INDICATIONS AND USAGE 4% Citanest Plain Dental Injection, Prilocaine Hydrochloride Injection, USP, 4% (72 mg/1.8 mL) (40 mg/mL), 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.

WARNINGS DENTAL PRACTITIONERS WHO EMPLOY LOCAL ANESTHETIC AGENTS SHOULD BE WELL VERSED IN DIAGNOSIS AND MANAGEMENT OF EMERGENCIES THAT MAY ARISE FROM THEIR USE.

RESUSCITATIVE EQUIPMENT, OXYGEN AND OTHER RESUSCITATIVE DRUGS SHOULD BE AVAILABLE FOR IMMEDIATE USE.

Methemoglobinemia Cases of methemoglobinemia have been reported in association with local anesthetic use.

Although all patients are at risk for methemoglobinemia, patients with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants under 6 months of age, and concurrent exposure to oxidizing agents or their metabolites are more susceptible to developing clinical manifestations of the condition.

If local anesthetics must be used in these patients, close monitoring for symptoms and signs of methemoglobinemia is recommended.

Signs of methemoglobinemia may occur immediately or may be delayed some hours after exposure, and are characterized by a cyanotic skin discoloration and/ or abnormal coloration of the blood.

Methemoglobin levels may continue to rise; therefore, immediate treatment is required to avert more serious central nervous system and cardiovascular adverse effects, including seizures, coma, arrhythmias, and death.

Discontinue CITANEST and any other oxidizing agents.

Depending on the severity of the signs and symptoms, patients may respond to supportive care, i.e., oxygen therapy, hydration.

A more severe clinical presentation may require treatment with methylene blue exchange transfusion, or hyperbaric oxygen.

To minimize the likelihood of intravascular injection, aspiration should be performed before the local anesthetic solution is injected.

If blood is aspirated, the needle must be repositioned until no return of blood can be elicited by aspiration.

Note, however, that the absence of blood in the syringe does not assure that intravascular injection will be avoided.

ADVERSE REACTIONS Swelling and persistent paresthesia of the lips and oral tissues may occur.

Persistent paresthesias lasting weeks to months, and in rare instances paresthesia lasting greater than one year, have been reported.

Adverse experiences following the administration of prilocaine are similar in nature to those observed with other amide local anesthetic agents.

These adverse experiences are, in general, dose-related and may result from high plasma levels caused by excessive dosage, rapid absorption or unintentional intravascular injection, or may result from a hypersensitivity, idiosyncrasy or diminished tolerance on the part of the patient.

Serious adverse experiences are generally systemic in nature.

The following types are those most commonly reported: Central Nervous System CNS manifestations are excitatory and/or depressant and may be characterized by lightheadedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression, and arrest.

The excitatory manifestations may be very brief or may not occur at all, in which case the first manifestation of toxicity may be drowsiness merging into unconsciousness and respiratory arrest.

Drowsiness following the administration of prilocaine is usually an early sign of a high blood level of the drug and may occur as a consequence of rapid absorption.

Cardiovascular System Cardiovascular manifestations are usually depressant and are characterized by bradycardia, hypotension, and cardiovascular collapse, which may lead to cardiac arrest.

Signs and symptoms of depressed cardiovascular function may commonly result from a vasovagal reaction, particularly if the patient is in an upright position.

Less commonly, they may result from a direct effect of the drug.

Failure to recognize the premonitory signs such as sweating, a feeling of faintness, changes in pulse or sensorium may result in progressive cerebral hypoxia and seizure or serious cardiovascular catastrophe.

Management consists of placing the patient in the recumbent position and ventilation with oxygen.

Supportive treatment of circulatory depression may require the administration of intravenous fluids, and, when appropriate, a vasopressor (e.g., ephedrine) as directed by the clinical situation.

Allergic Allergic reactions are characterized by cutaneous lesions, urticaria, edema, or anaphylactoid reactions.

Allergic reactions as a result of sensitivity to prilocaine are extremely rare and, if they occur, should be managed by conventional means.

The detection of sensitivity by skin testing is of doubtful value.

Neurologic The incidences of adverse reactions (e.g., persistent neurologic deficit) associated with the use of local anesthetics may be related to the technique employed, the total dose of local anesthetic administered, the particular drug used, the route of administration, and the physical condition of the patient.