Animal experiment:

Rats: On the day of the experiment the animal is given an intravenous bolus injection of 200 mg/kg as pure free acid sodium flucloxacillin (dose volume: 1 mL sterile water per kg) and then return to the metabolism cage. Urine is collected directly into individual CO2 cooled containers for a period of 24 h before dosing and then at frequent intervals after dosing[3].

Flucloxacillin sodium is a highly active antibiotic against Gram-positive and Gram-negative bacteria.

The serum elimination half-life of flucloxacillin is 1.31-1.39 hours, and six hours after administration of a single 250 mg dose the serum concentration of flucloxacillin is 0.46 micrograms/mL[1]. Oral flucloxacillin does not affect sweat electrolytes and is not a contraindication to sweat testing[2]. Flucloxacillin has been reported to be metabolized in man to the penicilloic acid, the antibacterially active 5'-hydroxymethyl derivative and the penicilloic acid of the 5'-hydroxymethyl derivative. The metabolism of flucloxacillin in the rat is similar[3].

[1]. Paton DM, et al. Bioavailability and half-life of two preparations of flucloxacillin. N Z Med J. 1982 Nov 10;95(719):766-8. [2]. Williams J, et al.Sweat tests and flucloxacillin. Arch Dis Child. 1988 Jul;63(7):847-8. [3]. Everett JR, et al. 19F NMR spectroscopy study of the metabolites of flucloxacillin in rat urine. J Pharm Pharmacol. 1985 Dec;37(12):869-73.