EMLA® (eutectic mixture of lidocaine and prilocaine) cream is currently not recommended for use in infants < 1 month of age because of the potential risk of methemoglobinemia as a result of the o-toluidine metabolite of prilocaine. We studied bioavailability and changes in methemoglobin levels following topical penile exposure to 1 g of EMLA cream for 1 hour in piglets. Lidocaine, prilocaine, and o-toluidine concentrations were measured simultaneously using a high-performance liquid chromatography method. The systemic bioavailability of EMLA was low: 4.0 ± (SD) 4.7% for lidocaine (range 0-13.6; n = 8) and 7.2 ± 5.7% for prilocaine (range 0-14.5; n = 8). The ratio between exposure to o-toluidine with EMLA versus intravenous administration (i.e., AUCemla/AUQv; see text) was also low: 4.2 ± 9.3% (range 0–28.6; n = 9). The mean maximum methemoglobin value after intravenous administration was 1.23 ± 0.64% (range 0.5–3.0; n = 12) and after penile application 0.99 ± 0.36% (range 0.5–2.0; n = 12). The methemoglobin value was elevated significantly above baseline after intravenous administration (p = 0.03), but not after penile application of EMLA. These findings suggest that penile administration of 1 g of EMLA may be safe for neonatal circumcision, but further study is required.

Keywords:
Eutectic mixture, lidocaine/prilocaine, Local anesthesia, newborn animals, Methemoglobin concentration, Neonatal diseases, Penile circumcision, anesthetics, Pharmacokinetics, lidocaine/prilocaine
This content is only available via PDF.
© 1995 S. Karger AG, Basel
1995
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.