title: Effect of ciprofloxin on the pharmacokinetics of intravenous lidocaine.
abstract: OBJECTIVE
  Recent studies have suggested that cytochrome P-450 isoenzyme 1A2 has an important role in lidocaine biotransformation. We have studied the effect of a cytochrome P-450 1A2 inhibitor, ciprofloxacin, on the pharmacokinetics of lidocaine.
  
  
  METHODS
  In a randomized, double-blinded, cross-over study, nine healthy volunteers ingested for 2.5 days 500 mg oral ciprofloxacin or placebo twice daily. On day 3, they received a single dose of 1.5 mg kg[-1] lidocaine intravenously over 60 min. Plasma concentrations of lidocaine, 3-hydroxylidocaine and monoethylglycinexylidide were determined for 11 h after the start of the lidocaine infusion.
  
  
  RESULTS
  Ciprofloxacin increased the mean peak concentration and area under plasma concentration-time curve of lidocaine by 12% (range [-6] to+46%; P<0.05) and 26% (8--59%; P 0.01), respectively. The mean plasma clearance of lidocaine was decreased by ciprofloxacin by 22% (7--38%; P<0.01). Ciprofloxacin decreased the area under the plasma concentration-time curve of monoethylglycinexylidide by 21% (P<0.01) and that of 3-hydroxylidocaine by 14% (P< 0.01).
  
  
  CONCLUSIONS
  The plasma decay of intravenously administered lidocaine is modestly delayed by concomitantly administered ciprofloxacin. Ciprofloxacin may increase the systemic toxicity of lidocaine.
authors.affiliation: Diacor Hospital, Department of Anaesthesia, University of Helsinki, Helsinki, Finland. mika.isohonni@diakor
authors.forename: M H
authors.initials: MH
authors.lastname: Isohanni
authors.forename: J
authors.initials: J
authors.lastname: Ahonen
authors.forename: P J
authors.initials: PJ
authors.lastname: Neuvonen
authors.forename: K T
authors.initials: KT
authors.lastname: Olkkola
mesh_terms: D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001711:Biotransformation; D002939:Ciprofloxacin / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004347:Drug Interactions; D005260:Female; D006207:Half-Life; D006801:Humans; D007275:Injections, Intravenous; D008012:Lidocaine / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male
chemical_list: D000779:Anesthetics, Local; D000890:Anti-Infective Agents; C075860:3-hydroxylidocaine; D002939:Ciprofloxacin; D008012:Lidocaine; C001173:monoethylglycinexylidide