Your Compounding Questions Answered

Martn A. Erickson III, RPh
Published Online: Monday, January 14, 2013
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Q: I am interested in compounding the LET (lidocaine/epinephrine/tetracaine) solution you mentioned in a previous column (Erickson MA III, Pharm Times, 2003;69[7]:78). Have there have there been any updates since 2003 to the information presented? Furthermore, is there a standardized strength for the ingredients that every institution can use that is properly referenced as efficacious with a good safety profile and stability data?

A: The recent shortages of lidocaine HCl ( Zywgfn) gave rise to a number of questions about the use of lidocaine HCl with epinephrine bitartrate and tetracaine for topical anesthesia.

Trissel’s Stability of Compounded Formulations references several combinations of these medications for use in place of tetracaine, epinephrine, and cocaine solution, for which special security concerns arise. A study performed at Minneapolis Children’s Hospital led to an article from which a frequently referenced formulation has been derived.1 A gel can be prepared using this formulation as well. The formulation ingredients recently were released in a “LETS Kit” for compounding convenience.

Suggested formulation:

Lidocaine HCl USP.............................4000 mg
Epinephrine bitartrate USP..................180 mg
Tetracaine HCl USP..............................500 mg
Sodium metabisulfite NF .......................75 mg

Method of preparation1:
  1. Add approximately 20 mL of Purified Water USP to a graduated cylinder that will accurately measure 100 mL.
  2. Weigh/measure the powders accurately. Transfer to a ceramic or Wedgwood mortar and grind to a fine, uniform powder with the pestle.
  3. Add the powders to the graduated cylinder.
  4. When all the powders have been added to the graduated cylinder, pour approximately 50 mL of Purified Water USP into the graduated cylinder and stir to dissolve the powders completely.
  5. Add sufficient Purified Water USP to the graduated cylinder to reach a final volume of 100 mL.
  6. Label for use. A beyond-use date of “6 months refrigerated” can be applied to the final compounded solution.1

Mr. Erickson is director of professional affairs and director of professional services at Gallipot, a Fagron company.

  1. Schilling CG, Bank DE, Borchert BA, Klatzko MD, Uden DL. Tetracaine, epinephrine (adrenalin), and cocaine (TAC) versus lidocaine, epinephrine, and tetracaine (LET) for anesthesia of lacerations in children. Ann Emerg Med. 1995;25(2):203-208.

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