breast-feeding patients (Cengiz, 2007; Donaldson & Goodchild, 2012; Fayans, Stuart, Carsten, Ly, & Kim, 2010). Vasoconstrictors are often combined with local anesthetics to impede systemic absorption, increase the efficacy, and prolong the duration of these agents. In pregnant mothers there may be a concern that the alpha-adrenergic effects of epinephrine may decrease uterine blood flow, while its beta-adrenergic activity may decrease uterine activity and prolong labor (Donaldson & Goodchild, 2012; Hood, Dewan, & James, 1986). However, concentrations of vasoconstrictors in local anesthetics are in very small amounts – 1:100,000 (0.01 mg/mL) or 1:200,000 (0.005 mg/mL) of epinephrine or 1:20,000 (0.05 mg/mL) of levonordefrin – and a cumulative dose of up to 0.1 mg can be administered safely to pregnant patients. This amount equates to 5 cartridges of a local anesthetic containing 1:100,000 epinephrine, or 10 cartridges containing 1:200,000 epinephrine. OHCPs are reminded that careful technique is paramount to avoid an accidental intravascular injection (Donaldson & Goodchild, 2012). In spite of the general lack of studies concerning the use of epinephrine during human lactation, the drug’s short half-life means that it is not contraindicated for use during breast- feeding and it is unlikely that epinephrine distributes into breast milk (Donaldson & Goodchild, 2012; Gunatilake & Patil, n.d.; Hale, 2010). The other vasoconstrictor in dental local anesthetic cartridges, levonordefrin, is supplied as a 1:20,000 concentration, which is equipotent to 1:100,000 epinephrine. (Epinephrine is five times as potent as levonordefrin; Robertson, Taylor, & Gage, 1984.) Unlike epinephrine, levonordefrin disproportionately affects the alpha-adrenergic system and retains less vasopressor activity (75% alpha-adrenergic versus 25% beta-adrenergic effects; Lawaty, Drum, Reader, & Nusstein, 2010). In medicine, this property has shown levonordefrin to incite less cardiac and central nervous system stimulation, although this has not been the same experience in dentistry given the much lower concentrations used (Guglielmo, Reader, Nist, Beck, & Weaver, 1999). The use of levonordefrin cannot be recommended because, as is the case with epinephrine, there is no FDA pregnancy risk classification for this drug. Even so, some scholars suggest that levonordefrin is safe for women during pregnancy and lactation (Donaldson & Goodchild 2012; Fayans et al., 2010; Hilgers et al., 2003). Table 9 summarizes the recommendations for local anesthetic and vasoconstrictor use in dental patients who are either pregnant or lactating (Donaldson & Goodchild, 2012). In the case of combination products (such as lidocaine with epinephrine), the safety with respect to either pregnancy or breast-feeding is dependent on the highest risk moiety (AAP, 2001). Allergy status Although adverse reactions to local anesthetics are relatively common, most such events are not true allergic reactions. The two distinct types of allergic reactions to local anesthetics are allergic contact dermatitis with delayed swelling at the site of administration and urticaria (hives) with anaphylaxis. The former type of reaction is well established, while the latter is rare, with the data limited to case reports. However uncommon – their estimated prevalence is much less than 1% in the general population – allergic reactions to local anesthetics can occur (Batinac, Sotošek Tokmadžić, Peharda, & Brajac, 2013; Volcheck & Mertes, 2014; Chan, 2016; Bina, Hersh, Hilario, Alvarez, & McLaughlin, 2018). In general, the ester class of local anesthetics (mainly used as topicals in dentistry) pose a greater potential for true allergic reactions than the amide class (used in solutions).
Table 9: Key Medication Considerations During Pregnancy and Breastfeeding Medication Safe During Breastfeeding? FDA Risk Category Safe During Pregnancy?
Articaine
C
Use with caution Use with caution
Use with caution
Bupivacaine
C
Yes
Lidocaine Plain
B
Yes
Yes
Lidocaine (with epinephrine)
B
Yes
Yes
Mepivacaine Plain
C
Use with caution Use with caution
Yes
Mepivacaine (with levonordefrin)
C
Yes
Prilocaine Yes Note . Adapted from “Pregnancy, Breast-Feeding and Drugs Used in Dentistry,” by M. Donaldson and J. H. Goodchild, 2012, Journal of the American Dental Association, 143(8), pp. 858-871. In 2015 the FDA replaced the former pregnancy risk letter B Yes categories on prescription and biological drug labeling with new information to make them more meaningful to both patients and healthcare providers (Brucker & King, 2017). The old five-letter system left patients and providers ill- informed and resulted in false assumptions about the actual meaning of the letters. The new labeling system allows better patient-specific counseling and informed decision making for pregnant women seeking medication therapies. While the new labeling improves the old format, it still does not provide a definitive “yes” or “no” answer in most cases. Also, the Pregnancy and Lactation Labeling Final Rule (PLLR) went into effect on June 30, 2015 yet the timelines for implementing this new information on drug labels (also known as the package insert ) is still variable. Clinical interpretation is still required on a case-by-case basis, and for this reason most practitioners continue to rely on the traditional five-letter system. The A, B, C, D and X risk categories, in use since 1979, are now replaced with narrative sections and subsections as shown in Table 10 (U.S. Food and Drug Administration, 2016). Although nonallergic reactions to local anesthetics are more common than true allergic reactions, these “pseudoallergic reactions” can mimic true allergic reactions and include vasovagal syncope, sympathetic stimulation, psychomotor or anxiety-related reactions, and systemic toxic effects related to the pharmacologic properties of these agents. Clinical manifestations of nonallergic reactions can resemble aspects of allergic reactions and include palpitations, dyspnea, hypotension, lightheadedness, and syncope – signs and symptoms that can be seen in both allergic and nonallergic reactions. However, development in a patient of wheezing, pruritus, urticaria, or angioedema strongly suggests a true allergy.
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