Chemical formula: C₂₅H₄₈N₆O₁₀ Molecular mass: 592.691 g/mol PubChem compound: 42613186
Plazomicin is an aminoglycoside antibacterial.
The ratio of area under the plasma concentration-time curve to the minimum inhibitory concentration (AUC:MIC) for plazomicin has been shown to best correlate with efficacy in animal and in vitro models of infection against Enterobacteriaceae.
Based on exposure-response analysis for nephrotoxicity, defined as serum creatinine increases greater than or equal to 0.5 mg/dL from baseline, using the data from two cUTI clinical trials (Trial 1 and Trial 2), development of nephrotoxicity was associated with estimated plazomicin exposure (i.e., the plasma trough concentration [Cmin]) in patients with CLcr greater than 30 mL/min and less than or equal to 90 mL/min (N=243). The incidence of nephrotoxicity was higher in patients with plazomicin Cmin greater than or equal to 3 mcg/mL (36%, 10/28) compared to patients with plazomicin Cmin less than 3 mcg/mL (5%, 11/215).
The effect of plazomicin on the QTc interval was evaluated in a Phase 1 randomized, placebo and positive controlled, double-blind, single-dose, crossover thorough QTc study in 56 healthy adult subjects. At a single dose of 20 mg/kg (1.3 times the maximum recommended dose), plazomicin did not prolong the QTc interval to any clinically relevant extent.
The pharmacokinetic (PK) parameters of plazomicin are similar for single- and multiple-dose administration of plazomicin in healthy subjects. No appreciable accumulation of plazomicin was observed following multiple IV infusions of 15 mg/kg administered every 24 hours in subjects with normal renal function. The AUC, maximum plasma concentration (Cmax), and Cmin increased in proportion to the dose over the dose range of 4 to 15 mg/kg. The plazomicin AUC, Cmax, and Cmin are summarized in the following table.
Pharmacokinetic Parameters (Geometric Mean [±SD]) of Plazomicin Following Administration of Plazomicin 15 mg/kg by 30-Minute IV Infusion in Healthy Subjects and cUTI Patients with CLcr Greater than or Equal to 90 mL/min:
| Healthy Subjects* Geometric mean (±SD) N=54 | cUTI Patients† Geometric mean (±SD) N=87 | |
|---|---|---|
| AUC (mcg∙h/mL) | 257 (±67.0) | 226 (±113) |
| Cmax (mcg/mL) | 73.7 (±19.7) | 51.0 (±26.7) |
| Cmin (mcg/mL) | 0.3 (±0.2) | 0.5 (±1.2) |
* PK parameters following a single dose of 15 mg/kg; Based on non-compartmental analysis of PK data; AUC0-inf is reported; Cmin is concentration at 24 hours.
† Day 1 PK parameters following administration of 15 mg/kg; Derived based on population PK model; AUC0-24h is reported.
The mean (±SD) volume of distribution of plazomicin in healthy adults and cUTI patients is 17.9 (±4.8) and 30.8 (±12.1) L, respectively. The average binding of plazomicin to human plasma proteins is approximately 20%. The degree of protein binding was concentration-independent across the range tested in vitro (5 to 100 mcg/mL).
The mean (±SD) total body clearance of plazomicin in healthy adults and cUTI patients is 4.5 (±0.9) and 5.1 (±2.01) L/h, respectively. The mean (±SD) half-life of plazomicin was 3.5 h (±0.5) in healthy adults with normal renal function (n=54).
Plazomicin does not appear to be metabolized to any appreciable extent.
Plazomicin is primarily excreted by the kidneys. Following a single 15 mg/kg IV dose of radiolabeled plazomicin in healthy subjects, 56% of the total administered radioactivity was recovered in urine within 4 hours, 89.1% was recovered within 168 hours, with less than 0.2% in feces. In total, 97.5% of the dose was recovered in the urine as unchanged plazomicin. The mean renal clearance (±SD) of plazomicin (4.6 [±1.2] L/h) was similar to total body clearance, suggesting that plazomicin is eliminated by the kidneys.
No clinically significant differences in the pharmacokinetics of plazomicin were observed based on age (18 to 90 years of age), sex, or race/ethnicity. The pharmacokinetics of plazomicin in patients with hepatic impairment is unknown.
Following a single 7.5 mg/kg IV dose (0.5 times the recommended dose) of plazomicin as a 30-minute infusion, the geometric mean AUC0-inf of plazomicin in subjects with mild (CLcr 60 to <90 mL/min, n=6), moderate (CLcr 30 to <60 mL/min, n=6), and severe (CLcr 15 to <30 mL/min, n=6) renal impairment was 1.01-fold, 1.98-fold, and 4.42-fold higher, respectively, compared to subjects with normal renal function (CLcr ≥90 mL/min, n=6).
Based on the population PK model, the recommended dosage of plazomicin was associated with a mean (±SD) Cmin of 1.0 (±1.3) and 1.7 (±1.4) mcg/mL in cUTI patients with mild (CLcr 60 to <90 mL/min, n=104) and moderate (CLcr 30 to <60 mL/min, n=89) renal impairment, respectively. The mean (±SD) area under the curve from time zero to 24 hours (AUC0-24h) was 261 (±102) and 224 (±147) mcg∙h/mL in cUTI patients with mild (CLcr 60 to <90 mL/min, n=104) and moderate (CLcr 30 to <60 mL/min, n=89) renal impairment, respectively. There were insufficient data to calculate Cmin and AUC0-24h for patients with severe renal impairment (CLcr 15 to <30 mL/min).
No clinically relevant trend in plazomicin exposure (Cmax and AUC0-24h) was observed with regard to age alone. Higher Cmin in elderly subjects (65 to 90 years of age) as compared to non-elderly adult subjects (18 to 64 years of age) was mainly attributable to age-related changes in renal function.
Based on the results of a clinical drug-drug interaction (DDI) study that evaluated the effect of a single dose of plazomicin (15 mg/kg) on the single dose plasma PK of metformin, plazomicin did not affect the PK of metformin, which is a substrate of OCT and MATE transporters.
Drug-Metabolizing Enzymes: Plazomicin does not inhibit the following cytochrome P450 isoforms: CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4/5. Plazomicin does not induce CYP1A2, CYP2B6, and CYP3A4.
Membrane Transporters: Plazomicin is not a substrate of P-gp or BCRP transporters. Plazomicin does not inhibit the following hepatic and renal transporters in vitro at clinically relevant concentrations: P-gp, BCRP, BSEP, MRP2, OATP1B1, OATP1B3, OAT1, OAT3, OCT1, and OCT2. Plazomicin selectively inhibited the MATE1 and MATE2-K renal transporter in vitro with an IC50 value of 1300 and 338 mcg/mL, respectively.
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