Lipopeptide

Daptomycin showed linear pharmacokinetics, with a half-life of 0.9 to 1.4 hours and an area under the concentration-time curve (AUC) of 9.4 from time zero to infinity/dose. Ninety percent of the protein bound [5].

Absorption, Distribution and Excretion
Daptomycin administered as a 30 minute IV infusion to healthy volunteers in doses of 4, 6, 8, 10, and 12 mg/kg once daily resulted in a Cmax between 57.8 ± 3.0 and 183.7 ± 25.0 μg/mL and an AUC0-24 of between 494 ± 75 and 1277 ± 253 μg\*h/mL. Daptomycin pharmacokinetics are generally linear, with some variation observed above 6 mg/kg, and the Cmax and AUC values are approximately 20% higher at steady-state, suggesting some accumulation. Steady-state trough concentrations between 5.9 ± 1.6 and 13.7 ± 5.2 μg/mL are reached following the third once-daily dose. The data for a single daptomycin dose of 6 mg/kg administered IV over 30 minutes was used to estimate steady-state Cmax values for both 4 and 6 mg/kg doses administered over two minutes, which were estimated at 77.7 ± 8.1 and 116.6 ± 12.2 μg/mL, respectively. Administration of IV daptomycin (4 or 6 mg/kg) over two minutes did not allow for measurement of the Cmax but resulted in steady-state AUC values of 475 ± 71 and 701 ± 82 μg\*h/mL. Patients with severe renal impairment and those on dialysis had mean steady-state AUC values approximately 2-3 times higher than those with normal renal function. No clinically significant differences in daptomycin pharmacokinetics were observed in patients with mild to moderate hepatic impairment. The mean AUC0-∞ obtained in healthy elderly individuals (75 years of age and older) was approximately 58% higher than in healthy young adult controls, with no difference in Cmax. The AUC0-∞ is also increased in obese patients by approximately 30%. No significant differences in body weight- and age-adjusted Cmax or AUC was observed in pediatric patients.
Daptomycin is excreted primarily by the kidneys, approximately 78% of an administered dose recovered in urine and only 5.7% recovered in feces. Approximately 52% of the dose, recovered in urine, retains microbiological activity.
Daptomycin has a very small volume of distribution, averaging ~0.1 L/kg in healthy adult subjects independent of dose. The volume of distribution tends to increase with decreasing renal function, being estimated at ~0.2 L/kg in patients with severe renal impairment.
Daptomycin administered as a 30 minute IV infusion to healthy volunteers in doses of 4, 6, 8, 10, and 12 mg/kg once daily resulted in total plasma clearance values between 7.2 ± 1.1 and 9.6 ± 1.3 mL/h/kg, with no clear dose association. As daptomycin is primarily renally excreted, patients with mild, moderate, and severe renal impairment had reduced total plasma clearance 9, 22, and 46 percent lower than healthy controls, respectively. Daptomycin clearance was also lower in obese (15-23%) and geriatric (aged 75 and older, by 35%) patients, whereas it tended to be higher in pediatric patients, even when normalized for body weight.

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Metabolism / Metabolites
Radiolabeled daptomycin administered to five healthy adults revealed the presence of inactive metabolites in the urine. A separate study using 6 mg/kg daptomycin in healthy adults revealed small amounts of three oxidative and one unidentified metabolite(s) in urine but not in plasma. The site of metabolism is unclear, as studies using human hepatocytes suggest that daptomycin effectively does not interact at all with the various CYP450 enzymes present in the liver.

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Biological Half-Life
Daptomycin has a relatively long half-life, with ranges of 7.5-9 hours depending on dosing schemes and dose strength. The half-life lengthens in patients with increasing renal impairment, being 27.83 ± 14.85 hours in patients with creatinine clearance <30 mL/min, 30.51 ± 6.51 hours in hemodialysis patients, and 27.56 ± 4.53 hours in continuous ambulatory peritoneal dialysis (CAPD) patients. Daptomycin half-life also tends to decrease with decreasing age.

