Pharmacodynamics of antibiotic penetration of tissue and surgical prophylaxis

The morbidity and mortality of infection in surgical treatment remains substantial. Many principles for the prevention and treatment of surgical infections have been established. Proper selection and preparation of patients and meticulous operative techniques are of primary importance in the prevention of surgical infections. Surgical antibiotic prophylaxis is also beneficial when an adequate tissue level is present before and throughout the duration of the procedure. The level attained in the tissues is dependent on many factors that affect the pharmacokinetics of antibiotic distribution and excretion. One factor is protein binding, which alters the fraction of free drug available for diffusion into tissues. However, the singular importance of this effect on the concentration of antibiotics in tissues is minimal. In surgical prophylaxis, the maintenance of antibiotic tissue activity at the sites of potential infection for the duration of the operation is crucial. Failure to provide persistent antibiotic tissue activity throughout the entire procedure results in an increased number of surgical infections. The pharmacokinetics of distribution and the half-life of antibiotics in the serum are directly related to the duration of activity of antibiotic in the tissue. Antibiotics with longer half-lives maintain levels in the tissues for longer periods than do antibiotics with shorter half-lives. The maintenance of the levels of a given antibiotic is similar for all tissues. The application of the pharmacokinetic properties of antibiotics to surgical prophylaxis can provide the surgeon with certainty that adequate coverage and protection with antibiotics are achieved before and throughout the operation.