For normal healthy adults, the maximum individual dose should not exceed 4.5 mg/kg of body weight, and in general it is recommended that the maximum total dose does not exceed 300 mg.
The maximum recommended dose per 90 minute period of lidocaine hydrochloride for paracervical block in obstetrical patients and non-obstetrical patients is 200 mg total. One half of the total dose is usually administered to each side. Inject slowly, five minutes between sides
[see Pregnancy (
8.1)].
A maximum dose of lidocaine hydrochloride injection for children varies based on age and weight. For children over 3 years of age with a normal lean body mass and normal body development, the maximum dose is determined by the child's age and weight. For example, in a child of 5 years weighing approximately 23 kg, the dose of lidocaine hydrochloride should not exceed approximately 75 mg to 100 mg (3.3 mg/kg to 4.4 mg/kg).
- 1% (500 mg per 50 mL) (10 mg per mL), 50 mL multiple-dose vials
Risk of Severe, Persistent Hypertension Due to Drug Interactions Between Lidocaine Hydrochloride Injection and Monoamine Oxidase Inhibitors and Tricyclic Antidepressants
Administration of lidocaine hydrochloride injection in patients receiving monoamine oxidase inhibitors (MAOI), or tricyclic antidepressants may result in severe, prolonged hypertension. Concurrent use of these agents should generally be avoided. In situations when concurrent therapy is necessary, careful monitoring of the patient's hemodynamic status is essential
[see Drug Interactions (
7.2)].
Risk of Severe, Persistent Hypertension or Cerebrovascular Accidents Due to Drug Interactions Between Lidocaine Hydrochloride Injection and Ergot-Type Oxytocic Drugs
Concurrent administration of lidocaine hydrochloride injection and ergot-type oxytocic drugs may cause severe, persistent hypertension or cerebrovascular accidents. Avoid use of lidocaine hydrochloride injection concomitantly with ergot-type oxytocic drugs
[see Drug Interactions (
7.3)]
.
Risk of Hypertension and Bradycardia Due to Drug Interactions Between Lidocaine Hydrochloride Injection and Nonselective Beta-Adrenergic Antagonists
Administration of lidocaine hydrochloride injection in patients receiving nonselective beta-adrenergic antagonists may cause severe hypertension and bradycardia. Concurrent use of these agents should generally be avoided. In situations when concurrent therapy is necessary, careful monitoring of the patient's blood pressure and heart rate is essential
[see Drug Interactions (
7.4)].
Nervous System Disorders
Adverse reactions were characterized by excitation and/or depression of the central nervous system and included 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 incidences of adverse reactions associated with the use of local anesthetics may be related to the total dose of local anesthetic administered and are also dependent upon the particular drug used, the route of administration and the physical status of the patient. In a prospective review of 10,440 patients who received lidocaine hydrochloride for spinal anesthesia, the incidences of adverse reactions were reported to be about 3 percent each for positional headaches, hypotension and backache; 2 percent for shivering; and less than 1 percent each for peripheral nerve symptoms, nausea, respiratory inadequacy and double vision.
There have been reported cases of permanent injury to extraocular muscles requiring surgical repair following retrobulbar administration.
Neurologic effects following other procedures or routes of administration have included persistent anesthesia, paresthesia, weakness, paralysis, all with slow, incomplete, or no recovery.
Convulsions: Incidence varied with the procedure used and the total dose administered. The incidences of adverse neurologic reactions associated with the use of local anesthetics may be related to the total dose of local anesthetic administered and are also dependent upon the particular drug used, the route of administration, and the physical status of the patient.
Cardiac Disorders
High doses or unintentional intravascular injection have led to high plasma levels and related depression of the myocardium, decreased cardiac output, heartblock, hypotension, bradycardia, ventricular arrhythmias, including ventricular tachycardia and ventricular fibrillation, and cardiac arrest
[see Warnings and Precautions (
5.9)]
.
Immune System Disorders
Allergic reactions are characterized by cutaneous lesions, urticaria, edema or anaphylactoid reactions. Allergic reactions may occur as a result of sensitivity either to local anesthetic agents or to the methylparaben used as a preservative in the multiple dose vials
[see Warnings and Precautions (
5.6)].