Hepatotoxicity
Elevations in serum aminotransferase levels occur in 2% to 6% of patients receiving daptomycin, rates that are minimally higher than with placebo or comparator drugs. The elevations are generally mild-to-moderate, asymptomatic and self-limited, frequently resolving without discontinuation or even interruption of therapy. Isolated case reports of possible liver injury from daptomycin have been reported, but serum bilirubin was normal in most cases, and the serum aminotransferase elevations were mild-to-moderate and typically accompanied by severe muscle injury with marked CK elevations. Such cases without jaundice or alkaline phosphatase elevations are more likely due to muscle rather than liver injury. Nevertheless, a few case reports of mild jaundice with a hepatocellular pattern of serum enzyme elevations and normal CK levels has been published. The latency to onset was 5 weeks, immunoallergic and autoimmune features were not present, and resolution was slow with mild abnormalities still present 6 weeks later. Thus, clinically apparent liver injury from daptomycin probably occurs, but is quite rare.
Likelihood score: C (probable cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited and somewhat inconsistent information indicates that daptomycin produces very low levels in milk and it would not be expected to cause any adverse effects in breastfed infants. No special precautions are required.
◉ Effects in Breastfed Infants
A mother nursing (extent not stated) a 5-month-old infant received intravenous daptomycin 500 mg and ertapenem 1 gram once daily for 28 days to treat a pelvic infection. No adverse events were noted in the infant during the treatment or follow-up examination.
A woman nursing a newborn was given daptomycin 500 mg intravenously once daily for 14 days. No adverse effects were noted in the infant during therapy and for 7 days after the end of therapy.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Daptomycin reversibly binds plasma proteins between 90-94% and independently of concentration. Although daptomycin is mainly bound to serum albumin (HSA; 85-96%), it also binds appreciably to α-1-acid-glycoprotein (AGP; 25-51%). Surface plasmon resonance (SPR) experiments revealed that daptomycin also binds a number of other plasma proteins including α-1-antitrypsin, low-density lipoprotein (LDL), hemoglobin, sex hormone-binding globulin (SHBG), hemopexin, fibrinogen, α2-macroglobulin, β2-microglobulin, high-density lipoprotein (HDL), fibronectin, haptoglobulin, transferrin, and IgG. Of these, it was determined that the main determinants of plasma binding were HSA, AGP, α-1-antitrypsin, LDL, SHBG, and hemopexin. Consistent with observations regarding calculated distribution volumes, daptomycin protein binding tends to decrease with decreasing renal function, being approximately 88% in patients with creatinine clearance <30 mL/min, approximately 86% in those on hemodialysis, and approximately 84% in those on continuous ambulatory peritoneal dialysis (CAPD).

[1]. Antimicrob Agents Chemother . 2003 Aug;47(8):2538-44.

[2]. Antimicrob Agents Chemother . 2000 Apr;44(4):1062-6.

[3]. Antimicrob Chemother . 2005 Mar;55(3):283-8.

[4]. Antimicrob Agents Chemother . 2001 Mar;45(3):845-51.

[5]. Antimicrob Agents Chemother . 2004 Jan;48(1):63-8.

