Products
Local anesthetics are commercially available as injectables, in the form of creams, ointments, gels, plasters, lozenges, throat sprays, and gargle solutions, among others (selection). The first active ingredient from this group was cocaine, used in the 19th century by Carl Koller and Sigmund Freud; see also Sigmund Freud and cocaine. Local anesthetics are also combined with vasoconstrictors such as epinephrine. What is special about cocaine is that it itself also has vasoconstrictor properties.
Structure and properties
Local anesthetics were originally derived from cocaine. They usually consist of a lipophilic aromatic ring, an ester or amide linker, and an amine.
Effects
Local anesthetics (ATC N01B) have local anesthetic (local anesthetic), antipruritic, and antiarrhythmic properties. They inhibit the influx of sodium ions into nerve cells via voltage-gated sodium channels, thereby inhibiting depolarization and conduction along nerve fibers. As a result, the tissue becomes insensitive to pain. Furthermore, sensory and motor functions are also inhibited in a concentration-dependent manner. The active substances bind to the channel from within the cell and must therefore first cross the cell membrane. In the process, only the uncharged portion passes the membrane (amino group). The various local anesthetics differ in their physicochemical properties (e.g., lipophilicity), potency, onset and duration of action. In general, lipophilicity correlates with potency and duration of action.
Indications
Indications for use include:
- For anesthesia, for example, in the context of surgical, dental and diagnostic procedures.
- For the treatment of pain of various causes, for example, nerve pain, sore throat, for itching and sunburn.
- For the treatment of cardiac arrhythmias.
Dosage
According to the professional information. Local anesthetics must not be administered intravascularly (into blood vessels), because otherwise the sodium channels of the cardiovascular system and the central nervous system will be inhibited. In the worst case, this can lead to convulsions, coma, respiratory arrest, cardiac arrest, and death.
Active Ingredients
Ester-type local anesthetics:
- Benzocaine
- Chloroprocaine
- Cocaine
- Oxybuprocaine
- Proxymetacaine
- Procaine
- Tetracaine
Amide-type local anesthetics:
- Articaine
- Bupivacaine
- Cinchocaine
- Flecainide
- Levobupivacaine
- Lidocaine, lidocaine patches
- Mepivacaine
- Oxetacaine
- Prilocaine
- Quinisocaine
- Ropivacaine
See also under local anesthetic eye drops, e.g., oxybuprocaine eye drops.
Contraindications
For complete precautions, see the drug label.
Adverse effects
The most common potential adverse effects associated with parenteral administration include:
- Local reactions at the injection site
- Paresthesias (sensory disturbances), dizziness.
- Bradycardia (low heart rate).
- Low blood pressure, hypertension
- Nausea, vomiting
