Lefamulin (formerly also known as BC-3781; Xenleta) is a semi-synthetic, oral pleuromutilin antibiotic approved to treat adults with community-acquired bacterial pneumonia. It potently inhibits the synthesis of bacterial protein, which is required for bacteria to grow. Lefamulin acts by binding to the peptidyl transferase center, or PTC, on the bacterial ribosome in such a way that it interferes with the interaction of protein production at two key sites known as the 'A' site and the 'P' site, resulting in the inhibition of bacterial proteins and the cessation of bacterial growth. Lefamulin's binding occurs with high affinity, high specificity and at molecular sites that are different than other antibiotic classes. Lefamulin exhibited MIC50 and MIC90 values of 0.12 and 0.25 μg/ml, respectively, against the entire collection (n = 822). Similar results were obtained for lefamulin against each of the most common serotypes as well as against multidrug-resistant isolates and strains that are nonsusceptible to ceftriaxone or erythromycin. Lefamulin may be useful for the treatment of community-acquired respiratory tract infections.

Physicochemical Properties

Molecular Formula	C28H45NO5S
Molecular Weight	507.725607633591
Exact Mass	507.302
Elemental Analysis	C, 66.24; H, 8.93; N, 2.76; O, 15.76; S, 6.31
CAS #	1061337-51-6
Related CAS #	Lefamulin acetate;1350636-82-6
PubChem CID	25185057
Appearance	Solid powder
LogP	4.567
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	7
Rotatable Bond Count	6
Heavy Atom Count	35
Complexity	851
Defined Atom Stereocenter Count	11
SMILES	S([C@@H]1CC[C@H](C[C@H]1O)N)CC(=O)O[C@@H]1C[C@](C=C)(C)[C@H]([C@H](C)[C@]23CCC([C@H]2[C@@]1(C)[C@H](C)CC3)=O)O
InChi Key	KPVIXBKIJXZQJX-FCEONZPQSA-N
InChi Code	InChI=1S/C28H45NO5S/c1-6-26(4)14-22(34-23(32)15-35-21-8-7-18(29)13-20(21)31)27(5)16(2)9-11-28(17(3)25(26)33)12-10-19(30)24(27)28/h6,16-18,20-22,24-25,31,33H,1,7-15,29H2,2-5H3/t16-,17+,18-,20-,21-,22-,24+,25+,26-,27+,28+/m1/s1
Chemical Name	(3aR,4R,5R,7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propanocyclopenta[8]annulen-5-yl 2-(((1R,2R,4R)-4-amino-2-hydroxycyclohexyl)thio)acetate
Synonyms	BC-3781; BC 3781; BC3781
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	Lefamulin (0–1 mg/L) inhibits the growth of N. gonorrhoeae, M. genitalium, and C. trachomatis[2]. With MIC values of less than 0.008 μg/mL, lefamulin exhibits strong activity against every strain of M. pneumoniae[3].
ln Vivo	Lefamulin (10–140 mg/kg, s.c.) reduces inflammation in a mouse model of lung neutrophilia caused by lipopolysaccharide (LPS)[4]. In mice with lung infections caused by S. pneumoniae or S. aureus, lefamulin (1.25-160 mg/kg, s.c.) exhibits antibacterial activity[5].
Cell Assay	Cell Line: C. trachomatis, N. gonorrhoeae, and M. genitalium Concentration: 0-1 mg/L Incubation Time: Result: MIC50s of 0.02 mg/L, 0.063 mg/L, and 0.12 mg/L, respectively, were used to inhibit bacterial activity.
Animal Protocol	Animal Model: LPS-induced lung neutrophilia mouse model[4] Dosage: 10-140 mg/kg Administration: Subcutaneous injection (s.c.) Result: decreased numbers of BALF neutrophil cells. Diminished levels of MMP-9, chemokines (CXCL-1, CXCL-2, and CCL-2) and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β, and GM-CSF) in mouse lung tissue.
Toxicity/Toxicokinetics	Effects During Pregnancy and Lactation ◉ Summary of Use during Lactation No information is available on the use of lefamulin during breastfeeding. The manufacturer recommends that mothers should avoid breastfeeding during treatment and for 2 days after the final dose. An alternate drug may be preferred, especially while nursing a newborn or preterm infant. ◉ Effects in Breastfed Infants Relevant published information was not found as of the revision date. ◉ Effects on Lactation and Breastmilk Relevant published information was not found as of the revision date.
References	[1]. Lefamulin: Review of a Promising Novel Pleuromutilin Antibiotic. Pharmacotherapy. 2018 Sep;38(9):935-946. doi: 10.1002/phar.2166. Epub 2018 Aug 20. [2]. Antimicrob Agents Chemother. 2018 Apr 26;62(5):e02380-17. [3]. In Vitro Activities of Lefamulin and Other Antimicrobial Agents against Macrolide-Susceptible and Macrolide-Resistant Mycoplasma pneumoniae from the United States, Europe, and China. Antimicrob Agents Chemother. 2017 Jan 24;61(2):e02008-16. [4]. Anti-inflammatory activity of lefamulin versus azithromycin and dexamethasone in vivo and in vitro in a lipopolysaccharide-induced lung neutrophilia mouse model. PLoS One. 2021 Sep 29;16(9):e0237659. [5]. Pharmacokinetics/pharmacodynamics of lefamulin in a neutropenic murine pneumonia model with Staphylococcus aureus and Streptococcus pneumonia. J Antimicrob Chemother. 2019 Apr 1;74(Suppl 3)
Additional Infomation	See also: Lefamulin (annotation moved to). Drug Indication Xenleta is indicated for the treatment of community-acquired pneumonia (CAP) in adults when it is considered inappropriate to use antibacterial agents that are commonly recommended for the initial treatment of CAP or when these have failed. Consideration should be given to official guidance on the appropriate use of antibacterial agents.

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *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. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	1.9696 mL	9.8478 mL	19.6955 mL
	5 mM	0.3939 mL	1.9696 mL	3.9391 mL
	10 mM	0.1970 mL	0.9848 mL	1.9696 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.