Liquid chromatographic determination of minocycline in brain-to-plasma distribution studies in the rat.
An isocratic reversed-phase high-performance liquid chromatographic procedure was developed for the determination of minocycline in rat plasma and brain and applied to brain-to-blood (plasma) distribution studies. The procedure is based on isolation of the compound and the internal standard (either demeclocycline or tetracycline may be used) from plasma and brain constituents using the Oasis HLB cartridge, with satisfactory recovery and specificity, and separation on a Symmetry Shield RP8 (15 cm x 4.6 mm, 3.5 microm) column coupled with a UV detector set at 350 nm. The assay was linear over a wide range, with a lower limit of quantification of 50 ng ml(-1) or g(-1), using 0.2 ml of plasma and about 200 mg of brain tissue. Precision and accuracy were acceptable. In the rat minocycline crossed the blood-brain barrier slowly, achieving mean brain concentrations between 30 and 40% of the equivalent systemic exposure, regardless of the dose and route of administration.
Colovic
Milena
M
Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157 Milan, Italy.
Caccia
Silvio
S
D000818:Animals; D000900:Anti-Bacterial Agents / Q000097:blood / Q000493:pharmacokinetics*; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008297:Male; D008911:Minocycline / Q000097:blood / Q000493:pharmacokinetics*; D051381:Rats; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
D000900:Anti-Bacterial Agents; D008911:Minocycline