Prilocaine (3 brand names, 3 dosage forms, 2 routes)
Available dosage forms: CREAM, GEL, DISC.
Routes of administration: TOPICAL, PERIODONTAL.
Brand Names
- EMLA
- LIDOCAINE AND PRILOCAINE
- ORAQIX
Indications and Usage
Lidocaine and prilocaine cream, 2.5%/2.5% (a eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) is indicated as a topical anesthetic for use on: - normal intact skin for local analgesia. - genital mucous membranes for superficial minor surgery and as pretreatment for infiltration anesthesia. Lidocaine and prilocaine cream, 2.5%/2.5% is not recommended in any clinical situation when penetration or migration beyond the tympanic membrane into the middle ear is possible because of the ototoxic effects observed in animal studies (see WARNINGS ).
Contraindications
Lidocaine and prilocaine cream, 2.5%/2.5% is contraindicated in patients with a known history of sensitivity to local anesthetics of the amide type or to any other component of the product.
Drug Interactions
Drug Interactions: Lidocaine and prilocaine cream, 2.5%/2.5% should be used with caution in patients receiving Class I antiarrhythmic drugs (such as tocainide and mexiletine) since the toxic effects are additive and potentially synergistic. 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: Class Examples Nitrates/Nitrites nitric oxide, nitroglycerin, nitroprusside, nitrous oxide Local anesthetics articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, ifosfamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants Phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine Specific interaction studies with lidocaine/prilocaine and class III anti-arrhythmic drugs (e.g., amiodarone, bretylium, sotalol, dofetilide) have not been performed, but caution is advised (see WARNINGS ). Should lidocaine and prilocaine cream, 2.5%/2.5% be used concomitantly with other products containing lidocaine and/or prilocaine, cumulative doses from all formulations must be considered.
Mechanism of Action
Mechanism of Action: Lidocaine and prilocaine cream, 2.5%/2.5%, applied to intact skin under occlusive dressing, provides dermal analgesia by the release of lidocaine and prilocaine from the cream into the epidermal and dermal layers of the skin and by the accumulation of lidocaine and prilocaine in the vicinity of dermal pain receptors and nerve endings. Lidocaine and prilocaine are amide-type local anesthetic agents. Both lidocaine and prilocaine stabilize neuronal membranes by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action. The onset, depth and duration of dermal analgesia on intact skin provided by lidocaine and prilocaine cream, 2.5%/2.5% depends primarily on the duration of application. To provide sufficient analgesia for clinical procedures such as intravenous catheter placement and venipuncture, lidocaine and prilocaine cream, 2.5%/2.5% should be applied under an occlusive dressing for at least 1 hour. To provide dermal analgesia for clinical procedures such as split skin graft harvesting, lidocaine and prilocaine cream, 2.5%/2.5% should be applied under occlusive dressing for at least 2 hours. Satisfactory dermal analgesia is achieved 1 hour after application, reaches maximum at 2 to 3 hours, and persists for 1 to 2 hours after removal. Absorption from the genital mucosa is more rapid and onset time is shorter (5 to 10 minutes) than after application to intact skin. After a 5 to 10 minute application of lidocaine and prilocaine cream, 2.5%/2.5% to female genital mucosa, the average duration of effective analgesia to an argon laser stimulus (which produced a sharp, pricking pain) was 15 to 20 minutes (individual variations in the range of 5 to 45 minutes). Dermal application of lidocaine and prilocaine cream, 2.5%/2.5% may cause a transient, local blanching followed by a transient, local redness or erythema.
Overdosage
Peak blood levels following a 60 g application to 400 cm2 of intact skin for 3 hours are 0.05 to 0.16 mcg/mL for lidocaine and 0.02 to 0.10 mcg/mL for prilocaine. Toxic levels of lidocaine (>5 mcg/mL) and/or prilocaine (>6 mcg/mL) cause decreases in cardiac output, total peripheral resistance and mean arterial pressure. These changes may be attributable to direct depressant effects of these local anesthetic agents on the cardiovascular system. In the absence of massive topical overdose or oral ingestion, evaluation should include evaluation of other etiologies for the clinical effects or overdosage from other sources of lidocaine, prilocaine or other local anesthetics. Consult the package inserts for parenteral Xylocaine (lidocaine HCl) or Citanest (prilocaine HCl) for further information for the management of overdose.