Absorption, Distribution and Excretion
After intramuscular injection, it dissolves slowly at the site of injection, giving a plateau type of blood level at about 4 hours which falls slowly over a period of the next 15 to 20 hours.
The drug is rapidly and predominantly cleared via renal elimination, with 90% being through tubular secretion. Approximately 60 -90 % of a dose of parenteral penicillin G is excreted in the urine within 24 to 36 hours.
The drug is distributed throughout the body tissues in widely varying amounts and spinal fluid to a lesser degree. Highest levels are found in the kidneys with lesser amounts in the liver, skin, and intestines. It displays low solubility thus results in blood serum levels much lower but more prolonged than other parenteral penicillins.

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Metabolism / Metabolites
Procaine is rapidly hydrolyzed by plasma esterases to nontoxic metabolites.

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Biological Half-Life
Intramuscular injection of benzylpenicillin has a plasma half-life of 30 minutes.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited information indicates penicillin G produces low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush have been reported with penicillins, but these effects have not been adequately evaluated. Procaine penicillin G is acceptable in nursing mothers.
◉ Effects in Breastfed Infants
A breastfed 1-month-old infant with congenital syphilis developed a Herxheimer reaction 6 hours after its mother received 2.4 million units of benzathine penicillin G intramuscularly. However, the baby had also received 10 units of penicillin G at about the same time as the mother's injection. The reaction was possibly caused by penicillin in breastmilk.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Approximately 60% of penicillin G is bound to serum protein.

[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 antiobiotic. It is a poorly soluble salt form of penicillin which is a combination of naturally occuring benzylpenicillin (penicillin G) and the local anaesthetic agent procaine in equimolar amounts. Procaine benzylpenicillin is administered by deep intramuscular injection. It is slowly absorbed and hydrolyzed to benzylpenicillin. This drug is used where prolonged exposure to benzylpenicillin at a low concentration is required. This combination is aimed at reducing the pain and discomfort associated with a large intramuscular injection of penicillin. It is widely used in veterinary settings. Benzylpenicillin is active against a wide range of organisms and is the drug of first choice for many infections.
Penicillin G Procaine is the procaine salt form of penicillin G, a broad-spectrum, beta-lactam, naturally occurring penicillin antibiotic with antibacterial activity. Penicillin G binds to and inactivates the penicillin binding proteins (PBPs) located inside the bacterial cell wall. Inactivation of PBPs interferes with the cross-linkage of peptidoglycan chains necessary for bacterial cell wall strength and rigidity. This interrupts bacterial cell wall synthesis and results in the weakening of the bacterial cell wall, eventually causing cell lysis.
Semisynthetic antibiotic prepared by combining penicillin G with PROCAINE.
See also: Procaine (has active moiety); Penicillin G (has active moiety); Penicillin G Benzathine; Penicillin G Procaine (component of) ... View More ...

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Drug Indication
For the treatment of a number of bacterial infections such as syphilis, anthrax, mouth infections, pneumonia and diphtheria.
FDA Label

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Mechanism of Action
Procaine benzylpenicillin is hydrolyzed into penicillin G once it is released from the injection site. Penicillin G attaches to the penicillin-binding proteins on bacterial cell wall and inhibit the transpeptidation enzyme that crosslinks the peptide chains attached to the backbone of the peptidoglycan. The final bactericidal event involves the inactivation of an inhibitor of autolytic enzymes in the cell wall, leading to lysis of the bacterium.

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Pharmacodynamics
It is an antibiotic against penicillin-susceptible microorganisms with bactericidal effect. Like all penicillins, procaine benzylpenicillin interferes with the synthesis of the bacterial cell wall peptidoglycan. It acts through the inhibition of biosynthesis of cell-wall peptidoglycan, rendering the cell wall osmotically unstable. It is part of the penicillin and beta lactam family of antibacterial drugs.

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.)