Absorption, Distribution and Excretion
Following intramuscular injection, the drug dissolves slowly at the injection site, reaching a plateau in plasma concentration approximately 4 hours later, followed by a slow decline over the next 15 to 20 hours. The drug is primarily eliminated rapidly by the kidneys, with 90% cleared via renal tubular secretion. Approximately 60% to 90% of the injectable penicillin G dose is excreted in the urine within 24 to 36 hours. The drug is distributed throughout the body in varying amounts, with less distribution in the cerebrospinal fluid. The highest concentrations are found in the kidneys, with lower concentrations in the liver, skin, and intestines. Due to its low solubility, its serum concentrations are lower compared to other injectable penicillins, but its duration of action is longer. Metabolism/Metabolites Procaine is rapidly hydrolyzed by plasma esterases into non-toxic metabolites. Biological Half-Life The plasma half-life of intramuscularly administered benzylpenicillin is 30 minutes.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited information suggests that the concentration of penicillin G in breast milk is low and is not expected to have adverse effects on breastfed infants. There are reports that penicillin-type drugs occasionally disrupt the infant's gut microbiota, leading to diarrhea or thrush, but these effects have not been fully assessed. Procaine penicillin G can be used in breastfeeding women. ◉ Effects on Breastfed Infants
A one-month-old breastfed infant with congenital syphilis developed a Herxheimer reaction 6 hours after his mother received an intramuscular injection of 2.4 million units of benzathine penicillin G. However, the infant also received 10 units of penicillin G concurrently with the mother's injection. This reaction was likely caused by penicillin in the breast milk. ◉ Effects on Lactation and Breast Milk
No relevant published information was found as of the revision date.
Protein Binding
Approximately 60% of penicillin G binds to serum proteins.

[1]. Efficacy of intramammary treatment with procaine penicillin G vs. procaine penicillin G plus neomycin in bovine clinical mastitis caused by penicillin-susceptible, gram-positive bacteria--a double blind field study. J Vet Pharmacol Ther. 2003 Jun;26(3):193-8.

Procaine benzylpenicillin (INN), also known as procaine G penicillin, is an injectable antibiotic. It is a poorly soluble salt form of penicillin, composed of an equimolar amount of natural benzylpenicillin (penicillin G) and the local anesthetic procaine. Procaine benzylpenicillin is administered via deep intramuscular injection. It is slowly absorbed and hydrolyzed to benzylpenicillin. This drug is suitable for situations requiring prolonged treatment with low concentrations of benzylpenicillin. This compound preparation is designed to reduce the pain and discomfort caused by high-dose intramuscular injections of penicillin. It is widely used in veterinary medicine. Benzylpenicillin is effective against a variety of microorganisms and is the drug of choice for many infections. Procaine penicillin G is the procaine form of penicillin G, a broad-spectrum β-lactam naturally occurring penicillin antibiotic with antibacterial activity. Penicillin G binds to and inactivates penicillin-binding proteins (PBPs) located within the bacterial cell wall. The inactivation of PBPs interferes with the cross-linking of peptidoglycan chains, which is crucial for the strength and rigidity of the bacterial cell wall. This interrupts bacterial cell wall synthesis, leading to weakening of the bacterial cell wall and ultimately cell lysis. Procaine penicillin G is a semi-synthetic antibiotic formed by the combination of penicillin G and procaine. See also: procaine (active moiety); penicillin G (active moiety); benzathine penicillin G. Penicillin G procaine (ingredients)...see more...

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Drug Indications
Used to treat a variety of bacterial infections, such as syphilis, anthrax, oral infections, pneumonia, and diphtheria.
FDA Label

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Mechanism of Action
Procaine benzathine penicillin is released from the injection site and hydrolyzes to penicillin G. Penicillin G binds to penicillin-binding proteins on the bacterial cell wall, inhibiting transpeptidase, an enzyme that cross-links peptide chains attached to a peptidoglycan backbone. The final bactericidal process involves the inactivation of autolysin inhibitors in the cell wall, leading to bacterial lysis.

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Pharmacodynamics
It is an antibiotic with bactericidal activity against penicillin-sensitive microorganisms. Like all penicillin drugs, procaine benzylpenicillin interferes with the synthesis of peptidoglycan in bacterial cell walls. It works by inhibiting the biosynthesis of peptidoglycan in the cell wall, making the cell wall osmotic pressure unstable. It belongs to the penicillin and β-lactam antibiotic class.

C29H38N4O6S

570.70

570.251

54-35-3

Penicillin G procaine hydrate;6130-64-9

5903

Typically exists as solid at room temperature

1.1335 (rough estimate)

663.3ºC at 760 mmHg

129-130 °C(lit.)

355ºC

1.6000 (estimate)

3.538

3

9

11

40

752

3

CCN(CCOC(C1C=CC(N)=CC=1)=O)CC.O=C(N[C@@H]1C(=O)N2[C@H](C(S[C@H]12)(C)C)C(=O)O)CC1C=CC=CC=1

WHRVRSCEWKLAHX-LQDWTQKMSA-N

InChI=1S/C16H18N2O4S.C13H20N2O2/c1-16(2)12(15(21)22)18-13(20)11(14(18)23-16)17-10(19)8-9-6-4-3-5-7-9;1-3-15(4-2)9-10-17-13(16)11-5-7-12(14)8-6-11/h3-7,11-12,14H,8H2,1-2H3,(H,17,19)(H,21,22);5-8H,3-4,9-10,14H2,1-2H3/t11-,12+,14-;/m1./s1

2-(diethylamino)ethyl 4-aminobenzoate;(2S,5R,6R)-3,3-dimethyl-7-oxo-6-[(2-phenylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid

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)

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

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.

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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).

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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)

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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).

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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

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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.

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