Instasia14%+2%+2%

Instasia is a combination topical (surface) anesthetic used to numb accessible mucous membranes before certain procedures. It is not an FDA-approved new drug application product but is a long-marketed topical anesthetic used under physician/dentist supervision.

Established uses

• Topical anesthesia of accessible mucous membranes (excluding the eyes) prior to examination, endoscopy, or minor surgical procedures involving the ear, nose, mouth, pharynx, larynx, trachea, bronchi, and esophagus.
• Control of pain and suppression of the gag reflex during dental procedures, endotracheal intubation, endoscopic examinations, and impression-taking in dentistry.
• Topical anesthesia prior to vaginal or rectal examinations or minor procedures, where clinically feasible.

Not established / off-label

Use on non-mucosal, extensively broken, or denuded skin, or use for prolonged/repeated application beyond labeled directions, is not supported by evidence and is discouraged (see Contraindications and Precautions and Warnings).

Benzocaine + Butamben + Tetracaine is a fixed combination of three ester-type local anesthetic agents formulated as a topical spray, liquid, or gel. A representative unit dose (e.g., a single 200 mg liquid application) contains approximately 14% benzocaine, 2% butamben, and 2% tetracaine hydrochloride (approximately 28 mg benzocaine, 4 mg butamben, and 4 mg tetracaine hydrochloride per 200 mg), together with inactive vehicle/excipient ingredients that vary by dosage form (spray, liquid, or gel). Exact strengths and excipients should be confirmed on the specific product label/packaging.

Instasia is a topical local anesthetic combination containing three ester-type anesthetic agents that act together to provide rapid onset and extended duration of surface numbing compared with a single agent alone. Benzocaine provides fast onset, tetracaine contributes potency and depth of anesthesia, and butamben (poorly water-soluble) helps prolong the duration of effect.

It is applied directly to accessible mucous membranes by a healthcare professional (physician, dentist, or trained clinician) to reduce pain, discomfort, and gagging during examinations and minor procedures. It is available as a metered spray, liquid, and gel, and is intended for short-term, professionally supervised topical use only.

Instasia belongs to the therapeutic class of topical/local anesthetics, specifically an ester-type local anesthetic combination used for surface (mucosal) anesthesia.

Benzocaine + Butamben + Tetracaine combines three ester-linked local anesthetics that share a common mechanism of action but differ in onset, potency, and duration, giving a combined profile of rapid onset with extended duration.

Mechanism

All three components reversibly block voltage-gated sodium channels in nerve cell membranes. This prevents the influx of sodium ions required for depolarization, blocking initiation and conduction of nerve impulses along sensory nerve fibers in the applied mucosa, producing localized loss of sensation (anesthesia) without loss of consciousness.

Pharmacokinetics

Ester-type anesthetics such as those in Benzocaine + Butamben + Tetracaine are hydrolyzed primarily by plasma cholinesterase (pseudocholinesterase) and, to a lesser extent, tissue esterases. Systemic absorption from mucous membranes depends on the site, area, and duration of application; excessive application area, concentration, or duration increases systemic absorption and the risk of systemic toxicity, including methemoglobinemia (see Precautions and Warnings).

Instasia is for topical (surface) application only to accessible mucous membranes by a trained healthcare professional. It must never be injected, swallowed deliberately, or applied to the eyes. The spray nozzle or applicator should be directed only at the intended treatment area, avoiding excessive area coverage. Application should be brief (per labeled directions for each dosage form), and the area should be observed for adequate anesthesia before proceeding with the intended examination or procedure.

Well-established, clinically significant interactions with Instasia include the following.

Other local anesthetics

Concurrent or closely-timed use of additional local anesthetic products (topical or injectable) with Instasia can have additive systemic toxic effects, including central nervous system and cardiovascular effects; concurrent use should be avoided or closely supervised by a clinician.

Methemoglobinemia-inducing agents

Concurrent use of other agents capable of inducing methemoglobinemia (for example, certain sulfonamides, nitrates/nitrites, dapsone, chloroquine, and similar oxidizing drugs) increases the risk of clinically significant methemoglobinemia when combined with Instasia, particularly with the benzocaine component. Careful clinical monitoring is advised if such agents cannot be avoided.

Cholinesterase-affecting drugs

Because the ester components of Instasia are metabolized by plasma cholinesterase, drugs or conditions that reduce cholinesterase activity (e.g., certain cholinesterase inhibitors, or inherited pseudocholinesterase deficiency) may slow metabolism of the anesthetic components and increase the risk of systemic toxicity.

Adverse effects with Instasia are generally uncommon when it is used as labeled by a trained professional, but include:

• Local reactions: transient stinging or burning on application, localized erythema (redness), pruritus (itching), contact dermatitis, vesiculation (blistering), or oozing, particularly with prolonged or repeated use.
• Hypersensitivity reactions: allergic contact dermatitis or, rarely, more generalized allergic reactions including urticaria and edema.
• Methemoglobinemia: a rare but serious, potentially life-threatening systemic adverse effect associated particularly with the benzocaine component (see Precautions and Warnings for symptoms and required action).
• Systemic toxicity: with excessive dose, area, or duration of application, central nervous system effects (dizziness, restlessness, tremor, or in severe cases seizures) and cardiovascular effects (arrhythmia, hypotension) can occur due to excess systemic absorption.