Daptomycin is a polypeptide comprising N-decanoyltryptophan, asparagine, aspartic acid, threonine, glycine, ornithine, aspartic acid, D-alanine, aspartic acid, glycine, D-serine, threo-3-methylglutamic acid and 3-anthraniloylalanine (also known as kynurinine) coupled in sequence and lactonised by condensation of the carboxylic acid group of the 3-anthraniloylalanine with the alcohol group of the threonine residue. It has a role as an antibacterial drug, a bacterial metabolite and a member of calcium-dependent antibiotics. It is a lipopeptide, a macrolide, a heterodetic cyclic peptide, a macrocycle and a lipopeptide antibiotic.
Daptomycin is a cyclic lipopeptide antibacterial agent with a broad spectrum of activity against Gram-positive bacteria, including methicillin-susceptible and -resistant Staphylococcus aureus (MSSA/MRSA) and vancomycin-resistant Enterococci (VRE). Chemically, daptomycin comprises 13 amino acids, including several non-standard and D-amino acids, with the C-terminal 10 amino acids forming an ester-linked ring and the N-terminal tryptophan covalently bonded to decanoic acid. Daptomycin was first discovered in the early 1980s by researchers at Eli Lilly in soil samples from Mount Ararat in Turkey. Early work on developing daptomycin was abandoned due to observed myopathy but was resumed in 1997 when Cubist Pharmaceuticals Inc. licensed daptomycin; it was found that a once-daily dosing scheme reduced side effects while retaining efficacy. Daptomycin was approved by the FDA on September 12, 2003, and is marketed under the name CUBICIN® by Cubist Pharmaceuticals LLC (Merck & Co.).
Daptomycin is an intravenously administered, broad spectrum antibiotic used to treat complex skin and tissue infections, endocarditis and bacteremia. Daptomycin is associated with a low to modest rate of serum enzyme elevations during therapy, but is a very rare cause of clinically apparent liver injury.
Cubicin has been reported in Streptomyces filamentosus with data available.
Daptomycin is a semi-synthetic cyclic lipopeptide antibiotic isolated form the bacterium Streptomyces roseosporus with broad-spectrum antibiotic activity against Gram-positive bacteria. Daptomycin has a distinct mechanism of action, in which it binds to bacterial membrane and causes rapid depolarization of the cell membrane due to calcium-dependant potassium efflux; the loss of membrane potential leads to inhibition of DNA, RNA and protein synthesis, resulting in bacterial cell death. This agent does not penetrate the outer membrane of gram-negative bacteria.
A cyclic lipopeptide antibiotic that inhibits GRAM-POSITIVE BACTERIA.
See also: Daptomycin (annotation moved to).

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Drug Indication
Daptomycin is indicated for the treatment of complicated skin and skin structure infections (cSSSI) in patients one year of age and older. It is also indicated for the treatment of _Staphylococcus aureus_ bloodstream infections (bacteremia) in patients one year of age and older, including in adult patients with right-sided infective endocarditis. Daptomycin is not indicated for the treatment of pneumonia or left-sided infective endocarditis due to _S. aureus_. Use is not recommended in pediatric patients younger than one year of age due to the risk of potential effects on muscular, neuromuscular, and/or nervous systems (either peripheral and/or central). As with all antibacterial drugs, it is strongly suggested to perform sufficient testing before treatment initiation in order to confirm an infection caused by susceptible bacteria. Failure to do so may result in suboptimal treatment, treatment failure, and the development of drug-resistant bacteria.
FDA Label
Cubicin is indicated for the treatment of the following infections. Adult and paediatric (1 to 17 years of age) patients with complicated skin and soft-tissue infections (cSSTI). Adult patients with right-sided infective endocarditis (RIE) due to Staphylococcus aureus. It is recommended that the decision to use daptomycin should take into account the antibacterial susceptibility of the organism and should be based on expert advice. Adult and paediatric (1 to 17 years of age) patients with Staphylococcus aureus bacteraemia (SAB). In adults, use in bacteraemia should be associated with RIE or with cSSTI, while in paediatric patients, use in bacteraemia should be associated with cSSTI. Daptomycin is active against Gram positive bacteria only. In mixed infections where Gram negative and/or certain types of anaerobic bacteria are suspected, Cubicin should be co-administered with appropriate antibacterial agent(s). Consideration should be given to official guidance on the appropriate use of antibacterial agents.
Daptomycin is indicated for the treatment of the following infections. Adult and paediatric (1 to 17 years of age) patients with complicated skin and soft-tissue infections (cSSTI). Adult patients with right-sided infective endocarditis (RIE) due to Staphylococcus aureus. It isrecommended that the decision to use daptomycin should take into account the antibacterial susceptibility of the organism and should be based on expert advice. Adult and paediatric (1 to 17 years of age) patients with Staphylococcus aureus bacteraemia (SAB). In adults, use in bacteraemia should be associated with RIE or with cSSTI, while in paediatric patients, use in bacteraemia should be associated with cSSTI. Daptomycin is active against Gram positive bacteria only. In mixed infections where Gram negative and/or certain types of anaerobic bacteria are suspected, daptomycin should be co-administered with appropriate antibacterial agent(s). Consideration should be given to official guidance on the appropriate use of antibacterial agents.

