Laboratory and clinical studies of SY5555

Hironobu Koga, Masanori Iwamoto, Shigeru Kohno, Kohei Hara, Chikako Mochida, Kazuyuki Sugawara, Mitsuo Kaku, Koichi Watanabe, Takeshi Ishizaki, Takakazu Otubo, Yuichi Inoue, Toru Ishino, Kenji Kawano, Masaaki Yatsugi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


A newly developed oral penem, SY5555, was compared in vitro and in vivo with imipenem (IPM), cefixime (CFIX) and cefteram (CFTM). The results were as follows: 1. Antimicrobial activity: The minimum inhibitory concentrations (MICs) against 515 clinical isolates of 16 different species were determined by the microbroth dilution method. SY5555 showed excellent antimicrobial activity against gram-positive and -negative bacteria except for methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter anitratus. The MICs of SY5555 were nearly equal to those of IPM, and those for gram-positive bacteria were greater than those of CFIX and CFTM. 2. SY5555 concentrations in serum and sputum: A patient was given 300 mg of SY5555 orally before meal and its concentrations in serum and sputum were measured at intervals using HPLC. A peak serum concentration of 1.32 μg/ml was achieved 1 hour after administration, and the peak sputum level of 0.45 μg/ml was observed 1~2 hours after administration. This suggests that SY5555 has rapid and good penetration into the lung. Similarly, two patients were given 300 mg of SY5555 orally after a meal. Peak concentrations in serum of 1.17 μg/ml and 1.54 μg/ml were achieved 2 hours after the administration. 3. Clinical efficacy and adverse reactions: 14 patients with respiratory tract infections were treated with SY5555, and the overall efficacy rate was 66.7%(good in 8 cases, fair in 2, poor in 2, not evaluable in 2). As to side effects, nausea and loose stool were observed in 2 cases but improved after the completion of SY5555 treatment. As to abnormal laboratory findings, eosinophillia in 1 case, decrease of platelets in 1 and elevation of BUN in 1 were observed, but they were mild and transient.

Original languageEnglish
Pages (from-to)381-388
Number of pages8
Publication statusPublished - 1994 Jan 1


  • Sy5555

ASJC Scopus subject areas

  • Pharmacology (medical)
  • Infectious Diseases
  • Pharmacology
  • Drug Discovery
  • Oncology


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