Studies on mechanism of vitamin K defficiency associated with antibiotic therapy

Vitamin K (VK) deficiency associated with antibiotic therapy was been attracting the attention. It is not clearly understood it is attributable to suppression of intestinal bacterial flora or inhibition of VK reductase by N-methyl-tetrazole-thiol (NMTT) side chain in the structure of some antibiotics. In order to clarify the cause, coagulation studies were carried out with patients who had been on antibiotic therapy. The results were as follows;1. Thrombotest (ThT) and hepaplastintest (HpT) values of patients with starvation were lower than those of patients without starvation.2. ThT and HpT values of patients treated with antibiotics including NMTT side chain were significantly lower than those of patients with antibiotics excluding NMTT.3. No significant difference in ThT and HpT values was observed between male and female patients treated antibiotics. However, all patients with severely decreased values of ThT and HPT were male.4. No significant difference in ThT and HPT values was observed between the periods of antibiotic therapy less than 7 days and more than 8 days.5. In patients treated with antibiotics including NMTT side chain, concentrations of VK families in liver were decreased compared with those in normal liver.6. After intravenous administration of MK-4 into patients who had been on therapy of antibiotics including NMTT side chain for more than 5 days, neither MK-4 nor the epoxiade detected in their sera.