SYNERA®: Pharmacokinetics

The amount of lidocaine and tetracaine systemically absorbed from SYNERA is thought to be directly related to the duration of application. However, this was not clearly demonstrated in clinical trials. Application of one SYNERA patch for 30 minutes in adults produced peak plasma concentrations of lidocaine less than 5 ng/mL while plasma levels of tetracaine were below the limit of quantitation (<0.9 ng/mL) in all subjects tested (n = 12). SYNERA application up to 60 minutes did not significantly increase plasma levels of lidocaine or tetracaine compared to a 30-minute application.

*Estimated absorbed dose was calculated by subtracting the residual amount of drug in each patch from the labeled claim.
na = not applicable
The surface area of application was 10cm² per SYNERA Patch.


	Before using SYNERA, review the full prescribing information

*Variability in mean systemic absorption of lidocaine increased in infants with the lowest body weights.
While not observed in pharmacokinetic studies, individual systemic absorption levels of concern are possible.

^†Below the level of quantitation or not detectable.

	•	CNS toxicity may typically be observed around 5000 ng/mL of lidocaine
	•	A small number of patients may reportedly show signs of toxicity at approximately 1000 ng/mL
	•	Simultaneous or sequential application of multiple patches or application longer than recommended could result in serious adverse events (SAEs). Application of SYNERA to broken or inflammed skin, or simultaneous or sequential appliction of multiple SYNERA patches could result in higher plasma levels of local anesthetic that could, in susceptible individuals, produce systemic toxicity.
	•	SYNERA should be used with caution in patients receiving class I antiarrhythmics and/or other local anesthetics, because the systemic toxic effects may be additive and potentially synergistic with lidocaine and tetracaine


	Important Safety Information SYNERA^® topical patch is indicated for use on intact skin to provide local dermal analgesia for superficial venous access and superficial dermatological procedures. SYNERA^® is contraindicated in patients with a known history of sensitivity to lidocaine, tetracaine, local anesthetics of the amide or ester type, or any other component of the product and in patients with para-aminobenzoic acid (PABA) hypersensitivity. Keeping a patch on longer than recommended or applying multiple patches simultaneously or sequentially could result in systemic absorption sufficient to result in serious adverse effects that are typical of drugs in this class. Even a used SYNERA^® patch contains a large amount of lidocaine and tetracaine (at least 90% of the initial amount). Chewing or ingesting a new or used SYNERA^® patch may result in serious adverse effects. Store and dispose of SYNERA^® out of the reach of children and pets. SYNERA^® should be used with caution in patients who may be more sensitive to the systemic effects of lidocaine and tetracaine, including the acutely ill, the debilitated, and those with compromised hepatic function. Patients with severe hepatic disease or pseudocholinesterase deficiency are at greater risk of developing toxic plasma concentrations. Allergic or anaphylactoid reactions (urticaria, angioedema, bronchospasm, and shock) to the active or inactive components of SYNERA^® can occur and should be managed by conventional means. Avoid contact of SYNERA^® with the eyes due to potential irritation or abrasion. If contact occurs, immediately wash out the eye with water or saline, and protect it until sensation returns. Safety and effectiveness of SYNERA^® have been established in patients 3 years and older. Lidocaine has been shown to inhibit viral and bacterial growth. The effect of SYNERA^® on intradermal injections of live vaccines has not been determined. The heating component contains iron powder, and the patch must be removed before magnetic resonance imaging. SYNERA^® may lead to diminished or blocked sensation in the treated skin; therefore, patients should avoid inadvertent trauma (rubbing, scratching, or exposure to heat or cold) before complete sensation returns. SYNERA^® should be used with caution in patients receiving class I antiarrhythmics and/or other local anesthetics, because the systemic toxic effects may be additive and potentially synergistic with lidocaine and tetracaine. In clinical studies, the most common local reactions were erythema (71%), blanching (12%), and edema (12%); these reactions were generally mild, resolving spontaneously soon after treatment. Do not cut or remove the top cover of the patch as this could result in thermal injury. SYNERA^® is not for home use by patient. Please see accompanying full Prescribing Information before using SYNERA.

Reference:

SYNERA Prescribing Information