Permethrin對頭蝨的治療不再有效


  Dec. 9, 2002─一般最常用的去頭蝨藥是permethrin 1%藥膏(PLT),在藥房就可以買到,藥品說明書表示療效達97%,但十一月號小兒科期刊的研究顯示,目前這種藥效果明顯較差,甚至與除卵一併進行也是如此。
  
  在最初管制批准1% PLT成為處方去頭蝨藥時,多種研究出版文件顯示病患接受一次10分鐘治療的7和14天後分別接受評估,成功率至少為97%。佛羅里達州邁阿密大學醫學院Terri L. Meinking及其同僚表示,在美國和其他國家有愈來愈多臨床治療出現抗藥性的報告,同時對於去除頭蝨及其體外衍生物的效果也減少。
  
  在這個隨機、觀察者隱藏的研究中,95名有頭蝨的成人和孩童在第一天接受1% PLT的治療,如果還有頭蝨,則在第八天接受第二次治療,隨機選出三分之一的家庭進行梳頭除蟲卵的動作,三分之二的家庭沒有梳頭除蟲卵。
  
  在沒有梳頭的組當中,透過目視及洗頭過濾發現除頭蝨的比例分別是第二天為83.1%(95%信賴區間[CI],71.0 - 91.6),第八天進行第二次治療之前為為45.8%(95% CI, 32.7 - 59.2),第九天為77.6%(95% CI, 64.7 - 87.5),第十五天為78.3%(95% CI, 65.8 - 87.9)。梳頭的那一組效果並沒有比較好。
  
  大多數的研究對象在第八天都需要第二次治療,在56名再度接受治療的病患中,15名在第十五天仍然有頭蝨,失敗率為27%。一名研究對象出現輕微頭皮毛囊炎,粗略認為可能與PLT有關,另兩名則出現自限性的嘔吐及上呼吸道感染。
  
  Terri L. Meinking認為,在這個母體中,1% PLT的效果明顯低於95%,而且出現對1% PLT的抗藥性。由非專業照護者進行梳頭除蟲卵的效果不佳,顯示將梳頭作為附屬的治療法並不可靠。
  
  Merck研究實驗室支持這項計畫並雇用其中幾位作者。
  
  

Permethrin No Longer as Effect

By Laurie Barclay, MD
Medscape Medical News

Dec. 9, 2002 — The most commonly used pediculicide for lice is permethrin 1% cream (PLT), now available over the counter. At its introduction, it was 97% effective, but a study in the November issue of the Journal of Pediatrics showed that it is currently significantly less effective, even when combined with nit removal.

"Multiple studies were published at the time of the initial regulatory approval of 1% PLT as a prescription pediculicide documenting success rates of at least 97% when patients were evaluated at both 7 and 14 days after a single 10-minute treatment," write Terri L. Meinking, BA, from the University of Miami School of Medicine in Florida, and colleagues. "Increasingly, clinical resistance to treatment is being reported in the U.S. and multiple other countries, as well as reduced efficacy of permethrin and derivatives in vitro."

In this randomized, observer-blinded study, 95 infested adults and children were treated with 1% PLT on day 1 and, if still infested, on day 8. One-third of households were randomized to combing, and two-thirds did not attempt to remove nits by combing.

In the no-combing group, the lice-free rate determined by visual inspection and shampooing/straining was 83.1% on day 2 (95% confidence interval [CI], 71.0 - 91.6), 45.8% on day 8 before the second treatment (95% CI, 32.7 - 59.2), 77.6% on day 9 (95% CI, 64.7 - 87.5), and 78.3% on day 15 (95% CI, 65.8 - 87.9). Efficacy was no better on any given day in the combing group.

Most subjects required a second treatment on day 8. Of the 56 participants who were retreated, 15 still had lice on day 15, yielding a failure rate of 27%. One subject had mild scalp folliculitis and rash thought to be possibly related to PLT, and two others had self-limited vomiting and upper respiratory infection.

"In this population, 1% PLT was significantly less than 95% effective and suggests resistance to 1% PLT," the authors write. "The failure of nit removal combing by nonprofessional caregivers to improve efficacy demonstrates the unreliability of combing as adjunctive treatment in this setting."

Merck Research Laboratories supported this study and employs some of its authors.

J Pediatr. 2002;141:665-670

Reviewed by Gary D. Vogin, MD

    



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