There have been no reports of cross sensitivity between lidocaine hydrochloride and procainamide or between lidocaine hydrochloride and quinidine.
Hematologic
Methemoglobinemia
[See Warnings and Precautions (
5.2)]
.
Risk Summary
Available published data and decades of clinical use with lidocaine hydrochloride injection in pregnant women have not identified any drug-associated risk for major birth defects, miscarriage, or other adverse maternal or fetal outcomes. Local anesthetics may cause varying degrees of toxicity to the mother and fetus and adverse reactions include alterations of the central nervous system, peripheral vascular tone and cardiac function
(see
Clinical Considerations).
In a published animal reproduction study, pregnant rats administered lidocaine by continuous subcutaneous infusion at a dose approximately 9.6 times the maximum recommended human dose (MRHD) of 500 mg in lidocaine hydrochloride injection during the period of organogenesis resulted in lower fetal body weights
[see
Data].
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss, or other adverse outcomes. In the United States general population, the estimated background risks of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
Clinical Considerations
Maternal adverse reactions
Maternal hypotension has resulted from regional anesthesia. Local anesthetics produce vasodilation by blocking sympathetic nerves. Therefore, during treatment of systemic toxicity, maternal hypotension or fetal bradycardia following regional block, the parturient should be maintained in the left lateral decubitus position if possible or manual displacement of the uterus off the great vessels be accomplished. Elevating the patient's legs will also help prevent decreases in blood pressure. The fetal heart rate also should be monitored continuously, and electronic fetal monitoring is highly advisable.
Labor or delivery
Local anesthetics rapidly cross the placenta, and when used for epidural, paracervical, pudendal or caudal block anesthesia, can cause varying degrees of maternal, fetal and neonatal toxicity
[see Clinical Pharmacology (
12.3)].
The incidence and degree of toxicity depend upon the procedure performed, the type and amount of drug used, and the technique of drug administration. Adverse reactions in the parturient, fetus and neonate involve alterations of the central nervous system, peripheral vascular tone and cardiac function. However, dosage recommendations for spinal anesthesia are much lower than dosage recommendations for other major blocks.
Spinal anesthesia may alter the forces of parturition through changes in uterine contractility or maternal expulsive efforts. Spinal anesthesia has also been reported to prolong the second stage of labor by removing the parturient's reflex urge to bear down or by interfering with motor function. The use of obstetrical anesthesia may increase the need for forceps assistance. The use of some local anesthetic drug products during labor and delivery may be followed by diminished muscle strength and tone for the first day or two of life.
Data
Animal Data
Reproduction studies have been performed in rats at doses up to 6.6 times the human dose and have revealed no evidence of harm to the fetus caused by lidocaine hydrochloride.
In a published study, lidocaine administered to pregnant rats by continuous subcutaneous infusion during the period of organogenesis at 100, 250, and 500 mg/kg/day, did not produce any structural abnormalities, but did result in lower fetal weights at 500 mg/kg/day dose (approximately 9.6 times the maximum recommended human dose [MRHD] of 500 mg lidocaine on a mg/m
2basis) in the absence of maternal toxicity.
Risk Summary
Published data report the presence of lidocaine and its metabolites in human milk in low amounts, along with poor oral bioavailability. There are no data on the effect of lidocaine on the breastfed infant or the effect on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for lidocaine hydrochloride injection and any potential adverse effects on the breastfed child from lidocaine hydrochloride injection or from the underlying maternal condition.
Clinical Presentation
Acute emergencies from local anesthetics are generally related to high plasma levels encountered during therapeutic use of local anesthetics or to unintended subarachnoid injection of local anesthetic solution
[see Warnings and Precautions (
5.1) and Adverse Reactions (
6)].
Management
The first consideration is prevention, best accomplished by careful and constant monitoring of cardiovascular and respiratory vital signs and the patient's state of consciousness after each local anesthetic injection. At the first sign of change, oxygen should be administered.