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Mechanism of Action
The mechanism of action of daptomycin remains poorly understood. Studies have suggested a direct inhibition of cell membrane/cell wall constituent biosynthesis, including peptidoglycan, uridine diphosphate-N-acid, acetyl-L-alanine, and lipoteichoic acid (LTA). However, no convincing evidence has been presented for any of these models, and an effect on LTA biosynthesis has been ruled out by other studies in _S. aureus_ and _E. faecalis_. It is well understood that free daptomycin (apo-daptomycin) is a trianion at physiological pH, which binds Ca²⁺ in a 1:1 stoichiometric ratio to become a monoanion, which is thought to rely primarily on the Asp(7), Asp(9), and L-3MeGlu12 residues that form a DXDG motif. Calcium-binding facilitates daptomycin's insertion into bacterial membranes preferentially due to their high content of the acidic phospholipids phosphatidylglycerol (PG) and cardiolipin (CL), wherein it is proposed that daptomycin can bind two calcium equivalents and form oligomers. PG is recognized as the main membrane requirement for daptomycin activity; daptomycin preferentially localizes in PG-rich membrane domains, and mutations affecting PG prevalence are linked to daptomycin resistance. Calcium-dependent membrane binding is the generally accepted mechanism of action for daptomycin, but the precise downstream effects are unclear, and numerous models have been proposed. One mechanism proposes that the daptomycin membrane binding alters membrane fluidity, causing dissociation of cell wall biosynthetic enzymes such as the lipid II synthase MurG and the phospholipid synthase PlsX. This is consistent with the observed effects of daptomycin on cell shape in various bacteria at concentrations at or above the minimum inhibitory concentration (MIC). Aberrant cell morphology is also consistent with the observed localization of daptomycin at the division septa and a hypothesized role in inhibiting cell division. A recent study suggested the formation of tripartite complexes containing calcium-bound daptomycin, PG, and various undecaprenyl-coupled cell envelope precursors, which subsequently include lipid II. This complex is proposed to inhibit cell division, lead to the dispersion of cell wall biosynthetic machinery, and eventually cause lysis of the membrane bilayer at the septum causing cell death. Another popular model is based on early observations that daptomycin, in a calcium-dependent manner, caused potassium ion leakage and loss of membrane potential in treated bacterial cells. Although this lead some to suggest that daptomycin could bind PG to form oligomeric pores in the bacterial membrane, no cell lysis was observed in _S. aureus_ or _E. faecalis_, and the daptomycin-induced ion conduction is inconsistent with pore formation. Rather, it has been proposed that daptomycin forms calcium-dependent dimeric complexes in fixed ratios of Dap₂Ca₃PG₂, which can act as transient ionophores. The observed loss of membrane potential is suggested to result in a non-specific loss of gradient-dependent nutrient transport, ATP production, and biosynthesis, leading to cell death. Notably, these models are not strictly mutually exclusive and are supported to varying extents by observed resistance mutations. The strict requirement for PG for daptomycin bactericidal action is supported by mutations in _mprF_, _cls2_, _pgsA_, and the _dlt_ operon in _S. aureus_, _cls_ in various enterococci, and _pgsA_, PG synthase, and the _dlt_ operon in _E. faecium_, all of which alter the bacterial membrane composition and specifically the PG content of bacterial membranes. Other noted mutations in various regulatory systems that control membrane homeostasis also support the cell membrane as the site of daptomycin action. Curiously, in _E. faecalis_, the most commonly observed form of daptomycin resistance is characterized by abnormal division septa, which supports the cell division-based mechanism of daptomycin action.

