Abstract
Laboratory and clinical studies were conducted on a new semi-synthetic penicillin, aminocyclohexyl penicillin (Cyclacillin ‘Takeda’), and the followings were observed.
1. Serum levels after the oral administration of 500mg to 3 healthy volunteers were studied. Peak concentration, 9.5mcg/ml in average, were obtained at 30 minutes to 1 hour after the administration.
2. The sensitivity of 31 strains of coagulase-positive staphylococci to aminocyclohexyl penicillin was studied with plate dilution method. The distribution of minimum inhibitory concentration was as follows: 16% at 0.8 mcg/ml, 6% at 1.56mcg/ml, 3% at 3.13 mcg/ml, 32% at 6.25mcg/ml, 23% at 12.5mcg/ml and 19% at 25mcg/ml. Thus, 58% was inhibited by the concentration lower than attainable peak blood level. No complete cross resistance with ampicillin was observed.
3. The clinical effect of the antibiotic was examined in 7 cases, and good effect was obtained in 4. Four staphylococci isolated from the patients showed resistance to ampicillin.
4. No remarkable side effects were seen except headache in a case, but it is uncertain that the complaint was due to the drug.
