b. Administration. Procaine solutions of 0.25 percent to 0.5 percent, often
combined with epinephrine 1:50,000, are used for infiltration anesthesia. For nerve
block, a 1 percent to 2 percent solution is used. To produce spinal anesthesia, a
dosage up to 150 mg may be used; the actual dosage varies with the technique used.
The onset of surgical anesthesia requires 5 to 15 minutes and the duration is 45 to 90
minutes.
c. Untoward Effects. Procaine is one of the least toxic of the injectable local
anesthetics. However, untoward reactions to the drug occur occasionally and may be
manifested as discussed previously. Treatment of reactions has also been discussed in
paragraph 2-39b.
d. Cautions and Contraindications. Care must be taken to have available
facilities for combating overdosage. If symptoms of overdosage appear while the drug
is being given, its administration should be stopped immediately. Procaine should not
be administered to people allergic to it. An intradermal skin test should be administered
to any person suspected of being allergic to the drug. (NOTE: An intradermal skin test
will yield information concerning allergy only. It will not indicate a person's susceptibility
to toxic effects.) The use of procaine is contraindicated during therapy with sulfonamide
drugs because these have an antagonistic effect.
e. Supply. Procaine hydrochloride is supplied in 100 mg and 1 gram quantities
of sterile crystals in ampules and as a parenteral 1percent solution in 2 ml ampules.
2-41. LIDOCAINE HYDROCHLORIDE
a. Actions. Lidocaine hydrochloride (Xylocaine) is a potent local anesthetic
agent which produces a prompt (5 to 15 minutes for the onset of operating analgesia),
intense, and extensive anesthesia. Unlike procaine, lidocaine is effective when applied
topically. Its anesthetic potency and area of anesthesia are greater than those of
procaine hydrochloride. At a concentration of 0.5 percent, lidocaine has approximately
the same toxicity as does procaine, but as the concentration of lidocaine is increased,
its toxicity exceeds that of procaine. Moreover, lidocaine diffuses rapidly, a property
that may increase the incidence of systemic reactions. Lidocaine is dissimilar to
procaine in its chemical structure and, hence, may be used for persons sensitive to
procaine. In addition, it produces effective anesthesia without the use of epinephrine,
and so it may be used for persons allergic to epinephrine.
b. Uses of Lidocaine Hydrochloride. This agent is useful for topical,
infiltration, and nerve block anesthesia. Lidocaine is also used for peridural block
anesthesia. Its effect lasts from 1 1/2 to 3 hours with low dosage. This agent is often
used in individuals sensitive to procaine. The drug is administered according to the type
of local anesthesia to be induced. The onset of mucosal anesthesia may require 5 to 15
minutes, and depending on the procedure and the amount used, the anesthesia may
persist for 30 minutes. The jelly form of the drug may be applied by means of cotton
pledgets or applicators to the mucous membrane of the oral cavity and the urethra. An
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