Stopping Head Lice: Why to Move on From OTC Treatment to Prescription Therapy

Sponsored Editorial Head lice are grayish-white insects about the size of a sesame seed that feed on human blood and spread primarily through head-to-head contact.1-3 Cases of head lice occur in an estimated 6 million to 12 million people in the United States each year, with most cases occurring in children aged 3 to 12 years.4 Although often considered a benign condition, head lice causes anxiety among the parents of school-aged children and may lead to absences from school and work.3 Additionally, among affected individuals, persistent pruritus may cause sleeplessness, and scratching may lead to skin damage and potential secondary bacterial infections.1,3 Pharmacists should be aware of the limitations of over-the-counter (OTC) treatments, to which lice are widely resistant in 28 states, and opportunities with prescription treatment to ensure rapid resolution of head lice, minimize patient costs, and maximize patient satisfaction.5 TREATMENT GUIDELINES Current treatment guidelines published by the American Academy of Pediatrics (AAP) mention the availability of 2 OTC treatments for self-treatment of head lice (permethrins and pyrethrins) but emphasize the increasing need for guidance by health care professionals in selecting treatment.2 Limitations of self-treatment include misdiagnosis, OTC product misuse, and repeated infestations resulting from treatment resistance and a lack of ovicidal activity with OTC products.2 Pharmacists can help patients understand current trends in the effectiveness of OTC treatments, recognize key differences between prescription treatment options, and select an appropriate prescription treatment option in collaboration with patients and prescribers. Of the available OTC treatments for head lice, active ingredients include permethrins and pyrethrins.2 In using OTC treatment options, patients should be aware that permethrins and pyrethrins are typically applied twice, with treatments separated by 7 to 10 days.6,7 It is also important to inform patients that OTC lice treatment products may trigger breathing difficulties and asthmatic episodes, particularly in patients with a ragweed allergy.6,7 In addition to explaining the appropriate use of OTC treatments, pharmacists can alert patients that these treatments are often overused, are often used inappropriately in cases when there is no infestation, and have become increasingly ineffective over time due to widespread resistance.3,8 THE GROWING CHALLENGE OF OTC TREATMENT RESISTANCE Resistance to OTC products has become progressively worse over the past several decades.3,5 In the late 1980s, cure rates with permethrins and pyrethrins were very high, with 93.5% to 100% efficacy, often with a single treatment. By the late 1990s, OTC treatments had effectiveness rates lower than 80%, and by the early 2000s, OTC permethrin efficacy rates hovered at 45% to 55%.3 Contemporary estimates of efficacy rates are as low as 25% to 28%, with widespread resistance mutations documented in head lice collected from 138 sites in 48 states (TABLE 1).5,9 In discussing OTC treatments with patients, it is important to manage expectations by emphasizing the duration of treatment (approximately 7 to 10 days) and that lice eradication rates with OTC products are low.6,7,9 Due to high rates of resistance to OTC treatment, pharmacists must be aware of the characteristics of prescription treatment options and must be ready to answer questions about alternatives to OTC therapy. PRESCRIPTION TREATMENT OPTIONS Prescription treatments with an indication for treatment of head lice recommended by the AAP include malathion, benzyl alcohol, spinosad, and ivermectin.2 In explaining the available treatments to patients, it is important to consider the mechanism of action, potential toxicity, and duration of treatment, including reapplication (TABLE 2).10-13 Although many treatments for head lice are toxic enough to kill lice immediately, treatments have varying efficacy against the eggs of head lice. When eggs hatch, for many products, retreatment may be necessary to fully eradicate the infestation. Because ivermectin paralyzes both active lice and developing lice, lice exposed to ivermectin can no longer feed on human blood. As a result, repeat application is unnecessary.2,10-13 ROLE OF THE PHARMACIST Head lice is a bothersome condition that may cause pruritus, difficulty sleeping, and secondary infection, as well as lost productivity for both parents and children.1,3 Patients should be counseled about the low efficacy rate of OTC products due to widespread resistance.9 In consideration of the challenges of OTC treatment, which also extend to the 7- to 10-day duration of OTC treatment, the risks of misuse, and inappropriate product use, pharmacists should encourage patients to see a physician or a nurse practitioner who can prescribe a prescription lice treatment. Pharmacists have an important role in characterizing prescription treatments and helping both prescribers and patients understand the appropriate use of these therapies. Differences in product action, efficacy, and use characteristics may affect treatment selection. Notably, only 1 product on the US market, Sklice (ivermectin), stops head lice with a single application, with no need for a second application and consequent adherence concerns. In educating patients and caregivers on treatment options for head lice, pharmacists can help patients understand their options and give their patients the best chance of rapid resolution of this common and disruptive condition. REFERENCES Centers for Disease Control and Prevention (CDC). Parasites-lice-head lice: frequently asked questions (FAQ). CDC website. https://www.cdc.gov/parasites/lice/head/gen_info/faqs.html. Updated September 1, 2015. Accessed February 28, 2017. Devore CD, Schutze GE; Council on School Health and Committee on Infectious Diseases, American Academy of Pediatrics. Head lice [erratum in: Pediatrics. 2015;136(4):781-782]. Pediatrics. 2015;135(5):e1355-e1365. doi:10.1542/peds.2015-0746. Lebwohl M, Clark L, Levitt J. Therapy for head lice based on life cycle, resistance, and safety considerations. Pediatrics. 2007;119(5):965-974. doi:10.1542/peds.2006-3087. Gao J-R, Yoon KS, Frisbie RK, Coles GC, Clark JM. Esterase-mediated malathion resistance in the human head louse, Pediculus capitis (anoplura: pediculidae). Pesticide Biochem and Physiol. 2006;85:28-37. doi:10.1016/j.pestbp.2005.09.003. Gellatly KJ, Krim S, Palenchar DJ, et al. Expansion of the knockdown resistance frequency map for human head lice (phthiraptera: pediculidae) in the United States using quantitative sequencing. J Med Entomol. 2016;53(3):653-659. doi:10.1093/jme/tjw023. Nix [package insert]. Langhorne, PA: Insight Pharmaceuticals Corp; 2009. Rid [package insert]. Whippany, NJ: Bayer HealthCare, LLC; 2016. Hansen RC, O’Haver J. Economic considerations associated with Pediculus humanus capitis infestation. Clin Pediatr (Phila). 2004;43(6):523-527. doi:10.1177/000992280404300603. Koch E, Clark JM, Cohen B, et al. Management of head louse infestations in the United States—a literature review. Pediatr Dermatol. 2016;33(5):466-472. doi:10.1111/pde.12982. Ovide [package insert]. Hawthorne, NY: TaroPharma; 2014. Ulesfia [package insert]. Dublin, Ireland: Lachlan Pharmaceuticals; 2015. Natroba [package insert]. Brownsburg, IN: ParaPRO LLC; 2015. Sklice [package insert]. Atlanta, GA: Arbor Pharmaceuticals, LLC; 2016.

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