Lidocaine and prilocaine (topical)

Drug Interactions: Lidocaine and Prilocaine Cream 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: TABLE 3 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 be used concomitantly with other products containing lidocaine and/or prilocaine, cumulative doses from all formulations must be considered.

Pregnancy. Use in Pregnancy: Teratogenic Effects: Reproduction studies with lidocaine have been performed in rats and have revealed no evidence of harm to the fetus (30 mg/kg subcutaneously; 22 times SDA). Reproduction studies with prilocaine have been performed in rats and have revealed no evidence of impaired fertility or harm to the fetus (300 mg/kg intramuscularly; 188 times SDA). There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, Lidocaine and Prilocaine Cream should be used during pregnancy only if clearly needed.

Reproduction studies have been performed in rats receiving subcutaneous administration of an aqueous mixture containing lidocaine HCl and prilocaine HCl at 1:1 (w/w). At 40 mg/kg each, a dose equivalent to 29 times SDA lidocaine and 25 times SDA prilocaine, no teratogenic, embryotoxic or fetotoxic effects were observed.

Nursing Mothers: Lidocaine, and probably prilocaine, are excreted in human milk. Therefore, caution should be exercised when Lidocaine and Prilocaine Cream is administered to a nursing mother since the milk:plasma ratio of lidocaine is 0.4 and is not determined for prilocaine.