title: Exposure-response analyses of tigecycline efficacy in patients with complicated skin and skin-structure infections.
abstract: Exposure-response analyses were performed for the microbiological and clinical efficacy of tigecycline in the treatment of complicated skin and skin-structure infections, where Staphylococcus aureus and streptococci are the predominant pathogens. A prospective method was developed to create homogeneous patient populations for PK-PD analyses. Evaluable patients from three clinical trials were pooled for analysis. Patients received a tigecycline 100-mg loading dose/50 mg every 12 h or a 50-mg loading dose/25 mg every 12 h. At the test-of-cure visit, microbiologic and clinical responses were evaluated. Patients were prospectively evaluated and classified into cohorts based on baseline pathogens: S. aureus only (cohort 1), monomicrobial S. aureus or streptococci (cohort 2), two gram-positive pathogens (cohort 3), polymicrobial (cohort 4), or other monomicrobial infections (cohort 5). A prospective procedure for combining cohorts was used to increase the sample size. Logistic regression evaluated steady-state 24-h area under the concentration-time curve (AUC(24))/MIC ratio as a predictor of response, and classification and regression tree (CART) analyses were utilized to determine AUC/MIC breakpoints. Analysis began with pooled cohorts 2 and 3, the focus of these analyses, and included 35 patients with 40 S. aureus and/or streptococcal pathogens. CART analyses identified a significant AUC/MIC breakpoint of 17.9 (P = 0.0001 for microbiological response and P = 0.0376 for clinical response). The continuous AUC/MIC ratio was predictive of microbiological response based on sample size (P = 0.0563). Analysis of all pathogens combined decreased the ability to detect exposure-response relationships. The prospective approach of creating homogeneous populations based on S. aureus and streptococci pathogens was critical for identifying exposure-response relationships.
authors.affiliation: Cognigen Corp., 395 Youngs Rd., Buffalo, NY 14221, USA. julie.passarell@cognigencorp.com
authors.forename: A K
authors.initials: AK
authors.lastname: Meagher
authors.forename: J A
authors.initials: JA
authors.lastname: Passarell
authors.forename: B B
authors.initials: BB
authors.lastname: Cirincione
authors.forename: S A
authors.initials: SA
authors.lastname: Van Wart
authors.forename: K
authors.initials: K
authors.lastname: Liolios
authors.forename: T
authors.initials: T
authors.lastname: Babinchak
authors.forename: E J
authors.initials: EJ
authors.lastname: Ellis-Grosse
authors.forename: P G
authors.initials: PG
authors.lastname: Ambrose
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D019540:Area Under Curve; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008911:Minocycline / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D017192:Skin Diseases, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D013207:Staphylococcal Skin Infections / Q000188:drug therapy / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects*; D013290:Streptococcal Infections / Q000188:drug therapy / Q000382:microbiology; D013291:Streptococcus / Q000145:classification / Q000187:drug effects*; D000078304:Tigecycline; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D000078304:Tigecycline; D008911:Minocycline