The safety of Instasia in human pregnancy has not been formally established. As with topical local anesthetics generally, Instasia should be used during pregnancy, particularly early pregnancy, only if clearly needed and only if the potential benefit justifies the potential unknown risk to the fetus; a physician should be consulted before use in pregnant patients.

There is no well-established data on excretion of the components of Instasia into human breast milk. Because systemic absorption from labeled topical/mucosal use is generally low, but is not zero, breastfeeding mothers should consult a physician before use, and use should be limited to the smallest effective amount for the shortest necessary time.

Methemoglobinemia (serious warning)

Use of Instasia, particularly its benzocaine component, has been associated with cases of methemoglobinemia, a serious and potentially life-threatening condition in which the blood's ability to carry oxygen is reduced. Risk is higher in infants under 6 months of age, patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, and in patients concurrently exposed to other oxidizing drugs or chemicals. Signs and symptoms include cyanosis (bluish discoloration of the skin, lips, or nail beds), unusual fatigue, shortness of breath, headache, rapid heart rate, and lightheadedness, and can develop within minutes to hours of application. If any of these symptoms occur, discontinue use immediately and seek emergency medical attention.

External/topical use only

Instasia is for topical application to labeled accessible mucous membranes only, applied by a trained healthcare professional. Do not apply to the eyes, do not inject, and do not use on areas or in a manner not specifically described in the product labeling.

Avoid exceeding the labeled application area, frequency, or duration, as this increases systemic absorption and the risk of methemoglobinemia and other systemic toxicity. Avoid prolonged or repeated application beyond labeled directions.

Local irritation and allergy

Local irritation or allergic contact dermatitis can occur; discontinue use if rash, swelling, or significant irritation develops.

Use with caution

Use with caution, and with reduced dosage, in elderly, debilitated, or acutely ill patients, and in patients with known cholinesterase deficiency (see Interactions).

Excessive dosing, application area, frequency, or duration of Instasia can result in significant systemic absorption and toxicity, which may present as methemoglobinemia (cyanosis, fatigue, shortness of breath), central nervous system excitation or depression (dizziness, restlessness, tremor, confusion, or in severe cases seizures), and cardiovascular effects (irregular heartbeat, low blood pressure, or, rarely, cardiovascular collapse).

If overdose or signs of systemic toxicity are suspected, discontinue application immediately and seek immediate emergency medical attention or contact a poison control center; do not attempt to manage significant symptoms at home. Supportive care and, where indicated, specific treatment for methemoglobinemia should be provided in a medical facility.

Store at controlled room temperature, between 20°C and 25°C (68°F-77°F), away from direct light, heat, and moisture. Keep the container tightly closed when not in use, and keep out of reach of children.

Pediatric use

Instasia is contraindicated in infants and children under 2 years of age because of an increased risk of serious methemoglobinemia (see Contraindications). Safety and efficacy in children under 2 years have not been established. In children 2 years and older, use the smallest effective amount for the shortest necessary time under professional supervision.

Geriatric use

Dosage should be reduced in elderly patients, who may be more susceptible to systemic toxicity; use the minimum effective amount.

Hepatic/renal impairment

No well-established dosage adjustment guidance exists for hepatic or renal impairment; because ester-type anesthetics are cleared mainly by plasma cholinesterase rather than hepatic or renal pathways, clinically significant dose adjustment is not typically required, but caution and reduced dosing are advised in debilitated patients with hepatic or renal disease.

Debilitated or acutely ill patients

Use with caution and reduced dosage, as these patients may have reduced tolerance for systemic absorption of local anesthetics.

Instasia is intended for short-term, single-session, professionally supervised topical use immediately before or during a specific procedure or examination; anesthetic effect typically lasts approximately 30-60 minutes. It is not intended for prolonged, repeated, or unsupervised home use; avoid application beyond labeled directions given the cumulative risk of systemic absorption and methemoglobinemia with repeated or extended use.

Benzocaine + Butamben + Tetracaine is classified as a topical/local anesthetic, specifically a fixed-dose combination of three ester-type local anesthetics (benzocaine, butamben, and tetracaine).

Each component of Benzocaine + Butamben + Tetracaine reversibly blocks voltage-gated sodium channels along sensory nerve fibers in the applied mucosa, preventing sodium influx needed for nerve membrane depolarization and thereby blocking initiation and conduction of nerve impulses, producing localized anesthesia. Benzocaine provides rapid onset; tetracaine adds potency and depth of anesthetic effect; butamben, being poorly water-soluble, contributes to a prolonged duration of action. Together, the combination provides faster onset and longer-lasting surface anesthesia than a single agent typically provides alone.

Instasia is contraindicated in infants and children under 2 years of age because of a significantly increased risk of serious, potentially life-threatening methemoglobinemia, particularly linked to the benzocaine component. Safety and efficacy in this age group have not been established, and this product should not be used in this population.

In children 2 years of age and older, Instasia may be used by a trained healthcare professional at a reduced dose/application amount appropriate to the child's size and the procedure, using the smallest effective amount for the shortest time, with close observation for signs of methemoglobinemia (cyanosis, unusual fatigue, shortness of breath) during and after use.