Anh.Duong-Log

Article
Chihara, Y., Sato, A., Ohtani, M., Fujimoto, C., Hayashi, T., Nishijima, H., Yagi, M. & Iwasaki, S. 2013, "The effect of a first-generation H1-antihistamine on postural control: a preliminary study in healthy volunteers", Experimental Brain Research, vol. 231, no. 3, pp. 257-266. (DOI)

Abstract
- A double-blind study was conducted on young adults to investigate the effect of d-chlorpheniramine, a H1-antihistamine, on postural control. The results revealed that visual and vestibular systems were affected by d-chlorpheniramine. **Introduction** - Visual, vestibular, and somatosensory are the three main systems having big impacts on postural control. A foam posturography system was used to evaluate the importance of each sensory input on postural control under the effects of the first-generation H1-antihistamine. - First-generation H1-antihistamines were known to cause many problems to the central nervous system and several key receptors which lead to sedation although they were widely used for allergic relief. There have been many studies on sedative effects of the antihistamines but not on postural control; therefore, this study evaluated the their effects on postural sway. **Materials and methods**

Subjects
- The study was conducted on three 9-member groups (place-bo, 2-mg d-chlorpheniramine, and 4-mg d-chlorpheniramine) with some restricted conditions.

Allocation concealment
- All the members of three groups were not told which group they belonged to.

Postural sway measurement
- An instrument was used to measure the changes in posture of each person while they were standing either on the foam rubber or on the ground with their eyes open or closed.

Statistical analysis
- Two variables, path length and path area, were collected and analyzed to determine the effect of the antihistamine on each person. - Several analytical methods such as t-test and the analysis of variance (ANOVA) were used to statistically evaluate the results. **Results** - A diagram showed that one male subject who took 4-mg d-chlorpheniramine exhibited major postural sway. However, there was not any cases in which the subjects asked for the assistance.

Control subjects
- The changes in path length and path area for placebo group were generally stable.

Inter-group analysis of the effect of d-chlorpheniramine
- Larger postural sway were observed in the group taking 4-mg d-chlorpheniramine.

Inter-individual analysis of the effect of 4-mg d-chlorpheniramine
- The differences in sex, age, BMI did not have significant effects on the results. **Discussion** - In a reduced somatosensory condition, larger sway were observed. - Histamine is an important neurotransmitter for sensory and motor activities in biological pathways. - After 2-3 hours of drug intake, the subjects expressed the maximum effects on postural sway. - The eye open with foam rubber condition had the biggest effects on postural sway. This indicated that the d-chlorpheniramine mainly affected the visual and vestibular systems. - The largest sway, not small sways, was reflected by the path area while all sways were reflected by the path length. - The larger the path area, the more risk of sudden falls of a subject. - One of the limitations of this study was that it only study the effects of the antihistamine on young adults. The drug may cause significant problems if it was used for older and younger people. - Future approaches would be putting the postural sway together with driving performance for comparison. Also, to see whether the effects of the antihistamines are the same for all people, a broader age range would be chosen for the study.

**Research topic**

Introduction
- Allergy and its causes - Definition of an antihistamine and history of use - Different types of antihistamine - The importance of H1-antihistamine

First generation H1-antihistamine
- Common features - Efficacy - Adverse drug reactions

Second generation H1-antihistamine
- Common features - Efficacy - Adverse drug reactions

Third generation H1-antihistamine
- Common features - Efficacy - Adverse drug reactions