Clinical investigation on doxycycline, a new long acting TC derivative, has brought forth the following results:
1. Recent clinical isolates of coagulase-positive staphylococci and pathogenic coli-form bacilli showed higher sensitivity to this new derivative than to the known antibiotics of TC series.
2. Blood concentration in children given 4. 0 mg/kg reached its maximum at 6 hours after the administration and remained at a measurable level as long as 20 hours.
3. Chemotherapy of 61 children with various infections except infantile diarrhoea with this antibiotic alone produced significant effect in 90% of the treated patients, especially in acute respiratory infection. The effect on 22 patients of infantile diarrhoea was somewhat less pronounced than on other infections, the effective rate being 68%.
4. The administration schedule in the present study consisted of a single first dose of 4∼7 mg/kg on the first day and subsequent daily dose, given once a day, of about one-half of the first dos.
5. Vomiting in only one case was seen in the treatment of 61 patients except infantile diarrhoea, while adverse effects of vomiting and nausea were seen in the treatment of 22 cases of infantile diarrhoea.