Prilocaine with Epinephrine Injection

For Local Anesthesia in Dentistry

Rx only

Mechanism of Action

Prilocaine stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action.

Onset and Duration of Action

When used for infiltration injection in dental patients, the time of onset of anesthesia averages less than 2 minutes with an average duration of soft tissue anesthesia of approximately 2.25 hours.

When used for inferior alveolar nerve block, the time of onset averages less than three minutes with an average duration of soft tissue anesthesia of approximatelty 3 hours.

Hemodynamics

Excessive blood levels may cause changes in cardiac output, total peripheral resistance, and mean arterial pressure. These changes may be attributable to a direct depressant effect of the local anesthetic agent on various components of the cardiovascular system and/or the beta-adrenergic receptor stimulating of epinephrine.

Pharmacokinetics and Metabolism

Information derived from diverse formulations, concentrations and usages reveals that prilocaine is completely absorbed following parenteral administration, its rate of absorption depending, for example, upon such factors as the site of administration and the presence or absence of a vasoconstrictor agent. Prilocaine is metabolized in both the liver and the kidney and excreted via the kidney. It is not metabolized by plasma esterases. Hydrolysis of prilocaine by amidases yields ortho-toluidine and N-proylalanine. Both of these compounds may undergo ring hydroxylation.

O-toluidine has been found to produce methemoglobin, both in vitro and in vivo (see ADVERSE REACTIONS).

Because prilocaine is metabolized in both the liver and kidneys, hepatic and renal dysfunction may alter prilocaine kinetics.

As with other local anesthetic agents, the plasma binding of prilocaine may be dependent on drug concentration. At 0.5 to 1.0 mg/mL it is 55% protein bound.

Prilocaine crosses the blood-brain and placental barriers, presumably by passive diffusion.

Factors such as acidosis and the use of CNS stimulants and depressants affect the CNS levels of prilocaine required to produce overt systemic effects. In the rhesus monkey, arterial blood levels of 20 mg/mL have been shown to be the threshold for convulsive activity.

Prilocaine Hydrochloride 4% with Epinephrine 1:200,000 injection is indicated for the production of local anesthesia in dentistry by nerve block or infiltration techniques. Only accepted procedures for these techniques as described in standard textbooks are recommended.

Prilocaine is contraindicated in patients with a known history of hypersensitivity to local anesthetics of the amide type and in those rare patients with congenital or idiopathic methemoglobinemia.

The dosage of Prilocaine Hydrochloride 4% with Epinephrine 1:200,000 Injection varies and depends on the physical status of the patient, the area of the oral cavity to be anesthetized, the vascularity of the oral tissues, and the technique of anesthesia. The least volume of injection that results in effective local anesthesia should be administered. For specific techniques and procedures of local anesthesia in the oral cavity, refer to standard textbooks.

Inferior Alveolar Block

There are no practical clinical differences between prilocaine with and without epinephrine when used for inferior alveolar blocks.

Maxillary Infiltration

Prilocaine Hydrochloride 4% without epinephrine is recommended for use in maxillary infiltration anesthesia for procedures in which the painful aspects can be completed within 15 minutes after the injection. Prilocaine Hydrochloride 4% without epinephrine is therefore especially suited to short procedures in the maxillary anterior teeth. For long procedures, or those involving maxillary posterior teeth where soft tissue numbness is not troublesome to the patient, Prilocaine HCl 4% with epinephrine 1:200,000 is recommended.

For most routine procedures, initial dosages of 1 to 2 mL of Prilocaine Hydrochloride 4% with Epinephrine 1:200,000 Injection will usually provide adequate infiltration or major nerve block anesthesia.

The maximum recommended dose that should ever be administered within a two-hour period in normal healthy adults should be calculated based upon the patient's weight as follows:

In children under 10 years of age it is rarely necessary to administer more than one-half cartridge (40 mg) of Prilocaine Hydrochloride 4% with Epinephrine 1:200,000 injection per procedure to achieve local anesthesia for a procedure involving a single tooth. In maxillary infiltration, this amount will often suffice to the treatment of two or even three teeth. In the mandibular block, however, satisfactory anesthesia achieved with this amount of drug will allow treatment of the teeth in an entire quadrant.

ASPIRATION PRIOR TO INJECTION IS RECOMMENDED, since it reduces the possibility of intravascular injection, thereby keeping the incidence of side effects and anesthetic failure to a minimum.

NOTE: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever the solution and container permit. Solutions that are discolored and/or contain particulate matter should not be used.

Any unused portion of a cartridge should be discarded.

Maximum Recommended Dosages

In patients weighing <150 lbs (70 kg), no more than 4 mg/lb (8 mg/kg) should be administered. In patients weighing <150 lbs, no more than 600 mg (8 cartridges) of prilocaine HCl should be administered as a single injection.

Children

It is difficult to recommend a maximum dose of any drug for children since this varies as a function of age and weight. For children of less than ten years who have a normal lean body mass and normal body development, the maximum dose may be determined by the application of one of the standard pediatric drug formulas (e.g., Clark's rule). For example, in a child of five years weighing 50 lbs., the dose of prilocaine hydrochloride should not exceed 150 to 200 mg (6.6 to 8.8 mg/kg or 3 to 4 mg/lb of body weight) when calculated according to Clark's rule.

Prilocaine Hydrochloride 4% with Epinephrine 1:200,000 Injection (NDC 0362-9013-50) is dispensed in 1.8 mL cartridges, packed 50 per box.

Sterilization, Storage and Technical Procedures:

1. Cartridges should not be autoclaved, becausee the closures employed in cartridges cannot withstand autoclaving temperatures and pressures.
2. If chemical disinfection of anesthetic cartridges is desired, either 91% isopropyl alcohol or 70% ethyl alcohol is recommended. Many commercially available brands of rubbing alcohol, as well as solutions of ethyl alcohol not of U.S.P. grade, contain denaturants that are injurious to rubber and, therefore, are not to be used. It is recommended that chemical disinfection be accomplished by wiping the cartridge cap thoroughly with a pledget of cotton that has been moistened with the recommended alcohol just prior to use. IMMERSION IS NOT RECOMMENDED.
3. Certain metallic ions (mercury, zinc, copper, etc.) have been related to swelling and edema after local anesthesia in dentistry. Therefore, chemical disinfectants containing or releasing those ions are not recommended. Antirust tablets usually contain metal ions. Accordingly, aluminum sealed cartridges should not be kept in such solutions.
4. Quaternary ammonium salts, such as benzalkonium chloride, are electrolytically incompatible with aluminum. Cartridges are sealed with aluminum caps and therefore should not be immersed in any solution containing these salts.
5. To avoid leakage of solutions during injection, be sure to penetrate the center of the rubber diaphragm when loading the syringe. An off-center penetration produces an oval shaped puncture that allows leakage around the needle.
6. Other causes of leakage and breakage included badly worn syringes, aspirating syringes with bent harpoons, the use of syringes not designed to take 1.8 mL cartridges, and inadvertent freezing.
7. Store at 20 to 25° C (68 to 77°F) [See USP Controlled Room Temperature].
8. Solutions containing epinephrine should be protected from light.

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