[Fosfomycin-trometamol (monuril): pharmacokinetics and food-drug interactions]

A new water soluble monobasic salt of fosfomycin with trometamol has been recently developed for oral administration. The objective of this study was to evaluate the pharmacokinetics of trometamol-fosfomycin (monuril) in serum and urine in 10 healthy volunteers after oral administration of one single dose (50 mg/kg). In the volunteers, the concentrations of fosfomycin were measured before and after food absorption in serum and urine samples taken at t = 0, 2, 4, 6, 8, 24 h after the dose (plus 0.5 hand 1 h for serum samples). The measurement of fosfomycin levels was carried out by means of a microbiological procedure using Proteus mirabilis ATCC 21100 as test organism. The results indicated at 2 h after oral administration of the antibiotic, a mean serum peak level of 21.04 +/- 6.88 micrograms/ml. The urine concentrations reached 2,000 to 2,750 micrograms/ml at the 2nd hour, with high levels (mean: 1,876 +/- 709 micrograms/ml) till the 8th hour and persistence of noticeable concentrations at 24 h (334 +/- 210 micrograms/ml). The influence of food absorption, even variable, decreased significantly the rate of absorption with lower serum and urine levels. Taking into account this factor influencing the bioavailability and the distribution of the drug, the results of the study confirm that a high proportion of the oral dose of trometamine salt of fosfomycin is well absorbed; the extremely high urinary recovery of the drug could certainly allow short course therapy in the treatment of uncomplicated urinary tract infection.