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Polymorphism control of pharmaceutical compound acetaminophen by ultrasonic irradiation

Yoichiro Mori 1Yoshinori Takahashi 1,2Kenji Ikeda 1Toshihiko Yamada 1Ken Nishimura 1Mihoko Maruyama 1Hiroshi Yoshikawa 1,3Shino Okada 2Hiroaki Adachi 1,2Shigeru Sugiyama 4Hiroyoshi Matsumura 1,2Kazuhumi Takano 2,5Tsuyoshi Inoue 1,2Satoshi Murakami 2,6Masashi Yoshimura 1Yusuke Mori 1,2

1. Graduated School of Engineering, Osaka University (OSAKAUNIV), Osaka, Japan
2. SOSHO Inc., Osaka 565-0871, Japan
3. Saitama University, 255 Shimo-ookubo, Sakuraku, Saitama 338-8570, Japan
4. Graduate School of Science, Osaka University, Osaka 565-0871, Japan
5. Kyoto Prefectural University, Kyoto 606-0823, Japan
6. Tokyo Institute of Technology, Tokyo 152-8550, Japan

Abstract

Polymorphs are solid phases in which the chemical composition is equal but the crystal structure differs. In the pharmaceutical industry, especially, most of compounds have polymorphs, and polymorphism control is very important because different polymorphs exhibit different stabilities, drug effects, formation properties, etc. Acetaminophen (Figure 1), which is one of the typical pharmaceutical compounds, has three known polymorphs, numbered I, II and III. The stable form I is the commercially used form because of its stability. In contrast, the metastable form II has been shown to be more soluble and more readily compressible into tablets than form I, and controlled crystallization of the form II is an important issue for practical use. Hence we attempted to control polymorphism of acetaminophen form II by ultrasonic irradiation in this study.

Acetaminophen aqueous solutions (32 mg/ml, total 50 bottles) were prepared, cooled to 0°C at a constant cooling rate (3°C/h), maintained at that temperature for about 2 days,  and irradiated with ultrasound with different frequencies (no irradiation, 28, 45, 100 kHz) for investigating the effect of crystallization and polymorphism control. Figure 2 shows the probability of nucleation and form II crystallization on each condition. In the cases of no irradiation and 100 kHz irradiation, nucleation did not occur in solutions (no irradiation: 0/20 (0%), 100 kHz: 0/10 (0%)). In contrast, ultrasonic irradiation with the frequency of 28 or 45 kHz promoted the nucleation (28 kHz: 9/9 (100%), 45 kHz: 10/10 (100%)), and also increased probability of the form II crystallization as shown in Figure 2 (28 kHz: 6/9 (67%), 45 kHz: 6/10 (60%)).

Fig. 1. Structural formula of acetaminophen

 Fig. 2. Frequency dependence of crystallization probability

 

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Related papers

Presentation: Oral at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, General Session 3, by Yoichiro Mori
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-04-15 18:42
Revised:   2013-07-16 17:03