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A possible prevention strategy of radiation pneumonitis: combine radiotherapy with aerosol inhalation of hydrogen-rich solution.

水素リッチ溶液のエアロゾル吸入と放射線療法の併用による放射線肺炎予防戦略の提案

letter inhalation not assessed

Abstract

Radiation pneumonitis represents a significant barrier to dose escalation in radiotherapy. Molecular hydrogen has been identified as a potentially safe radioprotective agent owing to its selective scavenging of hydroxyl radicals and peroxynitrite. Because the majority of ionizing radiation-induced cellular injury is attributable to hydroxyl radical generation, this paper proposes that aerosol inhalation of hydrogen-rich physiological saline combined with radiotherapy could serve as a novel preventive approach against radiation pneumonitis. The use of hydrogen-saturated saline rather than pure hydrogen gas is emphasized for safety reasons, given the explosive nature of gaseous hydrogen at high concentrations.

Mechanism

Molecular hydrogen selectively neutralizes hydroxyl radicals and peroxynitrite generated by ionizing radiation, thereby reducing radiation-induced cellular damage without interfering with the therapeutic effects of radiotherapy.

Bibliographic

Authors
Chuai Y, Zhao L, Ni J, Sun D, Cui J, Li B, et al.
Journal
Med Sci Monit
Year
2011
PMID
21455114
DOI
10.12659/msm.881698
PMC
PMC3539519

Tags

Disease:cancer radiation (side-effect) (41) Delivery:inhalation delivery (196) Mechanism:hydroxyl radical scavenging (352) anti-inflammatory (743) oxidative stress (899) peroxynitrite scavenging (64) reactive oxygen species (774)

Delivery context

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

→ Evidence by delivery route

Safety notes

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

See also:

Other papers on the same disease / condition