Pertinent Information

Classification. Ester.
Chemical formula. (Diethylamino)ethyl 4-aminobenzoate hydrochloride.

Prepared by. Alfred Einhorn, 1904–5.
Potency. 1 (procaine = 1)
Toxicity. 1 (procaine = 1)
Metabolism. Hydrolyzed rapidly in plasma by plasma pseudocholinesterase.
Excretion. More than 2% unchanged in the urine (90% as
p-aminobenzoic acid, 8% as diethylaminoethanol).
Vasodilating properties. Produces the greatest degree of vasodilation of all currently used local anesthetics.
pKa. 8.9.a
pH of plain solution. 5.0 to 6.5.
pH of vasoconstrictor-containing solution. 3.5 to 5.5.
Onset of action. 6 to 10 minutes.
Effective dental concentration. 2% to 4%.
Anesthetic half-life. 6 minutes.
Topical anesthetic action. Not in clinically acceptable concentrations.
Comments. Procaine hydrochloride, the first synthetic injectable local anesthetic, is no longer available in North
America in dental cartridges. However, its proprietary name, Novocain, is synonymous, throughout the world, with dental local anesthesia. Until 1996 procaine was available in dental cartridges in combination with another ester anesthetic, propoxycaine.

Local anesthetic

Procaine hydrochloride is a topical anesthetic, which can block the nerve fiber conduction temporarilyand has a narcotic effect,strong effect, low toxicity, and non-addictive, but on the skin, mucosal penetration is weak, unsuitable for surface anesthesia, patients are used for infiltration, conduction and spinal anesthesia. White fine needle crystal or crystalline powder at room temperature, no smell, taste slightly bitter and Ma, soluble in water, soluble in ethanol, slightly soluble in chloroform, almost insoluble in ether. Procaine hydrochloride ester bond structure can be hydrolyzed to produce amino acid and diethylaminoethanol, under certain conditions, the amino acid may be further decarboxylated toxic aniline.

The structure of procaine hydrochloride with aromatic primary amino, easy oxidation discoloration pH, temperature, UV, oxygen and metal ions can accelerate the oxidation discoloration. The aqueous solution was stable in pH3.0~5. So preparation of procaine hydrochloride injection, it generally takes add acid to regulate pH 3.3 to 5.5, and strictly control the sterilization temperature and time. to 100 ℃ steam sterilization 30min circulation is appropriate, and should pay attention to shading, sealed save.

The product structure of aromatic primary amino group in dilute hydrochloric acid can generate diazonium salt with sodium nitrite, coupling reaction occurs when add alkaline β-naphthol, generating azo compounds scarlet.

Used as the sole local anesthetic agent for pain control in dentistry, as it was from its introduction in 1904 until the introduction of the amide local anesthetic lidocaine in the late 1940s, 2% procaine (plain) provided essentially no pulpal anesthesia and from 15 to 30 minutes of soft tissue anesthesia. This is a result of its profound vasodilating properties. Procaine produces the greatest vasodilatory effect of all clinically used local anesthetics. Thus a clean (e.g., bloodless) surgical field is more difficult to maintain with procaine because of increased bleeding.