Antimicrobial dose selection

Surgical antimicrobial Timing, selection, and Preoperative doses... 

Infectious diseases pharmacists typically practice in a hospital setting that allows them to devote all their time to managing antimicrobial therapy. All aspects of infectious diseases pharmacotherapy, including interventions on antimicrobial selection, antimicrobial dosing, and intravenous-to-oral conversion are the responsibility of the infectious diseases pharmacist. In addition, the pharmacist is usually responsible for analyzing new antimicrobials for formulary inclusion, medication use evaluations, and antimicrobial restriction or therapeutic interchange policies. 

Drug-specific considerations in antimicrobial selection include the spectrum of activity, effects on nontargeted microbial flora, appropriate dose, pharmacokinetic and pharmacodynamic properties, adverse-effect and drug-interaction profile, and cost. 

Host factors can help to ensure selection of the most appropriate antimicrobial agent. Age is an important factor in antimicrobial selection. With regard to dose and interval, renal and hepatic function varies with age. Populations with diminished renal function include neonates and the elderly. Hepatic function in the neonate is not fully developed, and drugs that are metabolized or eliminated by this route may produce adverse effects. For example, sulfonamides and ceftriaxone may compete with bilirubin for binding sites and may result in hyperbilirubinemia and kernicterus. Gastric acidity also depends on... 

Guidelines suggest that if an operation exceeds two half-lives of the selected antimicrobial, then another dose should be administered.1 Repeat dosing has been shown to lower rates of SSI. For example, cefazolin has a half-life of about 2 hours, thus... 

Improper administration of antimicrobial prophylaxis leads to excessive surgical wound infection rates. Common errors in antibiotic prophylaxis include selection of the wrong antibiotic, administering the first dose too early or too late, failure to repeat doses during prolonged procedures, excessive duration of prophylaxis, and inappropriate use of broad-spectrum antibiotics. 

The question is not whether there may be in vitro evidence but whether residue levels, singly or in combination, can select for resistant populations in vivo experiments. Under in vivo conditions, an antimicrobial residue that is stable to cooking processes would have to move through the stomach and the intestine, would then be metabolized during the passage or would be absorbed and excreted. A portion of it will not occur in the colon, the site of this specific action. Only a small portion of the ingested dose will reach the colon and remain there for a certain time, since many conditions have an influence upon the final concentration at the site of action in the colon. 

The most important approach to treatment of IE includes isolation of the infecting pathogen and determination of antimicrobial susceptibilities, followed by high-dose, bactericidal antibiotics for an extended period. Treatment usually is started in the hospital, but in selected patients, it may be completed in the outpatient setting. 

Pharmaceutical care of the hospitalized patient with infection is the most traditional role for infectious diseases pharmacists. Numerous opportunities for proactive interventions in antimicrobial selection, dosing, route of administration, and monitoring of patients with changing clinical status make this a popular practice setting for many individuals. 

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