Background. The study was aimed to the increase the effectiveness of β-lactam antibiotics in pregnant women with obesity by optimiz- ing the intermittent regimen of their administration.
Objective. Evaluation of the degree of penetration into the myometrium of cephalosporins and aminopenicillins, recommended in abdominal delivery for antibiotic prophylaxis of endometritis, with a «single dose» in the standard bolus regimen of their administration and in an alternative regimen in the form of an prolonged infusion to optimize the intermittent regimen of administration in patients with grade I obesity.
Methods. The study involved 58 pregnant women with grade I obesity, delivered by caesarean section (CS) in a planned manner. For perioperative antibiotic prophylaxis (AP), cefazolin, cefuroxime, amoxicillin and ampicillin were used in the bolus regimen and as a pro- longed perioperative infusion. The quantitative content of the investigated β-lactam antibiotics in the myometrium was studied using chromatographic and spectrophotometric methods.
Results. The routine regimen of AP in CS – intravenous bolus administration of cephalosporins and aminopenicillins 30 minutes before the operation at the recommended dosages – created an effective bactericidal concentration in the myometrium only with the use of cefuroxime.
Conclusion. The prolonged perioperative infusion creates higher tissue antibiotic concentrations in the myometrium, providing more reliable antimicrobial protection of the operating wound on the uterus.

Keywords: penetration into the myometrium, caesarean section, penicillins, cephalosporins, antibiotic prophylaxis, pharmacokinetics, obesity