[The pharmacokinetics of metronidazole and gentamicin in a single preoperative dose as antibiotic prophylaxis in colorectal surgery].
OBJECTIVE
To describe, in patients undergoing colorectal surgery (CRS), the pharmacokinetics of a single, prophylactic preoperative dose of 1,500 mg of metronidazole plus 240 mg gentamicin and measure its efficacy in accordance with the accepted pharmacodynamic and microbiological parameters.


METHODS
Thirty-six patients undergoing CRS agreed to participate in the study. Three blood samples were taken from each. Cmax 15 minutes after finishing the infusion of the mixture, CfinIQ on finishing the surgery, and Cmin between 12 and 24 hours post-administration. The concentrations of metronidazole and gentamicin in each simple were measured and the pharmacokinetic parameters were estimated (dV- distribution volume , Cl-plasma clearance). For the metronidazole, concentrations in excess of 8 microg/ml were considered effective, and for gentamicin, C(max) in excess of 9 microg/ml and inhibition quotients above 8.


RESULTS
All the concentrations of metronidazole, both CmaxMTZ and CfinIQMTZ were above 8 microg/ml and all the CmaxGEN in excess of 9 microg/ml. The CIGEN was 13.8+/-3.8, with no individual value below 8. For the metronidazole, a dV of 0.68+/-0.2 l/kg was estimated and a Cl of 3.15+/-1.20 l/h and for the gentamicin, the dV as 0.23+/-0.06 l/kg and the Cl was 4.71+/-1.95 l/h.


CONCLUSIONS
In patients undergoing CRS, surgical intervention did not significantly modify the pharmacokinetics of metronidazole or gentamicin in comparison with other groups of patients. The prophylaxis using a single, pre-surgical dose enables the achievement, for both antimicrobial agents, concentrations of a sufficient size to guarantee clinical efficacy.
Ventura Cerdá
J M
JM
Servicio de Farmacia, Hospital General de Castellón, Castellón, España. ventura_jma@gva.es
Alós Almiñana
M
M
Nomdedeu Guinot
J
J
Merino Sanjuán
V
V
Salvador Sanchís
J L
JL
D000890:Anti-Infective Agents / Q000493:pharmacokinetics*; D019072:Antibiotic Prophylaxis; D003108:Colonic Diseases / Q000601:surgery*; D005260:Female; D005839:Gentamicins / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000493:pharmacokinetics*; D008875:Middle Aged; D011300:Preoperative Care; D011446:Prospective Studies; D012002:Rectal Diseases / Q000601:surgery*
D000890:Anti-Infective Agents; D005839:Gentamicins; D008795:Metronidazole