Onozawa Akihiko, Kikukawa Azusa, Miyamoto Yoshinori
Aeromedical Laboratory, Japan Air Self-Defense Force, Tachikawa, Tokyo, Japan.
Dyn Med. 2008 Jan 28;7:3. doi: 10.1186/1476-5918-7-3.
Loratadine (Claritin), an over-the-counter antihistamine in U.S. and UK, is acceptable for use without adverse side effects by aircrew with mild or moderate allergic or other situations requiring an antihistamine. Although +Gz (head to foot direction) tolerance testing for aircrew with loratadine has not been documented in the published literature, it is commonly accepted that loratadine dose not effect +Gz tolerance. The purpose of this study was to offer and validate a new evaluation method for +Gz tolerance testing with loratadine by using a near-infrared spectroscopy (NIRS).
A double-blind, placebo-controlled, randomized, crossover protocol was used to administer 10 mg of loratadine or placebo in nine healthy subjects. The subjects didn't wear anti-G suit. The +Gz exposure profiles consisted of, in series, a gradual onset ran (0.1 G.sec-1) to the subject's visual end-point (peripheral light loss) or loss of consciousness (GLOC), and rapid onset run (1.0 G.sec-1) to the subject's same end-point. In this study, G-level tolerance was defined as the +Gz level at visual end-point and/or at GLOC. As a subject's G-duration tolerance, we measured the total time (seconds) during rapid onset run. Otherwise, to confirm the effect of loratadine on +Gz tolerance, we measured the cerebral NIRS variables (hemoglobin concentration changes and tissue oxygenation index) as a new quantitative method for +Gz tolerance during a centrifuge experiments.
No significant differences were observed in +Gz tolerance (+Gz level, duration time and NIRS variables) between subjects taking loratadine and placebo.
Our results demonstrate that loratadine has no detectable effect on +Gz tolerance by using a new method with cerebral NIRS variables and the traditional method with +Gz level and duration time. This study represents the first use of a quantitative parameter such as cerebral NIRS variables to assess the effects of a drug on acceleration tolerance.
氯雷他定（克敏能）在美国和英国是一种非处方抗组胺药，对于患有轻度或中度过敏或其他需要使用抗组胺药情况的机组人员来说，使用该药是可以接受的，且无不良副作用。尽管氯雷他定对机组人员的 +Gz（头至脚方向）耐力测试在已发表的文献中尚无记载，但人们普遍认为氯雷他定不会影响 +Gz 耐力。本研究的目的是通过使用近红外光谱（NIRS）提供并验证一种用于氯雷他定 +Gz 耐力测试的新评估方法。
采用双盲、安慰剂对照、随机、交叉试验方案，给 9 名健康受试者服用 10 毫克氯雷他定或安慰剂。受试者未穿抗荷服。+Gz 暴露曲线依次包括一个逐渐增加至受试者视觉终点（周边光损失）或意识丧失（GLOC）的递增阶段（0.1 G·秒⁻¹），以及一个快速增加至受试者相同终点的快速递增阶段（1.0 G·秒⁻¹）。在本研究中，G 水平耐力定义为视觉终点和/或 GLOC 时的 +Gz 水平。作为受试者的 G 持续时间耐力，我们测量了快速递增阶段的总时间（秒）。此外，为了确认氯雷他定对 +Gz 耐力的影响，我们在离心机实验中测量了大脑 NIRS 变量（血红蛋白浓度变化和组织氧合指数），作为一种用于 +Gz 耐力的新定量方法。
服用氯雷他定和安慰剂的受试者在 +Gz 耐力（+Gz 水平、持续时间和 NIRS 变量）方面未观察到显著差异。
我们的结果表明，通过使用大脑 NIRS 变量的新方法以及 +Gz 水平和持续时间的传统方法，氯雷他定对 +Gz 耐力没有可检测到的影响。本研究首次使用诸如大脑 NIRS 变量这样的定量参数来评估药物对加速度耐力的影响。
