Effect of relative humidity on the photocatalytic activity of Titanium dioxide and photostability of famotidine

✍ Scribed by K. Kakinoki; K. Yamane; R. Teraoka; M. Otsuka; Y. Matsuda

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 124 KB
• Volume: 93
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.10575

✦ Synopsis

Titanium dioxide (TiO 2 ) has been widely used as a pharmaceutical excipient and is also known to be a strong photocatalyst. An investigation into the relationship between the photocatalytic activity of TiO 2 and the photostability of famotidine, which is known as an H 2 -blocker, is presented. The photocatalytic activity of the anatase form of TiO 2 , as measured by the four-probe method, is $1.5 times higher than that of the rutile form. Discoloration of famotidine in a binary system containing TiO 2 depends significantly on both the wavelength of the irradiating light and the crystal form of the TiO 2 , with the degree of discoloration of anatase higher than that of the rutile form. Discoloration of famotidine also depends on relative humidity. The relationship between discoloration rate constant and water vapor pressure is linear. These results demonstrate that famotidine is easily discolored by the photocatalytic activity of TiO 2 and suggest that the solid-state photocatalytic activity of TiO 2 is strongly affected by relative humidity.