The first step in the management of convulsions, as well as underventilation or apnea due to unintended subarachnoid injection of drug solution, consists of immediate attention to the maintenance of a patent airway and assisted or controlled ventilation with oxygen and a delivery system capable of permitting immediate positive airway pressure by mask. Immediately after the institution of these ventilatory measures, the adequacy of the circulation should be evaluated, keeping in mind that drugs used to treat convulsions sometimes depress the circulation when administered intravenously. Should convulsions persist despite adequate respiratory support, and if the status of the circulation permits, a benzodiazepine (such as diazepam) may be administered intravenously. The clinician should be familiar, prior to the use of local anesthetics, with these anticonvulsant drugs. Supportive treatment of circulatory depression may require administration of intravenous fluids and, when appropriate, a vasopressor as directed by the clinical situation (e.g., ephedrine).
If not treated immediately, both convulsions and cardiovascular depression can result in hypoxia, acidosis, bradycardia, arrhythmias and cardiac arrest. Underventilation or apnea due to unintentional subarachnoid injection of local anesthetic solution may produce these same signs and also lead to cardiac arrest if ventilatory support is not instituted. If cardiac arrest should occur, standard cardiopulmonary resuscitative measures should be instituted.
Endotracheal intubation, employing drugs and techniques familiar to the clinician, may be indicated, after initial administration of oxygen by mask, if difficulty is encountered in the maintenance of a patent airway or if prolonged ventilatory support (assisted or controlled) is indicated.
Dialysis is of negligible value in the treatment of acute overdosage with lidocaine hydrochloride.
Absorption
Information derived from diverse formulations, concentrations and usages reveals that lidocaine hydrochloride is completely absorbed following parenteral administration, its rate of absorption depending, for example, upon various factors such as the site of administration and the presence or absence of a vasoconstrictor agent. Except for intravascular administration, the highest blood levels are obtained following intercostal nerve block and the lowest after subcutaneous administration.
Distribution
The plasma binding of lidocaine hydrochloride is dependent on drug concentration, and the fraction bound decreases with increasing concentration. At concentrations of 1 to 4 mcg of free base per mL 60 to 80 percent of lidocaine hydrochloride is protein bound. Binding is also dependent on the plasma concentration of the alpha-1-acid glycoprotein. Lidocaine hydrochloride crosses the blood-brain and placental barriers, presumably by passive diffusion.
Elimination
The elimination half-life of lidocaine hydrochloride following an intravenous bolus injection is typically 1.5 to 2 hours.
Metabolism
Lidocaine hydrochloride is metabolized rapidly by the liver, and biotransformation includes oxidative N-dealkylation, ring hydroxylation, cleavage of the amide linkage, and conjugation. N-dealkylation, a major pathway of biotransformation, yields the metabolites monoethylglycinexylidide and glycinexylidide. The pharmacological/toxicological actions of these metabolites are similar to, but less potent than, those of lidocaine hydrochloride.
Excretion
Approximately 90% of lidocaine hydrochloride administered is excreted in the form of various metabolites, and less than 10% is excreted unchanged by the kidneys. The primary metabolite in urine is a conjugate of 4-hydroxy-2,6-dimethylaniline.
Specific Populations
Patients with Hepatic Impairment
Because of the rapid rate at which lidocaine hydrochloride is metabolized, any condition that affects liver function may alter lidocaine HCl kinetics. The half-life may be prolonged two-fold or more in patients with liver dysfunction.
Patients with Renal Impairment
Renal dysfunction does not affect lidocaine hydrochloride kinetics but may increase the accumulation of metabolites.
Carcinogenesis
Studies of lidocaine hydrochloride in animals to evaluate the carcinogenic potential have not been conducted.
Mutagenesis
Studies of lidocaine hydrochloride in animals to evaluate the mutagenic potential have not been conducted.
Impairment of Fertility
In a published study, female Sprague-Dawley rats were treated subcutaneously with lidocaine via osmotic pumps starting two weeks prior to mating, and reproductive effects were assessed. Rats dosed up to the high dose of 500 mg/kg/day (approximately 45 times the MRDD on a mg/m
2basis) showed no effects on copulatory rate, pregnancy rate, numbers of corpora lutea, or implantations.