title: Detection and pharmacokinetics of salbutamol in thoroughbred racehorses following inhaled administration.
abstract: Salbutamol sulphate (Ventolin Evohaler) was administrated via the inhalation route to six horses at a dose of 0.5 mg every 4 h during the day for 2 days (total dose 4 mg). Urine and blood samples were taken up to 92 h postadministration. Hydrolyzed plasma and urine were extracted using solid phase extraction (SPE). A sensitive tandem mass spectrometric method was developed in this study, achieving a lower limit of quantification (LLOQ) for salbutamol of 10 pg/mL in plasma and urine. The parent drug was identified using UPLC-MS/MS. Most of the determined salbutamol plasma concentrations, post last administration, lie below the LLOQ of the method and so cannot be used for plasma PK analysis. Urine PK analysis suggests a half-life consistent with the pharmacological effect duration. An estimate of the urine average concentration at steady-state was collected by averaging the concentration measurements in the dosing period from -12 to 0 h relative to the last administered dose. The value was averaged across the six horses and used to estimate an effective urine concentration as a marker of effective lung concentration. The value estimated was 9.6 ng/mL and from this a number of detection times were calculated using a range of safety factors.
authors.affiliation: LGC, Fordham, Cambridgeshire, UK.
authors.forename: M E
authors.initials: ME
authors.lastname: Wieder
authors.forename: S W
authors.initials: SW
authors.lastname: Paine
authors.forename: P R
authors.initials: PR
authors.lastname: Hincks
authors.forename: C M
authors.initials: CM
authors.lastname: Pearce
authors.forename: J
authors.initials: J
authors.lastname: Scarth
authors.forename: L
authors.initials: L
authors.lastname: Hillyer
mesh_terms: D000280:Administration, Inhalation; D000420:Albuterol / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D000818:Animals; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D006736:Horses / Q000378:metabolism* / Q000652:urine; D008297:Male
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol