Lidocaine Hydrochloride I.P          21.30 mg

Methyl Paraben I.P.                        0.61 mg

Propyl Paraben I.P                         0.21 mg

Flavored viscous aqueous base q.s.

Lidocaine stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses thereby, effecting local anesthetic action. Local anesthetics of the amide-type are thought to act within the sodium channels of the nerve membrane. The effect starts within 3 to 5 minutes and lasts for up to half an hour.

Lidocaine is absorbed following topical administration to mucous membranes, its rate and extent of absorption being dependent upon concentration and total dose administered, the specific site of application, and duration of exposure. In general, the rate of absorption of local anesthetic agents following topical application occurs most rapidly after intratracheal administration. Lidocaine is also well-absorbed from the gastrointestinal tract, but little intact drug appears in the circulation because of biotransformation in the liver. The plasma binding of lidocaine 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 is protein bound. Binding is also dependent on the plasma concentration of the alpha-1-acid glycoprotein.

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

Lidocaine is metabolized rapidly by the liver, and metabolites and unchanged drug are excreted by the kidneys. 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. Approximately 90% of lidocaine administered is excreted in the form of various metabolites, and less than 10% is excreted unchanged. The primary metabolite in urine is a conjugate of 4-hydroxy-2, 6-dimethylaniline.

The elimination half-life of lidocaine following an intravenous bolus injection is typically 1.5 to 2.0 hours. Because of the rapid rate at which lidocaine is metabolized, any condition that affects liver function may alter lidocaine kinetics. The half-life may be prolonged two-fold or more in patients with liver dysfunction. Renal dysfunction does not affect lidocaine kinetics but may increase the accumulation of metabolites.

Factors such as acidosis and the use of CNS stimulants and depressants affect the CNS levels of lidocaine required to produce overt systemic effects. Objective adverse manifestations become increasingly apparent with increasing venous plasma levels above 6.0 mcg free base per ml. In the rhesus monkey arterial blood levels of 18 to 21 mcg/ml have been shown to be threshold for convulsive activity.

• For the production of topical anesthesia of irritated or inflamed mucous membranes of the mouth and pharynx.
• It is also useful for reducing gagging during the taking of X-ray pictures and dental impressions.
• Special care needs to be taken when used in the treatment of irritated or inflamed mucous membrane of pharynx. (Refer to Special Precautions).

Adults:

The maximum recommended single dose of Lidocaine Hydrochloride Oral Topical Solution, USP (Viscous) 2% for healthy adults should be such that the dose of lidocaine HCI does not exceed 4.5 mg/kg or 2 mg/lb body weight and does not, in any case, exceed a total of 300 mg.

For symptomatic treatment of irritated or inflamed mucous membranes of the mouth and pharynx, the usual adult dose is 15 mL undiluted. For use in the mouth, the solution should be swished around in the mouth and spit out.

This dose should not be administered at intervals of less than three hours, and not more than eight doses should be given in a 24-hour period. The dosage should be adjusted commensurate with the patient’s age, weight, and physical condition.

On the other hand, the Canadian manufacturer advises a lesser number of doses schedule (not more than 6 doses in 24 – hour period).  Waiting for at least 3 hours before the next dose is a must.

For use in the treatment of irritated or inflamed mucous membranes of the pharynx, the undiluted solution should be gargled and may be swallowed. However, it must be remembered that this has inherent risks and needs precautionary measures and seeking medical advice at the earliest (See Special Precautions below).

Pediatrics:

Care must be taken to ensure correct dosage in all pediatric patients as there have been cases of overdose due to inappropriate dosing.

It is difficult to recommend a maximum dose of any drug for children since this varies as a function of their age and weight. For children over 3 years of age who have a normal lean body mass and normal body development, the maximum dose is determined by the child’s weight or age. For example: in a child of 5 years weighing 50 lbs., the dose of lidocaine hydrochloride should not exceed 75-100 mg (3.7 to 5 mL of Lidocaine Hydrochloride Oral Topical Solution, USP (Viscous) 2%).

For infants and children under 3 years of age, the solution should be accurately measured and no more than 1.2 mL be applied to the immediate area with a cotton-tipped applicator. Wait at least 3 hours before giving the next dose; a maximum of four doses may be given in a 12-hour period. Lidocaine Hydrochloride Oral Topical Solution, USP (Viscous) 2%) should only be used if the underlying condition requires treatment with a volume of product that is less than or equal to 1.2 ml.

Children should not swallow this medication unless advised by the doctor.

According to US manufacturers, do not give more than 4 doses in a 12-hour period in children. On the other hand, the Canadian manufacturer advises not more than 4 doses in the 24-hour period in children.

Special Precautions:

It is usually advised to swish and gargle and spit out the solution. Only in exceptional cases and under medical supervision a patient with irritated or inflamed pharynx may be advised to swallow the well-measured viscous solution, keeping in mind the potential adverse effects and seek medical advice at the earliest occurrence of serious adverse effects like dizziness, drowsiness, slow or shallow breathing, mood changes such as confusion or nervousness, shaking, seizures, vision changes (like double vision or blurred vision), ringing in the ear, fainting, pale/ bluish/gray skin, unusual tiredness, shortness of breath or fast/slow or irregular heartbeats. Though a very serious allergic reaction to this drug is rare, seeking prompt medical attention is indicated in case of rash, itching/swelling (especially of face, tongue, or throat), severe dizziness, or trouble breathing.

• Lidocaine Hydrochloride Oral Topical Solution should be used with extreme caution if the mucosa in the area of application has been traumatized, since under such conditions there is the potential for rapid systemic absorption.
• For patients under 3 years of age, special care must be given to accurately measuring the prescribed dose and not administering the product more often than prescribed.
• The product should only be used for the prescribed indication.
• Patients should be informed that when topical anesthetics are used in the mouth or throat, the production of topical anesthesia may impair swallowing and thus enhance the danger of aspiration. For this reason, food should not be ingested for 60 minutes following use of local anesthetic preparations in the mouth or throat area. This is particularly important in children because of their frequency of eating.
• Numbness of the tongue or buccal mucosa may increase the danger of biting trauma. For this reason, food and/or chewing gum should not be used while the mouth or throat area is anesthetized.
• Patients should be informed that the use of local anesthetics may cause methemoglobinemia, a serious condition that must be treated promptly. Patients or caregiver should be advised to seek immediate medical attention if they or someone in their care experience the following signs or symptoms: pale, gray, or blue-colored skin (cyanosis); headache; rapid heart rate; shortness of breath; light-headedness; or fatigue.
• Lidocaine Hydrochloride should be used with caution in persons with known drug sensitivities. Patients allergic to para-aminobenzoic acid derivatives (procaine, tetracaine, benzocaine, etc.) have not shown cross-sensitivity to lidocaine.

Adverse experiences following the administration of lidocaine 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 or rapid absorption, 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 light-headedness, 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 lidocaine 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.

Allergic:

Allergic reactions are characterized by cutaneous lesions, urticaria, edema or anaphylactoid reactions. Allergic reactions may occur as a result of sensitivity either to the local anesthetic agent or to the methylparaben and/or propylparaben used in this formulation. Allergic reactions as a result of sensitivity to lidocaine are extremely rare and, if they occur, should be managed by conventional means. The detection of sensitivity by skin testing is of doubtful value.

Patients who are administered local anesthetics are at increased risk of developing methemoglobinemia when concurrently exposed to the following drugs, which could include other local anesthetics:

Examples of Drugs Associated with Methemoglobinemia:

Carcinogenesis, Mutagenesis, Impairment of Fertility:

Studies of lidocaine in animals to evaluate the carcinogenic and mutagenic potential or the effect on fertility have not been conducted.

Pregnancy:

Teratogenic Effects. Pregnancy Category B.

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. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used in pregnancy only if clearly needed.

Nursing Mothers:

It is not known whether this drug is secreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when the lidocaine is administered to nursing women.

Pediatric Use:

Dosages in children should be reduced, commensurate with age, body weight, and physical condition. (See DOSAGE AND ADMINISTRATION).

Acute emergencies from local anesthetics are generally related to high plasma levels encountered during therapeutic use of local anesthetics.

CONTRAINDICATIONS

Known hypersensitivity to lidocaine or other anesthetics of the amide-type.

Store in a cool and dry place

Clear, viscous liquid with a very slight strawberry flavor.

Available in 200ml bottle

• https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=ff6b27bc-2ed7-4292-b8c8-da910bf68167&type=display
• https://www.rxlist.com/xylocaine-viscous-drug.htm#indications
• https://www.webmd.com/drugs/2/drug-11492/lidocaine-viscous-mucous-membrane/details
• https://www.medicines.org.uk/emc/product/6281/smpc
• https://www.rxmed.com/b.main/b2.pharmaceutical/b2.1.monographs/cps-_monographs/CPS-_(General_Monographs-_X)/XYLOCAINE_VISCIOUS.html