0.75 mg/kg (up to a maximum dose of 50 mg for each dose) of tigecycline every 12 hours infused over approximately 30 minutes. Escalation to next dose cohort will occur only after safety and tolerability at preceding dose have been established by sponsor (after tigecycline LDOT data are received) and if at least 5 of 6 PK samples per patient have been received by central laboratory in acceptable condition for 10 to 12 patients in cohort. Treatment period of tigecycline will be a minimum of 3 days (unless patient is considered a treatment failure before this time) and a maximum of 14 days. On or after Day 4, based on investigator's decision, patients can switch to oral antibiotic therapy (to be chosen and provided by the investigator) and discharged after collection of planned PK samples.

1 mg/kg (up to a maximum dose of 50 mg for each dose) of tigecycline every 12 hours infused over approximately 30 minutes. Escalation to next dose cohort will occur only after safety and tolerability at preceding dose have been established by sponsor (after tigecycline LDOT data are received) and if at least 5 of 6 PK samples per patient have been received by the central laboratory in acceptable condition for 10 to 12 patients in the cohort. Treatment period of tigecycline will be a minimum of 3 days (unless the patient is considered a treatment failure before this time) and a maximum of 14 days. On or after Day 4, based on investigator's decision, patients can switch to oral antibiotic therapy (to be chosen and provided by the investigator) and discharged after collection of planned PK samples.

1.25 mg/kg (up to maximum dose of 50 mg for each dose) of tigecycline every 12 hours infused over approximately 30 minutes. Treatment period of tigecycline will be a minimum of 3 days (unless patient is considered a treatment failure before this time) and a maximum of 14 days. On or after Day 4, based on investigator's decision, patients can switch to oral antibiotic therapy (to be chosen and provided by the investigator) and discharged after collection of planned PK samples.

Cmax: tigecycline serum concentration measured in nanograms per milliliter (ng/mL) determined by a validated liquid chromatography with mass spectrophotometric (LC/MS/MS) detection method. Peak concentration was taken directly from the observed data.

Time of peak concentration taken directly from the observed data.

AUCτ: AUC between doses from time zero to the time of estimated concentration at 12 hours reported in nanograms * hours divided by milliliters (ng*h/mL) was calculated using the log-trapezoidal rule for decreasing concentrations and the linear-trapezoidal rule for increasing concentrations estimating the 12 hour drug concentration if necessary.

Weight normalized drug clearance measured in liters per hour per kilogram (L/hr/kg). Drug clearance (CL) was determined as the ratio of dose/area under the concentration-time curve from time zero (start of infusion) to 12 hours (start of next infusion) (AUCτ). CLW was determined as the ratio of CL/weight.

CR = Cure: resolution of all signs, symptoms (SS) of infection (INF) or improvement, no further antibacterial therapy (AT) necessary; Improved (IMP): SS IMP to extent that switch to oral AT deemed appropriate; Failure: lack of response, required additional AT, initial recovery then deterioration requiring further AT, death due to the INF after day 2, death due to treatment (TR)-related adverse event (AE), required non-routine surgical TR >48 hours after 1st dose of TR due to failure to IMP or clinical worsening. TOC = CR, vital signs, physical exam, laboratory results, concomitant TR, and AEs.

Two compartment model with linear clearance and effect of weight on clearance using pooled PK data from 2 pediatric studies. All concentration-time data were combined and analyzed using population PK methods to investigate potential influence of age, weight, and height (dose, tigecycline concentrations, times, subject weight, height, age, body surface area, serum creatinine, estimated creatinine clearance, serum bilirubin.