(1) It should be recognized that the injection of epinephrine-containing solutions in or around fingers, toes, and the penis is not recommended.
(2) Freshly prepared combinations of vasoconstrictors and local anesthetics are more effective than commercially premixed epinephrine-containing local anesthetic solutions. This is because a very low pH is required to stabilize the epinephrine in these mixtures. In general, the content of one part epinephrine to 200,000 parts of the local anesthetic agent (is optimum) will minimize the side effects inherent with epinephrine. Great care must be taken in calculating this dilution. Small, precisely calibrated syringes should be used in the mixing process. It should be noted that the standard solution of epinephrine supplied is a 1:1000 (1 to 1000) concentration in each glass ampule. This means that 1 milliliter of the 1:1000 epinephrine solution contains 1 milligram of epinephrine. In preparing a 1:200,000 dilution, epinephrine should be added to a local anesthetic solution on a ratio of 0.1 milliliter-20 milliliters of local anesthetic solution. This does not apply to subarachnoid injections, in which a higher concentration of epinephrine is required.
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