones) structurally related to nalidixic acid. [PubChem]


Pharmacology of Penetrex

Penetrex is a quinolone/fluoroquinolone antibiotic. Penetrex 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. Penetrex is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria. Penetrex may be active against pathogens resistant to drugs that act by different mechanisms.


Penetrex for patients

Patients should be advised:

  • Not to take magnesium-, aluminum-, or calcium-containing antacids, bismuth subsalicylate, products containing iron, or multivitamins containing zinc for 8 hours prior to enoxacin or for 2 hours after enoxacin administration.
  • To drink fluids liberally.
  • To avoid consumption of caffeine-containing products (certain drugs, coffee, tea, chocolate, certain carbonated beverages) during enoxacin therapy.
  • That convulsions have been reported in patients taking quinolones, including enoxacin, and to notify their physicians before taking this drug if there is a history of this condition.
  • To discontinue treatment and inform their physician if they experience pain, inflammation, or rupture of a tendon, and to rest and refrain from exercise until the diagnosis of tendinitis or tendon rupture has been confidently excluded.
  • That enoxacin may cause dizziness and lightheadedness and, therefore, patients should know how they react to enoxacin before they operate an automobile or machinery or engage in activities requiring mental alertness and coordination.
  • That enoxacin may be associated with hypersensitivity reaction, even following the first dose, and to discontinue the drug at the first sign of a skin rash or other allergic reaction.
  • To avoid undue exposure to excessive sunlight while receiving enoxacin and to discontinue therapy if phototoxicity occurs.


Penetrex Interactions

Bismuth:   Bismuth subsalicylate, given concomitantly with enoxacin or 60 minutes following enoxacin administration, decreased enoxacin bioavailability by approximately 25%. Thus, concomitant administration of enoxacin and bismuth subsalicylate should be avoided.

Caffeine:   Enoxacin is a potent inhibitor of the cytochrome P-450 isozymes responsible for the metabolism of methylxanthines. In a multiple-dose study, enoxacin caused a dose-related increase in the mean elimination half-life of caffeine, thereby decreasing the clearance of caffeine by up to 80% and leading to a five-fold increase in the AUC and the half-life of caffeine. Trough plasma enoxacin levels were also 20% higher when caffeine and enoxacin were administered concomitantly. Caffeine-related adverse effects have occurred in patients consuming caffeine while on therapy with enoxacin.

Cyclosporine:   Elevated serum levels of cyclosporine have been reported with concomitant use of cyclosporine with other members of the quinolone class.

Digoxin:   Enoxacin may raise serum digoxin levels in some individuals. If signs and symptoms suggestive of digoxin toxicity occur when enoxacin and digoxin are given concomitantly, physicians are advised to obtain serum digoxin levels and adjust digoxin doses appropriately.

Non-steroidal anti-inflammatory agents:   Seizures have been reported in patients taking enoxacin concomitantly with the nonsteroidal anti-inflammatory drug fenbufen. Animal studies also suggest an increased potential for seizures when these two drugs are given concomitantly. Fenbufen is not approved in the United States at this time.

Sucralfate and antacids:   Quinolones form chelates with metal cations. Therefore, administration of quinolones with antacids containing calcium, magnesium, or aluminum; with sucralfate; with divalent or trivalent cations such as iron; or with multivitamins containing zinc may substantially interfere with drug absorption and result in insufficient plasma and tissue quinolone concentrations. Antacids containing aluminum hydroxide and magnesium hydroxide reduce the oral absorption of enoxacin by 75%. The oral bioavailability of enoxacin is reduced by 60% with coadministration of ranitidine. These agents should not be taken for 8 hours before or for 2 hours after enoxacin administration.

Theophylline:   Enoxacin is a potent inhibitor of the cytochrome P-450 isozymes responsible for the metabolism of methylxanthines. Enoxacin interferes with the metabolism of theophylline resulting in a 42% to 74% dose-related decrease in theophylline clearance and a subsequent 260% to 350% increase in serum theophylline levels. Theophylline-related adverse effects have occurred in patients when theophylline and enoxacin were coadministered.

Warfarin:   Quinolones, including enoxacin, decrease the clearance of R-warfarin, the less active isomer of racemic warfarin. Enoxacin does not affect the clearance of the active S-isomer, and changes in clotting time have not been observed when enoxacin and warfarin were coadministered. Nevertheless, the prothrombin time or other suitable coagulation test should be monitored when warfarin or its derivatives and enoxacin are given concomitantly.


Penetrex Contraindications

Penetrex is contraindicated in persons with a history of hypersensitivity, tendinitis, or tendon rupture associated with the use of enoxacin or any member of the quinolone group of antimicrobial agents.


Additional information about Penetrex

Penetrex Indication: For the treatment of adults (≥18 years of age) with the following infections caused by susceptible strains of the designated microorganisms: (1) uncomplicated urethral or cervical gonorrhea due to Neisseria gonorrhoeae, (2) uncomplicated urinary tract infections (cystitis) due to Escherichia coli, Staphylococcus epidermidis, or Staphylococcus saprophyticus, and (3) complicated urinary tract infections due to Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus epidermidis, or Enterobacter cloacae.
Mechanism Of Action: Penetrex exerts its bactericidal action via the inhibition of the essential bacterial enzyme DNA gyrase (DNA Topoisomerase II).
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Enoxacin
Synonyms: Not Available
Drug Category: Anti-Infective Agents
Drug Type: Small Molecule; Approved

Other Brand Names containing Enoxacin: Penetrex;
Absorption: Rapidly absorbed following oral administration, with an absolute oral bioavailability of approximately 90%.
Toxicity (Overdose): Not Available
Protein Binding: Enoxacin is approximately 40% bound to plasma proteins in healthy subjects and is approximately 14% bound to plasma proteins in patients with impaired renal function.
Biotransformation: Hepatic. Some isozymes of the cytochrome P-450 hepatic microsomal enzyme system are inhibited by enoxacin. After a single dose, greater than 40% was recovered in urine by 48 hours as unchanged drug.
Half Life: Plasma half-life is 3 to 6 hours.
Dosage Forms of Penetrex: Tablet, film coated Oral
Chemical IUPAC Name: 1-ethyl-6-fluoro-4-oxo-7-piperazin-1-yl-1,8-naphthyridine-3-carboxylic acid
Chemical Formula: C15H17FN4O3
Enoxacin on Wikipedia:
Organisms Affected: Enteric bacteria and other eubacteria