C72H101N17O26

1620.67

1619.71

C, 53.36; H, 6.28; N, 14.69; O, 25.67

103060-53-3

16134395

Off-white to light yellow solid powder

1.5±0.1 g/cm3

2078.2±65.0 °C at 760 mmHg

202-204?C

1210.7±34.3 °C

0.0±0.3 mmHg at 25°C

1.638

-4.07

22

28

35

115

3480

13

O1C(C([H])(C([H])([H])C(C2=C([H])C([H])=C([H])C([H])=C2N([H])[H])=O)N([H])C(C([H])(C([H])(C([H])([H])[H])C([H])([H])C(=O)O[H])N([H])C(C([H])(C([H])([H])O[H])N([H])C(C([H])([H])N([H])C(C([H])(C([H])([H])C(=O)O[H])N([H])C(C([H])(C([H])([H])[H])N([H])C(C([H])(C([H])([H])C(=O)O[H])N([H])C(C([H])(C([H])([H])C([H])([H])C([H])([H])N([H])[H])N([H])C(C([H])([H])N([H])C(C([H])(C1([H])C([H])([H])[H])N([H])C(C([H])(C([H])([H])C(=O)O[H])N([H])C(C([H])(C([H])([H])C(N([H])[H])=O)N([H])C(C([H])(C([H])([H])C1=C([H])N([H])C2=C([H])C([H])=C([H])C([H])=C12)N([H])C(C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H])=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O)=O

OAKLVKFURWEDJ-RWDRXURGSA-N

InChI=1S/C72H101N17O26/c1-5-6-7-8-9-10-11-22-53(93)81-44(25-38-31-76-42-20-15-13-17-39(38)42)66(108)84-45(27-52(75)92)67(109)86-48(30-59(102)103)68(110)89-61-37(4)115-72(114)49(26-51(91)40-18-12-14-19-41(40)74)87-71(113)60(35(2)24-56(96)97)88-69(111)50(34-90)82-55(95)32-77-63(105)46(28-57(98)99)83-62(104)36(3)79-65(107)47(29-58(100)101)85-64(106)43(21-16-23-73)80-54(94)33-78-70(61)112/h12-15,17-20,31,35-37,43-50,60-61,76,90H,5-11,16,21-30,32-34,73-74H2,1-4H3,(H2,75,92)(H,77,105)(H,78,112)(H,79,107)(H,80,94)(H,81,93)(H,82,95)(H,83,104)(H,84,108)(H,85,106)(H,86,109)(H,87,113)(H,88,111)(H,89,110)(H,96,97)(H,98,99)(H,100,101)(H,102,103)/t35-,36-,37-,43+,44+,45+,46+,47+,48+,49+,50-,60+,61+/m1/s1

(3S)-3-[[(2S)-4-amino-2-[[(2S)-2-(decanoylamino)-3-(1H-indol-3-yl)propanoyl]amino]-4-oxobutanoyl]amino]-4-[[(3S,6S,9R,15S,18R,21S,24S,30S,31R)-3-[2-(2-aminophenyl)-2-oxoethyl]-24-(3-aminopropyl)-15,21-bis(carboxymethyl)-6-[(2R)-1-carboxypropan-2-yl]-9-(hydroxymethyl)-18,31-dimethyl-2,5,8,11,14,17,20,23,26,29-decaoxo-1-oxa-4,7,10,13,16,19,22,25,28-nonazacyclohentriacont-30-yl]amino]-4-oxobutanoic acid

LY146032; LY 146032; Daptomycin; Cidecin; LY-146032; LY146032; trade name: Cubicin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.08 mg/mL (1.28 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (1.28 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (1.28 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 100 mg/mL (61.70 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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 (Please use freshly prepared in vivo formulations for optimal results.)