1977 Volume 25 Issue 1 Pages 155-162
Pivmecillinam was clinically studied to give the following results.
1. Antibacterial activities
In vitro antibacterial activities of mecillinam which is produced by hydrolysis of pivmecillinam were influenced by inoculum sizes. With inoculum size of 108 cells/ml, a peak MIC distribution of E. coli was at 12.5 μg/ml, and that of Klebsiella and Proteus mirabilis was at 100 μg/ml. While, with inoculum size of 106 cells/ml, mecillinam showed MIC of 0.39-0.78 μg/ml against these organisms.
2. Absorption and excretion
Three fasting healthy adults were given pivmecillinam in a 50mg oral dose. Peak serum Mecillinam level (1.15-1.56 μg/ml.) appeared one hour after administration. The level rapidly decreased with half-life of about 1 hour. Mean 6-hour urinary recovery was 49.1%. While, in a patient with chronic renal insufficiency (creatinine clearance : 14.0ml/min), high serum mecillinam level was maintained for a comparatively long time (hal-lfife in serum : 2.26 hours) and 6-hour urinary recovery was only 12.5%.
3. Clinical responses
One case with cystitis, 1 case with acute cystitis, 1 case with chronic cystitis and 2 cases with acute pyelonephritis were given pivmecillinam at daily doses of 400mg for 10-31 days. Of them, the responses were good in 4 cases and poor in 1 case. Against the Klebsiella pneumoniae which was a causative organism of the poor clinical response, mecillinam showed MIC of 6.25 μg/ml at the beginning of treatment. However, after 10-day treatment with daily doses of 400mg, 100 μg/ml of mecillinam did not inhibit the Klebsiella isolated from the patient. No side effects were observed.
