Procaine hydrochloride
[CAS# 51-05-8]

Identification

• Classification: API >> Anesthetic agents >> Local anesthetics
• Name: Procaine hydrochloride
• Synonyms: 2-(Diethylamino)ethyl 4-aminobenzoate hydrochloride
• Molecular Formula: C₁₃H₂₀N₂O₂.HCl
• Molecular Weight: 272.77
• CAS Registry Number: 51-05-8
• EC Number: 200-077-2
• SMILES: CCN(CC)CCOC(=O)C1=CC=C(C=C1)N.Cl

Properties

• Solubility: 10 mM (DMSO)
• Melting point: 154-158 °C
• Boiling point: 195-196 °C

Safety Data

• Hazard Symbols: GHS06;GHS07;GHS09 Danger
• Risk Statements: H301-H317-H319-H360-H370
• Safety Statements: P203-P260-P261-P264-P264+P265-P270-P272-P280-P301+P316-P302+P352-P305+P351+P338-P308+P316-P318-P321-P330-P333+P317-P337+P317-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	1	H370
Reproductive toxicity	Repr.	1A	H360
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	2	H330
Respiratory sensitization	Resp. Sens.	1	H334
Acute toxicity	Acute Tox.	3	H311
Skin sensitization	Skin Sens.	1B	H317
Specific target organ toxicity - single exposure	STOT SE	3	H335

• Transport Information: UN 2811

Discovery and Applications

Procaine hydrochloride, a local anesthetic, was first synthesized in 1905 by German chemist Alfred Einhorn. In search of a safer alternative to cocaine, the dominant local anesthetic of the time, Einhorn's discovery addressed the addictive nature and severe side effects of cocaine. Marketed as Novocain, procaine hydrochloride quickly gained recognition for its ability to block nerve signals without significant toxicity or addiction risk.

Procaine hydrochloride is a white crystalline powder that is soluble in water. It belongs to the ester group of local anesthetics and works by inhibiting sodium channels in nerve cells, blocking the generation and transmission of pain signals. Its chemical stability and ease of synthesis make it widely used in a variety of formulations.

Procaine hydrochloride is primarily used for local anesthesia in minor surgeries, dental procedures, and wound closure. It provides temporary numbness, allowing patients to undergo surgery without pain. Its relatively rapid onset of action and duration of action sufficient for short surgeries make it ideal for outpatient treatment.

In dentistry, procaine hydrochloride is used to numb specific areas prior to drilling, fillings, or tooth extractions. It significantly reduces patient discomfort, enhances the overall experience, and reduces anxiety associated with dental treatment. Its low toxicity and effectiveness make it a top choice for dental anesthesia.

Procaine has mild anti-inflammatory properties and has been used in neurotherapy formulations to relieve chronic pain and inflammation. Although its effectiveness is less documented, some doctors use it for pain relief in specific medical conditions.

Procaine hydrochloride is also used in diagnostic procedures such as nerve blocks. By temporarily blocking nerve signals, it helps identify the source of chronic pain and assess nerve function, which can aid in the diagnosis and treatment of neuropathic pain disorders.

Procaine hydrochloride is available in a variety of pharmaceutical forms, including injectable solutions, creams, and gels. Injectable formulations are the most common and are used in medical and dental practices. Topical formulations provide local pain relief for minor skin irritations and conditions.

Use of procaine hydrochloride is generally well tolerated. Common side effects include mild irritation at the injection site, dizziness, or allergic reactions in some people. Serious side effects are rare but may include central nervous system effects if the drug is accidentally administered intravascularly. Proper administration technique minimizes such risks.

While procaine hydrochloride is still in use, its popularity has declined with the advent of newer local anesthetics such as lidocaine and bupivacaine. These alternatives offer longer-lasting effects and better safety profiles, especially in more complex or prolonged procedures. However, procaine hydrochloride's historical significance and continued use in certain situations highlight its lasting impact.

References

1991. Salvaging inadequate epidural anaesthetics: “The chloroprocaine save”. Canadian journal of anaesthesia = Journal canadien d'anesthesie, 38(1).
DOI: 10.1007/bf03009177

1979. CYTOTOXIC EFFECTS OF PROCAINE, LIGNOCAINE AND BUPIVACAINE. British Journal of Anaesthesia, 51(4).
DOI: 10.1093/bja/51.4.273

1979. Pharmacokinetic Model for Procaine in Humans during and following Intravenous Infusion. Journal of Pharmaceutical Sciences, 68(8).
DOI: 10.1002/jps.2600680826