procaína

Procaine, also known as procaine hydrochloride in its salt form, is an injectable ester local anesthetic. It was synthesized by the German chemist Alfred Einhorn and introduced in 1905, marketed for many years under the brand name Novocain. While still used in some settings, it has largely been replaced by amide-type anesthetics such as lidocaine in modern practice.

Procaine is an ester-type local anesthetic. Its primary mechanism is reversible blockade of voltage-gated sodium channels on nerve membranes, which inhibits initiation and propagation of nerve impulses and produces localized loss of sensation in the area where it is applied.

Pharmacokinetics and duration: Procaine is rapidly hydrolyzed in plasma by cholinesterases to para-aminobenzoic acid (PABA) and diethylaminoethanol, resulting in a relatively short duration of action. The onset of anesthesia is typically 2–5 minutes. Without vasoconstrictors, the effect lasts about 30–60 minutes; adding vasoconstrictors such as epinephrine can prolong duration and reduce local bleeding.

Clinical use and history: It has been used for infiltration anesthesia and nerve blocks in dental procedures and minor surgery. Due to concerns about ester-related hypersensitivity and the availability of newer agents, procaine has declined in many regions in favor of lidocaine and other amide local anesthetics. It remains in limited use in some markets and formulations.

Safety and adverse effects: Hypersensitivity or allergic reactions to ester-type anesthetics can occur. Systemic toxicity from overdose or rapid absorption may cause CNS stimulation or depression and cardiovascular effects. Procaine should be used with caution in patients with known ester allergies or with significant hepatic, cardiovascular, or other comorbidities.