The lethal dose (LD50) of chloroprocaine hydrochloride in mice is 950 mg/kg for subcutaneous injection and 97 mg/kg for intravenous injection[2].

Absorption, Distribution and Excretion
Due to its low risk of systemic toxicity, chloroprocaine has a rapid onset of action, typically within 6 to 12 minutes. The duration of anesthesia induced by chloroprocaine can reach 60 minutes. The absorption rate of local anesthetics depends on the total dose and concentration of chloroprocaine, as well as the route of administration, vascular distribution at the administration site, and the presence of epinephrine in the anesthetic injection solution. The presence of epinephrine reduces the absorption rate and plasma concentration of local anesthetics. Systemic exposure to chloroprocaine following local ocular administration has not been evaluated. Like most local anesthetics and their metabolites, chloroprocaine is primarily excreted via the kidneys. Urinary excretion of chloroprocaine may be affected by urinary perfusion and factors influencing urinary pH. Procaine is readily absorbed after parenteral administration… and does not remain at the injection site for an extended period. ...Upon absorption, procaine is rapidly hydrolyzed.../Procaine/
...The anesthetic binds to proteins in serum and tissues, reducing the concentration of the free drug in systemic circulation, thereby reducing toxicity. .../Ester-based local anesthetics/ are primarily hydrolyzed and inactivated by plasma esterases (possibly plasma cholinesterase). The liver also participates in the hydrolysis of local anesthetics. Local Anesthetics
Chloroprocaine has lower systemic toxicity than all other local anesthetics because it is rapidly hydrolyzed by plasma cholinesterase, thus shortening its plasma half-life.
The enzymatic hydrolysis products of procaine are para-aminobenzoic acid and diethylaminoethanol. Approximately 80% of the former is excreted in the urine, either unchanged or in conjugated form. Only 30% of diethylaminoethanol is recovered from the urine; the remainder is metabolically degraded.../Procaine/
For more complete data on the absorption, distribution, and excretion of chloroprocaine (9 types), please visit the HSDB record page.

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Metabolism/Metabolites
In plasma, chloroprocaine is rapidly metabolized by pseudocholinesterases, a class of enzymes that hydrolyze ester bonds. In ocular tissue, chloroprocaine is metabolized by nonspecific esterases. Chloroprocaine is hydrolyzed to β-diethylaminoethanol and 2-chloro-4-aminobenzoic acid, the latter of which can inhibit the effects of sulfonamides. 2-Diethylaminoethyl 4-amino-2-chlorobenzoate is converted to 4-amino-2-chlorobenzoic acid in guinea pigs. LIVETT, BH & RM LEE, BIOCHEM PHARMAC 17, 385 (1968). /Excerpt from Table/
Primarily hydrolyzed by plasma pseudocholinesterases, but also by hepatic esterases, to produce diethylaminoethanol and 2-chloro-4-aminobenzoic acid. /Human, parenteral administration. Animal studies have shown that some local anesthetics may be excreted via bile circulation. //Chloroprocaine Hydrochloride/
Chloroprocaine is rapidly metabolized in plasma via the hydrolysis of ester bonds by pseudocholinesterase.
Excretion pathway: Chloroprocaine is rapidly metabolized in plasma via the hydrolysis of ester bonds by pseudocholinesterase. Urinary excretion is affected by urine perfusion and factors influencing urine pH.
Half-life: 21 ± 2 seconds

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Biological half-life
In adults, the mean in vitro plasma half-life of chloroprocaine is 21 seconds for males and 25 seconds for females. In newborns, the mean in vitro plasma half-life is 43 seconds. Following epidural anesthesia during labor, the apparent in vivo half-life of chloroprocaine detected in maternal plasma is 3.1 minutes (range 1.5 to 6.4 minutes).
...The plasma half-life is approximately 25 seconds.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Currently, there is no information regarding the use of chloroprocaine during lactation. Given the low excretion of other local anesthetics in breast milk and the extremely short half-life of chloroprocaine, adverse effects on breastfed infants are unlikely. However, especially in breastfed newborns or premature infants, other medications may be preferred.
◉ Effects on Breastfed Infants
As of the revision date, no relevant published information was found.
◉ Effects on Lactation and Breast Milk
As of the revision date, no relevant published information was found.

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Protein Binding
Compared to other clinically used local anesthetics, chloroprocaine has the lowest protein binding rate.

[1]. Inhibition of the Na,K-ATPase of Canine Renal Medulla by Several Local Anesthetics. Pharmacol Res. 2001 Apr;43(4):399-403.

[2]. Chloroprocaine HCl Injection.

Chloroprocaine is a derivative of procaine, in which a hydrogen atom adjacent to the carboxylic acid group is replaced by a chlorine atom. It is used as a local anesthetic in the form of its hydrochloride salt, particularly suitable for oral surgery. Compared to lidocaine, its advantage lies in its ability to constrict blood vessels, thereby reducing bleeding. It has a dual effect of local anesthesia, peripheral analgesia, and central nervous system depression. It is a benzoic acid ester, belonging to the monochlorobenzene class of compounds. Its structure is related to 2-diethylaminoethanol and 4-amino-2-chlorobenzoic acid. Chloroprocaine is an ester-based local anesthetic, usually used in its salt form—chloroprocaine hydrochloride. Similar to other local anesthetics, it increases the electrical excitation threshold of nerves by slowing nerve impulse conduction and reducing the rate of rise of action potentials. The pharmacological characteristics of chloroprocaine are rapid onset and short duration of action, similar to lidocaine. Chloroprocaine is available by injection, in formulations containing and without methylparaben as preservatives. Both can be administered intrathecally for peripheral and central nerve blocks, but only preservative-free formulations are suitable for lumbar and coccygeal epidural blocks. In September 2022, the U.S. Food and Drug Administration (FDA) approved chloroprocaine for local anesthesia of the eye. Chloroprocaine is an ester-based local anesthetic. Its physiological action is achieved through local anesthesia. Chloroprocaine hydrochloride is a local anesthetic that can be administered by injection for use during surgery and childbirth. Like other local anesthetics, chloroprocaine blocks the generation and conduction of nerve impulses by increasing the nerve's electrical excitation threshold, slowing the conduction velocity of nerve impulses, and reducing the rate of action potential rise. See also: Chloroprocaine hydrochloride (salt form). Drug Indications Intrathecal administration of chloroprocaine is indicated for subarachnoid block (spinal anesthesia) in adults. It is also suitable for infiltration anesthesia, peripheral and central nervous system blocks, and preservative-free formulations can be used for lumbar and coccygeal epidural blocks. Local chloroprocaine is suitable for ocular surface anesthesia.

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Mechanism of Action
Chloroprocaine primarily works by binding to the α subunit of the cytoplasmic region of voltage-gated sodium channels, inhibiting the influx of sodium ions onto the neuronal cell membrane. This reduces the permeability of the nerve membrane to sodium ions and slows the rate of action potential rise. Therefore, chloroprocaine inhibits signal transduction, leading to reversible nerve conduction block. The progression of anesthesia depends on the diameter of the nerve fiber, the degree of myelination, and the conduction velocity. The order of loss of nerve function is as follows: 1) pain, 2) temperature, 3) touch, 4) proprioception, 5) skeletal muscle tone.
Local anesthetics prevent the generation and conduction of nerve impulses. Their primary site of action is the cell membrane. Local anesthetics block conduction by reducing or preventing a transient, significant increase in the permeability of excitatory membranes to Na+, usually caused by slight membrane depolarization. As the anesthetic's effect on the nerve gradually intensifies, the electrical excitation threshold gradually rises, the rate of action potential rise decreases, impulse conduction speed slows, and the conduction safety factor decreases; these factors reduce the probability of action potential propagation, ultimately leading to nerve conduction failure. Local anesthetics can also block K+ channels. Due to the blockage of K+ channels, conduction blockade does not cause any significant or sustained change in the resting membrane potential. The site of action of local anesthetics, at least in the charged state, can only enter from the inner surface of the membrane. When applied topically, local anesthetics must first penetrate the cell membrane to exert their blocking effect. /Local Anesthetics/
…/Two possibilities:/By increasing the surface pressure of the lipid layer that makes up the nerve membrane…closing the pores through which ions pass. …/Or:/By increasing the degree of disturbance of the cell membrane, affecting its permeability. Local anesthetics…The acidic salts in the drug must be neutralized in the tissue to release free amines before the drug can penetrate the tissue and produce an anesthetic effect. The active molecules in nerve fibers are in the form of cations. Cations bind to certain receptors on the membrane, thereby preventing the generation of action potentials. Local anesthetics…Studies have shown that procaine…can reduce the release of acetylcholine at motor nerve endings. Procaine/

C13H19CLN2O2

270.7549

306.09

133-16-4

Chloroprocaine hydrochloride;3858-89-7

8612

Typically exists as solid at room temperature

1.17g/cm3

402.6ºC at 760mmHg

173-174ºC

197.3ºC

1.08E-06mmHg at 25°C

1.553

3.804

1

4

7

18

259

0

CCN(CC)CCOC(=O)C1=CC=C(C=C1)NCl

VDANGULDQQJODZ-UHFFFAOYSA-N

InChI=1S/C13H19ClN2O2/c1-3-16(4-2)7-8-18-13(17)11-6-5-10(15)9-12(11)14/h5-6,9H,3-4,7-8,15H2,1-2H3

2-(diethylamino)ethyl 4-amino-2-chlorobenzoate

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.)